Pall Corporation Comments To: 

United States Environmental Protection Agency 

Docket ID EPA–HQ–OAR–2011–0344 

National Emission Standards for Hazardous Air Pollutants: 

Secondary Lead Smelting 

Federal Register Volume 76, Number 97, pages 29032 to 29081, Thursday May 19th, 

2011 

Krag Petterson, Douglas Barth, Marty Ladner, Brent VanZandt, Joseph Kelly 

Pall Corporation 

3669 Route 281 

Cortland, NY 13045 

Pall Corporation is a Fortune 1000 Business and the world leader in filtration products. 

Pall has recently acquired an exclusive license to sell and manufacture the Xact*

(previously manufactured by Cooper Environmental Services, LLC) an X-ray based 

continuous emissions monitor for lead and other metals. 

Direct Correspondence to Krag Petterson, krag_petterson@pall.com 607-778-0158 

*

Xact is a trademark of Cooper Environmental Services, LLC 
    2

1.0 Introduction

On May 19th, 2011 the EPA proposed new National Emission Standards for secondary 

lead smelters. As part of this proposal, EPA is expressly seeking comments and 

information on the use of lead (Pb) continuous emissions monitoring systems (CEMS) to 

monitor lead from point sources at these smelters saying: 

“We are seeing comments and information on the feasibility of applying 

this technology for monitoring lead emissions from these sources and the 

potential to require CEMS on existing sources in the source category.”1 

Pall Corporation (Pall) has recently acquired the exclusive license to sell and manufacture 

the Xact, an X-ray fluorescence based multi-metals continuous emissions monitor 

capable of monitoring up to 20 metals, including lead. This instrument has been used for 

several years as part of a hazardous waste incinerator’s Alternative Monitoring Petition 

(AMP)2 at Eli Lilly’s Tippecanoe Laboratories. It has been Method 301 approved by the 

US EPA,3,4 has been the recipient of the EPA’s Clean Air Excellence Award,5 and has 

passed annual relative accuracy test audits (RATAs) at Eli Lilly’s hazardous waste 

incinerator for five years. This technology has demonstrated that it is reliable, produces 

accurate and precise concentration data, and can be used in a wide variety of applications 

on a diverse set of source types. 

Pall believes that it is feasible to use this technology to measure source emissions from 

secondary lead smelters. In these comments, Pall is supplying data to show that the Xact 

has demonstrated: 

1. Stable, reliable operation, 

2. Accuracy, 

3. Operation in a wide variety of sampling conditions, and 

4. Wide measurement range that is more than adequate to meet the monitoring 

 requirements of secondary lead smelters. 

In addition to this data, Pall is proposing performance specifications and on-going quality 

assurance (QA) procedures for Pb CEMS that will 1) provide adequate demonstration of 

instrument accuracy, and 2) are general enough to be useful for many different types of 

potential lead measurement technologies. These performance specifications and on going 

QA procedures are those that have been used for several years to demonstrate the 

accuracy of the Xact as multi-metal CEMS and have been rewritten to specifically 

address lead. The performance specifications and on-going QA procedures can be found 

in Appendices A and B, respectively, of this document. In addition, we have provided 

supporting documentation on a reference aerosol generator that is used in the 

performance specification and as an annual auditing device for on-going QA. This 

document, Traceability Protocol for Reference Aerosol Generators,6

 was produced by 

Cooper Environmental Services, LLC as part of an EPA funded project. 

   
    3

2.0 Principle of Measurement

The Xact operates by withdrawing a large sample of stack effluent from the source and 

transporting it to a stilling chamber where the flow is slowed or stilled. A subsample of 

this main flow is then drawn through a reactive filter tape mounted on a reel-to-reel type 

tape drive. The filter tape captures both vapor phase and particulate phase metals. 

Following sampling, the sample deposit is automatically advanced into the analysis area 

where the deposited metal mass (including lead) is determined using X-ray fluorescence 

(XRF) while the next sample is collected. The stack concentration (μg/m3) is determined 

by dividing the XRF determined mass (μg) by the total sample flow through the tape 

(m3). 

The core technologies of the Xact have been used extensively for years in a variety of 

applications. Reel-to-reel tape drives have been used for decades on beta gauge 

instruments that measure particulate matter (PM) in the air. There are literally thousands 

of operating instruments deployed utilizing this technology. XRF has been used in a 

wide variety of applications for years and has demonstrated that it is a rugged and robust 

technology. XRF has been used for metals measurement on Mars and the sea floor, and 

is now commonly used in handheld devices for determining Pb content in paint and for 

determining alloy types in scrap metal. The EPA has long approved the use of XRF for 

the measurement of metals on filter samples to determine the concentration of metals in 

ambient air. The procedures for making these measurements can be found in the EPA 

Compendium of Methods for the Determination of Inorganic Compounds in Ambient 

Air7

 and are the basis for the XRF measurement methods used by the Xact. 

3.0 Method 301 Approval

In 2005, the Xact demonstrated its measurement accuracy and precision on a thermal 

hazardous waste incinerator using EPA Method 3018

 which is the procedure by which 

new emissions measurement technologies are approved. During this test the Xact was 

challenged with aerosol concentrations traceable to NIST standards and containing 

arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg) and lead (Pb) at three 

different concentration levels (20, 60 and 130 μg/m3). These concentrations were 

generated using a reference aerosol generator that was itself Method 301 approved. The 

average relative accuracy for all five metals over all three concentrations was 8.3%.4

 In 

addition, the linearity of the Xact’s response over this measurement range was also 

determined by plotting the Xact reported concentration against the known aerosol 

concentration. A linear, least squares fit was performed and the results of this fit can be 

seen in Figure 1.4 

   
    4

y = 0.952x - 1.10

r = 0.995

n = 960 

0

20

40

60

80

100

120

140

0 20 40 60 80 100 120

Xact Concentration (μg/dscm) 

a

QAG Reference Concentration (μg/dscm) 

Cr

As

Hg

Pb

Cd

Figure 1. Xact Method 301 Results 

The Xact passed all criteria required by Method 301 and was approved by the EPA for 

compliance monitoring on Eli Lilly’s hazardous waste incinerator. 

4.0 QA Procedures

The Xact determines concentrations in stack effluent by dividing the XRF determined 

metal mass by the volume of sample through the tape. The Xact utilizes several 

automated QA procedures to check the on-going accuracy of these two measurements. 

These QA procedures are outlined below and several of these QA procedures have been 

accepted by the EPA and published in the form of class C Other Methods.9,10

4.1. X-ray Fluorescence Quality Assurance 

4.1.1. Stability check with every sample 

X-ray fluorescence has the unique ability to be able to measure multiple elements 

simultaneously. This makes it possible to use a rare element, not likely to be present in 

the sampled aerosol, to check the stability of the Xact’s XRF analyzer. The Xact does 

this by measuring the instrument’s response to a palladium (Pd) rod fixed into a stable 

position under the sample tape. The Xact’s response at the time of calibration is 

compared to the response during each and every sample analysis. This means that XRF 

analysis on every value reported by the Xact is quality assured. 

   
    5

4.1.2. Daily Upscale 

One time each day, a rod with a small mass of metals on the tip is inserted into the 

analysis area. These metals are typically those most critical to measure, such as lead for a 

lead monitor. This technique checks the stability of the upscale response once per day. 

4.1.3. Daily Zero or Blank 

Additionally, the Xact analyzes a blank (unsampled) section of tape one time per day. 

This blank does not contain metals and this check helps insure that there is no 

contamination impacting the analysis for any of the key metals of interest. 

4.1.4. XRF Audits 

The Xact can also be audited periodically using thin film standards with certified areal 

concentrations in terms of μg/cm2. These thin film standards consist of metals vapor 

deposited on Nucleoporea

 substrates. The mass of the standard is measured before and 

after the vapor deposit using a NIST traceable balance. These standards are produced 

commercially by Micromatterb and are recommended by EPA IO 3.37 for calibration of 

XRF equipment used to measure ambient filter concentrations. These standards can be 

inserted into the analysis area to check the accuracy of the XRF analyzer portion of the 

XactTM. 

4.2. Flow Quality Assurance 

4.2.1. Daily flow check 

One time per day the flow measured by the Xact’s sample flow meter is compared to the 

flow as measured by a second flow meter. This second flow meter is only used during 

this flow check and is calibrated to the same reference flow meter as the Xact’s sample 

flow meter. This check ensures the stability of the Xact’s sample flow meter. 

4.2.2. Flow Audits 

The sample and quality assurance flow meter can be checked periodically using a NIST 

traceable reference flow meter to ensure the accuracy of the flow measurements. 

4.3. Total Instrument Checks 

On an annual basis, the Xact can be challenged with a reference aerosol with 

concentrations traceable to NIST standards. This procedure involves dynamically 

spiking the Xact at a point as close as possible to the probe and comparing the spiked 

concentration to the concentration reported by the Xact over a range of concentrations. 

This procedure challenges the entire Xact system including the transport line, the 

   

 

a

 Nuclepore is a registered trademark of Whatman, Inc. 

b

 Micromatter is a registered trademark of Advanced Applied Physics Solutions 
    6

sampling system, and the XRF analyzer. Figure 2 shows a diagram of the dynamic 

spiking arrangement as it has been performed as part of an Alternative Monitoring 

Petition. 

Figure 2. Diagram of Dynamic Spiking Protocol 

   
    7

5.0 Stability

5.1. Daily Flow Checks

The Xact has demonstrated its reliability with over five years of operation on a hazardous 

waste incinerator. Over the course of that time, the Xact demonstrated excellent 

measurement stability passing every quarterly audit and every annual RATA. 

Additionally the Xact demonstrated excellent stability on daily flow, zero and upscale 

XRF checks as well as excellent stability on the check of XRF stability that occurs with 

every sample. Figures 3 and 4 show the stability of the daily upscale and flow checks 

over the course of a year between March 2006 and March 2007. 

Xact Upscale March 2006 - March 2007

0

500

1000

1500

2000

2500

Feb-06 May-06 Aug-06 Nov-06 Mar-07

Date

Concentration (μg/dsc

m

Cd

Cr

Hg

Pb

Figure 3. Xact Daily Upscale Stability Over the Course of a Year 

   
    8

-10.00

-5.00

0.00

5.00

10.00

3000

Date

Percent Differenc

e

Figure 4. Daily Flow Stability over the Course of a Year 

5.2. Quarterly Audits

The Xact was required under the hazardous waste incinerator’s Alternative Monitoring 

Petition to have less than 10% error on quarterly audits for each regulated element 

(chromium, arsenic, cadmium, mercury and lead) and less than 10% flow error for each 

audit. Over the last five years the overall average XRF audit error was 1.6% while the 

overall average flow error was 1.8%. Table 1 shows the data for every flow and XRF 

audit for which data was available. 

   
    9

Table 1. Xact Flow and Audit Data

Cr As Cd Hg Pb

1 3/1/2007 3.04% 1.46% 2.18% 2.84% 1.75% 2.34%

2 5/25/2007 3.13% 3.32% 0.13% 4.23% 2.60% 2.96%

3 8/29/2007 0.68% -3.74% 2.18% -4.13% 2.36% 2.76%

4 12/26/2007 1.42% 6.50% 0.36% 7.36% 4.18% 0.40%

1 2/15/2008 NA 0.22% 0.11% 1.20% -0.99% 0.87%

2 3/17/2008 1.07% 1.93% 0.66% 1.82% 2.16% 2.34%

3 5/20/2008 0.53% 2.96% 2.61% 3.30% 2.53% 0.68%

4 10/20/2008 1.37% 1.77% 0.72% 1.48% 0.56% 1.06%

1 1/7/2009 2.10% 0.60% 2.94% 1.52% 3.45% 0.46%

2 5/6/2009 3.67% 1.49% 4.09% 1.07% 1.78% 0.30%

3 7/9/2009 0.84% 2.00% 5.43% 2.78% 0.72% 0.22%

4 NA NA NA NA NA NA NA

1 1/12/2010 NA 1.60% 5.13% 0.45% 0.71% 2.11%

2 4/25/2010 NA 1.61% 5.92% 1.12% 4.00% 0.96%

3 7/13/2010 1.68% -3.47% -0.92% -2.82% -2.42% -2.11%

4 12/10/2010 NA 2.00% 0.82% 2.70% 1.83% 2.91%

1.77% 1.35% 2.16% 1.66% 1.68% 1.22%

NA - Data Not Available

2009

2010

XRF Audit Error

Flow Error

AVE

Audit Year Quarter Audit Date

2007

2008

5.3. Annual Relative Accuracy Test Audits (RATA)

Annual relative accuracy test audits were also a part of the Xact’s quality assurance 

procedures required by Eli Lilly’s Alternative Monitoring Petition. These RATAs 

consisted of challenging the Xact with a reference aerosol containing each of the five 

metals regulated at the facilities (a description of this procedure can be found in Section 

4.3 of this document). The reported Xact concentration was plotted against the reference 

aerosol concentration for each metal and the slope, intercept and correlation coefficient 

for each fit was determined. The Xact meet these criteria for each of the six RATAs 

performed. The slope of the best fit line for each of these RATAs can be found in Table 

2. 

Table 2. Xact RATA Results 

Cr As Cd Hg Pb Average

2006 0.83 0.90 0.85 0.82 0.85 0.85

2006 (Quarterly) 0.91 0.77 0.95 0.92 0.93 0.89

2007 0.84 0.82 0.88 0.84 0.81 0.84

2008 0.96 0.71 0.98 0.99 0.97 0.92

2009 0.96 0.99 0.99 1.10 1.00 1.01

2010 0.97 1.06 1.11 1.02 1.04 1.04

Average 0.91 0.87 0.96 0.95 0.93 0.93

Year

Slope

   
    10

6.0 Source Types Sampled by the Xact

6.1. Overview

In addition to the testing that has taken place at a hazardous waste incinerator, the Xact 

has been tested at several different types of combustion facilities, including: 

1. A US Army Demilitarization Furnace 

2. A pilot scale coal combustion source 

3. A full scale coal fired power plant 

These facilities constitute a diverse range of fuel types, controls, stack temperatures and 

stack conditions. Table 3 summarizes the types of sources and some of the stack 

characteristics at those sources. More detail on each test is contained in Sections 6.2 to 

6.4. 

Table 3. Summary of Sampling Conditions for Xact Testing 

Source Type Fuel Controls Stack 

Temp (oF) 

PM (μg/m3) HCl (ppm) 

Hazardous 

Waste 

Incinerator 

Natural Gas ESP and 

Wet 

Scrubber 

120 8 to 16 

mg/m3 

10 ppm 

Demilitarization 

Incinerator 

Diesel Fuel Baghouse 500 10 mg/m3 ? 

Pilot Scale Coal 

Combustor 

Bituminous ESP and 

Wet 

Scrubber 

120 ? ? 

Coal Fired 

Power Plant 

subbituminous

ESP 300 275 ? 

Many lead smelters are natural gas fired and operate with fabric filter (baghouse) 

controls. The Xact has demonstrated accurate measurement of lead on natural gas 

sources and on sources using baghouses.11 ICR data from the four individual facilities 

available on the Docket as of 6/21/11 also indicates that typical PM concentrations 

downstream of controls at secondary lead smelters are around 1 to 2 mg/m3, significantly 

   
    11

less challenging than the conditions in which the Xact has already demonstrated accurate 

measurement.12,13,14,15 Finally typical lead smelter outlet temperatures range from about 

300oF to 430oF. The Xact has demonstrated accurate lead measurement in conditions up 

to 500o

F. 

6.2. Pb Accuracy Testing at a Demilitarization Incinerator

In 2002, the Army Core of Engineers sponsored a study that compared the concentrations 

reported by the XCEM to that of Method 29. The XCEM was a prototype to the current 

Xact that utilized the same filter media and XRF analysis. This test was performed on a 

U.S. Army munitions demilitarization furnace in Toole, Utah. This facility burns diesel 

fuel and is equipped with a baghouse. Typical PM concentrations are around 10mg/dscm 

and the stack exit temperature is around 500o

F.16 

During testing, munitions were incinerated and metals solutions were then spiked into the 

emission stream downstream of the furnace. Concentrations of lead (Pb), and other 

metals were measured with paired Method 29 trains and with the XCEM at 

approximately the same location in the stack. Lead concentrations ranged from about 25 

to 150 μg/dscm. Figure 5 shows a plot of the average reported XCEM concentration 

versus the average Method 29 lead concentration. The slope of the best fit line is 1.09, 

indicating excellent agreement between the XCEM and Method 29. The relative 

accuracy the XCEM was also calculated and found to be 4.4% again indicating excellent 

agreement between the XCEM and method 29.16 

M29 vs. Xact Prototype

y = 1.09x - 9.60

R2

 = 0.98

0

20

40

60

80

100

120

140

160

180

0 50 100 150 200

M29 Pb (μg/dscm)

Xact Pb (μg/dscm)

Figure 5. Comparison of Xact Prototype Versus M29. 

   
    12

6.3. Multi-metals on a Coal Fired Source

As part of a Small Business Innovative Research (SBIR) funded grant, the Xact 

participated in a test designed to determine the feasibility of using the instrument on coal 

fired incineration sources. This study took place at the US EPA’s Multi-Pollution 

Control Research Facility (MPCRF), located in Research Triangle Park North Carolina. 

The MPCRF is a pilot-scale combustor operated by the Air Pollution Technology Branch 

(APTB) of the EPA’s National Risk Management Research Laboratory. The MPCRF is 

able to fire pulverized coal, distillate oil, and/or natural gas at 4 million Btu/hr. The 

MPCRF is equipped with wet and dry flue gas cleaning systems and closely simulates 

full-scale emission sources. During this study the facility burned bituminous coal with 

ESP and wet scrubber controls. The Xact extracted a sample of stack effluent 

downstream of all controls. This extracted effluent was dynamically spiked with five 

different metals (chromium, arsenic, cadmium, mercury and lead) at three different 

concentration levels (27, 92, 250 μg/dscm) using a reference aerosol generator. These 

spiking procedures are identical to those performed on the hazardous waste incinerator 

and to those proposed as performance specifications and on-going quality assurance in 

appendices A and B of this document. 

Figure 6 shows a plot of the Xact reported concentration versus the reference aerosol 

concentration. The slope of the best fit line shows a slope of 1.09 indicating excellent 

agreement between the reference aerosol and the Xact reported concentrations for all 

metals. Figure 7 shows the same plot, but for lead only. In this case the slope is 0.99, 

indicating nearly perfect agreement between the Xact reported lead concentration and the 

reference lead concentration.17 

y = 1.0949x + 0.1847

R2

 = 0.9918

0

50

100

150

200

250

300

350

0 50 100 150 200 250 300

Reference Aerosol Concentration (μg/dscm)

Xact Reported Concentration (μg/dscm)

Cr

As

Cd

Hg

Pb

Figure 6. Xact Reported Concentrations versus Reference Aerosol Concentrations 

on a Coal-Fired Pilot Scale Source

   
    13

y = 0.9977x - 0.4203

R2

 = 0.9993

-50

0

50

100

150

200

250

300

0 50 100 150 200 250 300

Reference Aerosol Pb Conc. (μg/m3)

Xact Pb Conc. (μg/m3)

Figure 7. Xact Reported Pb Concentrations versus Reference Aerosol Pb 

Concentrations on a Pilot Scale Coal-Fired Source 

6.4. Mercury at a Coal Fired Power Plant

The measurement accuracy of the Xact has also been tested on a full scale coal 

combustion source. In 2008, the Xact was deployed for several weeks at coal fired 

electric generating facility in the northwest. This facility is a 585 MW electric generating 

station burning pulverized coal and operating with electrostatic precipitator (ESP) 

controls. The Xact was deployed at the sampling level and operated there for three 

weeks. As part of the testing the Xact was compared against Method 30B under the 

procedures described by Performance Specification 12A. Figure 8 below shows the Xact 

test results for each measured point versus Method 30B. The Xact’s relative accuracy for 

the test was 3.5%, which is well below the PS-12A criteria of 20%.18,19 Although lead 

was not measured in this study, at the request of the host site, this study does demonstrate 

the ability of the Xact to make accurate measurements on a full scale coal combustion 

source. 

   
    14

0

1

2

3

4

5

6

7

8

9

10

0 1 2 3 4 5 6 7 8 9 10 11 12 13

RATA Number

Mercury Conc. (g/dscm)

Xact

Method 30B

Figure 8. Xact Comparison With Method 30B 

7.0 Measurement Range

The EPA has proposed a facility wide MACT standard for Pb emissions from secondary 

lead smelter stacks of 0.20 mg/dscm with an individual stack limit of 1 mg/dscm. The 

Xact has demonstrated linearity from its detection limit for lead of 0.0004 mg/m3 (with 

15 minute sampling and analysis time) to an upper end of nearly 2 mg/m3. Since the 

highest recorded lead concentration in ICR test is 1.6 mg/m3, the Xact’s analytical range 

is more than adequate to meet the monitoring requirements of this industry. Sections 7.1 

and 7.2 document how the Xact’s measurement range was determined. 

7.1. Testing to determine the upper limits 

As part of developing its alternative monitoring petition, Eli Lilly performed a study to 

determine the upper limits of the Xact’s quantitative range. During that study, the Xact 

was challenged at several concentration levels up to about 2500 μg/m3 using a reference 

aerosol. The Xact reported concentration was compared to the reference aerosol 

concentration, and a linear least squares fit was performed. Figure 9 shows the results for 

this linearity testing for lead. 

   
    15

y = 0.7588x + 13.157

R2 = 0.9949

0.00

500.00

1000.00

1500.00

2000.00

2500.00

0.00 500.00 1000.0

0

1500.0

0

2000.0

0

2500.0

0

3000.0

0

Reference Pb Conc (μg/m3)

Xact Pb Conc (μg/m3)

Figure 9. Lead Quantitative Range Testing. 

7.2. Detection Limits 

The Xact’s detection limits for lead and several other metals were determined 

immediately after initial deployment on a hazardous waste incinerator. The detection 

limit represents the 95% confidence interference-free limit and is based on the analysis of 

3899 individual blank samples. This represents one of the most rigorous determinations 

of a minimum detection limit for a continuous emissions monitor anywhere. 

8.0 Conclusions 

The EPA has specifically requested comments on whether it is feasible to monitor lead at 

secondary lead smelters with a CEMS, and the answer is emphatically yes! The Xact has 

demonstrated its accuracy, reliability, and stability for five years on a hazardous waste 

incinerator. It has also demonstrated measurement accuracy on a wide variety of sources 

encompassing a large range of fuel types, controls, and stack conditions, including 

conditions similar to those found on secondary lead smelters. Finally, the measurement 

range is more than adequate to meet the monitoring needs of secondary lead smelters. 

The performance specifications and on-going quality assurance procedures presented in 

appendices A and B are nearly identical to those used for years at Eli Lilly’s hazardous 

waste incinerator. They supply a robust quality assurance and quality control regime that 

will ensure that emissions data collected from secondary lead smelters are accurate. 

9.0 References 

1. National Emissions Standards for Hazardous Air Pollutants: Secondary Lead 

Smelting. Federal Register Vol. 76. No. 97. May 19, 2011. 

   
    16

2. Eli Lilly and Company. 2005. Alternative Monitoring Petition for the SolidLiquid Incinerator, Tippecanoe Laboratories: Lafayette, IN. 

3. Cooper, J.A., Johnsen, B.E., Barth, D.C., Ginochio, P.R., Nakanishi, M.P., 

Petterson, K.A., and Yanca, C.A. Method 301 Evaluation of Three Methods for 

Multi-Metals Measurement and Validation; Cooper Environmental Services: 

Portland, OR. 2005. 

4. Yanca, C.A.; Barth, D.C.; Petterson, K.A.; Nakanishi, M.P.; Johnsen, B.E.; 

Cooper, J.A.; Lambert, R.H.; Bivins, D.G. 2006. Validation of Three New 

Methods for Determination of Metal Emissions using a Modified EPA Method 

301. J. Air & Waste Manage. Assoc., 56, 1733–1742. 

5. 2006 Clean Air Excellence Award for Development of the Xact Muli-Metals 

CEMS. http://www.epa.gov/air/cleanairawards/winners-2006.html, accessed June 

24, 2011. 

6. Siemers, A.; Petterson, K.A.; Cooper, J.A.; Barth, D.; Draft Traceability Protocol 

for Certification of Reference Aerosol Generators.; EPA Contract EP-D-05-096. 

April, 2011. 

7. EPA Compendium of Methods for the Determination of Inorganic Compounds in 

Ambient Air. June, 1999. Compendium Method IO-3.3 Determination of Metals 

in Ambient Particulate Matter Using X-Ray Fluorescence (XRF) Spectroscopy. 

EPA/625/R-96/010a. U.S. Environmental Protection Agency. 2005. Method 301, 

Field Validation of Pollution Measurement Methods for Various Media; Code of 

Federal Regulations, 40 CFR 56; U.S. Government Printing Office: Washington, 

DC. 

8. U.S. Environmental Protection Agency. 2005. Method 301, Field Validation of 

Pollution Measurement Methods for Various Media; Code of Federal 

Regulations, 40 CFR 56; U.S. Government Printing Office: Washington, DC. 

9. Other Test Method 16. Specifications for X-ray Fluorescence Based Multi-Metals 

CEMS at Stationary Sources. http://www.epa.gov/ttnemc01/prelim/otm16.pdf. 

Accessed June 24, 2011. 

10. Other Test Method 20. Quality Assurance Requirements for X-Ray Fluorescence 

Based Multi-Metals CEMS at Stationary Sources. 

http://www.epa.gov/ttnemc01/prelim/otm20.pdf. Accessed June 24, 2011 

11. Draft Summary of the Technology Review for the Secondary Lead Smelting 

Source Category. US Environmental Protection Agency. EPA-HQ-OAR-2011-

0344-0055. Accessed June 24, 2011. 

12. 2010 ICR Required Source Emissions Testing Data for Metal HAP and 

Particulate. Prepared for Saunders Lead Company, Troy, Alabama by URS 

   
    17

Corporation, Franklin TN. EPA-HQ-OAR-2011-0344-0064. Accessed June 24, 

2011. 

13. Gopher Resource Corporation ICR Data, Gopher Resource Corporation, Eagan 

MN. EPA-HQ-OAR-2011-0344-0067. Accessed June 24, 2011. 

14. Excide Vernon ICR Response. Excide Technologies Vernon, CA. EPA-HQOAR-2011-0344-0065. Accessed June 24, 2011. 

15. East Penn ICR Response, East Penn Manufacturing Co. Inc. EPA-HQ-OAR2011-0344-0066. Accessed June 24, 2011. 

16. Hay, J. K., Boddu, V., Johnsen, B. H., Cooper, J. A.; X-ray Fluorescence Based 

Multi-Metal Continuous Emissions Monitor. US Army Core of Engineers, 

Construction Research Engineering Laboratory, March 2005. Document ID: 

ERDC/CERL TR-05-09. http://www.dtic.mil/cgibin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA433778. Accessed 

6/29/2011. 

17. Cooper Environmental Services LLC. Feasibility of Monitoring Heavy Metal 

Emissions from a Coal Fired Hazardous Waste Incinerator Using a Multi-Metal 

Continuous Emissions Monitor. EPA Contract ID EP-D-07-026. April 30, 2007. 

http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/ab

stract/8311/report/F. Accessed June 21, 2011. 

18. Continuous X-Ray Fluorescence Mercury Emissions Monitor, Unofficial Relative 

Accuracy Test Audit. Avogadro Group, LLC. April 28, 2009. 

19. Petterson, K.A., Cooper, J.A., Pittenger, T., Nakinishi, M., Doherty, J., Ladner, 

M.; Using the Xact Multi-Metals CEMS as a Mercury Monitor on a Coal-Fired 

Power Plant: A Feasibility Study; Presented at Energy Utility Environment 

Conference, February, 2011. 

   
    18

Appendix A 

Performance Specification ZZ. Specifications and Test Procedures for Lead 

Continuous Emissions Monitoring Systems on Stationary Sources. 

1.0 Scope and Application 

1.1. Analyte. 

The analyte measured by these procedures and specifications is total lead (Pb) in 

concentrations of micrograms per standard cubic meter (μg/m3).

1.2. Applicability

1.2.1. This specification is for evaluating the acceptability of Pb continuous 

emissions monitoring systems (CEMS) installed at stationary sources at the time of, or 

very soon after installation. The lead CEMS must be capable of measuring total Pb in 

μg/m3 on a continuous basis regardless of speciation and record that data at standard 

conditions on a wet or dry basis.

1.2.2. This specification is not designed to evaluate an installed CEMS’s 

performance over an extended period of time nor does it address calibration techniques or 

procedures specific to each CEMS manufacturer. The source owner is required to 

calibrate, maintain and operate the CEMS properly. The Administrator may require, 

under Section 114 of the Clean Air Act, the operator to conduct performance evaluations 

at other times besides the initial performance evaluation test.

2.0 Summary of Performance Specification 

Procedures for determining the relative accuracy, linearity, and calibration drift are 

outlined. Additionally CEMS installation and measurement location specifications, and 

performance criteria are included.

3.0 Definitions 

3.1. Lead (Pb) CEMS 

The total equipment required to measure lead in stack or duct effluent. Major systems in 

a lead CEMS may include the probe and transport line, the analyzer, the flow system, and 

the data recorder.

   
    19

3.2. Analyzer 

The portion of the lead CEMS that identifies Pb and measures its mass.

3.3. Flow System 

If a lead CEMS is an extractive type and the flow or volume measurement is used in the 

calculation of total Pb concentrations, the flow system consists of all the components 

required to withdraw, treat, measure and control the flow. These components may 

include, but are not necessarily limited to the following: pump, dryer, flow sensor, and 

control valve.

3.4. Reference Aerosol Generator 

A reference aerosol generator produces an aerosol by nebulizing a solution of known 

concentration at a measured rate into a measured carrier gas flow to emit an aerosol at a 

known concentration that is traceable to NIST standards.

3.5. Upscale Drift Standard 

The reference material used to challenge the upscale measurement stability of a Pb 

CEMS. 

3.6. Zero Drift Standard 

The reference material used to challenge the low or blank measurement stability of a Pb 

CEMS.

3.7. Emission Limit 

This is the maximum lead (Pb) emission concentration allowed under the applicable 

regulation.

3.8. Dynamic Spiking 

A procedure used to determine the accuracy, precision and bias of a monitoring system 

by quantitatively spiking a certified gas or aerosol into a pollutant gas stream.

3.9. Upscale Drift 

The difference between the expected upscale response to a reference standard and the 

actual response of the Pb CEMS expressed as a percentage of the emission limit. 

3.10. Zero Drift 

The difference between the expected zero response to a reference standard and the actual 

response of the Pb CEMS expressed as a percentage of the emission limit. 

   
    20

3.11. Flow Drift Check 

A procedure to check the stability of the Pb CEMS sample flow rate against the flow rate 

as measured by a quality assurance flow meter. 

3.12. Flow Drift

The difference between the flow as measured by the Pb CEMS primary flow meter and a 

quality assurance flow meter expressed as a percentage of the quality assurance flow 

meter.

3.13. Flow Audit 

A procedure to check the flow of the Pb CEMS sample flow rate against the flow rate as 

measured by NIST traceable reference flow meter. 

3.14. Flow Calibration Error 

The difference between the flow as measured by the Pb CEMS primary flow meter and a 

quality assurance flow meter expressed as a percentage of the quality assurance flow 

meter. 

3.15. Analyzer Audit Standard 

A standard with a known concentration or mass of lead that is NIST traceable or 

traceable to NIST standards.

3.16. Analyzer Calibration Audit 

The procedure by which a Pb CEMS’s response to the analyzer audit standard is 

compared to the certified concentration or mass of that standard. 

3.17. Analyzer Calibration Error 

The difference between the Pb CEMS analyzer’s response to the analyzer audit standard 

and that standard’s certified value expressed as a percentage of the certified value. 

3.18. Linearity Accuracy Audit 

A test used to evaluate the accuracy and precision of the Pb CEMS over a range of 

concentrations. The audit is performed by dynamically spiking the Pb CEMS transport 

line with aerosols of known lead concentrations.

4.0 Interferences [Reserved]

   
    21

5.0 Safety 

The procedures required under this performance specification may involve hazardous 

materials, operations, and equipment. This performance specification may not address all 

of the safety problems associated with these procedures. It is the responsibility of the 

user to establish the appropriate safety and health practices and determine the applicable 

regulatory limitations prior to performing these procedures. Please consult the CEMS 

manufacturer or appropriate reference material manufacturer for proper safety 

procedures. 

6.0 Equipment and Supplies 

6.1. CEMS Equipment Specifications

6.1.1. Data Recorder

The Pb CEMS must have a data recorder with an output range that includes the full range 

of the expected lead concentration values.

6.1.2. Quality Assurance Equipment

The Pb analyzer must be equipped with an upscale and zero standard to check the upscale 

and zero drifts respectively, on an automatic basis. In addition, for the analyzer audit, a 

NIST traceable or traceable-to-NIST lead analyzer audit standard is required. 

If the Pb CEMS is an extractive type that measures the sample volume and uses that 

measured volume in the calculation of the output value of the CEMS, the lead CEMS 

needs to be equipped with a quality assurance flow meter. This meter must allow the 

CEMS to check the primary flow measurement automatically on a daily basis. In 

addition a NIST traceable flow meter is required to check the accuracy of the CEMS 

primary flow meter as part of the flow audit 

6.1.3. Reference Aerosol Delivery System 

The Pb CEMS must allow for the introduction of a reference Pb aerosol at a point as 

close to the probe tip as possible.

6.2. Other Equipment and Supplies

Other equipment or supplies may be necessary to perform the procedures found in this 

document. Please check with your CEMS manufacturer. 

   
    22

7.0 Reagents and Standards 

7.1. Upscale Drift Standard 

Each Pb CEMS must be equipped with a lead (Pb) upscale drift standard. This standard 

must allow for automated daily checks of the analyzer portion of the Pb CEMS. The 

expected response from this standard should be greater than 80 percent of the emission 

limit. 

7.2. Zero Drift Standard 

Each Pb CEMS must be equipped with a zero drift standard. This standard must allow 

for automated daily checks of the analyzer portion of the Pb CEMS. The expected 

response from this standard should be less than 20 percent of emission limit.

7.3. Quality Assurance Flow Meter 

If your Pb CEMS is an extractive type that measures the sample volume and uses the 

measured sample volume as part of calculating the output value your CEMS must be able 

to check the sample flow rate to verify the precision of the flow measurement equipment. 

The flow check must be able to be performed automatically on a daily basis. 

7.4. Analyzer Audit Standard 

A standard with a known concentration or mass of lead that is NIST traceable or 

traceable to NIST standards.

7.5. Flow Audit Reference Flow Meter

If your Pb CEMS is an extractive type that measures the sample volume and uses the 

measured sample volume as part of calculating the output value of your CEMS you must 

have a NIST traceable reference flow meter to verify the accuracy of the flow 

measurement equipment. The reference flow meter must be within its certification period 

and be able to measure flow in the units used by the Pb CEMS. 

7.6. Reference Aerosol Generator 

A reference aerosol generator is needed to perform the linearity audit. It must be capable 

of generating a range of Pb concentrations up to and including the emission limit 

specified in the applicable regulation.

   
    23

8.0 Performance Specification Test Procedures 

8.1. Installation and Measurement Location Specifications

8.1.1. CEMS Installation 

Install the Pb CEMS at an accessible location downstream of all pollution control 

equipment. Place the probe inlet or any other sampling interface at a location in the stack 

or vent that is representative of the stack gas concentration of Pb. If the Pb CEMS 

samples from a single point within the stack or duct, that location should be free from 

stratification of Pb. Locations likely to meet these criteria are given in sections 8.1.2 and 

8.1.3.

8.1.2. Measurement Location 

The measurement location should be 1) at least two equivalent diameters downstream of 

the nearest pollution control device, point of pollution generation, or other point at which 

a change of pollutant concentration may occur and 2) at least half a diameter upstream 

from the pollutant exhaust. The equivalent duct diameter is calculated according to 

Method 1 in appendix A-1 of CFR Part 60.1

8.1.3. Pb CEMS Sample Extraction Point 

Use a sample extraction point that is either 1) no less than 1.0 meters from the stack or 

duct wall, or 2) within the centroidal velocity traverse area of the stack. This does not 

apply to cross stack or in situ Pb CEMS.

8.2. Seven-Day Calibration Drift Check 

8.2.1. Calibration Drift Test Period 

While the affected facility is operating normally, or as specified in an applicable 

regulation, determine the magnitude of the zero drift, the upscale drift and the flow drift, 

one at least one time per day for seven consecutive unit operating days. The seven 

consecutive unit operating days need not be seven consecutive calendar days.

8.2.2. Purpose 

The purpose of the calibration drift checks is to determine the stability of the analyzer 

and flow system portions of the Pb CEMS. If your Pb CEMS is not an extractive type of 

CEMS and does not use a flow measurement to determine Pb concentrations than the 

flow calibration drift check is not required.

   
    24

8.2.3. Zero Drift Check 

Challenge the Pb CEMS with a zero standard and calculate the zero drift by dividing the 

difference between the zero drift standard value (R) and the Pb CEMS response (A) to the 

zero drift standard by the applicable emission limit (L) (Equation 1).

8.2.4. Upscale Drift Check

Challenge the Pb CEMS with the upscale standard and calculate the upscale drift by 

dividing the difference between upscale drift value (R) and the Pb CEMS response (A) by 

the applicable emission limit (L) (Equation 1).

8.2.5. Calculation of Upscale and Zero Drift Checks

Both the upscale and zero drift are calculated according to Equation 1 below.

x100

L

AR

CD   Equation 1 

Where: 

CD = Either the upscale or zero calibration drift check. 

R = Either the upscale or zero standard reference value 

A = Either the Pb CEMS response to the upscale or zero standard 

L = The emission limit expressed in the μg/m3 

8.2.6. Flow Drift Check 

If your Pb CEMS is an extractive type that uses a flow or volume measurement to 

determine the Pb concentration, a flow drift check must be performed at least once each 

day. During this flow drift check, the flow as measured by CEMS’s primary flow or 

volume measurement device is compared to a secondary quality assurance flow 

measurement device that is used exclusively for the purpose of performing the flow drift 

check. The flow calibration drift is calculated according to Equation 2. The flow rate 

during the flow check must be the same as during normal sampling. The sample flow 

check may be performed over a time period shorter than the normal Pb CEMS sampling 

interval.

x100

F

FF

FD

QA

 QAP

 Equation 2 

Where: 

FD = The flow drift as a percentage of the flow measured by the quality assurance 

 flow meter. 

   
    25

Fp = The flow as measured by the primary flow measurement device in the Pb CEMS 

FQA = The flow as measured by the CEMS’s secondary quality assurance flow meter.

8.3. Calibration Audits

8.3.1. Analyzer Calibration Audit

The analyzer portion of each Pb CEMS must be challenged with a NIST traceable or 

traceable-to-NIST standard for Pb. The analyzer calibration error (AE) is calculated by 

dividing the difference between the known concentration of the Pb audit standard (Cs) 

and the concentration reported by the Pb CEMS (Cc) by the known concentration of the 

Pb audit standard (Equation 3).

x100

C

CC

AE

s

cS   Equation 3

8.3.2. Flow Calibration Audit 

If your Pb CEMS is an extractive type that measures flow or volume and utilizes that 

flow or volume measurement as part of calculating the output value you must perform a 

flow calibration audit to determine the flow calibration error. During this procedure you 

must compare the Pb CEMS measured flow rate to the flow rate as measured by a NIST 

traceable reference flow meter. The flow rate during the audit must be the same as that 

used during normal instrument sampling. You must make at least three measurements of 

flow on both the Pb CEMS and the reference flow meter. For each measurement set, 

calculate the flow calibration error (FE) by dividing the difference between the flow as 

measured by the reference flow meter (Fs) and the flow as measured by the Pb CEMS 

(Fc) by the reference flow meter (Equation 4). Then calculate the average error for each 

of the three measurements. 

x100

F

FF

FE

s

cS   Equation 4 

8.4. Linearity Accuracy Audit 

The linear accuracy audit is a dynamic spiking procedure in which the lead CEMS is 

challenged with a reference aerosol containing lead at several different concentration 

levels. The aerosol concentrations are produced using a Reference Aerosol Generator 

(RAG) and are introduced into the Pb CEMS transport line while it is sampling stack 

effluent. The concentrations reported by the CEMS are plotted against concentrations 

generated using a reference aerosol generator and a best fit linear regression curve is 

generated. The slope of this line is an indication of the accuracy of the Pb CEMS over a 

range of concentrations, while the correlation coefficient is an indicator of instrument 

precision. Sections 8.4.1 to 8.4.8 describe procedures for the linear accuracy audit.

   
    26

8.4.1. Spiking Location 

The Pb reference aerosol must be introduced into the Pb CEMS transport line at a point 

as close to the probe tip as possible. In this way the entire Pb CEMS including, the 

transport line, flow system, analyzer and data recorder are challenged.

8.4.2. Reference Aerosol Generator 

The reference aerosol generator used for the linear accuracy audit must comply with the 

specifications and procedures laid out in the Traceability Protocol for Certification of 

Reference Aerosol Generators.2

 This means that the expanded uncertainty in the 

concentration of the reference lead aerosol must not exceed 10%.

8.4.3. Transport Line Flow Measurement 

The linear accuracy audit is a dynamic spiking procedure, meaning that the lead 

containing aerosol is introduced into the stack effluent sampled by the Pb CEMS. For 

this reason the total flow (sampled stack gas and reference aerosol) in the Pb CEMS 

transport line must be measured to determine the concentration of lead being sampled by 

the CEMS. Flow in the transport line may be measured in several ways. This procedure 

outlines two approaches: laminar flow elements and flow by dilution.

8.4.3.1. Laminar Flow 

Prior to spiking, a calibrated laminar flow element may be inserted into the Pb CEMS’s 

transport line downstream of all instrument sampling. The measured flow from the 

laminar flow element may be used to calculate the lead concentration being sampled by 

the Pb CEMS.

8.4.3.2. Flow by Dilution 

Flow by dilution is a method of measuring flow where a concentration of a gas is 

quantitatively introduced into the flue gas stream and measured down stream by a 

calibrated instrument. For instance, a known concentration of propane can be 

quantitatively introduced into the flue gas stream and the diluted propane measured 

downstream using a gas chromatograph (GC). The calibration gas must be introduced 

into the gas stream quantitatively. Typically this is done by using a mass flow controller. 

Prior to spiking, the gas chromatograph or other measurement instrumentation must be 

calibrated at least three points through the expected measurement range. After the 

dynamic spiking procedure is completed the measurement instrument should be checked 

for bias at each of the four measurement points. The bias should be less than 5% of the 

expected value for each point. 

The transport line flow (FT) is related to the concentration of the spiked gas (Gs), flow 

rate of the spiked gas (Fs) and the measured gas concentration (GM) using the following 

relationship (Equation 5). 

   
    27

S

M

s

T F

G

F  G Equation 5 

8.4.3.3. Calculation of the Reference Lead Concentration

The reference aerosol generator (RAG) creates an aerosol of a known concentration 

which is then introduced into the Pb CEMS transport line which has a measured flow rate 

(Section 8.4.3.2). The concentration of lead produced by the RAG is therefore, diluted 

by the stack gas flow. This diluted concentration is the reference concentration then that 

should be measured by the Pb CEMS. This reference concentration (CR) is calculated by 

multiplying the RAG produced aerosol concentration (CRAG) by the ratio of the reference 

aerosol generator flow (FRAG) to the total flow as measured (FT) according to the 

procedures in Section 8.4.3.2 (Equation 6).

RAG

T

RAG

R C

F

C  F Equation 6 

8.4.4. Source Operation During Spiking

The linear accuracy audit procedures require that the background concentrations of lead 

be less than 15% of the applicable emission limit during the testing period. Therefore the 

source should be operated in a manner to prevent any lead emissions in excess of 15% of 

the emission limit (e.g. only burn natural gas). If this is not possible or if background 

concentrations of lead still exceed 15% of the emission limit even after taking reasonable 

steps to eliminate lead from the effluent emissions, it may be necessary to filter lead from 

the transport line upstream of the spiking location (e.g. use a particulate filter upstream 

of the spiking location).

8.4.5. Determination of Background Lead Concentrations

Prior to spiking, determine the background concentration of lead as measured by Pb 

CEMS by taking nine measurements while the unit is operating in the manner described 

in Section 8.4.4. If necessary this background concentration of lead may be subtracted 

from the total lead as measured by the CEMS during spiking.

8.4.6. Pb CEMS Operation

The Pb CEMS must be operated normally throughout the course of the spiking 

procedures. This includes operating at normal flow rates and maintaining sampling times 

that are the same as those used during normal instrument operation.

   
    28

8.4.7. Spiking Procedures 

The instrument must be challenged at three different lead concentration levels as listed 

below: 

1. Low – 10 to 30 percent of the emission limit 

2. Mid - 40 to 60 percent of the emission limit 

3. High – 80 to 120 percent of the emission limit 

You may spike at more concentration levels and include them in the regression analysis 

if, for example, you want to demonstrate a higher instrument span. 

At least nine valid measurements must be acquired at each concentration level. The first 

two measurements at each concentration level may be eliminated to allow for time for the 

reference aerosol concentration to stabilize. 

8.4.8. Linear Least Squares Regression Analysis

Plot each Pb CEMS reported concentration against the reference lead concentration (CR

from Equation 6) and determine the slope, intercept and correlation coefficient of the best 

fit line. This best fit line will have the form as shown in Equation 7. The slope, intercept 

and correlation coefficient may be calculated according to Equations 8, 9 and 10 

respectively. 

   

ˆ  xbby Equation 7 o 1

Where: 

yˆ = Concentration output of the Pb CEMS as predicted by the linear least 

 squares fit 

1 b = The slope of the best fit line 

bo = The intercept of the best fit line 

x = The reference aerosol 

 













 n

i

i

n

i

i i

xx

yyxx

b

1

2

1

1

)(

))((

Equation 8 

Where: 

1 b = The slope of the best fit line 
    29

i x = An individual reference aerosol Pb concentration 

x = The average reference aerosol Pb concentration 

i y = An individual reported Pb CEMS concentration 

y = The average reported Pb CEMS concentration 

 o  1 xbyb Equation 9 

Where: 

1 b = The slope of the best fit line 

bo = The intercept of the best fit line 

y = The average reported Pb CEMS concentration 

x = The average reference aerosol Pb concentration 

    





 



 



 n

i

i

n

i

i

n

i

i i

yyxx

yyxx

r

1

2

1

2

1

)()(

))((

Equation 10 

Where: 

r = The correlation coefficient 

i x = An individual reference aerosol Pb concentration 

x = The average reference aerosol Pb concentration 

i y = An individual reported Pb CEMS concentration 

y = The average reported Pb CEMS concentration 

9.0 Quality Control [Reserved]

10.0 Calibration and Standardization [Reserved]

11.0 Analytical Procedure [Reserved]

12.0 Calculations and Data Analysis [Reserved]

   
    30

13.0 Method Performance 

13.1. Zero Drift Criteria

The zero drift must be less than 20% of the emission limit every day for seven 

consecutive unit operating days. 

13.2. Upscale Drift Criteria

The upscale drift must be less than 15% of the emission limit every day for seven 

consecutive unit operating days.

13.3. Flow Drift Criteria

The flow drift must be less than 15% of the flow as measured by the Pb CEMS quality 

assurance flow meter every day for seven consecutive unit operating days.

13.4. Analyzer Calibration Error

When the analyzer calibration audit standard is analyzed the concentration of lead as 

reported by the Pb CEMS must be within 10% of the certified value of the analyzer audit 

standard.

13.5. Flow Calibration Error

When the unit is operating at normal flow rates, the average flow as measured by the Pb 

CEMS flow meter must be within 10% of the flow as measured by a NIST traceable 

reference flow meter.

13.6. Linear Accuracy Audit Criteria

Plot the Pb CEMS reported concentration versus the reference aerosol concentration. If 

the slope of the best fit line is between 0.85 and 1.15, the intercept is less than 20% of the 

emission limit, and the correlation coefficient is greater than 0.90, the Pb CEMS may be 

used without applying a correction factor. However, if the slope or intercept criteria fall 

outside of this range, a correction factor may be applied to the Pb CEMS data provided 

the following three criteria are met.

1. The slope of the best fit line is not greater than 1.30 or less than 0.70. 

2. The intercept is not greater than 40% of the emission limit

3. The correlation coefficient is greater than 0.90.

If both the slope and intercept need to be adjusted the concentration reported by the Pb 

CEMS may be adjusted using Equation 11. 

   
    31

1

0

b

C U

c   bC Equation 11

The slope may be adjusted using Equation 12. 

1 b

C U

C  C

 bCC

Equation 12 

The intercept may be adjusted using Equation 13. 

Equation 13 oUC

For all three equations 

CC = The corrected Pb CEMS concentration (μg/m3) 

CU = The uncorrected Pb CEMS concentration (μg/m3) 

b0 = The intercept of the best fit line 

b1 = The slope of the best fit line 

14.0 Pollution Prevention [Reserved]

15.0 Waste Management [Reserved]

16.0 Alternative Procedures [Reserved]

17.0 Bibliography 

1. United States. Environmental Protection Agency [EPA]. Technology Transfer 

Network. Emission Measurement Center. Promulgated Methods. Method 1: 

Sample and Velocity Traverses for Stationary Sources. Washington, DC: EPA; 

2004. Available: http://www.epa.gov/ttn/emc/promgate/m-01.pdf via the Internet. 

Accessed June 17, 2011. 

2. Siemers, A.; Petterson, K.A.; Cooper, J.A.; Barth, D.; Draft Traceability Protocol 

for Certification of Reference Aerosol Generators.; EPA Contract EP-D-05-096. 

April, 2011. 

   
    32

18.0 Tables and Figures 

Table 1. Initial Performance Tests and Test Criteria 

Test 

Category 

Test Test Requirements Test Criteria 

Zero Drift 

Monitor zero standard for 7 

consecutive days under normal 

operating conditions 

< 20% drift every day for seven 

consecutive days 

Upscale Drift 

Monitor upscale standard for 7 

consecutive days under normal 

operating conditions 

< 15% drift every day for seven 

consecutive days 

Seven Day 

Calibration 

Drift Check 

Flow Drift 

Monitor flow drift for 7 consecutive 

days under normal operating 

conditions 

< 15% drift every day for seven 

consecutive days 

Analyzer Calibration 

Audit 

Test a Pb standard designed to 

challenge the analyzer portion of the 

Pb CEMS 

< 10% drift 

Calibration 

Audits 

Flow Calibration Audit 

Check the flow or volume 

measurement of the Pb CEMS using 

a reference flow measurement 

device 

<10% Difference between the 

flow measurement device and 

the CEMS measured flow 

Accuracy Linearity Audit

 Use a Reference Aerosol 

Containing a known 

concentration of Pb 

 Dynamically Spike the stack gas 

sampled by the Pb CEMS 

 Need at least 3 concentration 

levels 

 Also include a zero or 

background concentration with 

no spiking. 

 Spike into source, or spike into 

transport line as close as possible 

to the probe 

 Slope = 0.85 to 1.15 

 r > 0.90 

 intercept < 20% of emission 

limit 

 if the above criteria are met 

then no correction 

 if not met a correction may 

be applied in certain 

instances 

   
    33

Appendix B 

Procedure W. Quality Assurance Requirements for Lead Continuous Emissions 

Monitoring Systems Used for Compliance Determination at Stationary Sources 

1.0 Purpose and Application 

1.1. Purpose

The purpose of Procedure W is to define the on-going quality control and assurance 

requirements for lead (Pb) continuous emissions monitors (CEMS). Adherence to the 

procedures in this document will assure the data integrity and accuracy of Pb CEMS 

results. Additionally, Procedure W contains reporting requirements and procedures for 

demonstrating that out of control Pb CEMS have been repaired and are producing 

accurate data. Initial performance requirements for Pb CEMS may be found in 

Performance Specification ZZ. Specifications and Test Procedures for Lead Continuous 

Emissions Monitoring Systems on Stationary Sources.1

 Pb CEMS meeting the 

performance criteria found in Procedure W and Performance Specification ZZ may be 

used by regulating agencies for compliance monitoring.

1.2. Applicability

1.2.1. Analytes

Procedure W covers the measurement of total lead (Pb) in stationary sources on a wet or 

dry basis.

1.2.2. Additional Quality Control and Assurance Requirements

Procedure W specifies the minimum requirements for controlling and assessing the 

quality of a Pb CEMS. Operators are encouraged to develop and implement more 

extensive quality assurance programs and to continue such programs where they already 

exist. 

2.0 Definitions 

2.1. Lead (Pb) CEMS 

The total equipment required to measure lead in stack or duct effluent. Major systems in 

a lead CEMS may include the probe and transport line, the analyzer, the flow system, and 

the data recorder.

   
    34

2.2. Analyzer 

The portion of the lead CEMS that identifies Pb and measures its mass.

2.3. Flow System 

If a lead CEMS is an extractive type and the flow or volume measurement is used in the 

calculation of total Pb concentrations, the flow system consists of all the components 

required to withdraw, treat, measure and control the flow. These components may 

include, but are not necessarily limited to the following: pump, dryer, flow sensor, and 

control valve.

2.4. Reference Aerosol Generator 

A reference aerosol generator produces an aerosol by nebulizing a solution of known 

concentration at a measured rate into a measured carrier gas flow to emit a known aerosol 

concentration that is traceable to NIST standards.

2.5. Upscale Drift Standard 

The reference material used to challenge the upscale measurement stability of a Pb 

CEMS. 

2.6. Zero Drift Standard 

The reference material used to challenge the low or blank measurement stability of a Pb 

CEMS.

2.7. Emission Limit 

This is the maximum lead (Pb) emission concentration allowed under the applicable 

regulations.

2.8. Dynamic Spiking 

A procedure used to determine the accuracy, precision and bias of a monitoring system 

by quantitatively spiking a certified gas or aerosol into a pollutant gas stream.

2.9. Upscale Drift 

The difference between the expected upscale response to a reference standard and the 

actual response of the Pb CEMS expressed as a percentage of the emission limit. 

2.10. Zero Drift 

The difference between the expected zero response to a reference standard and the actual 

response of the Pb CEMS expressed as a percentage of the emission limit. 

   
    35

2.11. Flow Drift Check 

A procedure to check the stability of the Pb CEMS sample flow rate against the flow rate 

as measured by a quality assurance flow meter. 

2.12. Flow Drift

The difference between the flow as measured by the Pb CEMS primary flow meter and a 

quality assurance flow meter expressed as a percentage of the quality assurance flow 

meter.

2.13. Flow Audit 

A procedure to check the flow of the Pb CEMS sample flow rate against the flow rate as 

measured by NIST traceable reference flow meter. 

2.14. Flow Calibration Error 

The difference between the flow as measured by the Pb CEMS primary flow meter and a 

quality assurance flow meter expressed as a percentage of the quality assurance flow 

meter. 

2.15. Analyzer Audit Standard 

A NIST traceable or traceable to NIST standard that can be used to challenge the 

analyzer portion of the Pb CEMS with a known mass or concentration of Pb.

2.16. Analyzer Calibration Audit 

The procedure by which a Pb CEMS’s response to NIST traceable or traceable to NIST 

lead standard is compared to the certified value of that standard. 

2.17. Analyzer Calibration Error 

The difference between the Pb CEMS analyzer’s response to a NIST traceable or 

traceable-to-NIST certified value and that standards certified value expressed as a 

percentage of the certified value. 

2.18. Linearity Accuracy Audit 

A test used to evaluate the accuracy and precision of the Pb CEMS over a range of 

concentrations. The audit is performed by dynamically spiking the Pb CEMS transport 

line with aerosols of known lead concentration.

3.0 Interferences [Reserved]

   
    36

4.0 Safety 

The procedures required by Procedure W may involve hazardous materials, operations, 

and equipment. This performance specification may not address all of the safety 

problems associated with these procedures. It is the responsibility of the user to establish 

the appropriate safety and health practices and determine the applicable regulatory 

limitations prior to performing these procedures. Please consult the CEMS manufacturer 

or appropriate reference material manufacturer for proper safety procedures. 

5.0 Equipment and Supplies 

5.1. CEMS Equipment Specifications

5.1.1. Data Recorder

The Pb CEMS must have a data recorder with an output range that includes the full range 

of the expected lead concentration values.

5.1.2. Quality Assurance Equipment

The Pb analyzer must be equipped with an upscale and zero standard to check the upscale 

and zero drifts respectively, on an automatic basis. In addition, for the analyzer audit, a 

NIST traceable or traceable-to-NIST lead analyzer audit standard is required. 

If the Pb CEMS is an extractive type that measures the sample volume and uses that 

measured volume in the calculation of the output value of the CEMS, the lead CEMS 

needs to be equipped with a quality assurance flow meter. This meter must allow the 

CEMS to check the primary flow measurement automatically on a daily basis. In 

addition a NIST traceable flow meter is required to check the accuracy of the CEMS 

primary flow meter as part of the flow audit 

5.1.3. Reference Aerosol Delivery System 

The Pb CEMS must allow for the introduction of a reference Pb aerosol at a point as 

close to the probe tip as possible.

5.2. Other Equipment and Supplies

Other equipment or supplies may be necessary to perform the procedures found in this 

document. Please check with your CEMS manufacturer. 

6.0 Reagents and Standards 

6.1. Upscale Drift Standard 

Each Pb CEMS must be equipped with a lead (Pb) upscale drift standard. This standard 

must allow for automated daily checks of the analyzer portion of the Pb CEMS. The 

   
    37

expected response from this standard should be greater than 80 percent of the emission 

limit. 

6.2. Zero Drift Standard 

Each Pb CEMS must be equipped with a zero drift standard. This standard must allow 

for automated daily checks of the analyzer portion of the Pb CEMS. The expected 

response from this standard should be less than 20 percent of emission limit.

6.3. Quality Assurance Flow Meter 

If your Pb CEMS is an extractive type that measures the sample volume and uses the 

measured sample volume as part of calculating the output value your CEMS must be able 

to check the sample flow rate to verify the precision of the flow measurement equipment. 

The flow check must be able to be performed automatically on a daily basis. 

6.4. Analyzer Audit Standard 

A standard with a known concentration or mass of lead that is NIST traceable or 

traceable to NIST standards.

6.5. Flow Audit Reference Flow Meter

If your Pb CEMS is an extractive type that measures the sample volume and uses the 

measured sample volume as part of calculating the output value of your CEMS, you must 

have a NIST traceable reference flow meter to verify the accuracy of the flow 

measurement equipment. The reference flow meter must be within its certification period 

and be able to measure flow in the units used by the Pb CEMS. 

6.6. Reference Aerosol Generator 

A reference aerosol generator is needed to perform the linearity audit. It must be capable 

of generating a range of Pb concentrations up to and including the emission limit 

specified in the applicable regulation.

7.0 Quality Control Requirements 

Each source owner or operator must develop and implement a quality control (QC) 

program. At a minimum, each QC program must include written procedures which 

should describe in detail, complete, step by step procedures and operations for all quality 

control activities. These activities include: 

1. Daily zero, upscale and flow (if applicable) drift checks 

2. Procedures for determining the zero, upscale and flow drift and methods of 

adjusting your Pb CEMS in response to the results of these drift checks. 

3. Quarterly Audits including the Analyzer Audit and the Flow Audit (if applicable) 

   
    38

4. Routine and preventative maintenance procedures for the Pb CEMS (including a 

spare parts inventory). 

5. Procedures for performing annual linear accuracy audits and procedures for 

adjusting your Pb CEMS results on the basis of linear accuracy audit results. 

6. Data recording, calculations and reporting 

7. A program of corrective action for malfunctioning Pb CEMS. 

These written procedures must be kept on record and available for inspection by the 

responsible enforcement agency for the lifetime of the Pb CEMS or until you are no 

longer subject to the requirements of this procedure. 

8.0 Calibration Drift Check and Audit Procedures 

8.1. Calibration Drift Check

8.1.1. Frequency Requirements 

Source owner and operators of Pb CEMS must check, record, and quantify the zero drift, 

the upscale drift and the flow drift (if applicable) at least once daily (approximately every 

24 hours) in accordance with the procedures prescribed by the manufacturer. 

8.1.2. Zero Drift

Challenge the Pb CEMS with a zero standard and calculate the zero drift by dividing the 

difference between the zero drift standard value (R) and the Pb CEMS response (A) to the 

zero drift standard by the applicable emission limit (L) (Equation 1).

8.1.3. Upscale Drift

Challenge the Pb CEMS with the upscale standard and calculate the upscale drift by 

dividing the difference between upscale drift value (R) and the Pb CEMS response (A) by 

the applicable emission limit (L) (Equation 1).

x100

L

AR

CD   Equation 1 

Where: 

CD = Either the upscale or zero calibration drift check. 

R = Either the upscale or zero standard reference value 

A = Either the Pb CEMS response to the upscale or zero standard 

L = The emission limit expressed in the μg/m3 

   
    39

8.1.4. Flow Drift

If your Pb CEMS is an extractive type that uses a flow or volume measurement to 

determine the Pb concentration, a flow drift check must be performed at least once each 

day. During this flow drift check, the flow as measured by CEMS’s primary flow or 

volume measurement device is compared to a secondary quality assurance flow 

measurement device that is used exclusively for the purpose of performing the flow drift 

check. The flow calibration drift is calculated according to Equation 2. The flow rate 

during the flow check must be the same as during normal sampling. The sample flow 

check may be performed over a time period shorter than the normal Pb CEMS sampling 

interval.

x100

F

FF

FD

QA

 QAP

 Equation 2 

Where: 

FD = The flow drift as a percentage of the flow measured by the quality assurance 

 flow meter. 

Fp = The flow as measured by the primary flow measurement device in the Pb CEMS 

FQA = The flow as measured by the CEMS’s secondary quality assurance flow meter.

8.2. Quarterly Audits

8.2.1. Frequency Requirements 

Analyzer and flow (if applicable) audits must be performed at least once per calendar 

quarter. The minimum time between regularly scheduled quarterly audits shall be two 

months, while the maximum allowed time between quarterly audits shall be four months. 

Audits may occur more frequently if the audit is required to demonstrate the accuracy of 

the Pb CEMS following repair or adjustment.

8.2.2. Analyzer Audit

The analyzer portion of each Pb CEMS must be challenged with a NIST traceable or 

traceable-to-NIST standard for Pb. The analyzer calibration error (AE) is calculated by 

dividing the difference between the known concentration of the Pb audit standard (Cs) 

and the concentration reported by the Pb CEMS (Cc) by the known concentration of the 

Pb audit standard (Equation 3).

x100

C

CC

AE

s

 cS  Equation 3

   
    40

8.2.3. Flow Audit

If your Pb CEMS is an extractive type that measures flow or volume and utilizes that 

flow or volume measurement as part of calculating the output value you must perform a 

flow calibration audit to determine the flow calibration error. During this procedure you 

must compare the Pb CEMS measured flow rate to the flow rate as measured by a NIST 

traceable reference flow meter. The flow rate during the audit must be the same as that 

used during normal instrument sampling. You must make at least three measurements of 

flow on both the Pb CEMS and the reference flow meter. For each measurement set 

calculate the flow calibration error (FE) dividing the difference between the flow as 

measured by the reference flow meter (Fs) and the flow as measured by the Pb CEMS 

(Fc) and divide it by the flow as measured by the reference flow meter (Equation 4). 

Then calculate the average error for each of the three measurements. 

x100

F

FF

FE

s

 cS  Equation 4 

8.3. Annual Linear Accuracy Audit

8.3.1. Frequency Requirements

Annual Linear Accuracy Audits for Pb CEMS are required annually. The minimum time 

between annual audits is nine months while the maximum time is 15 months. 

8.3.2. Procedures 

The linear accuracy audit is a dynamic spiking procedure in which the lead CEMS is 

challenged with a reference aerosol containing lead at several different concentration 

levels. The aerosol concentrations are produced using a Reference Aerosol Generator 

(RAG) and are introduced into the Pb CEMS transport line while it is sampling stack 

effluent. The concentrations reported by the CEMS are plotted against concentrations 

generated using a reference aerosol generator and a best fit linear regression curve is 

generated. The slope of this line is an indication of the accuracy of the Pb CEMS over a 

range of concentrations, while the correlation coefficient is an indicator of instrument 

precision

8.3.3. Spiking Location 

The Pb reference aerosol must be introduced into the Pb CEMS transport line at a point 

as close to the probe tip as possible. In this way the entire Pb CEMS including, the 

transport line, flow system, analyzer and data recorder are challenged. 

   
    41

8.3.4. Reference Aerosol Generator 

The reference aerosol generator used for the linear accuracy audit must comply with the 

specifications and procedures laid out in the Traceability Protocol for Certification of 

Reference Aerosol Generators.2

 This means that the expanded uncertainty in the 

concentration of the reference lead aerosol must not exceed 10%. 

8.3.5. Transport Line Flow Measurement 

The linear accuracy audit is a dynamic spiking procedure, meaning that the lead 

containing aerosol is introduced into the stack effluent sampled by the Pb CEMS. For 

this reason the total flow (sampled stack gas and reference aerosol) in the Pb CEMS 

transport line must be measured to determine the concentration of lead being sampled by 

the CEMS. Flow in the transport line may be measured in several ways. This procedure 

outlines two approaches: laminar flow elements and flow by dilution. 

8.3.6. Laminar Flow 

Prior to spiking, a calibrated laminar flow element may be inserted into the Pb CEMS’s 

transport line downstream of all instrument sampling. The measured flow from the 

laminar flow element may be used to calculate the lead concentration being sampled by 

the Pb CEMS. 

8.3.7. Flow by Dilution 

Flow by dilution is a method of measuring flow where a concentration of a gas is 

quantitatively introduced into the flue gas stream and measured down stream by a 

calibrated instrument. For instance, a known concentration of propane can be 

quantitatively introduced into the flue gas stream and the diluted propane measured 

downstream using a gas chromatograph (GC). The calibration gas must be introduced 

into the gas stream quantitatively. Typically this is done by using a mass flow controller. 

Prior to spiking the gas chromatograph or other measurement instrumentation must be 

calibrated at least three points through the expected measurement range. After the 

dynamic spiking procedure is completed the measurement instrument should be checked 

for bias at each of the four measurement points. The bias should be less than 5% of the 

expected value for each point. 

The transport line flow (FT) is related to the concentration of the spiked gas (Gs), flow 

rate of the spiked gas (Fs) and the measured gas concentration (GM) using the following 

relationship (Equation 5). 

 S

M

s

T F

G

F  G Equation 5 

   
    42

8.3.8. Calculation of the Reference Lead Concentration 

The reference aerosol generator (RAG) creates an aerosol of a known concentration 

which is then introduced into the Pb CEMS transport line which has a measured flow rate 

(Section 8.4.3.2). The concentration of lead produced by the RAG is therefore, diluted 

by the stack gas flow. This diluted concentration is the reference concentration then that 

should be measured by the Pb CEMS. This reference concentration (CR) is calculated by 

multiplying the RAG produced aerosol concentration (CRAG) by the ratio of the reference 

aerosol generator flow (FRAG) to the total flow as measured (FT) according to the 

procedures in Section 8.4.3.2 (Equation 6). 

RAG

T

RAG

R C

F

C  F Equation 6 

8.3.9. Source Operation During Spiking 

The linear accuracy audit procedures require that the background concentrations of lead 

be less than 15% of the applicable emission limit during the testing period. Therefore the 

source should be operated in a manner to prevent any lead emissions in excess of 15% of 

the emission limit (e.g. only burn natural gas). If this is not possible or if background 

concentrations of lead still exceed 15% of the emission limit even after taking reasonable 

steps to eliminate lead from the effluent emissions, it may be necessary to filter lead from 

the transport line upstream of the spiking location (e.g. use a particulate filter upstream 

of the spiking location). 

8.3.10. Determination of Background Lead Concentrations 

Prior to spiking determine the background concentration of lead as measured by Pb 

CEMS by taking nine measurements while the unit is operating in the manner described 

in Section 8.4.4. If necessary this background concentration of lead may be subtracted 

from the total lead as measured by the CEMS during spiking. 

8.3.11. Pb CEMS Operation 

The Pb CEMS must be operated normally throughout the course of the spiking 

procedures. This includes operating at normal flow rates and maintaining sampling times 

that are the same as those used during normal instrument operation. 

   
    43

8.3.12. Spiking Procedures 

The instrument must be challenged at three different lead concentration levels as listed 

below: 

1. Low – 10 to 30 percent of the emission limit 

2. Mid - 40 to 60 percent of the emission limit 

3. High – 80 to 120 percent of the emission limit 

You may spike at more concentration levels and include them in the regression analysis if 

for example you want to demonstrate a higher instrument span. 

At least nine valid measurements must be acquired at each concentration level. The first 

two measurements at each concentration level may be eliminated to allow for time for the 

reference aerosol concentration to stabilize. 

8.3.13. Linear Least Squares Regression Analysis

Plot each Pb CEMS reported concentration against the reference lead concentration (CR

from Equation 6) and determine the slope, intercept and correlation coefficient of the best 

fit line. This best fit line will have the form as shown in Equation 7. The slope, intercept 

and correlation coefficient may be calculated according to Equations 8, 9 and 10 

respectively. 

   

ˆ  xbby Equation 7 o 1

Where: 

yˆ = Concentration output of the Pb CEMS as predicted by the linear least 

 squares fit 

1 b = The slope of the best fit line 

bo = The intercept of the best fit line 

x = The reference aerosol 

 













 n

i

i

n

i

i i

xx

yyxx

b

1

2

1

1

)(

))((

Equation 8 

Where: 

1 b = The slope of the best fit line 
    44

i x = An individual reference aerosol Pb concentration 

x = The average reference aerosol Pb concentration 

i y = An individual reported Pb CEMS concentration 

y = The average reported Pb CEMS concentration 

 o  1 xbyb Equation 9 

Where: 

1 b = The slope of the best fit line 

bo = The intercept of the best fit line 

y = The average reported Pb CEMS concentration 

x = The average reference aerosol Pb concentration 

    





 



 



 n

i

i

n

i

i

n

i

i i

yyxx

yyxx

r

1

2

1

2

1

)()(

))((

Equation 10 

Where: 

r = The correlation coefficient 

i x = An individual reference aerosol Pb concentration 

x = The average reference aerosol Pb concentration 

i y = An individual reported Pb CEMS concentration 

y = The average reported Pb CEMS concentration 

9.0 Performance Criteria and Out of Control Procedures 

9.1. Calibration Drift Checks

9.1.1. Zero Drift Check Criteria

The zero drift must be less than 20% of the emission limit every day. If the Pb CEMS 

fails the zero drift check, immediately re-perform the zero drift check. If the Pb CEMS 

passes during the second check the CEMS may continue to operate. If it fails the second 

test the CEMS is out of control and the CEMS may require maintenance. Following the 

   
    45

CEMS repair, it must pass three zero drift checks before the CEMS is in control and can 

be used to monitor for Pb. 

9.1.2. Upscale Drift Check Criteria

The upscale drift must be less than 15% of the emission limit every day. If the Pb CEMS 

fails the upscale drift check, immediately re-perform the upscale drift check. If the Pb 

CEMS fails the second check the CEMS is out of control and may require maintenance. 

Following repairs the CEMS must pass at least three consecutive upscale checks before it 

is back in control.

9.1.3. Flow Drift Check Criteria

The flow drift must be less than 15% of the flow as measured by the Pb CEMS quality 

assurance flow meter every day. If the Pb CEMS fails the first drift check, immediately 

re-perform the flow audit. If the CEMS fails the second audit the CEMS is out of control 

and may require maintenance. Following repair the CEMS must pass three consecutive 

flow audits before it is back in control.

9.2. Quarterly Audit

9.2.1. Analyzer Audit Procedures

When the analyzer calibration audit standard is analyzed the concentration of lead as 

reported by the Pb CEMS must be within 10% of the certified value of the analyzer audit 

standard. If the Pb CEMS fails the flow audit it is out of control and may require 

maintenance. Following maintenance the Pb CEMS must pass an analyzer audit before it 

is back in control.

9.2.2. Flow Audit Procedures

When the unit is operating at normal flow rates, the average flow as measured by the Pb 

CEMS flow meter must be within 10% of the flow as measured by a NIST traceable 

reference flow meter. If the Pb CEMS fails the flow audit it is out of control and may 

require maintenance. Following maintenance the Pb CEMS must pass a flow audit 

before it is back in control.

9.3. Linear Accuracy Audit

9.3.1. Test Criteria

Plot the Pb CEMS reported concentration versus the reference aerosol concentration. If 

the slope of the best fit line is between 0.85 and 1.15, the intercept is less than 20% of the 

emission limit, and the correlation coefficient is greater than 0.90 the Pb CEMS may be 

used without applying a correction factor. If the slope or intercept criteria fall outside of 

this range a correction factor may be applied to the Pb CEMS data provided the following 

three criteria are met.

   
    46

1. The slope of the best fit line is not greater than 1.30 or less than 0.70. 

2. The intercept is not greater than 40% of the emission limit

3. The correlation coefficient is greater than 0.90.

If both the slope and intercept need to be adjusted the concentration reported by the Pb 

CEMS may be adjusted using Equation 11. 

1

0

b

C U

c   bC Equation 11

The slope may be adjusted using Equation 12. 

1 b

C U

C  C

 bCC

Equation 12 

The intercept may be adjusted using Equation 13. 

Equation 13 oUC

For all three equations 

CC = The corrected Pb CEMS concentration (μg/m3) 

CU = The uncorrected Pb CEMS concentration (μg/m3) 

b0 = The intercept of the best fit line 

b1 = The slope of the best fit line 

If the Pb CEMS fails the linear accuracy audit the CEMS must be repaired and must pass 

another linear accuracy audit before it can be used for compliance monitoring.

10.0 Reporting Requirements 

At the reporting interval specified in the applicable regulation report the results of all drift 

checks and audits performed during the reporting interval. For each out of control period 

report the results of the drift check or audit that caused the out of control period and those 

results that demonstrate that the Pb CEMS is back in control. Document all repairs and 

corrective actions undertaken during the out of control periods. 

11.0 References 

1. Performance Specification ZZ. Specifications and Test Procedures for Lead 

Continuous Emissions Monitors on Stationary Sources. June 2011. 

   
    47

2. Siemers, A.; Petterson, K.A.; Cooper, J.A.; Barth, D.; Draft Traceability Protocol 

for Certification of Reference Aerosol Generators.; EPA Contract EP-D-05-096. 

April, 2011. 

   
    48

12.0 Tables and Graphs 

Frequency Test Test Requirements Test Criteria 

Zero Drift Daily Monitor the Zero Standard < 20% drift each day 

Upscale Drift Daily Monitor the Upscale Standard < 15% drift each day 

Daily 

Flow Drift 

Monitor flow drift daily < 15% drift each day 

Analyzer Calibration 

Audit 

Audit with Pb standard designed to 

challenge the analyzer portion of the 

Pb CEMS 

< 10% difference between the 

CEMS reported value and the 

certified concentration 

Quarterly 

Flow Calibration Audit 

Check the flow or volume 

measurement of the Pb CEMS using 

a reference flow measurement 

device 

<10% Difference between the 

flow measurement device and 

the CEMS measured flow 

Annually Linearity Audit 

 Use a Reference Aerosol 

Containing a known 

concentration of Pb 

 Dynamically Spike the stack gas 

sampled by the Pb CEMS 

 Need at least 3 concentration 

levels which include a 2 fold 

concentration change and the 

emission limit 

 Also include a zero or 

background concentration with 

no spiking. 

 Spike into source, or spike into 

transport line as close as possible 

to the probe 

 Slope = 0.85 to 1.15 

 r > 0.90 

 intercept < 20% of emission 

limit 

 if the above criteria are met 

then no correction 

 if not met apply a correction 

(correlation criteria must be 

met) 

   
    49

Appendix C

Traceability Protocol for Certification of 

Reference Aerosol Generators 

DRAFT 

EPA Contract EP-D-05-096, Assignment 4-07 

EPA Project Manager: Daniel G. Bivins 

MACTEC Work Order No. 201001192 

MACTEC Project No. 688009S509 

Submitted To: 

MACTEC Federal Programs 

Research Triangle Park, NC 

Prepared By: 

Aaron Siemers, Krag A. Petterson, John A. Cooper, and Douglas Barth 

Cooper Environmental Services, LLC 

Portland, OR 

April 12, 2011 

   
    50

Executive Summary 

A reference aerosol generator (RAG) produces an aerosol by nebulizing a 

solution of known concentration, at a measured rate, into a measured carrier gas 

flow to emit a NIST traceable aerosol of specific concentration. Uncertainties are 

defined for each input and a total, combined uncertainty value for the generated 

aerosol concentration is established. The reference aerosol can be used to 

challenge the accuracy of monitors designed to measure species contained in 

aerosols. These monitors include metals and particulate matter continuous 

emissions monitors (CEMS), ambient PM10 and PM2.5 beta gauges, and metals 

continuous fence line monitors (CFLM). Typically gas monitors are challenged 

using NIST traceable gases, whose concentrations have been established using 

an unbroken chain of comparisons of a candidate gas standard to a primary 

NIST gas standard. However, no such primary NIST standards exist for analytes 

in aerosols. This document outlines the general requirements to certify and 

evaluate whether an aerosol concentration produced by a reference aerosol 

generator is traceable to NIST, and provides guidance on establishing 

uncertainty values for each input as well as the total expanded, combined, 

uncertainty value. In order to establish NIST traceability for a reference aerosol 

generator’s output, this protocol requires that all measurements required to 

produce the aerosol are NIST traceable, including using solutions with NIST 

traceable concentrations, using NIST traceable gas flow meters, and using NIST 

traceable balances to measure solution loss rate. A total capture test should be 

conducted to certify the output concentration of the RAG by verifying the NIST 

traceable reference value to within 15% of the analytical method result. Periodic 

quality assurance (QA) and recertification protocol should follow as required by 

the manufacturer or the applicable regulation. 

   
    51

1. Introduction

A reference aerosol generator (RAG) is a device which produces an aerosol of 

known concentration of an analyte or analytes of interest. Calibration gases 

have traditionally been used to establish the accuracy of continuous gas 

monitors. However, no such primary NIST standards exist for analytes in 

aerosols. Instead, a reference aerosol generator can be used to establish the 

accuracy of monitors measuring aerosol analytes. A NIST traceable certified 

reference aerosol generator is a useful calibration and auditing tool for several 

types of monitors including particulate matter (PM) continuous emissions 

monitors (CEMS), multi-metals CEMS, metals continuous fence line monitors 

(CFLM), and ambient PM10 and PM2.5 monitors. 

Traceability of gas standards are typically established using an unbroken chain of 

comparisons of a candidate gas standard to a primary National Institute of 

Standards and Technology (NIST) gas standard. Instead of utilizing direct 

comparisons to NIST standards, this protocol relies on an approach of 

establishing NIST traceability for the individual components and measurements 

of a reference aerosol generator that are critical to establishing the analyte 

concentration. This approach is similar to the approach EPA has taken 

recently to establish NIST traceability for mercuric chloride (HgCl2) gas 

generators.1 This protocol borrows heavily from that document. 

This Traceability Protocol for Certification of Reference Aerosol Generators 

proposes methods for: (1) establishing the initial NIST traceability and 

performance requirements of the key components of RAGs; (2) determining the 

uncertainty of each key component; (3) calculating NIST traceable output 

concentrations and the expanded, combined uncertainty values for the aerosol 

standards produced by the RAG; and (4) verifying the NIST traceable aerosol 

concentration with a total capture test and certifying the output of the RAG. The 

protocol also makes ongoing quality assurance (QA) recommendations. 

Like the Interim EPA Traceability Protocol for Qualification and Certification of 

Oxidized Mercury Gas Generators (Protocol for HgCl2 Generators), this 

traceability protocol sets a “target” expanded, combined uncertainty value of 10% 

for the generated aerosol standards. The NIST traceable RAG output 

concentration is verified using a total capture test. This protocol specifies that if 

the NIST traceable concentration is within 15% of the total capture test results, 

then the output of the RAG is considered certified as a NIST traceable reference 

aerosol generator. Like the HgCl2 Protocol, this document does not explicitly 

require assessment of the sample transfer lines or any other measurement 

system component as they are not considered part of the reference aerosol 

   
    52

generator. The total capture test is a practical tool for verification and 

certification of RAG output but does not in itself demonstrate traceability. 

This protocol could potentially be used to establish NIST traceability and to certify 

RAGs used in a variety of air quality monitoring capacities as quality assurance 

and auditing tools for both ambient and source CEMS, but certain aspects of the 

document are written with respect to Cooper Environmental Services’ (CES) 

Quantitative Aerosol Generator (QAG). 

2. Qualification Tests 

Manufacturers of RAGs are required to conduct qualification tests to demonstrate 

the performance of each RAG model prior to demonstrating NIST traceability and 

undergoing output certification. Documentation of the qualification test 

procedures and accompanying data should be available upon request to 

regulatory officials. The manufacturer is responsible for information and data that 

demonstrates that a RAG can operate reliably, with high precision and accuracy, 

over a range of conditions that could reasonably be encountered in the field 

application of the device. 

2.1 Definitions

2.1.1 Aerosol 

A suspension of solids and/or liquids in a gas 

2.1.2 Reference Aerosol Generator (RAG) 

A device which generates an aerosol with an analyte concentration that is traceable to 

NIST standards. This aerosol can then be used to audit or calibrate monitors and/or 

analytical methods measuring that analyte. 

A reference aerosol generator produces an aerosol by nebulizing a solution 

containing a known analyte concentration, at a measured rate, into a measured 

flow. All of the inputs can be directly linked to NIST-traceable standards. A 

reference aerosol generator consists of the following components and modules: 

1) Solution Delivery Module – This module includes any equipment necessary to 

contain and deliver the solution to the aerosol generation point. This module will 

often include a solution reservoir, solution delivery lines, a pump to generate 

flow, and a NIST certified balance. 

2) Aerosol Generation System – This system includes all of the equipment required 

to aerosolize the solution. This could include nebulizers, compressed air, and 

electronic equipment. 

   
    53

3) An Evaporation Zone – This is the zone where the nebulized solution droplets 

are evaporated to remove liquid water. 

4) Aerosol Dryer – This system consists of any of the components required to 

generate, measure, and treat the aerosol carrier gas flow. Key components 

could often include a pump or a blower, compressed air, flow meters, and valves. 

5) An Electronic and Data Processing System – This system encompasses the 

specific electronic configuration of the RAG as well as hardware and software for 

instrument control and data processing 

2.1.3 Expanded Uncertainty 

As used in this protocol, expanded uncertainty is defined by two (2) times the 

total uncertainty or standard deviation 

2.1.4 Nebulization, Aerosolization 

To convert a liquid to a fine spray 

2.1.5 Operational and Environmental Conditions 

The manufacturer should provide information on the operational range or 

limitations of the RAG, specifying the conditions in which the model can be 

expected to operate reliably and meet all performance specifications for 

parameters such as: 

 2.1.5.1 Carrier Gas Supply 

The minimum and maximum compressed air or nitrogen supply pressure, the 

acceptable variation in supply pressure, the necessary gas flow rate, and the 

quality of the carrier gas required 

 2.1.5.2 Back Pressure 

The range of back pressures over which the generator has been tested and can 

deliver reliable aerosol concentrations 

 2.1.5.3 Enclosure Temperature Operating Range 

The range of ambient temperatures over which the thermal stability of the 

generator has been tested and can deliver reliable aerosol concentrations. 

Alternately, the temperature range that must be maintained by on-board 

temperature controls for a RAG to deliver accurate and precise aerosol 

concentrations 

   
    54

 2.1.5.4 Line Voltage 

A range of acceptable line voltage limits in which the RAG can function reliably 

2.1.5 Operation, Maintenance and QA 

The manufacturer must provide standard operating procedures for the 

installation, start-up, operation, maintenance, and quality assurance of the RAG. 

The manufacturer must also identify the conditions and factors that would 

automatically require recertification of the RAG, such as known malfunctions, 

failures, component replacement, recalibrations, etc. 

2.1.6 Laboratory Output Verification and Performance Tests 

The manufacturer of the RAG should develop a report describing qualification 

tests performed to demonstrate that the RAG model will generate precise and 

accurate aerosol concentrations over a range of conditions. Specific tests 

include repeatability tests, thermal stability tests, supply pressure tests, line 

voltage variation tests, and generator output verification tests. 

2.1.6 Range(s) 

The minimum and maximum concentration range(s) of working solution in μg/m3 

and flow rate in liters per minute (lpm) over which the RAG has been 

demonstrated to meet performance specifications. Additionally, the description 

of the range should define the specific operating variables that must be selected 

and altered to establish the effective operating range and aerosol concentration. 

 2.1.7 Traceability to NIST 

A documented procedure by which traceability of measurement results to a 

respective National Institute of Standards and Technology reference standard is 

established through an unbroken chain of comparisons, each having stated 

uncertainties. Comparisons are based on appropriate physical and chemical 

measurements

   
    55

 2.1.8 Total Propagated Uncertainty Equations7

a)

b)

3. Reference Aerosol Generator Traceability, Initial Certification and 

Uncertainty Equations 

3.1. Introduction 

This section provides a protocol to establish NIST traceability for a reference 

aerosol generator by demonstrating NIST traceability of a RAG’s key inputs. It 

also provides the methods and equations necessary to quantify the expanded, 

combined uncertainty of the RAG’s output, as well as instructions for verifying the 

NIST traceable output of a RAG with a total capture test. A RAG that has 

performed and documented the following procedures and has met or surpassed 

the acceptance criteria satisfies the NIST traceability and certification 

requirements. 

The key system components of a RAG include: 

(a) A container for the working solution on the balance (reservoir) 

(b) A balance that communicates directly with the on-board computer and 

establishes a measured solution loss rate 

(c) A flow meter(s) and controller(s) to establish the flow rates of the carrier gas 

Initial certification of a RAG requires NIST traceability through a clear, unbroken 

chain of comparisons for each of the key inputs of the RAG, as well as the 

determination of the expanded, combined uncertainty of the generated “reference 

value” concentration. The key inputs include solution concentration, the solution 

loss rate, and the carrier gas flow rate. For the solution concentration, NIST 

traceability is demonstrated through use of commercial NIST solution standards 

and following protocol when diluting NIST standards. For the solution loss rate 

and carrier gas flow rate, NIST traceability is demonstrated through calibration of 

the balance and flow meters with NIST standards. 

A “reference value” of the concentration of each analyte in the aerosol can be 

calculated using Equation 1. 

   
    56

 Equation 1 

Where: 

 = The concentration of the ith analyte in the reference aerosol (grams of 

analyte / m3) 

 = The concentration of the ith analyte in the NIST traceable solution 

(grams ith analyte 

 per gram of solution) 

 = The solution loss rate for the ith analyte (grams per minute) 

 = The carrier flow for the aerosol (m3 per minute) 

NIST traceability for a reference aerosol generator is established through the traceability 

of the solution concentration, the traceability of the balance used to measure the solution 

loss rate, and the traceability of the aerosol carrier gas flow rate 

It is assumed that all of the nebulized analyte within the NIST standard solution is 

emitted by the RAG as a NIST traceable aerosol at the “reference value” concentration. 

This is subsequently verified with a total capture test before the RAG is certified. 

3.1 Solution Concentration 

The primary input in generating a NIST traceable aerosol is the NIST traceable 

solution, which is the basis for the other comparisons. For a RAG to be certified, 

NIST traceable solutions must be employed. NIST traceable solutions are 

available commercially for many different types of analytes. These solutions are 

traceable to NIST standard reference materials (SRM), their concentration 

uncertainty values are typically known to within ± 1% or better, and they are 

known to be stable for long periods of time (at least a year). Because they are 

independently produced, well-characterized and widely available, it is best to use 

these types of solutions whenever possible. However, solutions may not be 

available for all analytes of interest or at the desired concentrations. It is also 

possible that other components of these solutions (such as acids) could be 

incompatible with the monitors being challenged with the reference aerosol. For 

these reasons other potential methods for demonstrating NIST traceability of a 

solution are necessary. Two other approaches for demonstrating the NIST 

traceability of the solution include: 

1) Dilution or serial dilution of a commercially available NIST traceable 

solution 

   

2) Determination of a solution concentration utilizing an appropriate 

analytical method 
    57

Any dilution of a commercially available NIST traceable solution should be done 

in a manner so that each measurement in the dilution process is traceable to 

NIST. This includes assuring that any gravimetric or volumetric measurements 

are done using balances and/or glassware that are NIST traceable. Also, all 

dilutions should be done using deionized water, with high resistivity (16 mega 

ohms or higher). If solutions are diluted with acid, they should be high purity and 

free from contaminates. Generally, acids that are listed as being for use in trace 

metal analysis are of sufficient purity. Dilutions will also increase the uncertainty 

of the RAG output. See section 3.1.1. and Equation 3 to calculate the increase in 

combined uncertainty due to dilution. 

The NIST traceability of a solution can also be established by determining the 

concentrations of the analyte of interest in a solution using an appropriate 

analytical method. Examples of such analytical methods include, but are not 

limited to ICP, ICP-MS, and AA. Often these analytical methods operate by 

comparing the instrument response to a known NIST traceable solution 

concentration with the instrument response to the unknown concentration. To 

demonstrate NIST traceability using this approach, it is important to document 

the NIST traceability of the respective analytical method/instruments and to 

include this uncertainty in the combined uncertainty value of the respective 

working solution ( ). For the most sensitive laboratory analytical methods, 

will usually be less than about 5%. 

3.1.1 Calculating the Uncertainty of the Solution Concentration 

If an undiluted, NIST traceable SRM solution is used in the RAG, the uncertainty 

is equal to the uncertainty in the labeled concentration, which is usually about ± 

1%. 

If a commercially available solution has to be diluted to create a working solution 

for the RAG, then the concentration of that working solution may be calculated 

with Equation 2. 

 Equation 2 

Where: 

 = The concentration of the ith analyte in the working solution to be 

aerosolized 

 = The concentration of the ith analyte in the stock solution 

 = The mass of the stock solution 

   
    58

 = The mass of the solution after dilution 

However, dilution of the NIST traceable SRM solution increases the combined 

uncertainty. Combined uncertainty in the working solution is based on the 

gravimetric and volumetric standard uncertainties as well as the uncertainty in 

the SRM solution. The uncertainty of the diluted working solution can be 

calculated using Equation 3: 

 Equation 3

Where:

 = The uncertainty in the concentration of the diluted working 

solution 

 = The expanded uncertainty of stock solution 

 = The uncertainty of the aliquot weight or volume (%) 

 = The uncertainty of the final, diluted standard solution weight or 

volume (%) 

a) The uncertainty in the commercial standard is provided by the supplier, and 

given by the percent accuracy of the solution concentration, usually about ± 1%. 

b) The uncertainty of the aliquot weight , as recommended by USEPA, is 

calculated by multiplying the estimated readability (such as .001 to .00001) of the 

balance by three, dividing that number by the measured aliquot weight, and 

converting the results to a percentage. 

c) The uncertainty of the final, diluted working solution weight can be 

estimated by dividing the readability of the balance by three, dividing that number 

by the measured final aliquot weight, and converting the results to a percentage. 

3.2 Liquid Flow Measurement and Solution Loss Rate 

The solution loss rate (aerosolization rate or mass emission rate) is another key 

factor in controlling RAG output concentration, establishing NIST traceability, and 

certifying a RAG. For the CES Quantitative Aerosol Generator (QAG), the 

solution loss rate of the analyte-containing solution is determined using a NIST 

certified laboratory balance. 

CES’ QAG utilizes a sensitive balance that communicates directly to an on-board 

computer system. Before operation, the balance can be calibrated using NIST-

   
    59

traceable weights so that the data output of the balance is NIST traceable. The 

uncertainty of the balance and the associated data is given by the manufacturer, 

or alternately per EPA recommendations, by multiplying the readability of the 

balance by three, dividing that number by the weight or change in weight during 

the QAG run, and converting the results to a percentage. 

3.2.1 Calibrating a Laboratory Balance and Determining Uncertainty 

(a) Zero a three-place (or more accurate) balance and check its calibration 

against NIST traceable weights in the range of measurement appropriate 

for each solution loss rate determination. If necessary, calibrate the 

balance per manufacturer’s recommendations. 

 3.2.2 Solution Loss Rate Equations 

Some types of nebulization processes for CES’ QAG cause solution evaporation 

without aerosolization of the salts dissolved in the solutions. This effect is 

minimized by using carrier gas that is saturated at the same temperature as the 

nebulization chamber. However this control is not perfect and it is necessary to 

make a correction to the solution loss rate to account for solution evaporation 

with aerosolization, which is usually on the order of 1%, and the uncertainty in 

this correction is small relative to the total solution loss rate. The measurements 

required to account for evaporation should also be traceable to NIST and welldocumented in the standard operating procedures for the device. Consult the 

instrument’s operating manual for further reference. 

The equation for the solution loss rate for each analyte i in the reference 

aerosol is calculated using Equation 4 – 6 as noted below. 

 Equation 4

Where: 

= Concentration of the ith element in the in the NIST traceable solution 

(may be for a diluted working solution) 

= Measured rate of solution reservoir mass loss (solution loss rate), 

determined as the slope of a linear least squares fit of the reservoir mass 

data over the period of a test or tests (g/min). 

= Rate of vapor loss (converted from mg/min to g/min), calculated from the 

following equation: 

 Equation 5

   
    60

Where: 

= Flow rate of the nebulizer air (slpm)

= Mass of water lost from the nebulizing air (mg/l), calculated from the 

following equation: 

 Equation 6 

Where: 

 = Mass of water in a liter of air at (mg/l), taken from established NIST 

certified reference sources9; 

 = Mass of water in a liter of air at (mg/l), taken from established NIST 

certified reference sources9

; where 

= Temperature of the nebulizer air at the aerosol size-selection cone

= Temperature of nebulizer air at saturation 

3.2.3 Solution Loss Rate Uncertainty Calculation 

The uncertainty in the solution loss rate can be determined using standard 

propagation of error methodologies in respect to Equation 4. The uncertainty 

values for the parameters are either calculated or provided by the manufacturer 

of the respective measurement device. 

The uncertainty of the solution loss rate can be determined using the 

following Equations 7 - 10: 

= Equation 7 

   
    61

And: = 

Equation 8 

And: = 

Equation 9

And: = Equation 10 

3.3 Carrier Gas Flow Measurement 

The carrier gas transports the generated aerosol to the receptor. All carrier gas flows 

used to calculate the aerosol concentrations should be measured using NIST traceable 

flow meters. These flow meters are readily available, usually with specified calibration 

periods such as annually. An uncertainty value ( ) is provided by the manufacturer. If 

manufacturer data is not available, gas flow meters can also be calibrated and the 

uncertainty of the gas flow rate determined by using the procedure listed in steps (a) 

through (e) of this section. Before and after using a reference aerosol generator to 

calibrate or audit a monitor, all generator flow meters should be checked using an 

independent NIST traceable flow meter to verify their accuracy. 

3.3.1 Calibrating Carrier Gas Flow Meters and Determining Uncertainty

(a) Install a laboratory standard device for flow meter measurement such as a digital 

bubble meter or a piston displacement device at the outlet of the calibrator. 

The flow measurement device must have a NIST traceable calibration and an 

accuracy of 1% or better. Operate the flow rate measurement device, making 

sure to follow all the manufacturer’s instructions and specifications. 

(b) Operate the RAG according to the manufacturer’s instructions and allow the 

generator to run for enough time to equilibrate. 

(c) Test the gas flow output of the RAG against the NIST traceable flow meter 

device. For each gas flow rate level, record the data emerging from the carrier 

gas flow meter on the RAG and the NIST traceable standard. Record at least ten 

pairs of readings. 

   
    62

(d) To determine the uncertainty of the gas flow rate meter ( ) on the RAG, 

calculate the relative standard deviation (RSD) of the gas flow data pairs at each 

level. If the RSD is less than or equal to 2%, the gas flow rate determination is 

considered acceptable. 

(e) In the subsequent use of the flow meter, at each gas flow rate setting, compare 

the average of the NIST traceable flow measurements to the gas flow reading 

indicated on the RAG. If the difference of these values exceeds the uncertainty 

value , a linear correction value can be calculated which can calibrate the 

indicated gas flow rate. The linear correction can be: 1) a factor based on the 

ratio of the actual gas flow rate to the indicated flow rate; or 2) a combination of a 

factor with and adjustment value for zero offset. Record the linear correction, 

and utilize it until the gas flow rate measurement device is re-calibrated at the 

same operating level. 

4. Combined, Expanded Uncertainty Calculations and Acceptance Criteria 

4.1 Uncertainty of Reference Aerosol Generator 

The uncertainty of the reference aerosol generated standard can be calculated using 

standard propagation of error analysis and a coverage factor of 2. 

Therefore for Equation 1: Aerosol Standard “Reference Value” Concentration 

 

Where: 

 = The concentration of the ith analyte in the reference aerosol (or )

 = The solution loss rate for the ith analyte 

 = The concentration of the ith analyte in the NIST traceable solution

 = The carrier gas flow for the aerosol 

   
    63

The equation for uncertainty in the concentration of the generated aerosol with a 

coverage factor of 2 is Equation 11: 

         Equation 11

Where: 

= The uncertainty in the concentration of the ith analyte in the aerosol 

= The concentration of the ith analyte in the aerosol 

= The uncertainty of the solution loss rate

= The solution loss rate 

= The uncertainty in the SRM solution concentration ( if diluted 

(Equation 3)) 

= The concentration of the ith analyte in solution ( if diluted (equation 2)) 

= The uncertainty in the carrier gas flow rate 

= The flow rate of the carrier gas

4.2 Acceptance Criteria 

Like the Protocol for HgCl2 Generators, the acceptance criteria for the 

Traceability Protocol for Certification of Reference Aerosol Generators is targeted 

at an expanded, combined uncertainty of 10%. 

5. Total Capture Test Output Verification and Certification 

After NIST traceability is established through the use of NIST traceable inputs, 

calibration of key components and calculation of the combined, expanded 

uncertainty, a total capture test can be utilized to certify the output of the RAG by 

verifying that the generated aerosol concentration is within 15% of the NIST 

traceable reference value. A 15% performance criteria for the total capture test 

is reasonable due to the defined uncertainty of the NIST traceable reference 

value concentration and the uncertainty of analytical methodology employed by 

the total capture test. During a total capture test, a filter, free of contaminates 

(e.g. stretch Teflon), is placed at the end of the aerosol transport line (at a point 

as close as possible to the point where the aerosol is introduced into the audited 

monitor) in such a way that all the particulate matter is captured on the filter. The 

mass of each analyte on the filter can then be determined using appropriate 

   
    64

analytical techniques. If preferred or necessary, an impinger method may also 

be utilized. 

Appropriate analysis procedures will depend upon the analyte of interest. 

Methods for analysis of inorganic constituents may be found in the Compendium 

of Methods for the Determination of Inorganic Compounds (I.O.) in Ambient Air. 

Examples include X-ray Fluorescence (I.O. 3.3), inductively coupled plasma 

(ICP) spectroscopy (I.O. 3.4), inductively coupled plasma/mass spectrometry 

(I.O. 3.5), and proton induced X-ray emission (PIXE) spectroscopy (I.O. 3.6). 

Alternatively, the analyte concentration in the reference aerosol can be 

determined using a reference method. 

6. Ongoing Quality Assurance and Re-certification 

Periodic Quality Assurance (QA) tests in the field should also be conducted, 

verifying the output of the RAG to within 15% of the NIST traceable reference 

value, or to the specification set by the applicable regulation. The accuracy of 

the aerosol generator must be checked at each of the concentration levels used 

during the CEMS audit and at a zero concentration. This protocol recommends 

that recertification and calibration of the RAG occur at least annually, as needed, 

or as specified by the relevant regulations. 

7. References

1. U.S. Environmental Protection Agency; Interim EPA Traceability Protocol for 

Qualification and Certification of Oxidized Mercury Gas Generators; July 1, 2009. 

www.epa.gov/airmarkt/emissions/mercury/docs/OxHgProtocol.pdf (accessed 

September 22, 2010). 

2. U.S. Environmental Protection Agency; Interim EPA Traceability Protocol for 

Qualification and Certification of Elemental Mercury Gas Generators; July 1, 

2009. http://www.epa.gov/airmarkt/emissions/mercury/docs/ElemHgProtocol.pdf

(accessed September 22, 2010). 

3. US Environmental Protection Agency; Compendium of Methods for the 

Determination of Inorganic Compounds in Ambient Air; EPA/625/R-96/010a. 

Cincinnati, OH. June 1999. 

4. United States. Environmental Protection Agency [EPA]. Test Method 29. 

Determination of Metals Emissions From Stationary Sources. Washington, DC: 

EPA; July 1, 1996. 40 CFR 60 Appendix A. 

   
   

   

65

5. U.S. Environmental Protection Agency; Other Test Method 17, Determination of 

Metal Concentrations in CES’ Xact CEMS Stilling Chamber Using Filters and 

Solid Sorbents with X-ray Fluorescence Analysis. 

http://www.epa.gov/ttn/emc/prelim/otm17.pdf. (Accessed September 22, 2010). 

6. United States. Environmental Protection Agency [EPA]. Test Method 5. 

Determination of Particulate Matter Emissions from Stationary Sources. 

Washington, DC: EPA; July 1, 1996. 40 CFR 60 Appendix A. 

7. United States. Environmental Protection Agency [EPA]. Test Method 5i. 

Determination of Low Level Particulate Matter Emissions from Stationary 

Sources. Washington, DC: EPA, September 30, 1999. 40 CFR 60, Appendix A. 

8. Beers, Yardley. Introduction to the Theory of Error. 2nd Ed. Reading, MA: 

Addison-Wesley Publishing Co, Inc., 1957 

9. Weight in Grams of a Cubic Meter of Saturated Aqueous Vapor. CRC Handbook 

of Chemistry and Physics. R.C. Weast, M.J. Astle, W.H. Beyer (Eds.). Boca 

Raton, FL: CRC Press, Inc; 1984. p.E-37.