DRI STANDARD OPERATING PROCEDURE 

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Date: July 2008 

Title: DRI Model 2001 Thermal/Optical Carbon Analysis Number: 2-216r2 

 (TOR/TOT) of Aerosol Filter Samples - Method IMPROVE_A Revision: 2 

TABLE OF CONTENTS 

Page

1 INTRODUCTION....................................................................................................... 7 

1.1 Purpose of Procedure ...................................................................................................... 7 

1.2 Measurement Principle ................................................................................................... 7 

1.3 Measurement Interferences and Their Minimization...................................................... 8 

1.4 Ranges and Typical Values of Measurements................................................................ 9 

1.5 Typical Lower Quantifiable Limits, Precision, and Accuracy ..................................... 10 

1.6 Personnel Responsibilities ............................................................................................ 11 

1.7 Definitions for IMPROVE_A Thermal Protocol for Carbon Analysis ........................ 11 

1.8 Related Procedures ....................................................................................................... 14

2 APPARATUS, INSTRUMENTATION, REAGENTS, AND FORMS.................... 15 

2.1 Apparatus and Instrumentation..................................................................................... 15 

2.1.1 Description................................................................................................................ 15 

2.1.2 Instrument Characterization...................................................................................... 21 

2.1.3 Maintenance.............................................................................................................. 22 

2.2 Spare Parts List ............................................................................................................. 22 

2.3 Reagents........................................................................................................................ 25 

2.3.1 Chemicals.................................................................................................................. 25 

2.3.2 Gases......................................................................................................................... 25 

2.4 Forms, Paperwork, and Logbook.................................................................................. 26 

3 CALIBRATION PROCEDURES AND STANDARDS .......................................... 29 

3.1 Instrument Calibration .................................................................................................. 29 

3.1.1 End-of-Run Calibrations (Description) .................................................................... 29 

3.1.2 Routine Calibrations (Description)........................................................................... 29 

3.1.2.1 Automated Routine Calibration (Description & Instructions).......................... 29 

3.1.2.2 Manual Routine Calibration (Instructions)....................................................... 31 

3.1.3 Full Calibration (Description)................................................................................... 33 

3.1.3.1 Preparation, Ranges and Traceability of Standards.......................................... 34 

3.1.3.2 Calculating Calibration Slope........................................................................... 35 

3.1.3.3 Typical Accuracy of Calibration Standards...................................................... 35 

3.1.3.4 Data Treatment for Calibration Data ................................................................ 38 

3.1.3.5 Calculations ...................................................................................................... 39 

3.2 Instrument Calibration Instructions .............................................................................. 39 

3.2.1 Full Gas Calibration.................................................................................................. 39 

3.2.2 Full Sucrose and KHP Calibrations .......................................................................... 41 

3.2.3 Temperature Calibrations ......................................................................................... 42 

3.2.3.1 Temperature Indicators ..................................................................................... 42 
DRI STANDARD OPERATING PROCEDURE 

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Title: DRI Model 2001 Thermal/Optical Carbon Analysis Number: 2-216r2 

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TABLE OF CONTENTS, continued 

Page

3.2.3.2 Analyzer Preparation ........................................................................................ 43 

3.2.3.3 Standard Preparation......................................................................................... 43 

3.2.3.4 Temperature Program ....................................................................................... 43 

4 PROCEDURES ......................................................................................................... 47 

4.1 Detailed Procedures ...................................................................................................... 47

4.1.1 Analyzer Start-Up ..................................................................................................... 47 

4.1.2 Leak Checks.............................................................................................................. 48 

4.1.2.1 Manual Leak Check .......................................................................................... 48 

4.1.3 Oven Bake................................................................................................................. 50 

4.1.3.1 Manual Oven Bake ........................................................................................... 50 

4.1.3.2 Automatic Oven Bake....................................................................................... 50 

4.1.4 OC/EC Analysis........................................................................................................ 52 

4.1.4.1 Analysis Preparation ......................................................................................... 52 

4.1.4.2 Loading the Filter Punch................................................................................... 53 

4.1.4.3 Post-Analysis .................................................................................................... 53 

4.1.5 Special Analyses ....................................................................................................... 58

4.1.5.1 System Blanks................................................................................................... 58 

4.1.5.2 Carbonate Analysis ........................................................................................... 60 

4.1.6 Analyzer Shut-Down ................................................................................................ 60 

4.2 Abbreviated Procedures................................................................................................ 61 

4.2.1 Analyzer Start-Up ..................................................................................................... 61 

4.2.2 Leak Checks and Oven Baking................................................................................. 62 

4.2.3 OC/EC Analysis........................................................................................................ 63 

4.2.3.1 Analysis Preparation ......................................................................................... 63 

4.2.3.2 Loading the Filter Punch................................................................................... 63 

4.2.3.3 Post Analysis..................................................................................................... 64 

4.2.4 Special Analyses ....................................................................................................... 64

4.2.4.1 System Blanks................................................................................................... 64 

4.2.4.2 Carbonate Analysis ........................................................................................... 64 

4.2.5 Analyzer Shut-Down: ............................................................................................... 65 

5 QUANTIFICATION ................................................................................................. 66 

5.1 Measurement Calculations............................................................................................ 66 

5.2 Precision (Uncertainty) Calculations............................................................................ 66 

6 QUALITY CONTROL ............................................................................................. 67 

6.1 Performance Testing ..................................................................................................... 67 

6.2 Reproducibility Testing ................................................................................................ 68 

6.3 Control Charts and Procedures ..................................................................................... 68 

6.4 Data Validation ............................................................................................................. 69 
DRI STANDARD OPERATING PROCEDURE 

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Date: July 2008 

Title: DRI Model 2001 Thermal/Optical Carbon Analysis Number: 2-216r2 

 (TOR/TOT) of Aerosol Filter Samples - Method IMPROVE_A Revision: 2 

TABLE OF CONTENTS, continued 

Page

6.4.1 Analysis Flags........................................................................................................... 69 

6.4.2 Daily Validation........................................................................................................ 70 

6.4.2.1 Validation of Final Data File ............................................................................ 74 

7 REFERENCES.......................................................................................................... 81 

8 CHANGE DOCUMENTATION .............................................................................. 83 

APPENDIX A: Abbreviations and Acronyms............................................................................. 84 
DRI STANDARD OPERATING PROCEDURE 

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LIST OF TABLES 

Page

Table 6-1. Common DRI Analysis Flags..................................................................................... 70 

Table 6-2. DRI Carbon Analysis Operator Temporary Data Validation Flags. .......................... 78 

Table 6-3. DRI Carbon Analysis Validation Comments ............................................................. 79 
DRI STANDARD OPERATING PROCEDURE 

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Title: DRI Model 2001 Thermal/Optical Carbon Analysis Number: 2-216r2 

 (TOR/TOT) of Aerosol Filter Samples - Method IMPROVE_A Revision: 2 

LIST OF FIGURES 

Page

Figure 2-1. DRI Model 2001 Thermal/Optical Carbon Analyzer. .............................................. 16 

Figure 2-2. DRI Model 2001 Thermal/Optical Carbon Analyzer Schematic Diagram............... 17 

Figure 2-3. DRI Model 2001 Thermal/Optical Carbon Analyzer Sealing Diagram. .................. 18 

Figure 2-4. DRI Model 2001 Thermal/Optical Carbon Analyzer Gas Flow Schematic. ............ 19 

Figure 2-5. DRI Model 2001 Thermal/Optical Carbon Analyzer Combustion Oven. ................ 20 

Figure 2-6. DRI Carbon Analysis Logbook Format. ................................................................... 23 

Figure 2-7. DRI Carbon Sample Analysis Run List. ................................................................... 27 

Figure 2-8. DRI Carbon Daily Analyzer Checklist. .................................................................... 28 

Figure 3-1. Calibration thermogram from the cmdAutoCalibCheck command of the DRI Model 

2001 Thermal/Optical Carbon Analyzer. .................................................................. 30 

Figure 3-2. Setup Screen for Manual Gas Calibration for the DRI Model 2001 Thermal/Optical 

Carbon Analysis Program.......................................................................................... 32 

Figure 3-3. The Analysis Screen during Manual Gas Calibration for DRI Model 2001 

Thermal/Optical Carbon Analysis Program. ............................................................. 33 

Figure 3-4. Example of calibration summary worksheet used to determine calibration slope.... 36 

Figure 3-5. Example DRI Carbon Analyzer Calibration Curves................................................. 37 

Figure 3-6. Temperature ramping with a Tempilaqo G temperature indicator rated at 184 °C. 

Also shown are reflectance and transmittance of the temperature indicator (if 

available). The vertical dashed line indicates the achievement of the rated 

temperature................................................................................................................ 45 

Figure 3-7. Reflectance and transmittance measurements and their first and second derivatives 

over time with a Tempilaqo G temperature indicator rated at 184 °C (Figure 3-6). 

The vertical dashed line indicates the achievement of the rated target temperature. 46 

Figure 4-1. DRI Welcome Screen................................................................................................ 49 

Figure 4-2a. Setup Screen for the DRI Model 2001 Thermal/Optical Carbon Analysis Program.. 

 ................................................................................................................................... 54 

Figure 4-2b. The Analysis Screen during Sample Analysis for DRI Model 2001 Thermal/Optical 

Carbon Analysis Program.......................................................................................... 55 

Figure 4-3. Tabular Printout from DRI Model 2001 Thermal/Optical Carbon Analysis Program. 

 ................................................................................................................................... 56 

Figure 4-4. Graphical output (thermogram) from the DRI Model 2001 Thermal/Optical Analysis 

Program. .................................................................................................................... 59 

Figure 6-1. Example of carbon analyzer replicate checklist........................................................ 69 
DRI STANDARD OPERATING PROCEDURE 

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Date: July 2008 

Title: DRI Model 2001 Thermal/Optical Carbon Analysis Number: 2-216r2 

 (TOR/TOT) of Aerosol Filter Samples - Method IMPROVE_A Revision: 2 

1 INTRODUCTION 

1.1 Purpose of Procedure 

This standard operating procedure is intended to: 

• Provide a basic understanding of the principles of carbon analysis and carbon analyzer 

operation; 

• Describe routine determination of organic, elemental, and carbonate carbon from 

ambient- and source-filter samples using the DRI Model 2001 Thermal/Optical Carbon 

Analyzer; and 

• Detail the concerns and procedures which will ensure a state-of-the-art carbon analysis 

measurement process. 

This procedure will be followed by all analysts at the Environmental Analysis Facility (EAF) of 

the Division of Atmospheric Sciences (DAS) at the Desert Research Institute (DRI), Reno, 

Nevada, USA. 

1.2 Measurement Principle 

The operation of the DRI Model 2001 Thermal/Optical Carbon Analyzer is based on the 

preferential oxidation of organic and elemental carbon (OC and EC) compounds at different 

temperatures. Its function relies on the fact that organic compounds can be volatilized from the 

sample deposit in a non-oxidizing helium (He) atmosphere, while EC must be combusted with an 

oxidizer. The analyzer operates by: 1) liberating carbon compounds under different temperature 

and oxidation environments from a small sample punch taken from a quartz-fiber filter; 2) 

converting these compounds to carbon dioxide (CO2) by passing the volatilized compounds 

through an oxidizer (heated manganese dioxide, MnO2); 3) reducing CO2 to methane (CH4) by 

passing the flow through a methanator (hydrogen-enriched nickel catalyst); and 4) quantifying 

CH4 equivalents with a flame ionization detector (FID). 

The principal function of the optical (laser reflectance and transmittance) component of the 

analyzer is to correct for pyrolysis charring of OC compounds into EC. Without this correction, 

the OC fraction of the sample might be underestimated and the EC fraction might include some 

pyrolyzed OC. The correction for pyrolysis is made by continuously monitoring the filter 

reflectance and/or transmittance (via a He-neon laser and a photo-detector) throughout an 

analysis cycle. The reflectance and transmittance, largely dominated by the presence of light 

absorbing EC, decrease as pyrolysis takes place and increase as light-absorbing carbon is 

liberated during the latter part of the analysis. By monitoring the reflectance and transmittance, 
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the portion of the EC peak corresponding to pyrolyzed OC can be accurately assigned to the OC 

fraction. The correction for the charring conversion of OC to EC is essential for a less-biased 

measurement of carbon fractions (Johnson et al., 1981). The Thermal Optical Reflectance (TOR) 

and Thermal Optical Transmittance (TOT) charring corrections are not necessarily the same, 

owing to charring of organic vapors adsorbed within the quartz fiber filter (Chow et al., 2004; 

Chen et al., 2004). Charring by both reflectance and transmittance is reported in order to 

determine the differences in OC and EC. 

Carbonate carbon can be determined by measuring the CO2 evolved upon acidification of the 

sample punch before the normal carbon analysis procedure. 

Seven temperature fractions, as well as the TOR and TOT charring correction, are individually 

quantified and reported when the IMPROVE_A (Chow et al., 1993, 2001, 2007) temperature 

protocol is applied. Values routinely reported include total OC, total EC, total carbon (TC, sum 

of total OC and total EC), and pyrolyzed carbon, monitored by both reflectance (OPR) and 

transmittance (OPT). Depending on the thermal/optical protocol applied for quantification, 

thermally-derived subfractions of OC and EC, and of carbonate carbon, are reported. 

1.3 Measurement Interferences and Their Minimization 

Precision of thermal/optical carbon analysis depends on the sample temperature in the analysis. 

Therefore, the correlation between sample temperature and thermocouple temperature should be 

established and calibrated semiannually so that the thermal protocol can truly reflect the sample 

temperature during the analysis (Chow et al., 2005). The thermocouple’s position in relation to 

the sample, as well as the different heating properties of the thermocouple and the sample, 

govern the temperature offset. This relationship must be maintained for the temperature 

calibration to hold. The analyzer must not be used if the sample boat shifts position or becomes 

loose in its holder. 

Carbonate carbon may bias carbon concentrations if it constitutes more than 5% of TC in the 

ambient or source sample. Carbonate carbon may be measured as either OC or EC depending on 

the chemical nature of the carbonates and their thermal decomposition temperatures. Acid 

pretreatment of filter samples can eliminate the carbonate interference (Novakov, 1981, 1982; 

Rosen et al., 1982). Carbonate carbon has been found at only a few IMPROVE monitoring sites, 

and the levels at these sites do not appreciably bias OC and EC concentrations (Chow and 

Watson, 2002). 

The presence of certain minerals in some soils can affect the laser correction for pyrolysis. 

These minerals change color as the sample punch is heated, generally resulting in a darker 

sample. For samples which contain large fractions of resuspended soils, the split between OC 

and EC should be examined manually. 
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 (TOR/TOT) of Aerosol Filter Samples - Method IMPROVE_A Revision: 2 

Some minerals, again predominantly in soil samples or soil-dominated samples, may affect the 

laser correction by temporarily changing color or changing the surface texture of the deposit 

residue. Unlike the effect described above, these changes are reversible and temperaturedependent. 

Some colored organic compounds can affect the laser correction, causing increased reflectance 

or decreased transmittance as these compounds are removed. This effect is ascertained by 

examining the laser response during the organic portion of the analysis. The split between OC 

and EC should be examined manually if the effect is large. 

The presence of certain elements (Na, K, V, Cr, Mn, Co, Ni, Cu, and Pb), existing either as 

contaminants on the filters (e.g., glass-fiber filters or borosilicate binders), or as part of the 

deposit material, has been shown to catalyze the removal of EC at lower temperatures (Lin and 

Friedlander, 1988). Such catalysis would affect the distribution of carbon peaks during the 

analysis. 

Water vapor (either contained in the deposit or remaining after acidification of the sample 

punch), if present in sufficient levels, can shift the FID baseline. To eliminate this effect, allow 

the sample punch to dry in the analyzer by passing carrier gases over it before starting the 

analysis. 

1.4 Ranges and Typical Values of Measurements 

Source-dominated or heavily polluted environments, which would normally have carbon 

concentrations above the working range of the carbon analyzer, may be sampled and analyzed 

within the range of the carbon analyzer by increasing the filter deposit area or by decreasing the 

sampling flow in the field equipment. Deposits that are very black, such that the initial 

reflectance is close to zero, provide a less precise OC/EC split, because additional blackening 

due to OC charring is not quantified by the reflected light. 

The carbon analyzer can effectively measure between 0.05 and 750 μg carbon/cm2

 for a typical 

punch size of 0.5 cm2

. The upper limit depends on the particular compounds on the filter and the 

temperatures at which they evolve. This upper limit may be extended by reducing the punch size 

or extending analysis times at lower temperature plateaus to avoid an over-range FID signal. 

Typical carbon values range between 10 and 100 μg C/cm2

 for 24-hour ambient samples. The 

distribution between OC and EC depends on the particulate source types, ranging from 

negligible levels of EC (e.g., secondary sulfate) to 80% or more EC (e.g., diesel exhaust). 
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1.5 Typical Lower Quantifiable Limits, Precision, and Accuracy 

The lower quantifiable limits (LQLs) of thermal carbon methods depend on the variable carbon 

content of the field blank quartz-fiber filters, as well as the analysis method. For lower LQLs, 

the unexposed filters should be pre-fired in an oven at high temperatures for several hours to 

remove any residual carbon contamination (Fung, 1986; Huntzicker, 1986; Rau, 1986; DRI, 

2004). All quartz-fiber filters originating from DRI are pre-inspected for defects such as 

pinholes or tears. They are then pre-fired for a minimum of four hours at 900 °C; 2% are 

acceptance-tested for blank levels before use in the IMPROVE network. Batches containing 

filters that fail to pass the preset acceptance levels (1.5 μg OC, 0.5 μg EC, and 2.0 μg TC per 

cm

2

) are not used for sample collection. Average pre-fired blank levels are 0.15 ± 0.15 μg 

OC/cm2

, 0.00 ± 0.02 μg EC/cm2, and 0.15 ± 0.15 μg TC/cm2. Because pre-fired filters can 

adsorb organic vapors during shipping, storage, and exposure in the sampler, the analysis LQL 

on a particular set of filters depends on the number of field blanks analyzed and the variability in 

the results from those blanks. LQLs may vary between projects, depending on the sample and 

sample handling. To reduce the risk of contamination during shipping and storage, samples are 

vacuum-sealed and stored at < 4 °C. The vacuum sealing results in minimum air space 

surrounding the filter to ensure the blank levels are kept low. 

The minimum detection limits (MDLs) represent the best sensitivity of the method and should 

always be less than or equal to the LQLs. The IMPROVE_A protocol is based on the analyses of 

approximately 800 pre-fired laboratory blank quartz-fiber filters analyzed between January 2006 

and May 2007. The MDL is defined as three times the standard deviation of their measured 

results. They are: 

 total OC 0.39 μg/cm2

 total EC 0.01 μg/cm2

 TC 0.42 μg/cm2

Acid-evolved carbonate levels in pre-fired quartz-fiber filters have been shown to be quite 

variable (0.0-1.0 μg/cm2

) over time. The reaction of ambient CO2 with alkaline sites on the 

quartz fibers may be the cause of such variable blank levels. Acceptance testing for carbonate is 

only performed for special projects that require carbonate analysis. 

The precision of carbon analysis has been reported to range from 2 – 4% (Johnson, 1981). For 

analysis of actual ambient and source filters, homogeneity of the deposit is most important for 

reproducible results. This can be demonstrated by the precision of CH4 standard injection (by 

the Carle valve), which is always better than sample analysis. For homogeneous deposits 

containing > 5 μg/cm2 (~10 times MDL) TC, precision is generally 10% or better; for 

inhomogeneous deposits replicates may differ by as much as 30%. The precision of carbonate 

concentrations is approximately ±10%. 
DRI STANDARD OPERATING PROCEDURE 

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The precision of the laser-dependent split between OC and EC fractions depends upon how 

rapidly the laser is increasing at the time of the split and whether or not the split falls in the 

middle of a large carbon peak. Typically, relative laser split times are reproducible within 10 

seconds and deviations in calculated splits are < 5% of the total measured carbon. If the laser 

split is greater than 10 seconds and deviations are > 5%, the analysis is investigated for sample 

anomalies (e.g., inhomogeneous loading, low loading, etc.), instrument laser noise, or O2

contamination. 

The accuracy of TOR for TC, determined by analyzing a known amount of carbon, is between 2-

6% (Rau, 1986). Precision of the OC/EC split is between 5% and 10%. This precision is also 

influenced by the filter loading and source type. Most of the uncertainty for low concentration 

samples is from the standard deviation of the field blanks or backup filters. Uncertainty is not 

determined by precision at low levels. 

Since the MDL is always less than or equal to the LQL, and the LQL is included in the μg/m3

uncertainty when the blank (or backup filter, if available) is subtracted, the MDL has no effect 

on the uncertainty of ambient concentrations. The MDL is most useful to match flow rates and 

sample duration with expected carbon levels when planning field studies or sampling networks. 

1.6 Personnel Responsibilities 

Before performing carbon analysis, all analysts in the laboratory should read and understand the 

entire Standard Operating Procedure (SOP), including routine system calibration, actual analysis, 

and immediate review of the data as it is produced, and how to correct system problems. 

The responsibilities of the laboratory manager or supervisor are: to ensure that the carbon 

analyses procedures are properly followed; to examine and document all replicate, standard, and 

blank performance test data; to designate samples for reanalysis; to arrange for maintenance and 

repair of instruments; to verify an adequate quantity of supplies and gases are in stock to ensure 

uninterrupted analysis; and to deliver the analysis results in database format to the project 

manager within the specified time period. 

The quality assurance (QA) officer of DRI's DAS is responsible for determining the extent and 

methods of quality assurance to be applied to each project, to estimate the level of effort 

involved in this quality assurance, to periodically review and assess quality assurance and 

quality control data, to update this procedure periodically, and to ascertain that these tasks are 

budgeted and carried out as part of the performance on each contract. 

1.7 Definitions for IMPROVE_A Thermal Protocol for Carbon Analysis 

The following terms are used in this document: 
DRI STANDARD OPERATING PROCEDURE 

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 (TOR/TOT) of Aerosol Filter Samples - Method IMPROVE_A Revision: 2 

IMPROVE_A 

Thermal Protocol:

A thermal protocol used in carbon analyzers to quantify carbon 

fractions evolved at different temperature plateaus and atmospheres. 

The IMPROVE_A thermal protocol derives from the Interagency 

Monitoring of Protected Visual Environments (IMPROVE) thermal 

protocol initiated in 1987 (Chow et al., 2005, 2007). 

Calibration Injection: The injection of calibration gases, either CO2 or CH4, into the 

sample stream at the beginning and end of each work day to check 

instrument performance. 

Calibration Peak: The FID peak resulting from the automatic injection of methane 

calibration gas (CH4/He) at the end of each analysis run for each 

sample. All integrated peak areas are divided by the calibration peak 

area and multiplied by an instrument-specific calibration factor to 

obtain μg carbon per sample punch. 

FID Split Time: The time at which the laser split occurs plus the transit time required 

for thermally evolved carbon to travel from the sample punch to the 

FID. 

Elemental Carbon 

(EC):

Carbon evolved from the filter punch in a 98% He/2% O2

atmosphere at 580, 740, and 840 °C minus any pyrolyzed OC. 

EC1: Carbon evolved from the filter punch in a 98% He/2% O2 

atmosphere at 580 °C. 

EC2: Carbon evolved from the filter punch in a 98% He/2% O2

atmosphere from 580 to 740 °C. 

EC3: Carbon evolved from the filter punch in a 98% He/2% O2

atmosphere from 740 to 840 °C. 

High Temperature OC: Carbon evolved from the filter punch in a He-only atmosphere at 

280, 480, and 580 °C plus pyrolyzed organic carbon. This is OC 

minus the first OC peak (OC1). 

High Temperature EC: Carbon evolved from the filter punch in a 98% He/2% O2

atmosphere at 740 and 840 °C minus any pyrolyzed organic carbon 

present in these two peaks. This is EC minus the first EC peak 

(EC1). 
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Laser Split: The separation between OC and EC, which depends on the lasermeasured reflectance and/or transmittance of the filter punch 

returning to its initial value. At this point all pyrolyzed OC has been 

removed and EC is beginning to evolve. 

Lower Split Time: The time at which the laser-measured reflectance and/or 

transmittance of the filter punch reaches its initial value minus the 

precision of the laser signal (currently defined as 10 counts). 

Organic Carbon (OC): Carbon evolved from the filter punch in a He-only (> 99.999%) 

atmosphere at 140, 280, 480 and 580 °C plus pyrolyzed organic 

carbon. This is the same as Volatile Organic Carbon (VOC) plus 

high-temperature OC. 

OC1: Carbon evolved from the filter punch in a He-only (> 99.999%) 

atmosphere from ambient (~25 °C) to 140 °C. 

OC2: Carbon evolved from the filter punch in a He-only (> 99.999%) 

atmosphere from 140 to 280 °C. 

OC3: Carbon evolved from the filter punch in a He-only (> 99.999%) 

atmosphere from 280 to 480 °C. 

OC4: Carbon evolved from the filter punch in a He-only (> 99.999%) 

atmosphere from 480 to 580 °C. 

OP: The carbon evolved from the time that the carrier gas flow is 

changed from He to 98% He/2% O2 at 580 °C to the time that the 

laser-measured filter reflectance (OPR) or transmittance (OPT) 

reaches its initial value. A negative sign is assigned if the laser split 

occurs before the introduction of O2. 

Pyrolysis: The conversion of OC compounds to EC due to thermal 

decomposition; this may be envisioned as "charring" during the 

organic portion of the analysis. 

Regular Split Time: The time at which the laser-measured reflectance and/or 

transmittance of the filter punch reaches its initial value. 

Total Carbon (TC): All carbon evolved from the filter punch between ambient and 840 

°C under He and 98% He /2% O2 atmospheres. 

Upper Split Time: The time at which the laser-measured reflectance and/or 
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transmittance of the filter punch reaches its initial value plus the 

precision of the laser signal (currently defined as 10 counts). 

1.8 Related Procedures 

Standard Operating Procedures (SOPs), related carbon analysis activities, and other manuals that 

should be reviewed in conjunction with this document are: 

 DRI SOP #6-001 Shipping and Mailing SOPs. 

 DRI SOP #6-009 Field and Laboratory Safety SOPs. 

 DRI SOP #2-106r6 Pre-Firing of Quartz Filters for Carbon Analysis. 

 The DRI Model 2001 Thermal/Optical Carbon Analyzer Owner's Manual, revised 3/2004 

(Atmoslytic, Calabasas, CA). 

 The DRI Model 2001 Thermal/Optical Carbon Analyzer Installation, Operation and 

Troubleshooting Manual, revised 12/2004 (Atmoslytic, Calabasas, CA).
DRI STANDARD OPERATING PROCEDURE 

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2 APPARATUS, INSTRUMENTATION, REAGENTS, AND FORMS 

2.1 Apparatus and Instrumentation 

2.1.1 Description 

The components of the DRI Model 2001 Thermal/Optical Carbon Analyzer are depicted in 

Figures 2-1 through 2-3; the complete gas flow schematic is shown in Figure 2-4. Other details 

of the configuration of the DRI Model 2001 Thermal/Optical Carbon Analyzer are referred to in 

the owner's manual. The programmable combustion oven is the heart of the carbon analyzer and 

includes loading, combustion, and oxidation zones in a single quartz "oven" as depicted in 

Figure 2-5. 

In addition to the DRI Model 2001 Thermal/Optical Carbon Analyzer, which is connected to a 

Pentium compatible computer, the following items are needed for routine carbon analysis: 

• Stainless steel punching tool: 5/16-inch diameter, 0.5 cm2

 nominal area for removing 

small sample punches from quartz filters. This punching tool must be kept clean and 

sharp. If the punching tool is resharpened, the punch area must be re-verified. 

Verification is performed by removing 10 punches from a 47-mm quartz-fiber filter 

(17.35 cm2); then calculating the punch area [= 17.35 cm2 x (initial filter weight minus 

the final weight after punches have been removed) / 10 times the initial filter weight)]. 

Further verification can be done by taking a precise measurement of the punching tool. 

• Syringes: Hamilton Gas-Tight 1000 and 2500 μl syringes for calibration injections; 25 μl 

syringe for carbonate analysis and for analyzer calibration. 

• Quartz filters: Pallflex® Tissuquartz, 2500 QAT-UP (Pall Life Sciences, Ann Arbor, MI) 

quartz-fiber filter or equivalent. 

• Flat-tip tweezers. 

• Flat glass plate. 

• Logbook/notebook. 

• Transparent tape. 

• KIMTECH Pure* CL4 Critical Task Wipes and large KimWipes (EX-L). 

• Small Styrofoam cooler or refrigerator. 
DRI STANDARD OPERATING PROCEDURE 

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Title: DRI Model 2001 Thermal/Optical Carbon Analysis Number: 2-216r2 

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Figure 2-1. DRI Model 2001 Thermal/Optical Carbon Analyzer. 
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Figure 2-2. DRI Model 2001 Thermal/Optical Carbon Analyzer Schematic Diagram. 

Temperature Monitor

He O2/He 

CH4/ 

He 

Valve 

Network 

Sample 

Port 

Sample 

Oven

Laser

Photo 

Detector 

Oxidation 

Oven Methanator FID

Microcomputer

FID Signal

Reflectance/ 

Transmittance 

Signal 

Oven 

Control

Gas Flow Control 

H2 Air

Disk 

Files Display Printer

Ga Control s Stream
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Figure 2-3. DRI Model 2001 Thermal/Optical Carbon Analyzer Sealing Diagram. 

Note: In the breech, there is a Teflon-reducing ferrule to seal the pushrod thermocouple, plus 

two O-rings to seal the breech against the inlet (coupler) connector and one Teflon fitting (See 

the Model 2001 Owner’s Manual for more details). 
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Figure 2-4. DRI Model 2001 Thermal/Optical Carbon Analyzer Gas Flow Schematic. 
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Figure 2-5. DRI Model 2001 Thermal/Optical Carbon Analyzer Combustion Oven. 
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• Blue ice (if using Styrofoam cooler). 

• Butane or piezoelectric lighter. 

• A copy of DRICarb.exe (the analysis program), Carbon.par (the analysis parameter file), 

and Microsoft Access to run CarbonNetWork.mdb.

2.1.2 Instrument Characterization 

The DRI Model 2001 Thermal/Optical Carbon Analyzer is program-driven. Data is stored 

automatically to the hard drive via a PC-compatible computer processor board. Response times 

and signal lag times are built into the parameter file that is loaded when the analysis program 

begins. The program is driven by the thermal protocol. For example, when using the 

IMPROVE_A protocol, the program will advance to the next temperature or carrier gas mixture 

once the FID signal returns to its baseline; i.e., after a minimum of 150 seconds at one analysis 

condition. A maximum time limit (580 seconds) per analysis condition is also established to 

prevent a slight baseline drift from holding the analyzer in one condition indefinitely. For the 

Chemical Speciation Network (CSN, including the Speciation Trends Network [STN]) thermal 

protocol, the program advances from one specified temperature plateau to the next temperature 

or carrier gas mixture when the specified analysis time is reached. Both methods require at least 

one ~0.5 cm2 punch per filter and do not require sample pre-treatment. The sample punch is 

destroyed by both methods. 

Operator concerns for correct routine operation of the instrument include the following (refer to 

Section 4 for more details): 

• Verify sample oven pressure reading and specified flow range in the front-panel flow 

meters. 

• DO NOT leave the room until the analysis begins. 

• Check the graphical printout after each analysis run to ensure that the: 1) FID, 2) 

temperature, and 3) laser signals are behaving as expected (Section 3.1). Report any 

anomalies to the lab supervisor immediately. 

• The quartz oven is susceptible to breakage. Care should be taken when handling and 

cleaning. 

• Be careful that no fiber from the KIMTECH wipe is left on the sample punch, tweezers, 

and/or glass plate. 
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2.1.3 Maintenance 

Regular maintenance for the analyzer involves daily checking of compressed gas supplies, 

cleaning the punching tool and tweezers between each sample with dry KIMTECH wipes, 

ensuring that the lab is clean, and backing up data files to disc on a daily basis (unless files are 

automatically backed up to server). Temperature calibrations for the six temperature plateaus 

(140, 280, 480, 580, 580, 740, and 840°C) need to be performed semiannually (see details in 

Section 3.2.3). Checks of laser adjustments and leaks are made at least monthly or on an as 

needed basis. The procedure for leak checks can be found in Section 4.1.2. Additional leak tests 

are performed with a He leak detector each time a part is replaced, or whenever the analyzer fails 

the leak check during the daily routine. The system should show no He leaks at the various 

connections of the quartz cross oven. Since He has high diffusivity, freedom from He leaks will 

safeguard against O2 diffusion into the system. These O2 levels are determined semi-annually 

using a gas chromatography/mass spectrometry (GC/MS) instrument on the analyzer. Quarterly 

levels are determined using an O2 detector that is calibrated against the GC/MS. This is also 

used when a fresh He cylinder is installed to assure the quality of the gas supply and the 

condition of the O2 scrubber. If the cmdAutoCalibCheck command is used for calibration, the 

condition of the catalysts will be indicated and appropriate action can be taken (such as catalyst 

replacement). All calibrations, repairs, and checks must be recorded in the Carbon Analyzer 

Logbook (Figure 2-6). Flow rates of all operating gases should be checked and adjusted (if 

needed) whenever a new quartz oven or methanator is installed or serviced. Additionally, a flow 

check and balance should be performed as well. 

2.2 Spare Parts List 

The following spare parts must be kept on hand to ensure minimal interruptions in carbon 

analysis: 

• Quartz furnace tube available from the manufacturer (Atmoslytic, Calabasas, CA). 

• Quartz rods: 3 mm nominal diameter, optical quality (Atmoslytic, Calabasas, CA), 

polished for optical clarity with 104 mm (upper arm) and 119 mm (lower arm) lengths. 

The version of the carbon analyzer manufactured in 2001 uses a 98 mm rod for the upper 

arm. Measure the old rods for reference. 

• Catalyst ovens: Watlow 15.24 cm length, 2.54 cm tube diameter element from the 

analyzer supplier. 

• Quartz boats (Atmoslytic, Calabasas, CA). 

• Quartz wool: For repacking the oxidation oven (Alltech Associates, #4033, Deerfield, 

IL). 
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Figure 2-6. DRI Carbon Analysis Logbook Format. 
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• Thermocouple rods: 24.13 cm length by 0.32 cm outside diameter (OD), Type-K ground 

isolated with Inconel sheath (Omega, Part #TJ36-CAIN-18E-9.5, Stamford, CT). 

Remove 1 cm of the sheath with a file to obtain the longer tip needed in this application. 

• FID flame tips: for Gow-Mac #12-800 FIDs (Gow-Mac, #132-117, Bethlehem, PA). 

• Septa: Standard 0.32 cm or 0.64 cm cylindrical (Alltech Associates #6524, Deerfield, IL) 

for injection ports. Silicon septa 0.25 cm and 1.11 cm for oven seals (Alltech #15427 and 

#15429, Deerfield, IL). 

• 1 ml gas tight syringe for gas injections. 

• 25 μl syringes for liquid injections. 

• Replacement needles for syringes (Alltech #7729-06, Deerfield, IL). 

• Replacement oxygen/moisture trap (R&D Separations, Model OT3-2, Rancho Cordova, 

CA). 

• Replacement hydrocarbon trap (R&D Separations, Model HT200-4, Rancho Cordova, 

CA). 

• Replacement indicating oxygen trap (Chromatography Research Supplies, Model 

202223, Louisville, KY). 

• Viton O-rings: Size 013. Two needed for quartz oven tube inlet. 

• Teflon ferrules: Parker or Swagelok style 0.64 cm front and back ferrule for the quartz 

oven tube outlet connections (Swagelock, T-400-SET, Solon, OH). Refer to instrument 

user manual for specific ferrule sizes. 

• Teflon ferrules: 0.32 cm to 0.64 cm (Alltech Associates, #RF-400/200-T, Deerfield, IL), 

for the thermocouple rod at the inlet breech. Refer to instrument user manual for specific 

ferrule sizes (style varies by location on analyzer). 

• High temperature silicone seals for quartz light rods and connector, prepared by Alltech 

Associates, #15427 and #15429, Deerfield, IL. 

• Heating element for oven (Watlow, #VC401A06A-0000R [90° bend], Columbia, MO). 

• Printer paper and toner cartridge. 

• Computer CD for backup if not on server backup. 
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2.3 Reagents 

2.3.1 Chemicals 

The following chemicals should be reagent grade or better: 

• Potassium hydrogen phthalate (KHP), for calibration (Fisher Scientific, cat #P-243, CAS 

877-24-7, Fairlawn, NJ). 

• Sucrose, for calibration use (EM Science, #SX1075-1, Gibbstown, NJ). 

• Manganese dioxide (MnO2), crystalline, as an oxidizer in the oxidation oven (Nurnberg 

Scientific, #C5162, Portland, OR; Aldrich Chemicals #24344-2, St. Louis, MO; or 

equivalent). 

• Nickelous nitrate [Ni(NO3)2·6H2O], crystalline, used to prepare the nickel catalyst in the 

methanator (Fisher Scientific, cat #N62-5000, CAS 13478-00-70, Fairlawn, NJ). 

• Chromosorb A, 20/30 mesh, used as a support for nickel catalyst in the methanator (from 

any chromatography supplier, such as Alltech cat #2-0165). Both nickelous nitrate and 

Chromosorb A are for preparing the reduction catalyst in the methanator. 

• Hydrochloric acid (HCl), 0.4 molar solution, for use in cleaning punch and quartz ovens, 

and for use in carbonate analysis (Fisher Scientific, cat #A508-212, CAS 7647-01-0, 

Fairlawn, NJ). 

• Hydrofluoric acid (HF), diluted to 15% may be used for removing the white deposits 

from devitrification (white deposits of SiO2) on the quartz oven parts (Fisher Scientific, 

cat #A147-1LB, CAS 7664-39-3, Fairlawn, NJ). However, proper safety precautions 

must be followed when using HF and quartz oven parts may become brittle with repeated 

use. 

• Nanopure water (used as described in Section 3.1.3.1). 

2.3.2 Gases 

The following gases should be ultra-high purity (UHP) grade or better: 

• He for a carrier gas, regulated to 15-40 psi with a metal diaphragm regulator. The higher 

pressure is required due to the pressure drop across the Supelco oxygen scrubber. 

• 5% CH4 by volume in He for calibration injections and calibration peaks; regulated to 10 

psi by a metal diaphragm regulator. 
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• 5% CO2 by volume in He for calibration injections; regulated to 10 psi by a metal 

diaphragm regulator. 

• 10% O2 by volume in He as a carrier gas, regulated to 15 psi by a metal diaphragm 

regulator. 

• Hydrogen for the FID flame, regulated to 15 psi with a metal diaphragm regulator. 

• Hydrocarbon-free air to supply O2 to the FID, regulated to 15 psi by a metal diaphragm 

regulator from a zero air generator. 

• Compressed air for pneumatic activation, regulated to ~25 psi. 

At least one backup cylinder per gas type should be kept on hand at all times. Depending on 

analysis volume, the 90% He/10% O2 mixture are typically replaced every four to six weeks; H2

and He are replaced once a week. All gases are replaced when the cylinder pressure drops below 

500 psi (unless the cylinders are connected to an automatic change-over module). Check the O2

scrubber and follow the manufacturer’s recommendations for scheduling its replacement. 

The flow settings on the flow meters (rotameters) are based on an input of 15 psi for He, 90% 

He/10% O2, H2, and FID air. The pneumatic drivers for the breech should have a pressure of 

~25 psi to operate effectively (sealing the opening). 

2.4 Forms, Paperwork, and Logbook 

All samples are logged in upon receipt at the laboratory. A sample analysis list will be prepared 

by the laboratory supervisor or designated technician indicating which samples will be analyzed, 

plus any special instructions. As individual samples are analyzed, entries are made in the Carbon 

Analyzer Logbook, as shown in Figure 2-6. Figure 2-7 provides an example of the cover sheet 

of the sample analysis run list. Figure 2-8 provides an example of the Daily Analyzer Checklist 

that is completed at the start of each day in order to verify analyzer flow and FID response. 
DRI STANDARD OPERATING PROCEDURE 

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Figure 2-7. DRI Carbon Sample Analysis Run List. 

 
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Figure 2-8. DRI Carbon Daily Analyzer Checklist. 
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3 CALIBRATION PROCEDURES AND STANDARDS 

3.1 Instrument Calibration 

The calibration procedures for the carbon analyzers are of four types: 1) the end-of-run 

calibration peak; 2) the routine beginning and end-of-day calibration injections of He/CH4 and 

He/CO2 (or the auto calibration check using the cmdAutoCalibCheck command); 3) full 

instrument calibration, performed every six months, using KHP, sucrose, and the two calibration 

gases; and 4) temperature calibrations performed every six months using temperature-sensitive 

indicating liquids with different melting points. 

3.1.1 End-of-Run Calibrations (Description) 

The end-of-run calibration consists of a set quantity of He/CH4 calibration gas which is 

automatically injected by the carbon program. All FID readings during the analysis run are 

normalized to this peak to minimize the effects of FID performance and electronic drift over 

time. The end-of-run calibration occurs automatically at the end of each analysis run and 

requires no operator intervention. The integrated calibration peak counts should be checked by 

the operator immediately after each run to confirm that the analyzer is operating satisfactorily. 

Calibration peak area counts should be greater than 20,000 and within an acceptable range for 

the specific analyzer. Check daily records to compare and determine analyzer performance and 

stability. 

3.1.2 Routine Calibrations (Description) 

Routine calibrations must be performed at the beginning and end of each day, either manually or 

by using the automated routine calibration command (cmdAutoCalibCheck) in the 

CarbonNetWork database Command table. 

3.1.2.1 Automated Routine Calibration (Description & Instructions) 

The automated calibration uses the Carle valve to inject the CH4 standard once in a He-only 

atmosphere, once in a He/O2 atmosphere, and finally, the normal calibration peak at the end of 

analysis. The three peaks should have similar areas if the catalysts are in good condition and the 

calibration factor holds (See Figure 3-1). Use the following steps to perform this automated 

calibration: 

• From the DRICarb.exe Welcome screen, select “Analysis” from the “Main” submenu. 

• Set Type to “Sample” and select cmdAutoCalibCheck from the drop-down menu in the 

“Command table” field. 
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Figure 3-1. Calibration thermogram from the cmdAutoCalibCheck command of the DRI 

Model 2001 Thermal/Optical Carbon Analyzer. 
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• The project name should be “CALIB”, Batch # should be “MM” for the month, Subbatch # should be “DD” for the day, and the Sample ID should be in the format 

“CxxYYYYMMDD” where “xx” is the analyzer number (e.g. C0720050710 for analyzer 

number 7, run on July 10, 2005). 

• Set the Run # (“1” for first calibration of the day and “2” for second calibration of the 

day, etc.). Enter “1” in the Punch area, and Deposit area fields. Click on “OK” and then 

click “Run”. 

• Review the thermogram and record these values in the logbook and on the Daily 

Analyzer Checklist as shown in Figure 2-8. The three calibration peak counts (OC3, EC1, 

LtPyMid) should be above 20,000 and within the acceptable range for the specific 

analyzer, and should be almost identical in area (and within 10% of the “Calibration Peak 

Area” value show on the tabular printouts). Check the average C value for the calibration 

gas against those posted on each carbon analyzer. 

• Whenever the MnO2 or Ni catalyst is replaced, an automated routine calibration should 

be run to confirm that the previous calibration curve holds. 

3.1.2.2 Manual Routine Calibration (Instructions) 

• From the DRICarb.exe Welcome screen, select “Analysis” from the “Main” submenu. 

• Set Type to “Calib” and select cmdCalib-HeO2 (for example) from the drop-down menu 

in the “Command table” field. The setup screen is shown in Figure 3-2. 

• Project name, Batch #, and, Sub-batch # are not required or available fields for entry. The 

sample ID should be in the format “MIxxYYYYMMDD” for CH4 injection or 

“CIxxYYYYMMDD” for CO2 injection where xx is the analyzer number (e.g. 

MI0720050710 for a CH4 injection on analyzer number 7, run on July 10, 2005). 

• Set the Run # (“1” for first calibration of the day and “2” for second calibration of the 

day, etc.). Click on “OK” and then click “Run”. 

• Select the atmosphere for calibration under the “Cal Gas” (either CH4 or CO2) menu and 

select the proper “Carrier Gas” (either HeO2 or He; HeO2 for beginning of day and HE 

only for end of day). These should be alternated with the calibration gas. Verify the 

command table matches the options selected. 
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Figure 3-2. Setup Screen for Manual Gas Calibration for the DRI Model 2001 

Thermal/Optical Carbon Analysis Program. 

• Choose “OK” to proceed with the analysis, or “Exit” to leave the program. The analysis 

will start with the following screen as shown in Figure 3-3. You will note that the top 

portion contains all the information in the analysis Setup screen. The bottom half will 

display the thermogram when the run is initiated. 

• Start a run by clicking on “Run”. After the computer states, “Please load gas syringe”, 

flush the gas syringe with the calibration gas at least three times and then load it with the 

calibration gas. The computer will then state, the “Time remaining until load - XX 

seconds” and then “Inject calibration gas”. Follow the verbal instructions to inject the 

calibration gas through the septum. Inject the gas through the septum. Hold the plunger 

down with needle still inside septum for 10 seconds, or until peak appears. 

• Calibration gas injections should be in the following ranges for 1000 μl gas: 

Manual Injection Lower Allowable Limit Upper Allowable Limit 

CH4 20.36 μg carbon 1 * 22.50 μg carbon 1 *

CO2 20.28 μg carbon 2 * 22.41 μg carbon 2 *

Final Calibration Peak 20,000 -- 

1

 Calculated in a real laboratory environment. For a 5.12% CH4 standard at 646 mm Hg at 24 °C, actual mass of methane is 21.43 μg 

carbon. 2

 Calculated in a real laboratory environment. For a 5.10% CO2 standard at 646 mm Hg at 24 °C, actual mass of carbon dioxide is 

21.34 μg carbon. 

* Lower Allowable Limit equals to 5% lower than the actual mass; Upper Allowable Limit equals to 5% higher than the actual mass. 

Limits should be adjusted according to the real laboratory environment. 
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Figure 3-3. The Analysis Screen during Manual Gas Calibration for DRI Model 2001 

Thermal/Optical Carbon Analysis Program. 

• Note: Each time the MnO2 or Ni catalyst is replaced, the instrument calibration should 

be checked to confirm that the previous calibration curve holds. A flow check and 

balance should always be performed after catalyst changes. Additional checks can be 

done by running a comparison sample (if available) or running two points from the six 

CH4/He calibration volumes and two points from the six CO2/He volumes used in the full 

calibration. The calibration peak area may also need to be checked for significant 

changes that would require a full calibration to calculate a new slope. 

3.1.3 Full Calibration (Description) 

Full instrument calibration, performed semiannually or as needed, establishes the calibration 

slope used in converting counts to μg of carbon, as explained in the next section. Instrument 

calibration involves spiking pre-fired quartz punches with 5.0 to 20.0 μl of the 1800 ppm KHP 

and sucrose solutions and injecting 200 to 1000 μl of the CH4 and CO2 gases. 

Four types of standards are used to calibrate the carbon analyzers: 5% nominal CH4 in He, 5% 

nominal CO2 in He, KHP, and sucrose. Only the calibration gases are used on a daily basis as 

analyzer performance monitors. KHP and sucrose are used in conjunction with CH4 and CO2

semiannually to establish the calibration curve of each analyzer. 
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3.1.3.1 Preparation, Ranges and Traceability of Standards 

The calibration is done by injection of a known volume of the standard to yield a calibration 

curve of peak area ratio of injected carbon: CH4 (internal standard) versus μg C injected (Internal 

Standard Calibration Method). For the best accuracy, the temperature and pressure at the time of 

analysis need to be taken into account. For a 100% CH4 or CO2 standard at 760 mm Hg at 20 °C, 

each microliter = 0.499 μg carbon. For a 5% standard, it will be 0.02495 μg C/μl at standard 

temperature and pressure (STP; 20 °C, 760 mm Hg). The Ideal Gas Law should be used to 

correct for the temperature and pressure of the laboratory. 

 12gas cal of % 0.08206

1

(T 273.15)

1

760

Pa μLper C μg Acutal ⎟ × ×

⎠

⎞ ⎜

⎝

⎛

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

+

⎟

⎠

⎞ ⎜

⎝

⎛ =

 where Pa is pressure in mmHg, T is ambient temperature. 

The calibration gases are traceable to NIST standards. The calibration gases are assayed for 

exact concentrations by the gas supplier; the assay value is obtained from the tag on the cylinders 

and is typically determined by GC. 

To prepare an 1800 ppm standard, the KHP is dried at 110 °C for two hours before dispensing. 

Transfer 0.3826 g of KHP into a glass 100 ml volumetric flask after the KHP has come to room 

temperature inside a desiccator. The weight of KHP used must be recorded. Dilute to volume 

with 0.4 ml concentrated hydrochloric acid (HCl) and 99.6 ml Nanopure water. Mix the KHP 

thoroughly. Store this solution in a refrigerator until it is used for calibration purposes. This 

solution is good for 40 days. Label the flask with the chemical name, the date of preparation, the 

name of the chemist preparing the solution, and the exact concentration. The concentration, 

nominally 1800 ppm carbon, is calculated by: 

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ ×

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = KHP of MW

12 KHP in carbon of no

ml in prep solutionof vol

g in used KHP of weight mL per C μgActual

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

⎟

⎠

⎞ ⎜

⎝

⎛ × ⎟

⎠

⎞ ⎜

⎝

⎛ = g

μg 10

204.23

12 8

ml 100

gin used KHP ofweight ..

6

ge

The nominal 1800 ppm standard, the sucrose solution, is prepared by transferring 0.428 g of 

sucrose into a glass 100 ml volumetric flask. Dilute to volume with acidified Nanopure water 

(see blank solution preparation instructions below). Mix the sucrose thoroughly. Store this 

solution in a refrigerator until it is used for calibration purposes. This solution is good for 40 
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days. Label the flask with the chemical name, the date of preparation, the name of the chemist 

preparing the solution, and the exact concentration. The concentration is calculated by: 

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ ×

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = sucroseof MW

12 sucrosein carbon of no

ml in prep solutionof vol

g in used sucroseof weight mL per C μgActual

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

⎟

⎠

⎞ ⎜

⎝

⎛ × ⎟

⎠

⎞ ⎜

⎝

⎛ = g

μg 10

342.31

12 12

ml 100

gin used sucrose ofweight ..

6

ge

To prepare a blank solution, add 0.4 ml of concentrated HCl to a glass 100 ml volumetric flask 

and dilute to volume with Nanopure water. This acidified Nanopure water is made fresh each 

time a 1800 ppm KHP stock solution is prepared. 

Only a limited set of primary standards (NIST-traceable) currently exist for carbon analysis. 

Ideally, such standards should include a range of organic compounds from low- to highmolecular weights and with varying degrees of susceptibility to pyrolysis, as well as EC and 

carbonate compounds. Currently, KHP, sucrose, and the two calibration gases are used at DRI 

for calibration and system audit purposes. 

3.1.3.2 Calculating Calibration Slope 

The calibration slopes derived from the two gases and the KHP- and sucrose-spiked filter 

punches are averaged together to yield a single calibration slope for a given analyzer. This slope 

represents the response of the entire analyzer to generic carbon compounds and includes the 

efficiencies of the oxidation and methanator zones and the sensitivity of the FID. Note that the 

current calibration procedure is based only on TC, as no routine procedure exists to check the 

accuracy of the OC/EC split. An example of the spreadsheet is shown in Figure 3-4. 

3.1.3.3 Typical Accuracy of Calibration Standards 

The accuracy of the calibration standards is primarily limited by the accuracy of the calibration 

gas assays, the accuracy of the preparation of the KHP and sucrose solutions, and the 

technician’s injection technique. The calibration slopes determined by these four compounds 

historically differ by less than 5% on a given analyzer if sufficient care is taken during the 

calibration procedure (Section 3.1). Figure 3-5 shows an example of plotted calibration curves. 
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Title: DRI Model 2001 Thermal/Optical Carbon Analysis Number: 2-216r2 

 (TOR/TOT) of Aerosol Filter Samples - Method IMPROVE_A Revision: 2 

Figure 3-4. Example of calibration summary worksheet used to determine calibration 

slope. 

Calibration volume C in CH4/He Injection Calibration Injection/

Standard Run # (μL) (μg) Peak Counts Peak Counts Calibration Slope

CH4 MI040106-1 200 4.18 4913 25194 0.1950 21.45

CH4 MI040106-2 500 10.46 12240 25095 0.4877 21.44

CH4 MI040106-3 700 14.64 17081 25502 0.6698 21.86

CH4 MI040106-4 1000 20.92 24094 25769 0.9350 22.37

CH4 MI040106-5 1000 20.92 24011 25846 0.9290 22.51

CO2 CI040106-1 200 4.13 4807 25738 0.1868 22.10

CO2 CI040106-2 500 10.32 12196 25901 0.4709 21.92

CO2 CI040106-3 700 14.45 17214 26114 0.6592 21.92

CO2 CI040106-4 1000 20.64 24425 26204 0.9321 22.14

CO2 CI040106-5 1000 20.64 24433 25969 0.9409 21.94

SUC SU20060401-5UL 5 9.01 12490 25952 0.4813 18.72

SUC SU20060401-10UL 10 18.02 22626 25987 0.8707 20.70

SUC SU20060401-15UL 15 27.03 32686 26140 1.2504 21.62

SUC SU20060401-15UL 15 27.03 35584 26336 1.3512 20.01

SUC SU20060401-20UL 20 36.04 44753 26087 1.7155 21.01

KHP KHP20060401-5UL 5 9.00 11546 26386 0.4376 20.56

KHP KHP20060401-10UL 10 17.99 23878 26608 0.8974 20.05

KHP KHP20060401-15UL 15 26.99 33340 26702 1.2486 21.62

KHP KHP20060401-15UL 15 26.99 33156 26530 1.2498 21.60

KHP KHP20060401-20UL 20 35.99 44472 26504 1.6779 21.45
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Figure 3-5. Example DRI Carbon Analyzer Calibration Curves. 

CA#7 Calibration

y = 21.055x

0

5

10

15

20

25

30

35

40

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

Peak Area/Calibration Peak Area (no units)

Calculated Carbon (ug)
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3.1.3.4 Data Treatment for Calibration Data 

• Calibration values are plotted as ratio of the integrated sample peak counts to the 

calibration peak counts vs. the actual calculated μg carbon (Figure 3-5). Obvious 

outliers are identified and rerun. Linear regression is performed on each set of 

calibration data (separate calculations for KHP, sucrose, CH4/He, and CO2/He). The 

slope (m) is calculated from: 

( )

( ) ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ =

∑

∑

2

i

ii

x

xy

m

The standard deviation (s) is calculated by: 

( )

∑

∑ −

− = 2

2

1

1

i

ii

x

mxy

n

σ

where: 

( )

( ) x

injected carbon peak area

calibration peak area i =

and: 

y calculated carbon in spiked filter or manual injection g i = ( ) μ

• Note that this is a special form of the regression formula which ensures that the curve 

passes through the origin. 

• The resulting slope is compared to previous calibration results. New values should be 

no more than 10% different than previous calibrations if no major analyzer changes 

have been made. If variation is > 10%, calibration must be redone to verify values. 

• The new slope for each analyzer (derived from combined CH4, KHP, and sucrose 

data) is placed into the Carbon.par file for each analyzer; this file contains analyzer 

parameters which are read into the Carbon program when it is first started. Therefore 

the Carbon.par file must be edited while the program is closed and the parameters 
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will take affect when the program is restarted. The date and version number in the 

Carbon.par file is also updated. 

• Calibration data and plots are retained electronically and in file folders stored with the 

raw analysis data. 

3.1.3.5 Calculations 

 The conversion of integrated peak counts to μg of carbon for each peak in the thermogram 

is performed by the computer at the end of the analysis program. For reference purposes, 

the calculation is: 

)counts n ncalibratio internal(

) slopencalibratio(x)baseline above counts peak integrated( μ C/punch g peak =

For IMPROVE_A thermal protocol, the peaks reported are: four organic peaks (OC1, OC2, 

OC3, and OC4) corresponding to 140, 280, 480, and 580 °C in He atmosphere, 

respectively; three elemental carbon peaks (EC1, EC2, and EC3) corresponding to 580 °C 

after the introduction of O2, 740, and 840 °C, respectively; and three pyrolyzed organic 

carbon peaks (Lower, Regular, and Upper Splits) by reflectance and transmittance, 

corresponding to the peaks after the introduction of O2 and before the Lower Split Time, 

Regular Split Time, and the Upper Split Time, respectively, for the reflectance and 

transmittance optical charring correction (see Section 1.7 and Figure 4-4). The EC reported 

includes pyrolyzed carbon. 

 Carbon values per punch are converted to μg C/cm2

 by: 

( )

( ) areapunch

punchCg cmCg 2 μ =μ

 Finally, carbon values are converted to μg C/filter by: 

( )( areadepositfiltercmCgfilterCg ) 2 μ=μ

3.2 Instrument Calibration Instructions 

3.2.1 Full Gas Calibration 

• To perform the full calibration, select “Analysis” from the Main menu of the 

DRICarb.exe program Welcome screen. 
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 (TOR/TOT) of Aerosol Filter Samples - Method IMPROVE_A Revision: 2 

• Choose “Calib” under the “Type” drop down menu. Project name, Batch #, and, 

Sub-batch # are not required. In the “Command table drop-down”, select cmdCalibHe (for example). Fill out the Sample ID, Run #, and Tech Initials fields. The 

sample ID should be in the format, “MIxxYYYYMMDD_zzzz” (where “MI” is for 

CH4 injection; use “CI” for CO2 injection; xx is for the analyzer number and zzzz is 

the volume of gas injected). You can also select FID ID (typically FID_8) to 

determine the FID peak area and make comments and flag the analysis from this 

screen before the analysis starts. 

• Select the atmosphere for calibration under the “Cal Gas” menu and select the 

proper “Carrier Gas”. (He-only gas is recommended when doing full gas 

calibrations.) Verify the command table matches the options selected. 

• Enter the technician initials in the “Tech initials” field. 

• Choose “OK” to run the analysis, or “Exit” to leave the program. The analysis will 

start with the screen as shown in Figure 3-2. You will note that the top portion 

contains all the information in the Setup screen. The bottom half will display the 

thermogram when the run is initiated. 

• Start a run by clicking on the Run command button. After the computer states 

“Please load gas syringe” flush the gas syringe with the calibration gas at least three 

times and then load it with the calibration gas. Time remaining until load will be 

stated, and then “Inject calibration gas”. Inject the gas through the septum. Hold the 

plunger down with needle still inside septum for 10 seconds, or until peak appears. 

• The CO2 and CH4 calibrations are run using the “Calibration” options from the 

main menu. The following volumes are injected: 

– 200 μl CO2 gas (use 1000 μl syringe) 

– 500 μl CO2 gas (use 1000 μl syringe) 

– 700 μl CO2 gas (use 1000 μl syringe) 

– 1000 μl CO2 gas (do once with 1000 μl syringe and once with 2500 μl 

– syringe) 

– Repeat for CH4

• Record these calibration values in the logbook as in Figure 2-6. 

• The integrated peak counts are extracted manually from the tabular printouts and 

entered into the spreadsheet which is used to determine the final calibration. 
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3.2.2 Full Sucrose and KHP Calibrations 

• To perform the full calibration, select “Analysis” from the Main menu of the 

DRICarb.exe program Welcome screen. 

• Choose “Sample” under the “Type” drop down menu. Complete the information 

about the sample, including: Project Name, Batch #, and Sub-batch #. The Project 

name should be “SUKHPCAL”, the Batch # should be “MM” for the month; and the 

Sub-batch # should be “DD” for the date. 

• A clean blank quartz punch is baked in the analyzer oven at 900 °C for 10 minutes 

using cmdBakeOven from the Command table. 

• After baking the quartz punch, change to cmdImproveA under Command table. 

• Perform system blank before running KHP or sucrose. 

• Enter the Sample ID number or place your mouse cursor in the field. The sample ID 

should be in the format, “SUxxYYYYmmdd_zz” (where “SU” is for sucrose spiking; 

use “KHP” for KHP spiking; xx is the analyzer number and zz is the volume [05, 10, 

15, or 20 μl]). You can also select FID ID (typically FID_8) to determine the FID 

peak area and make comments and flag the analysis from this screen before the 

analysis starts. 

• Enter the Run #; the Punch area and Deposit area should be “1” for the filter being 

analyzed. 

• Enter technician initials in the “Tech initials” field. 

• After the punch has cooled to less than 50 °C, the KHP or sucrose solution (prepared 

as described in Section 3.1.3.1 and kept at room temperature) is injected onto the 

punch using a 25 μl syringe. The following volumes are used: 

– 5 μl KHP and sucrose solution 

– 10 μl KHP and sucrose solution 

– 15 μl KHP and sucrose solution (do twice) 

– 20 μl KHP and sucrose solution 

– no injection (as a system blank; see Section 4.1.5.1) 
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– 20 μl acidified Nanopure water only (check of background level of Nanopure 

water) 

• Flush the syringe at least three times with the calibration solution before taking up the 

volume for injection. Pump the syringe plunger to remove any trapped bubbles. 

• Slowly spike the solution in the center of quartz punch and wash the syringe with 

Nanopure after use. If the solution is spiked too quickly it will bead up and run off the 

punch. 

• Click “OK” on the analysis “Setup” screen. The boat will load to the calibration 

position. 

• The computer will ask, “Would you like to proceed or would you like to delay 

analysis?” Enter the length of time in seconds you wish to delay the beginning of the 

analysis in the Delay box. This is used to purge dry a filter disc that has been 

deposited with an aliquot of KHP or sucrose standard solution, or when the sample is 

acidified for carbonate removal. In general, allow ~1 minute of purge time for every 

μl of solution deposited (e.g., 5 μl=300s, 10μl=600s, 15μl=900s and 20μl=1200s). 

Click “OK” and analysis will begin. 

• Allow the punch to dry thoroughly; the punch will turn from translucent to opaque as 

it dries. The punch must be dry to avoid water vapor effects on the FID and the laser 

reflectance and transmittance signals. Select the cmdImproveA option from the 

analysis menu to start. 

• The integrated peak counts for all seven temperature fractions for the sample and 

calibration peaks are recorded. The total peak is calculated by adding the peak area 

from OC1, OC2, OC3, and OC4, as well as EC1, EC2, and EC3. Pyrolysis counts are 

not included in the total. 

3.2.3 Temperature Calibrations 

Temperature calibrations are performed semiannually on all instruments to verify that the sample 

temperature is as accurate as possible. 

3.2.3.1 Temperature Indicators 

Since it is not possible to sense the temperature of the sample directly, materials were sought 

that: 1) could be placed where the sample would normally be located, and 2) would cause sharp 

reactions when known temperatures were achieved. Quick-drying temperature-indicating liquids 

of different melting points, Tempilaqo G (Tempil, Inc., South Plainfield, NJ, USA), were used as 

temperature indicators in muffle furnaces. A Tempilaqo G set contains long-chain hydrocarbons 

suspended in an organic solvent, which change their appearance at 44 specific temperatures 
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spanning 80-1000 °C. The accuracy of Tempilaq° G is certified within ±1% of its designated 

temperature and is traceable to the National Institute of Standards and Technology (NIST). 

Tempilaqo G is bottled in liquid form and dries quickly to a dull, opaque film when applied to a 

surface. As the surface is heated to the designated temperature, the film liquefies and is 

accompanied by a change of appearance that can be optically monitored to determine sample 

temperature. 

3.2.3.2 Analyzer Preparation 

Preparation of the Model 2001 analyzer for temperature calibration includes the following: 

• Change par file to 1 and 0 for slope intercept (par file must be edited with the 

program closed). 

• Disconnect the back valve to prevent contaminating the system 

• Replace existing MnO2 oven with a clean backup oven (without a catalyst) to 

prevent contamination of the main oven. Install without connecting to the back 

valve. 

• Connect an Erlenmeyer flask with ice in it where the oven connects to the back 

valve. This will help condense the organics when the Tempilaq is heated up. 

3.2.3.3 Standard Preparation 

Temperature calibration requires two pre-fired quartz-fiber filter (#2500 QAT-UP, Pall Life 

Sciences, Ann Arbor, MI) punches (0.5 cm2

 for DRI analyzer) and a clean matching-sized quartz 

disk (Continental Glass Engineering, Burbank, CA). Quartz-fiber filter punches are sliced in half 

(horizontally) with a filter-slicing device (Fung et al., 2004). A thin layer of Tempilaqo G (~25 

μL) is uniformly applied to the glass and/or quartz disk surface with a 0.1 ml Eppendorf 

graduated Combitip (Brinkman Instruments Inc., Westbury, NY), and, before drying, is 

immediately covered with a sliced filter punch. For cost savings, a glass, instead of quartz, disk 

can prepared by a technician in the lab from a glass slide cover and used for Temiplaqo G at 

temperatures > 520 °C. Higher temperatures require the quartz disc to prevent melting. The disc 

sandwich (i.e., temperature standard) is then loaded on a sample holder for analysis. The mass of 

applied Tempilaqo G is determined gravimetrically to ensure its mass is ~10%. 

3.2.3.4 Temperature Program 

After insertion of the temperature standard into the analyzer, the temperature is slowly (2 

°C/min) ramped across a 50 °C range containing the specified Tempilaq° G melting point. This 

slow ramping creates a quasi-equilibrium condition that allows the phase transition point to be 
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resolved. Temperature indicators 121 through 510 are replicated three times and 704 and 816 

are replicated twice. When the specified temperature is reached, the Tempilaqo G liquefies, 

causing a detectable change in reflectance and transmittance. 

Figure 3-6 demonstrates the thermocouple temperature, reflectance, and transmittance as a 

function of thermal analysis time. In the example provided, the reflectance and transmittance 

remained relatively flat until the temperature approaches its specified value of 184 °C. Figure 3-

7 compares the time series of reflectance, transmittance, and their respective first- and secondorder derivatives. The second-order derivative (change in the slope) recorded the inflection point 

of reflectance or transmittance that provided the best indication of the attainment of the 

designated temperature. Thermocouple temperature at this critical point was recorded as 

“measured” temperature. The temperature deviation (ΔT) between the sample and the 

thermocouple temperatures is determined by comparing the rated Tempilaqo G temperature with 

this measured value (Chow et al., 2005). 

In the Model 2001, the reflectance-based method generally gave a lower liquefying temperature 

than the transmittance-based method, within ±2 oC. Given the uncertainty in the Tempilaqo G 

temperature rating of ±1%, calibrations based on the two optical methods were considered to be 

equivalent; therefore, their means were used. Among temperature indicators that achieve an 

adequate signal/noise ratio, temperature indicators of 121, 184, 253, 510, 704, and 816°C were 

chosen for IMPROVE_A protocol temperature calibration (Chow et al., 2005, 2007). Note, the 

510 °C temperature experiences charring and therefore, transmittance results are variable. 
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Figure 3-6. Temperature ramping with a Tempilaqo G temperature indicator rated at 184 

°C. Also shown are reflectance and transmittance of the temperature indicator (if 

available). The vertical dashed line indicates the achievement of the rated temperature. 

0

400

800

1200

1600

2000

2400

2800

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Time (sec)

0

50

100

150

200

250

Transmittance Reflectance Temperature

Laser Reflectance/Transmittance (mV)

Transmittance

Reflectance

Temperature

Thermocouple Temperature (°C) 

Transmittance 

Temperature 

Reflectance 

Laser Reflectance/Transmittance (mV) 

Time (sec) 
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Figure 3-7. Reflectance and transmittance measurements and their first and second 

derivatives over time with a Tempilaqo G temperature indicator rated at 184 °C (Figure 3-

6). The vertical dashed line indicates the achievement of the rated target temperature. 

0

400

800

1200

1600

2000

2400

2800

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Time (sec)

-35

-25

-15

-5

5

15

25

35

First/Second Derivative

Laser Reflectance/Transmittance (mV)

(Tempilaq’s melting point 184 ± 2 oC)

Transmittance

Reflectance

1st Reflectance Derivative

1st Transmittance Derivative

2nd Reflectance Derivative

2nd Transmittance Derivative
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4 PROCEDURES 

4.1 Detailed Procedures 

4.1.1 Analyzer Start-Up 

When the analyzer is started up for the first time, or after an extended period of non-operation, it 

will take a period of conditioning to reach a stable system background. At start-up, allow all the 

gases to purge through the system for ~30 minutes before heating the various zones in a stepwise 

manner. Allow the FID and Line Heaters to reach operating temperatures of 120 °C and 105 °C, 

respectively, before heating up the oxygenator and methanator. Heat both catalysts at 120 °C for 

about half an hour, then in ~100 °C increments with ~30 min. hold time until the final 

temperatures of 912 °C and 420 °C are reached for the oxygenator and methanator, respectively. 

The following steps outline analyzer start-up: 

• Check all gas cylinder pressures; cylinders with gas pressures less than 500 psi should be 

replaced before beginning the day's analysis. 

• Check that all gas delivery pressures are correct: 

Hydrogen (H2) 15 psi 

Helium(He) 15-40 psi (check label on 

regulator for current setting) 

Compressed air 15 psi for FID, 25 psi for 

breech actuation 

O2/He mix 15 psi 

CH4/He mix 10 psi 

CO2/He mix 10 psi 

• Check that the FID is lit by holding a pair of tweezers over the FID exhaust stack and 

watching for condensation. If the FID is not lit (as immediately after the H2 or 

compressed air cylinders are changed), relight the flame by turning the H2 rotameter to 

the upper limit (as posted on the flow meter) and holding a butane lighter or match over 

the FID stack. A soft pop indicates that the flame has been lighted. Verify that the flame 

remains lit by the tweezers test. Often the flame will not stay lit the first try, especially 
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after the H2 cylinder is changed and air gets into the gas lines. Return the rotameter to the 

operation setting after the flame is lit. 

• Check and readjust, if necessary, all gas flows at the analyzer. The correct readings are 

posted on each rotameter. Read through the center of the ball. If drastic adjustments are 

required on one analyzer, recheck that flows on the other analyzers have not been 

affected. 

• Turn on the computer monitor. Note: the computers are generally left on at all times; only 

the monitors are turned off when the analyzers are not in use. 

• Confirm that the date and time on the computer are correct. 

• Wipe the sample tweezers, flat glass plate, and punching tool with clean KIMTECH 

wipe, taking care not to contact the cleaned surfaces with fingers or other dirty items. 

Check to make sure that no fibers from the KIMTECH wipe are left on the surfaces. 

• Begin the daily entry in the Carbon Analyzer Logbook. Entries should follow the format 

in Figure 2-6. 

• Make sure that the printer has enough paper for the day and that the toner cartridge is 

producing legible text and graphics. 

• Go to C:\CarbonNet, then double click the DRICarb.exe program icon to begin the 

carbon program (or double click the DRICarb.exe shortcut on the computer desktop). The 

DRI welcome screen appears as depicted in Figure 4-1. Verify that the correct version of 

the software and database are being used. For normal analysis, the database should be 

“CarbonNetWorkXX.mdb”, where XX is the analyzer number. 

If for some reason the program freezes, allow the sample oven to cool to below 200 °C and then 

close the program and restart DRICarb.exe. 

4.1.2 Leak Checks 

Perform leak checks daily to detect leakage in the sample oven. 

4.1.2.1 Manual Leak Check 

• With the breech closed, flip the oven outlet toggle on the side of the analyzer down (off) 

and let the sample oven pressure reach ~3 psi. Most systems are working in the ~2-2.5 

psi range, but a leak is easier to detect when the pressure is at ~3 psi. Close the oven inlet 

toggle, on the front of the analyzer, and watch for a decline in the sample oven pressure. 
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Figure 4-1. DRI Welcome Screen. 

NOTE: When using the carbon analysis software, clicking on the Exit button closes the program. Exiting in the 

midst of an analysis is not advisable, as the analyzer will revert to the default settings (see settings under 

Options\Manual); in such a case, a hot thermocouple will retract, possibly damaging the Teflon seal. 

A “leak free” condition is indicated by a steady pressure reading, or a decline of 0.01 psi 

or less per second (~0.01 ml/sec). 

• If the pressure is stable, flip the outlet oven toggle and then the inlet oven toggle back to 

the on position (up). This is to avoid pressurizing the oven if the inlet toggle is flipped 

first. 

• If the pressure is not stable, use a He leak detector (Alltech, Deerfield, IL) to locate the 

leak. Check the following items and correct accordingly: 

– All ferrules (especially the reducing ferrule), fittings and seals. 

– Quartz oven. 

– All tubing. 

– Thermocouple. 
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– Breech O-ring. 

• If the system still leaks, wipe all threads and ferrules with a dry KIMTECH wipe, 

reassemble, and retry. 

• Also, check the breech O-ring to ensure that it sits squarely in the groove and that there is 

sufficient pressure to close the breech. 

• Refer to the carbon analyzer’s Troubleshooting Manual for additional tips and 

procedures. 

Once the system passes the leak test, make sure that the analyzer’s multi-function switch (at the 

left of the front panel) is set at Auto in order to continue with routine analysis. Allow the system 

pressure to return to its original value and record this value on the Daily Analyzer Checklist 

shown in Figure 2-8. The pressure should be consistent with previous day’s values. 

4.1.3 Oven Bake 

A daily oven bake is performed to ensure the system is clean before beginning analysis. The 

oven bake can be performed manually or by using an automated command from the command 

table. 

4.1.3.1 Manual Oven Bake 

Use the following procedure to perform a manual oven bake: 

• Select “Manual” from the “Main” submenu. From the “Manual” screen, select “Control” 

on the drop-down menu list. (Note: analyzer must be in “Auto” mode for the manual 

control to work.) This will bring up the “Control” screen. Change the “Oven 

Temperature” field to “1000”. Change the “Sample Position” field to “Analyze”. Click 

“Go”. This will heat the oven to approximately 950 °C, depending on the instrument’s 

calibration. Exercise caution when working around hot surfaces of the analyzer. 

• Repeat until the system is clean. Sample runs or calibrations may then begin. 

• System blanks (section 4.1.5.1) are run after the oven bake. 

• Stop bake after 15 minutes; set temperature to 5 °C 

4.1.3.2 Automatic Oven Bake 

Use the following procedures to perform an automatic oven bake: 
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• From the main welcome screen, select “Analysis”. 

• Set Type to “Sample” and select cmdBakeOven from the drop-down menu in the 

“Command table” field. 

• Use Project Name “SYSBLK”, Batch # “MM” for the month and Sub-batch # “DD” for 

the day. 

• The Sample ID should be in the format “BxxYYYYMMDD” where “xx” is the analyzer 

number and YYYY is the year (e.g. B0720050715 for analyzer number 7 on July 15, 

2005,). 

• Set the Run #, Punch area, and Deposit area fields to “1”. Click “OK”, then “Run”. 

• Repeat until the system is clean. Sample runs or calibrations may then begin. 

• System blanks (Section 4.1.5.1) are run after the autocalibration (Section 3.1.2.1) has 

been completed and shows an acceptable range. 

• The following items should be checked and recorded on the Daily Analyzer Checklist 

shown in Figure 2-8. These values can be obtained by choosing the manual option from 

the main welcome screen. 

– Reflectance and transmittance (must be measured with a clean blank filter in the 

“analyze” position). 

• Reflectance range should be between 1400 and 2000 and consistent with 

previous days’ values. 

• Transmittance range should be between 800 and 1300 and consistent with 

previous days’ values. 

– System blank values 

• Total carbon must be less than 0.2 ug/cm2

– Calibration values 

• Specific to analyzer and must be consistent with previous days’ values. 
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4.1.4 OC/EC Analysis 

Based on the analysis list for the day, retrieve the samples to be analyzed from the sample 

freezer and place in a Styrofoam cooler with blue ice, or in the analysis room refrigerator. 

Routine analysis procedure assumes carbonate will not be measured. For carbonate analysis, 

refer to Section 4.1.5.2, “Carbonate Analysis”. 

Always execute the cmdBakeOven command to bake the oven before beginning analysis each 

day (refer to section 4.1.3). This will ensure the system is clean (< 0.2 μg TC/cm2

). Run a 

system blank with the IMPROVE_A protocol. 

4.1.4.1 Analysis Preparation 

• Verify the computer date and time is correct. 

• Verify sample oven pressure reading and specified flow ranges in the front-panel flow 

meters. 

• Wipe the flat glass plate, tweezers, and punching tool thoroughly with a dry KIMTECH 

wipe. 

• Based on the analysis list, remove the sample to be analyzed from the Styrofoam cooler 

or refrigerator. 

• Record the filter ID in the analyzer log book (Figure 2-6). 

• Open DRICarb.exe from the c:\CarbonNet folder or use the desktop “shortcut” to 

DRICarb.exe. Verify correct software version number on the Welcome screen. 

• Select “Analysis” from the “Main” submenu of the Welcome form. This will initiate the 

analysis protocol, as shown in Figure 4-2a and 4-2b. You can also select FID ID 

(typically FID_8) to determine the FID peak sensitivity. 

• In the analysis “Setup” form, enter “Sample” for the Type. 

• Polarity should default to “Unipolar”. 

• Fill out the information about the sample, including: Project Name, Batch #, and Subbatch #. 

• Under “Command table” select cmdImproveA. 
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• Enter the Sample ID number, or place your mouse cursor in the field and use a barcode 

scanner to read the barcode on the Petri dish. 

• Enter the Run #, Punch area and Deposit area for the filter being analyzed. 

• Enter technician initials in the “Tech initials” field. 

• Select any pre-analysis flags from the drop-down menu in the “Flags” field. A list of 

valid choices is presented on the screen. 

• Visually examine the filter and note any non-uniformity or unusual deposit. Remove it 

from the Petri slide or Petri dish with tweezers, handling the filter only by the edge. Place 

the filter on the flat glass plate and remove a sample punch by pushing down gently on 

the punching tool. Rocking the punching tool slightly will ensure that the punch is 

completely severed. Try to remove the punch from the edge of the deposit to avoid 

wasting the filter, while trying to avoid areas of non-uniform deposits. 

• Leaving the sample punch in the punching tool, place the punching tool on a clean 

KIMTECH wipe. Return the filter to the Petri slide or dish, being careful to handle only 

the filter with the tweezers. 

• If this is the first run of the day, or if the analyzer has been cooled down, the analyzer 

will verbally prompt you to load the punch (“Please load filter analysis”). If the analyzer 

was previously used, it will cool to 100 °C, then pull the boat back to the calibration 

position, continue cooling to 50 °C, and pull the boat back to the load position for the 

next analysis. 

4.1.4.2 Loading the Filter Punch 

• Use tweezers to remove punch from punch tool and place in analyzer boat. 

• Click “OK” on the analysis “Setup” screen. The boat will load to the calibration position 

and the computer will ask, “Would you like to proceed or would you like to delay 

analysis?” Enter any appropriate flags and click “Commit”. Check to make sure a 90-

second delay is in the “delay” box. Click “OK” and analysis will begin. 

• Wipe the tweezers, flat glass plate, and punching tool with a clean KIMTECH wipe. 

4.1.4.3 Post-Analysis 

At the end of each analysis, data is saved to the database, split times are calculated, carbon peaks 

are integrated, and tabular and graphical printouts are produced. The sample boat will retract to 
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the calibration position when it is sufficiently cooled by the fan (to < 100 °C) and will continue 

to cool until it reaches less than 50 °C. 

• Examine the tabular printout (Figure 4-3) to confirm that the calibration peak counts are 

within specifications (typically >20,000 counts and within acceptable range for specific 

analyzer, see Section 3.1). 

Figure 4-2a. Setup Screen for the DRI Model 2001 Thermal/Optical Carbon Analysis 

Program. 
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Figure 4-2b. The Analysis Screen during Sample Analysis for DRI Model 2001 

Thermal/Optical Carbon Analysis Program. 
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Figure 4-3. Tabular Printout from DRI Model 2001 Thermal/Optical Carbon Analysis 

Program. 
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Figure 4-3, continued.
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• Examine the thermogram (Figure 4-4) for proper laser response, temperature profiles, 

realistic carbon peaks, and the presence of the calibration peak at the end of the analysis. 

• Examine the laser signal at the end of the run. 

• If a problem is found, register it in the analyzer log book and run list, and notify the lab 

supervisor immediately. 

• Add any appropriate analysis flags to the post-analysis form that appears at the end of the 

run. 

• Mark the analysis date on the sample analysis run list. 

• Using clean tweezers, remove the punch from the boat and tape it to the thermogram with 

transparent tape, ensuring that the punch is deposit-side up. 

Repeat the above steps for additional analysis runs. 

4.1.5 Special Analyses 

4.1.5.1 System Blanks 

System blanks are run at the beginning of each day. Follow the steps outlined in Section 4.1.3 

on oven baking with the following exceptions: 

• Follow the routine analysis procedure (Section 4.1.4), but when prompted to load 

filter punch, remove the filter from the previous day and leave the boat empty for the 

analysis. 

• Use Project Name “SYSBLK”, Batch # “MM” for the month, and Sub-batch # “DD” 

for the day. Punch area and Deposit area should be “1”. 

• Use a Sample ID number “SBYYYYMMDD” derived from the current date, where 

YYYY is the year (e.g. SB20050718 for July 18, 2005,). 

• Calculated carbon concentrations should not be more than 0.2 μg carbon. Values greater 

than this warrant additional system blanks. Samples may not be analyzed until the system 

blank is <0.2 μg carbon. 
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Figure 4-4. Graphical output (thermogram) from the DRI Model 2001 Thermal/Optical 

Analysis Program. 
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4.1.5.2 Carbonate Analysis 

• Enter the Sample ID, Run #, Punch area, and Deposit area. Select 

cmdImproveA_Carbonate from the “Command table” drop-down field and start the 

analysis program. 

• Follow the steps under Section 4.1.3 until the sample punch is loaded into the boat. 

Load sample and click “OK”. When asked if you want to delay or continue analysis, 

click “OK”. After 90 seconds the punch automatically centers under the acid injection 

port. The computer will prompt you to inject the hydrochloric acid (HCl), and then 

will state “Load syringe” and “XX seconds to acid injection”. 

• Prior to acidification (approximately 90 seconds elapsed analysis time), flush the 25 

μl syringe with 0.4 M HCl into a waste beaker. 

• Inject 20 μl of 0.4 M HCl through the septum port to the sample, ensuring that the 

needle bevel is turned toward the punch and that the needle tip is touching the top of 

the punch. 

• When the analysis is underway, flush the syringe with Nanopure water to prevent 

corrosion of the syringe plunger. 

• After analysis, the program will delay any further analysis for 900 seconds to allow 

the punch to dry. 

• After the carbonate analysis is completed, a tabular summary and a copy of the graph 

will be printed (similar in format to Figures 4-3 and 4-4). Select cmdImproveA from 

the “Command table” drop-down field and click “OK”. Click “Run” on the analysis 

Setup screen. The program will automatically cycle into the normal OC/EC analysis, 

using the same Sample ID. Heat from the oxidation oven will dry the sample in this 

position (for approximately 15 minutes) without prematurely baking carbon from the 

sample; the sample temperature should not exceed 42 °C. When the punch is dry 

proceed with normal OC/EC analysis. 

4.1.6 Analyzer Shut-Down 

After the final sample for the day is analyzed, shut down the analyzers using the following 

procedures: 

• Leave the last analyzed punch in the boat with the boat positioned in the Calibrate 

position. This punch will be used as the system blank the following morning and 

then taped to the corresponding thermogram. 
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• Perform end-of-the-day calibration gas injection routine, or use cmdAutoCalibCheck

command, and record the calibration peak counts. Any values outside the expected 

ranges should be investigated and rerun. Because low values from the end-of-day 

calibration could potentially invalidate the entire day's runs, any deviation from the 

accepted ranges must be noted and the cause identified. Notify the lab supervisor. 

• Leave the DRICarb.exe software open. 

• If desired, He-1, Cal Gas, He-2, and Air may be turned off with the toggle valves to 

conserve gases. However, all other gases should be left on as long as the oxygenator 

and methanator are heated. 

• Place all of the day’s printouts, including calibration data in a file folder labeled with 

the date and analyzer number. Place on the lab supervisor's desk for Level I 

validation (Section 6.4). 

• Leave the computers and analyzers on overnight unless the potential for power 

outages or surges exists. Turn off the monitors overnight. 

• Make a final check of the gas cylinder pressures to ensure that gas flow, especially 

the compressed air, will continue until someone will be available to check them 

again. 

• Move the samples and blue ice in the Styrofoam cooler or refrigerator back into the 

sample storage freezer and verify that the freezer is completely closed. 

• If the 25 or 50 μl syringe was used for carbonate analysis, thoroughly rinse the 

syringe with distilled water and tightly cap all solutions. Store solutions in the 

refrigerator. Freezer storage may cause crystallization. 

• Lock the carbon analysis room. 

4.2 Abbreviated Procedures 

4.2.1 Analyzer Start-Up 

• Check pressures and delivery pressures in all gas cylinders. 

• Check that all FIDs are lit by holding a pair of tweezers over the FID exhaust stack and 

watching for condensation. Relight if necessary. 

• Check all gas flows at the analyzer; readjust if necessary. 
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• Turn on the computer monitor. 

• Confirm that the date and time on the computer are correct. 

• Execute the DRICarb.exe either from the shortcut on the computer desktop or from 

C:\CarbonNet\. 

• Confirm that the printers have enough paper for the day and that the toner cartridge is 

producing legible text and graphics. 

• Wipe the sample tweezers, flat glass plate, and punching tool with a clean KIMTECH 

wipe. 

• Begin the daily entry in the Carbon Analyzer Logbook. 

• Bake the oven for 10 minutes, or bake during leak test. 

• Perform a leak test, involving isolating the oven and operating the Carle valve. 

• Execute the cmdAutoCalibCheck command to verify the analyzer’s performance. 

• Retrieve the samples to be analyzed from the sample freezer and place in the styrafoam 

cooler or refrigerator. 

• Complete Daily Analyzer Check Sheet posted on each analyzer. 

4.2.2 Leak Checks and Oven Baking 

• Use manual option to set temperature to 900 °C and let analyzer reach this temperature. 

• With breech closed, flip oven outlet toggle to the off position and let sample oven 

pressure reach ~3 psi. 

• Flip the oven inlet toggle to the off position and watch for a decline in the sample oven 

pressure. If system is leak free, the pressure will remain stable. 

• If the system is not stable, use a He leak detector to locate the leak; disassemble and 

reassemble the port fitting if necessary and check the O-ring for correct placement and 

pressure. 

• When system is stable, flip both the inlet and outlet oven toggles back to the on position. 
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• An oven bake can also be executed without a leak check by selecting cmdBakeOven from 

the drop-down menu in the “Command table”. 

• Update the Daily Analyzer Checklist and verify values are within expected range. 

4.2.3 OC/EC Analysis 

4.2.3.1 Analysis Preparation 

• Clean the tweezers, flat glass plate, and punching tool with dry KIMTECH wipe. 

• Based on the analysis list, remove the sample to be analyzed from the Styrofoam cooler 

or refrigerator. Verify the sample ID against the analysis list. 

• Remove a sample punch from the filter. 

• Record the Sample ID in the analyzer logbook, along with any comments on the 

condition of the deposit or any other conditions which might affect analysis results. 

4.2.3.2 Loading the Filter Punch 

• Begin the analysis by clicking on “Analysis” in the Welcome window and inputting 

the Project Name, Batch #, and Sub-batch #, verify the Command table is correct and 

enter the Sample ID, Run #, Punch area, Deposit area and Tech Initials. 

• Enter Flags if appropriate (e.g., b1, i4, etc.) 

• After the boat has cooled to 50 C or less, remove the previously analyzed sample 

punch and load the current sample punch. 

• Clean the tweezers, flat glass plate, and punching tool with a dry KIMTECH wipe. 

• Replace the Petri slide or Petri dish containing the filter into the Styrofoam cooler or 

refrigerator. 

• Upon analysis completion, use a small piece of transparent tape to attach the sample 

punch to its thermogram, ensuring that the deposit side is facing up. 

• At the end of the analysis, the push rod will automatically be pulled back to the 

Calibrate position to begin cooling. 
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4.2.3.3 Post Analysis 

• Examine the thermogram for proper laser response, temperature profiles, realistic 

carbon peaks, and the presence of the calibration peak at the end of the analysis. 

Examine the tabular printout to confirm that the calibration peak counts are within 

specifications (see Section 3.1). Finally, examine the laser signal at the end of the run. 

Indicate successful analyses on the sample analysis list by recording the date. Notify 

the lab supervisor of any problems and record them in the log book and on the run 

list. 

• Repeat the above steps for additional samples. 

4.2.4 Special Analyses 

4.2.4.1 System Blanks 

• Go through all the steps for a normal analysis, but do not remove the punch from the 

previous analysis. Proceed with the routine analysis. 

• Use project name “SYSBLK”, Batch # “MM” for the month and Sub-batch # “DD” 

for the day. Punch area and Deposit area should be “1”. 

• Calculated carbon concentrations from the system blank should not be more 0.2 μg 

carbon. Values greater than this warrant an additional system blank or oven bake. 

4.2.4.2 Carbonate Analysis 

• Follow the steps under Routine OC/EC Analysis until the sample punch is loaded into 

the boat. 

• Enter the Sample ID, Run #, Punch area, and Filter area. 

• When prompted for injection, spike 20 μl 0.4 M HCl onto the filter punch. 

• Flush the syringe with Nanopure water between samples. 

• Continue the normal OC/EC analysis when the carbonate cycle is complete, 

following the 20 minute delay allowed for drying. 
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4.2.5 Analyzer Shut-Down: 

• Leave the last analyzed punch in the boat with the boat positioned in the Calibrate 

position. This punch will be used as the system blank the following morning and then 

taped to the corresponding thermogram. 

• Execute the cmdAutoCalibCheck command to verify the analyzer’s performance. 

• When the analysis is complete, record the calibration peak counts and calculated 

injection calibration in the logbook. Any values outside the ranges defined in Section 

3.1 should be investigated and rerun. 

• Backup the day's data files to disk, if not automatically backed up on a server. 

• Remove the printouts and attach them to a file folder labeled with the date and 

analyzer number. Place on the lab supervisor's desk. 

• Turn off the computer monitors. 

• Make a final check of the gas cylinder pressures. 

• Move the samples and blue ice in the Styrofoam cooler or refrigerator back into the 

sample storage freezer and verify that the freezer is completely closed. 

• If the 25 or 50 μl syringe was used for carbonate analysis, thoroughly rinse the 

syringe with Nanopure water and tightly cap all solutions. Store at 4 °C. 

• Lock the carbon analysis room. 
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5 QUANTIFICATION 

5.1 Measurement Calculations 

Section 3.1.3 contains the equations used to determine measurement values. 

5.2 Precision (Uncertainty) Calculations 

Precision is determined from replicate measurements as the average fractional difference 

between original and replicate analysis concentrations. Concentration uncertainty is the 

fractional precision times sample concentration. If sample concentration times fractional 

precision is zero, then the detection limit is used as concentration uncertainty. 

The precision calculation program for chemical analysis methods also allows for rejection of 

outliers and selection of concentration ranges for precision calculations. The uncertainty is 

calculated using the following formulas: 

N

cc

cc

CV

N

i rii

rii

∑= +

−×

= 1 ,

, 2

2 2 Unci i)( +×= MDLcCV

Where CV = coefficient of variance 

N = number of samples 

ci = concentration of initial analysis 

ci,r = concentration of sample “i” replicate analysis 

Unc = uncertainty 
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6 QUALITY CONTROL 

6.1 Performance Testing 

System blanks are performed at the beginning of each day to confirm the system is not 

introducing bias in the carbon results and to confirm that the laser signal is not temperaturedependent. Contamination is potentially due to: 

• Operator practices, such as improper cleaning of tweezers and punch. 

• Teflon particles on the push rod getting into the heated zone of the quartz oven. 

• Sample boat contamination. 

• Contamination of the carrier gas. 

• Fibers left on the punch tool or on the flat glass plate during cleaning. 

• Contamination from field operator. 

• Contamination from normal use of analyzer. 

• Maintenance/part replacement. 

A temperature-dependent laser signal is potentially due to: 

• Physical coupling of the push rod to the boat during the run. 

• Boat movement due to loose boat holder. 

• A quartz rod (laser light pipe) ready for replacement. As quartz is heated to high 

temperatures, devitrification (white deposits of SiO2) occurs that leads to a decrease in 

the laser intensity. The end surface becomes frosty. The bottom light pipe also receives 

droppings of quartz particles from filter discs during analysis. Thus, the bottom light pipe 

will deteriorate faster than the upper light pipe. Microscopic cracks in the quartz rod will 

increase internal reflectance of the laser light; as the number of these cracks multiply, the 

effect of temperature on these cracks, and thus on the reflectance, becomes an 

interference in the laser signal. 

As described in Section 3.1, the calibration peak at the end of each analysis run serves as a 

regular standard; the integrated area under the calibration peak serves as a measure of analyzer 

performance. In addition, the daily injections of two calibration gases further serve as standards. 
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Only a limited set of primary standards (NIST-traceable) currently exist for carbon analysis. 

These do not include a range of organic compounds from low- to high-molecular weights, with 

varying degrees of susceptibility to pyrolysis, or EC and carbonate compounds. The 

cmdAutoCalibCheck command check allows the condition of the catalysts to be monitored and 

verified. 

6.2 Reproducibility Testing 

Replicates of analyzed samples are performed at the rate of one per group of ten samples. The 

replicate is selected randomly and run immediately after each group of ten is completed. The 

random analyzer for the replicate is identified using a chart created in Microsoft Excel (shown in 

Figure 6-1) using the random number generator, which results in replicate analysis on the same 

and different analyzers. 

This practice provides a better indication of potential differences if samples are analyzed by 

different laboratories. The μg/cm2 values for OC, EC and TC are compared with the original 

run. The values should meet the following criteria: 

Range Criteria 

OC, EC & TC < 10 μg/cm2 < ±1.0 μg/cm2

OC and TC > 10 μg/cm2 < 10 % of average of the 2 values 

EC > 10 μg/cm2 < 20 % of average of the 2 values 

Notice that the criteria converge at 10 μg/cm2

. Replicates which do not meet the above criteria 

must be investigated for analyzer or sample anomalies. Analyzer anomalies include poor 

response (as reflected in the calibration peak areas) or poor laser signals affecting the splits 

between OC and EC. Typical sample anomalies include inhomogeneous deposits or 

contamination during analysis or from the field sampling location. Inconsistent replicates for 

which a reason cannot be found must be rerun again unless the filter condition will not allow an 

additional representative punch to be taken. 

When samples are analyzed with an automated sample loader, the sample chamber tray will be 

set up such that the loader number six location will be a replicate of the first sample, the 12th

location a standard spike of sucrose or KHP, and the 18th location a replicate of the sample in 

loader position. 

6.3 Control Charts and Procedures 

Control charts are updated at the beginning of each month. These charts include a month of 

calibration data and are posted in the carbon room until the end of the month, after which they 

are filed with the raw analysis results. 
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Figure 6-1. Example of carbon analyzer replicate checklist. 

.

ORIG RUN

CA6 6 6 12 7 8 14 11 8 11 13 13 14 6 9 7 7 6 10 8 11 14 9 8 13 10 9 7

CA7 14 9 7 7 14 12 12 12 6 9 13 8 11 10 7 12 11 6 7 11 7 13 14 10 12 9 6

CA8 11 9 9 8 14 13 10 13 6 14 14 7 10 6 12 11 8 6 6 6 12 13 8 10 12 11 10

CA9 7 8 9 13 8 9 10 13 6 6 8 6 7 9 7 13 11 10 11 7 14 8 12 14 14 13 11

CA10 9 11 6 8 7 13 11 13 9 14 8 12 9 12 9 7 11 7 11 6 12 9 9 8 11 14 10

CA11 10 12 9 14 9 12 13 11 9 10 7 6 10 8 9 6 11 13 11 11 8 13 12 9 10 7 6

CA12 13 7 14 13 12 14 9 12 14 12 13 13 12 6 7 7 9 9 13 12 11 10 8 6 12 14 11

CA13 14 10 11 9 8 9 8 6 13 12 6 11 10 11 8 11 11 12 7 6 7 7 8 12 10 12 6

CA14 9 9 14 14 12 8 14 6 7 14 6 12 8 9 7 13 7 14 12 7 12 12 12 9 9 8 6

CARBON ANALYZER REPLICATE CHECKLIST

Replicate On

In order to keep track of the replicates between machines on large projects, please use the checklist below by placing an "X" in the appropriate 

box. For example in the first group below, once you have completed 10 runs on the run list, randomly select one QID from those 10 analyses, 

find that analyzer # in the "Orig Run" column and replicate it on the analyzer number listed in the next available box in the "Replicate On" 

section. Place an "X" on that number to indicate the replicate has been done. If an analyzer is not operating, draw a straight line through it and 

go to the next number in the column.

The control chart gives a plot of calibration peak counts as percent deviation from a historical 

mean versus date. Instances where the calibration peak area deviates by more than 10% from the 

historical mean must be investigated and the cause must be corrected. The historical mean 

covers results from the previous three months and is updated either quarterly, when the CH4

calibration gas is changed, when the catalysts are renewed, or when extensive repairs are 

performed. 

6.4 Data Validation 

6.4.1 Analysis Flags 

During Level 0 validation (see Section 6.4.2), unusual conditions of the deposit or analysis 

problems are noted on the analysis printouts. Errors in pre-analysis data entry (e.g., in filter ID, 

punch size, deposit area) are corrected. 

Flags are applied to the Access file created from the analysis results (see Section 6.4.2). The 

analysis flags commonly used are presented in Table 6-1. Note that all results flagged with "v" 

must include a description of the reason for invalidating the sample in the remarks field unless a 

subcode is included which provides additional information (such as v3-“potential 

contamination”). 
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6.4.2 Daily Validation 

Level 0 validation is performed by manually checking the tabular and thermogram printouts the 

day after the analysis is performed. The laboratory supervisor or a designated technician is 

responsible for checking the data. The following items are checked on the tabular data (Figure 

4-3): 

• The filter ID is correct and Punch #. 

• For calibration runs, the tabular and thermogram printouts are checked to make sure 

the catalysts are operating at required level. 

• The analysis date and time is correct. 

• The punch area is correct; errors in entry require that the calculated carbon 

concentrations be recalculated. 

• The deposit area is correct; errors in entry require that the calculated carbon 

concentrations be recalculated by hand. 

• The calibration peak area is in the correct range (Section 3.1). 

• The initial and the final FID baseline readings are within three counts of each other; 

excessive FID baseline drift is a cause for re-analysis. NOTE: Some very heavily 

loaded filters will have an FID baseline drift greater than three counts no matter 

which carbon analyzer the sample is run on; typically a FID baseline drift greater than 

three counts signals either a problem with the sample (e.g., very light or very heavy 

loading) or with the carbon analyzer. 

• The lower laser split time and the upper laser split time are within 10 seconds of each 

other. If the times differ by more than 10 seconds, check that the lower split OC and 

upper split OC differ by no more than 5%. OC values which differ by more than 5%, 

unless due to a small change in laser signal resulting from an extremely clean or very 

dark sample, requires re-analysis. Comments should be added to the data file print out 

as follows: 

– If Regular OC Reflectance split is greater than 5% note “RO” in comments 

field; If Transmittance split is greater than 5% note “TO” in comments field. 

Table 6-1. Common DRI Analysis Flags. 
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Validation Flag Sub Flag Description 

b Blank. 

b1 Field/dynamic blank. 

b2 Laboratory blank. 

b3 Distilled-deionized water blank. 

b4 Method blank. 

b5 Extract/solution blank. 

b6 Transport blank. 

c Analysis result reprocessed or recalculated. 

c1 XRF spectrum reprocessed using manually adjusted background. 

c2 XRF spectrum reprocessed using interactive deconvolution 

d Sample dropped. 

f Filter damaged or ripped. 

f1 Filter damaged, outside of analysis area. 

f2 Filter damaged, within analysis area. 

f3 Filter wrinkled. 

f4 Filter stuck to PetriSlide. 

f5 Teflon membrane separated from support ring. 

f6 Pinholes in filter. 

g Filter deposit damaged. 

g1 Deposit scratched or scraped, causing a thin line in the deposit. 

g2 Deposit smudged, causing a large area of deposit to be displaced. 

g3 Filter deposit side down in PetriSlide. 

g4 Part of deposit appears to have fallen off; particles on inside of PetriSlide. 

g5 Ungloved finger touched filter. 

g6 Gloved finger touched filter. 

h Filter holder assembly problem. 

h1 Deposit not centered. 

h2 Sampled on wrong side of filter. 

h4 Filter support grid upside down- deposit has widely spaced stripes or grid 

pattern. 

h5 Two filters in PetriSlide 

i Inhomogeneous sample deposit. 

i1 Evidence of impaction - deposit heavier in center of filter. 

i2 Random areas of darker or lighter deposit on filter. 

i3 Light colored deposit with dark specks. 

i4 Non-uniform deposit near edge - possible air leak. 
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Table 6-1, continued. 

Validation Flag Sub Flag Description 

m Analysis results affected by matrix effect. 

m1 Organic/elemental carbon split undetermined due to an apparent color 

change of non-carbon particles during analysis; all measured carbon 

reported as organic. 

m2 Non-white carbon punch after carbon analysis, indicative of mineral 

particles in deposit. 

m3 A non-typical, but valid, laser response was observed during TOR analysis. 

This phenomena may result in increased uncertainty of the 

organic/elemental carbon split. Total carbon measurements are likely 

unaffected. 

m4 FID drift quality control failure 

n Foreign substance on sample. 

n1 Insects on deposit, removed before analysis. 

n2 Insects on deposit, not all removed. 

n3 Metallic particles observed on deposit. 

n4 Many particles on deposit much larger than cut point of inlet. 

n5 Fibers or fuzz on filter. 

n6 Oily-looking droplets on filter. 

n7 Shiny substance on filter. 

n8 Particles on back of filter. 

n9 Discoloration on deposit. 

q Standard. 

q1 Quality control standard. 

q2 Externally prepared quality control standard. 

q3 Second type of externally prepared quality control standard. 

q4 Calibration standard. 

r Replicate analysis. 

r1 First replicate analysis on the same analyzer. 

r2 Second replicate analysis on the same analyzer. 

r3 Third replicate analysis on the same analyzer. 

r4 Sample re-analysis. 

r5 Replicate on different analyzer. 

r6 Sample re-extraction and re-analysis. 

r7 Sample re-analyzed with same result, original value used. 

s Suspect analysis result. 
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Table 6-1, continued.

Validation Flag Sub Flag Description 

v Invalid (void) analysis result. 

v1 Quality control standard check exceeded ± 10% of specified concentration 

range. 

v2 Replicate analysis failed acceptable limit specified in SOP. 

v3 Potential contamination. 

v4 Concentration out of expected range. 

v5 Instrument error 

v6 Operator error 

w Wet Sample. 

w1 Deposit spotted from water drops. 

y Data normalized 

y1 XRF data normalized to a sulfate/sulfur ratio of three 

y2 Each species reported as a percentage of the measured species sum 

– If Regular EC Reflectance split is greater than 20% note “RE” in comments 

field; If Transmittance split is greater than 5% note “TE” in comments field. 

• Calculated carbon values for calibration injection runs are within 10% of the current 

mean value for the injected gas type on that analyzer. 

Acceptance runs for pre-fired quartz filters result in < 1.5 μg/cm2

 OC, < 0.5 μg/cm2 EC, and 

< 2.0 μg/cm2 TC for IMPROVE_A thermal protocol. Filters which exceed these levels must be 

re-fired or rejected. 

Items which are found to be okay are underlined in red. Items which have problems are circled 

in red. 

The thermograms are checked for the following (Figure 4-4): 

• The initial FID baseline is flat, indicating that the analyzer has been thoroughly purged 

before analysis began. 

• The final FID baseline prior to the calibration peak is within three millivolts of the initial 

FID baseline; excessive drift is cause for reanalysis. 
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• The laser reflectance signal during the first two minutes, prior to sample introduction to 

the “Analysis” position, appears near the bottom of the graph and shifts position once the 

sample is in the “Analysis” position. The transmittance signal will be out-of-scale until 

the sample is in the “Analysis” position. 

• The laser signal should dip below the initial laser line until O2 is introduced, at which 

point the signal should rise steeply. (For most samples, charring does occur). High 

temperature soot samples may not show this characteristic. 

• The temperature readings reflect stable and smooth temperatures at each level and quick 

transitions between levels. 

• Problems or deviations from normal should be circled in red. If the sample punch taped 

to the thermogram is not white, it is also circled. 

If examination of the tabular and thermogram printouts results in a decision that a sample should 

be reanalyzed, write "Rerun" in red on the printouts and prepare a re-analysis list. This list 

should be posted immediately after the validation is complete, and those samples should be rerun 

as soon as they can be conveniently fit into the current day's analyses. 

Evidence of persistent analyzer problems must be resolved, either by physically examining the 

analyzer or reviewing the problems with the analyzer operator. 

6.4.2.1 Validation of Final Data File 

The following steps are followed to create an Excel or dbf file containing carbon data and to 

perform Level "I" validation on it: 

• Each analyzer will have an Access database containing all of the raw carbon data. 

• A query (manual or automated by connected server) is used to generate the project 

data in μg/cm2

 or μg/filter and a validation report is then generated from this query. 

• The output of the Access query is saved or exported as an Excel file or database 

report for data validation and processing. The MS Excel file naming convention calls 

for a name in the following format: 

 xxOETnnt.xls 

 where: 
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 xx is the two-character project identifier 

 OET is organic/elemental carbon 

 nn is the two- or three-digit batch number (generally used to distinguish between 

different projects for the same client or between sampling quarters for an extended 

project) 

 t is the sample type based on sampler technology: 

 A is agricultural burn emissions dilution sampler 

 C is combination particle/gaseous sampler 

 D is dichotomous sampler for PM2.5, PMcoarse, and PM10

 G is gaseous 

 H is high-volume sampler 

 I is IMPROVE/NPS sampler 

 P is MiniVol Sampler 

 Q is audit samples 

 R is resuspension chamber 

 S is sequential filter sampler (SFS) 

 W is wet Deposition 

 X is unknown 

 Y is y-sampler (DRI source sampler) 

• The final MS Excel or dbf file name is specified on the analysis list posted in the 

carbon room. 

• Begin validation by matching the filters listed on the analysis list with the filters 

listed on the MS Excel or database printout. There must be at least one entry on the 

printout for every filter listed on the analysis list. 

• Flag field and lab blanks while the list is being reviewed by placing "b1", "b2", "b3", 

or "b6" in the second column of the printout. Because the MS Excel or database 

printout is sorted by ID number, replicates and reruns will be grouped together. 

• Indicate missing data by writing the missing filter ID in the margin with an arrow 

drawn to the appropriate place of insertion. Scan the printout for unusual IDs which 

may have been mistyped or misread by the scanner during analysis. Generally, these 

will appear at the beginning or end of the printout, due to the sorting process. Make 

sure that all samples listed on a rerun list appear on the printout. 

• Resolve all missing data. Scan the deposit area column for incorrect entries. Circle 

the incorrect entries to ensure that corrected values replace those currently in the 

database. 
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• Scan the filter IDs for multiple entries of ID numbers. Under normal conditions, the 

only times multiple entries should occur are reruns and replicates. All multiple entries 

must be flagged to indicate the reason for their existence. 

• Scan for missing runs. The most common example is the first run being aborted or 

lost for some reason, and the only entry in the MS Excel file is the second run. An 

entry for the first run must be inserted, flagged as invalid, and labeled as to the reason 

it was invalid. All punches taken from the filters MUST be accounted for and 

documented in the file. 

• Pull the analysis folders and go through the analysis summaries and thermograms one 

by one. Check for the conditions listed in Section 6.4.2 

– Reflectance and Transmittance Regular OC Lower Split and Upper Split are 

within 5% and Regular EC Lower Split and Upper Split are within 20%. OC 

values which differ by more than 5%, unless due to a small change in laser 

signal resulting from an extremely clean or very dark sample, requires 

reanalysis. Comments should be added to the print out as follows: 

• If Regular OC Reflectance split is greater than 5% note “RO” in 

comments field; If Transmittance split is greater than 5% note “TO” in 

comments field. 

• If Regular EC Reflectance split is greater than 20% note “RE” in 

comments field; If Transmittance split is greater than 5% note “TE” in 

comments field. 

– Punch discoloration after analysis is complete (See Table 6.1 for m2 flag) 

• Verify and resolve all circled items and missing flags. 

– Determine if analyses flagged by the operator are legitimate. These flags are 

determined by the operator at the end of the analysis run (Section 6.4) and are 

defined in Table 6-2. 

– If the temporary flag is not warranted, draw a line through the flag to indicate 

that it should be removed. 

– If the sample should be rerun, add it to a rerun list. 

– If the analysis has some anomaly, but still appears to be legitimate, either flag 

or add notes to the comments field as appropriate. 
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– Analysis flags are defined in Table 6-1. 

– Invalid samples without a definitive void flag must have an entry in the 

comments field to describe the reason that the sample is invalid. Typical notes 

and comments are presented in Table 6-3. 

• Scan the OC and EC columns looking for unusually high or low values. At this time 

make sure that the field blanks and/or lab blanks are all close to one another. Circle 

any possible outliers for further investigation. 

• Compare replicates against original run. The values should meet the following 

criteria: 

Range Criteria 

OC, EC & TC < 10 μg/cm2 < ±1.0 μg/cm2

OC and TC > 10 μg/cm2 < 10 % of average of the 2 values 

EC > 10 μg/cm2 < 20 % of average of the 2 values 

• Check the OC/TC ratio. Typical rural samples should not be less than 0.65. Circle 

any possible outliers for further investigation. 

• Scan for records where EC is greater than OC. These may require additional 

investigation, depending on loading and sample source. Circle records for further 

investigation. 

• Scan blanks for OC being greater than 3.95 × deposit area and for EC greater than the 

deposit area. Rerun any unusually high blanks. 

• Compare primary and secondary filters for validity. Secondary filters should have OC 

and EC measurements less than the corresponding primary filter. Typical rural 

secondary filters should have EC < 3.8. OC should be less than or equal to 18. Circle 

any records that require further investigation. 

• All operator-generated flags must be either converted to standard analysis flags 

(Table 6-1) or removed. The flags in Table 6-2 are temporary flags only and are not 

recognized as legitimate analysis flags at DRI. 

• After all thermograms have been reviewed and all possible reruns have been 

identified, post the rerun list in the carbon room and have the reruns done as soon as 

possible. 
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Table 6-2. DRI Carbon Analysis Operator Temporary Data Validation Flags. 

Flag Description 

EI Error in sample ID 

EA Error in sample deposit area 

ST Suspect temperature profile 

SF Suspect FID signal 

SL Suspect laser signal 

Mi Miscellaneous problem 

m2 Non-white sample punch after analysis 

v Invalid run 

r Replicate 

b Blank 

i Inhomogeneous 

f Filter media damaged 

g Sample deposit damaged 

d Sample dropped 

n Foreign substance on filter 

w Sample wet 
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Table 6-3. DRI Carbon Analysis Validation Comments 

Comments Description 

"Anomalous laser" Despite good initial laser, laser signal drifted above initial laser 

signal before dropping (typical of auto emissions). 

"Operator error" Used with "v" flag; operator exited program unexpectedly. 

"Analyzer malfunction" Used with "v" flag; analyzer malfunction or problem beyond the 

control of the operator such as plugged FID, broken oven heater, 

etc. 

"Poor replicate" Replicate is outside the normal criteria, but no reason can be found 

for the discrepancy. 

"Poor initial laser" Used with "v" flag; severe coupling or boat not pushed in time for 

calculation of initial laser signal. 

"Potential contamination" Used with "v" flag; rerun of sample yields lower values or different 

peaks. Typically used with blanks or reruns of replicates. 

“Power failure” Used with "v" flag; power surge or power failure. 
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• Review the data from the reruns, looking for inconsistencies. Confirm that the 

reasons for the rerun have been addressed. Mark the printout with the new values for 

manual insertion into the MS Excel or database file. Previous runs must be flagged as 

invalid or the reruns flagged as replicates. 

• Finally, all comments, flags, insertions, and other changes made to the printout are 

entered into the MS Excel or database file. After all changes are made, generate a 

new printout. Label the new printout with the file name and printout date. Assemble a 

copy of the printout and the MS Excel or database file for the person putting the final 

report together. 
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7 REFERENCES 

Chen, L.-W.A.; Chow, J.C.; Watson, J.G.; Moosmüller, H.; and Arnott, W.P. (2004). Modeling 

reflectance and transmittance of quartz-fiber filter samples containing elemental carbon 

particles: Implications for thermal/optical analysis. J. Aerosol Sci., 35(6):765-780. 

Chow, J.C.; Watson, J.G.; Pritchett, L.C.; Pierson, W.R.; Frazier, C.A.; and Purcell, R.G. (1993). 

The DRI Thermal/Optical Reflectance carbon analysis system: Description, evaluation 

and applications in U.S. air quality studies. Atmos. Environ., 27A(8):1185-1201. 

Chow, J.C.; Watson, J.G.; Crow, D.; Lowenthal, D.H.; and Merrifield, T.M. (2001). Comparison 

of IMPROVE and NIOSH carbon measurements. Aerosol Sci. Technol., 34(1):23-34. 

Chow, J.C.; and Watson, J.G. (2002). PM2.5 carbonate concentrations at regionally 

representative Interagency Monitoring of Protected Visual Environment sites. J. 

Geophys. Res., 107(D21):ICC 6-1-ICC 6-9. 

Chow, J.C.; Watson, J.G.; Chen, L.-W.A.; Arnott, W.P.; Moosmüller, H.; and Fung, K.K. 

(2004). Equivalence of elemental carbon by Thermal/Optical Reflectance and 

Transmittance with different temperature protocols. Environ. Sci. Technol., 38(16):4414-

4422. 

Chow, J.C.; Watson, J.G.; Chen, L.-W.A.; Chang, M.C.; and Paredes-Miranda, G. (2005). 

Comparison of the DRI/OGC and Model 2001 Thermal/Optical carbon analyzers. 

Prepared for the IMPROVE Steering Committee, Fort Collins, CO, by Desert Research 

Institute, Reno, NV. 

Chow, J.C.; J.G. Watson; L.-W.A. Chen; M.C.O. Chang; N.F. Robinson; D.L. Trimble; and S.D. 

Kohl (2007). The IMPROVE_A Temperature Protocol for Thermal/Optical Carbon 

Analysis: Maintaining Consistency with a Long-Term Data Base. JAWMA, 57:1014-

1023. 

Desert Research Institute (2007). Pre-firing of quartz filters for carbon analysis. SOP #2-106r6. 

Desert Research Institute: Reno, NV. 

Fung, K.K. (1986). Personal communication. 

Huntzicker, J.J. (1986). Personal communication. 
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Johnson, R.L. (1981). Development and evaluation of a thermal/optical method for the analysis 

of carbonaceous aerosol. M.S. Thesis, Oregon Graduate Center, Beaverton, OR. 

Johnson, R.L.; Shah, J.J.; Cary, R.A.; and Huntzicker, J.J. (1981). An automated thermal-optical 

method for the analysis of carbonaceous aerosol. In Atmospheric Aerosol: Source/Air 

Quality Relationships, E.S. Macias and P.K. Hopke, Eds. American Chemical Society, 

Washington, DC, pp. 223-233. 

Lin, C.; and Friedlander, S.K. (1988). Soot oxidation in fibrous filters. 2. Effects of temperature, 

oxygen partial pressure, and sodium additives. Langmuir, 4(4):898-903. 

Novakov, T. (1981). Microchemical characterization of aerosols. In Nature, Air and Methods of 

Microchemistry, H. Malissa, M. Grasserbauer, and R. Belcher, Eds. Springer-Verlag, 

Wein, Graz, Austria, pp. 141-165. 

Novakov, T. (1982). Soot in the atmosphere. In Particulate Carbon: Atmospheric Life Cycle, 

G.T. Wolff and R.L. Klimisch, Eds. Plenum Press, New York, NY, pp. 19-41. 

Rau, J.A. (1986). Residential wood combustion aerosol characterization as a function of size 

and source apportionment using chemical mass balance modeling. Ph.D. Dissertation, 

Oregon Graduate Center, Beaverton, OR. 

Rosen, H.; Hansen, A.D.A.; Dod, R.L.; Gundel, L.A.; and Novakov, T. (1982). Graphitic carbon 

in urban environments and the Arctic. In Particulate Carbon: Atmospheric Life Cycle, 

G.T. Wolff and R.L. Klimisch, Eds. Plenum Press, New York, NY, pp. 273-294. 
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8 CHANGE DOCUMENTATION 

7/24/2008 – Made following changes to document: 

• Revised cover page to include signature lines 

• Updated Section 2 (Apparatus, Instrumentation, Reagents and Forms) with current 

information and forms 

• Updated Figures 2-1 and 2-3 with more current and detailed information 

• Renamed Quantification to Calibration and moved to Section 3 

• Moved Temperature Calibration to Section 3 

• Updated text and formulas in Section 3.1.3.1 under preparation of standards for 

clarification and accuracy. 

• Updated Figure 3-4 with new worksheet and new volumes. 

• Moved Procedures to Section 4 and updated to include additional details where needed 

• Moved Quantification to Section 5; added precision calculations. 

• Updated Quality Control (Section 6) 

• Updated References as needed (Section 7) 

• Added Section 8 (Change Documentation) 

• Added Section 9 (Appendix A) 
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APPENDIX A: Abbreviations and Acronyms 

°C Degrees Celsius 

μg/m3 Micrograms per cubic meter 

μl Microliters 

Cal Gas Calibration Gas 

Calibration 

Injection 

The injection of calibration gases, either CO2 or CH4, into the sample stream 

at the beginning and end of each work day to check instrument performance. 

Calibration Peak The FID peak resulting from the automatic injection of methane calibration 

gas (CH4/He) at the end of each analysis run for each sample. All integrated 

peak areas are divided by the calibration peak area and multiplied by an 

instrument-specific calibration factor to obtain μg carbon per sample punch. 

Chemicals Used: 

H2 Hydrogen 

HF Hydrofluoric Acid 

HCl Hydrochloric Acid 

He Helium 

CO2 Carbon Dioxide 

CH4 Methane 

O2 Oxygen 

Na Sodium 

SiO2 Silicon Dioxide 

K Potassium 

KHP Potassium hydrogen pthalate 

V Vanadium 

Cr Chromium 

Mn Manganese 

MnO2 Manganese Dioxide 

Co Cobalt 

Ni Nickel 

Cu Copper 

Pb Lead 

DRI Desert Research Institute 

EC Elemental Carbon 

EC1 Carbon evolved from the filter punch in a 98% He/2% O2 atmosphere at 580 

°C. 

EC2 Carbon evolved from the filter punch in a 98% He/2% O2 atmosphere from 

580 to 740 °C. 

EC3 Carbon evolved from the filter punch in a 98% He/2% O2 atmosphere from 

740 to 840 °C. 

Elemental 

Carbon (EC) 

Carbon evolved from the filter punch in a 98% He/2% O2 atmosphere at 580, 

740, and 840 °C minus any pyrolyzed OC. 
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FID Flame Ionization Detector 

FID Split Time The time at which the laser split occurs plus the transit time required for 

thermally evolved carbon to travel from the sample punch to the FID. 

GC Gas Chromatography 

GC/MS Gas Chromatography/Mass Spectrometry 

High 

Temperature EC 

Carbon evolved from the filter punch in a 98% He/2% O2 atmosphere at 740 

and 840 °C minus any pyrolyzed organic carbon present in these two peaks. 

This is EC minus the first EC peak (EC1). 

High 

Temperature OC 

Carbon evolved from the filter punch in a He-only atmosphere at 280, 480, 

and 580 °C plus pyrolyzed organic carbon. This is OC minus the first OC 

peak (OC1). 

IMPROVE Interagency Monitoring of PROtected Visual Environments 

IMPROVE_A 

Thermal Protocol 

A thermal protocol is used in carbon analyzers to quantify carbon fractions 

evolved at different temperature plateaus. The IMPROVE_A thermal 

protocol derives from the IMPROVE thermal protocol initiated in 1987 

(Chow et al., 2005). 

Laser Split The separation between OC and EC, which depends on the laser-measured 

reflectance and/or transmittance of the filter punch returning to its initial 

value. At this point all pyrolyzed OC has been removed and EC is beginning 

to evolve. 

Lower Split Time The time at which the laser-measured reflectance and/or transmittance of the 

filter punch reaches its initial value minus the precision of the laser signal 

(currently defined as 10 counts). 

LQL Lower quantifiable limit 

M Mole 

MDL Minimum detection limit 

NIST National Institute of Science and Technology 

OC Organic Carbon 

OC1 Carbon evolved from the filter punch in a He- only (>99.999%) atmosphere 

from ambient (~25 °C) to 140 °C. 

OC2 Carbon evolved from the filter punch in a He- only (>99.999%) atmosphere 

from 140 to 280 °C. 

OC3 Carbon evolved from the filter punch in a He- only (>99.999%) atmosphere 

from 280 to 480 °C. 

OC4 Carbon evolved from the filter punch in a He- only (>99.999%) atmosphere 

from 480 to 580 °C. 

OP The carbon evolved from the time that the carrier gas flow is changed from 

He to 98% He/2% O2 at 580 °C to the time that the laser- measured filter 

reflectance (OPR) or transmittance (OPT) reaches its initial value. A 

negative sign is assigned if the laser split occurs before the introduction of 

O2. 

OPR Pyrolyzed carbon measured by reflectance 
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OPT Pyrolyzed carbon measured by transmittance 

Organic Carbon 

(OC) 

Carbon evolved from the filter punch in a He- only (>99.999%) atmosphere 

at 140, 280, 480 and 580 °C plus pyrolyzed organic carbon. This is the same 

as Volatile Organic Carbon (VOC) plus high- temperature OC. 

psi Pounds per square inch 

Pyrolysis The conversion of OC compounds to EC due to thermal decomposition; this 

may be envisioned as "charring" during the organic portion of the analysis. 

QA Quality Assurance 

QC Quality Control 

Regular Split 

Time 

The time at which the laser-measured reflectance and/or transmittance of the 

filter punch reaches its initial value. 

SiO2 Silicon Dioxide 

STN Speciation Trends Network 

TC Total Carbon 

TOR Thermal/Optical Reflectance 

TOT Thermal/Optical Transmittance 

Total Carbon 

(TC) 

All carbon evolved from the filter punch between ambient and 840 °C under 

He and 98% He /2% O2 atmospheres. 

VOC Volatile Organic Carbon 

UHP Ultra-High Purity 

Upper Split Time The time at which the laser-measured reflectance and/or transmittance of the 

filter punch reaches its initial value plus the precision of the laser signal 

(currently defined as 10 counts). 

ΔT Temperature Deviation