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# EasyChem Methodology

Nitrate by Discrete Analysis

Easy (1-Reagent) Nitrate Method

(Colorimetric, Automated, 1 Reagent)

Revision Date: November 12, 2011



### Craig R. Chinchilla 900 Jorie Blvd., Suite 35 Oak Brook, Illinois 60523Page 2 of 23 

### CONTENTS

1. Scope and Application........................................................................................3

2. Summary of Method...........................................................................................3

3. Common Abbreviations.......................................................................................3

4. Interferences...................................................................................................4

5. Safety............................................................................................................4

6. Equipment and Supplies......................................................................................4

7. Reagents and Standards.......................................................................................5

8. Sample Collection, Preserva tion, and Storage.............................................................7

9. Quality Assurance/Quality Control. ........................................................................8

10. Calibration and Standardization............................................................................14

11. Procedure......................................................................................................15

12. Data Analysis and Calculations..............................................................................19

13. Method Performance.........................................................................................19

14. Pollution Prevention.........................................................................................19

15. Waste Management...........................................................................................19

16. References.....................................................................................................20

17. Tables, Diagrams, and Validation Data...................................................................20

18. Definitions.....................................................................................................20

19. Consumables...................................................................................................23Page 3 of 23 

# EasyChem Applications

Easy (1-Reagent) Nitrate

Nitrate in Water and Wastewater

1.0 Scope and Application

1.1 This method is applicable to the analysis of nitrate (CASRN 14797-55-8) in wastewater and drinking water. If this method is being used for compliance with the Clean Water act (CWA), the flexibility to modify this method as described in CFR 136.6 applies. Modifications to this method are not allowed when it is being used for compliance monitoring under the Safe Drinking Water Act (SDWA). Requirements for establishing method equivalency for CWA use are given in Section 9.1.2.

2.0 Summary of Method

2.1 The automated procedure for the determination of nitrate utilizes the reaction whereby nitrate is reduced to nitrite by a proprietary Chemical R1 under acidic conditions to form a soluble dye which is measured colorimetrically at 546nm. The final product measured represents the nitrite ion originally present plus that formed from the nitrate. Regardless of the sample matrix used, recovery of NO 3 to NO 2 is consistently between 95% and 105% recovery.

In order to determine nitrate levels, the nitrite alone must be subtracted from the total (nitrate+nitrite).

3.0 Definitions

3.1 The abbreviations below are specific to this method, but have been conformed to common usage as much as possible.

CWA Clean Water Act

DI Water Deionized Water EPA Environmental Protection Agency CASRN Chemical Abstracts Service Registry Number CERCLA Comprehensive Environmental Resource Compensation Liability Act IPR Initial Precision and Recovery

MDL Method Detection Limit MS Matrix Spike MSD Matrix Spike Duplicate MSDS Material Safety Data Sheets NIST National Institute of Standards and Technology OSHA Occupational Safety and Health Administration QC Quality Control RCRA Resource Conservation and Recovery ActPage 4 of 23 SWDA Safe Water Drinking Act

4.0 Interferences

4.1 Particulates create an interference, samples may be pre-filtered.

4.2 Residual chlorine can produce a ne gative interference by limiting reduction efficiency. Before analysis, samples should be checked and if required,

dechlorinated with sodium thiosulfate.

5.0 Safety

5.1 The toxicity or carcinogenicity of each analyte or reagent has not been precisely determined; however, each chemical s hould be treated as a potential health hazard. Exposure to these chemicals shoul d be reduced to the lowest possible level. It is suggested that the laborat ory perform personal hygiene monitoring of each analyst using this method and the resu lts of this be made available to the analyst.

5.2 This method does not address safety i ssues associated with its use. The laboratory is responsible for maintaini ng a safe work environment and a current awareness file of OSHA regulations regarding the safe handling of the chemicals specified in this method. A reference file of material safety data sheets (MSDS) should be available to all personnel i nvolved in the analyses. Additional information on laboratory safety can be found in References 16.4 - 16.6.

5.3 List of Raw Materials Unless otherwise specified all chemicals should be of ACS grade or equivalent

Safety Classification

5.3.1 R1 – Chemical IR (Proprietary) acidic

5.3.2 Potassium nitrate, KNO 3 (CASRN 7757-79-1) toxic

6.0 Equipment and Supplies

6.1 EasyChem analyzer

6.2 Computer for data collection

6.3 Printer

7.0 Reagents and Standards

7.1 Preparation of ReagentsPage 5 of 23 7.1.1 R1 Easy (1-Reagent) Nitrate Solution (Proprietary)

R1 - 1.0 Liter Size. Part Number E/R1-10

R1 - 0.5 Liter Size. Part Number E/R1-05

Available for purchase from: Craig R. Chinchilla 900 Jorie Blvd., Suite 35 Oak Brook, IL 60523

Phone: 630 645-0600

Fax: 630 645-0601

7.2 Preparation of Standards

7.2.1 Stock Standard, 1000mg/L N-NO 3 Potassium nitrate 7.218g

DI water to 1000mL

Dissolve 7.218g of potassium nitrate, in approximately 600mL of DI water. Mix thoroughly and dilute to one liter with DI water.

7.2.2 Working Standard Solution A, 100mg/L

1000 mg/L Stock Standard 10mL

DI water to 100mL

Dilute 10mL of 1000 mg/L Stock Standard A in a 100mL volumetric

flask with DI water

7.2.3 Working Standard Solution B, 10mg/L

100 mg/L Working Standard Solution A 10mL

DI water to 100mL

Dilute 10mL of 100 mg/L Working Standard A in a 100mL volumetric

flask with DI water

7.2.4 Working calibrants may be prepared to cover the desired range by adding the appropriate amount of working sta ndard solutions (Section 7.2.3) to 100mL volumetric flasks that contain approximately 80mL DI water.

Dilute the solutions to 100mL with DI water. Prepare working calibration standards daily. See the Table on page 7 for specific directions.

The following formula can be used to calculate the amount of stock (or working) calibrant to be used.

C 1 V 1 = C 2 V 2Page 6 of 23 where:

C 1 = desired concentration (in mg/L) of working calibrant to be prepared

V 1 = final volume (in mL) of working calibrant to be prepared (generally 100mL)

C 2 = concentration (in mg/L) of stock (or working) calibrant

V 2 = volume (in mL) of stock (or working) calibrant to be used

Rearranging the equation to solve for V 2 yields:

V 2 = C 1 V 1 C 2

For example, to prepare a 1.0mg/L working calibrant from a 1000mg/L stock calibrant, use 0.1mL (100μL) of the stock calibrant in 100mL final

volume.

V 2 = (1.0mg/L) (100mL) 1000mg/L

V 2 = 0.1mL

Add this amount of stock calibrant to the volumetric flask and then dilute

to volume.

Standard curves in desired ranges can be derived from the formula above or from the table on page 7 of this methodPage 7 of 23 The following table provides the quantity of secondary standard necessary to prepare working standards of the specified concentration.

Working Calibration

Standard

Concentration (mg/L) (100mL) Standard Solution Volume Added to Volumetric Flask

Working Standard

B

Concentration (Section 7.2.3) 10 mg/L Working Standard

A

Concentration (Section 7.2.2) 100 mg/L Stock Standard

Concentration (Section 7.2.1)

1000 mg/L

0.0 0.001 10 μL 1 μL 0.005 50 μL 5 μL 0.01 100 μL 10 μL 1 μL 0.05 500 μL 50 μL 5 μL 0.10 1,000 μL 100 μL 10 μL 0.50 5,000 μL 500 μL 50 μL 1.00 10,000 μL 1,000 μL 100 μL 5.00 5,000 μL 500 μL 10.0 10,000 μL 1,000 μL 50.0 5,000 μL

7.3 DI water refers to high quality water, Type I or Type II as defined in ASTM Standards, Part 31, D1193-91.

8.0 Sample Collection, Preservation, and Storage

8.1 Sample preservation and holding time requirements for drinking water samples

are as follows:

8.1.1 For nitrate: Chill the sample to 4 0 C and analyze within 48 hours, unless the sample is chlorinated. If the sampl e is chlorinated, chill the sample to

4 0 C and analyze within 14 days.

8.1.2 For nitrite: Chill the sample to 4 0 C and analyze within 48 hours. Do NOT acid preserve!

8.1.3 For nitrate-nitrite (combined): Acidify to pH<2 with concentrated H 2 SO 4 at the time of collection, and analyze within 28 days.Page 8 of 23 8.2 For wastewater samples, requirements ar e nearly identical, except that samples to be analyzed for nitrate only must be analyzed within 48 hours whether or not chlorine is present, and sample to be analy zed for nitrate-nitrite must be acidified to pH<2 with concentrated H 2 SO 4 at the time of collection, chilled to <6 0 C and analyzed within 28 days.

8.2.1 In all cases, samples should be analyzed as soon as possible after collection. For the analysis of nitrate or nitrite only, samples must be

chilled to 6 0 C and analyzed within 48 hours.

9.0 Quality Assurance/Quality Control

9.1 Each laboratory that uses this met hod is required to operate a formal quality assurance program (Reference 16.3). The minimum requirements of this program consist of an initial demonstr ation of laboratory capability, and the periodic analysis of QCSs and MS/MSDs as a continuing check on performance.

If the determined concentrations are not within +/- 10% of the stated values, performance of the determinative step of the method is unacceptable. The source of the problem must be identified and corrected before continuing with on-going analysis.

9.1.1 The analyst shall make an initial demonstration of the ability to generate acceptable precision and accuracy with this method. This ability is

established as described in Section 9.2.

9.1.2 In recognition of advances that are occurring in analytical technology, and to allow the analyst to overcom e sample matrix interferences, the analyst is permitted certain options to improve performance or lower the

costs of measurements. Alternate de terminative techniques, such as the substitution of spectroscopic or immuno-assay techniques, and changes that degrade method performance, are not allowed. If an analytical technique other than the techniques specified in this method is used, that technique must have specificity equal to or better than the specificity of the techniques in this method for the analytes of interest.

9.1.2.1 Each time a modification is made to this method, the analyst is required to repeat the procedure in Section 9.2. If the detection limit of the method will be affected by the change, the laboratory is required to demonstrate that the MDL (40 CFR Part 136, Appendix B) is lower than one-third the regulatory compliance

level or as low as or lower than that listed in Section 13. If calibration will be affected by the change, the analyst must recalibrate the instrument per Section 10. The laboratory is required to maintain records of modifications made to this

method. These records include the information in this subsection, at a minimum.

9.1.2.2 The names, titles, addresses, and telephone numbers of the analyst(s) who performed the analyses and modification, and ofPage 9 of 23 the quality control officer who witnessed and will verify the analyses and modification.

9.1.2.3 A narrative stating the reason(s) for the modification.

9.1.2.3 Results from all quality control (QC) tests comparing the modified method to this method including:

(a) Calibration (Section 10.3) (b) Calibration verification (Section 9.5) (c) Initial precision and recovery – IPR (Section 9.2.2) (d) Laboratory reagent blank – LRB (Section 9.4) (e) Laboratory Control Sample – LCS (Section 9.6) (f) Matrix spike and matrix spike duplicate (Section 9.3)

9.1.2.4 Data that will allow an independent reviewer to validate each determination by tracing the instrument output (optical density and reading) to the final result. These data are to include:

(a) Sample numbers and other identifiers (b) Analysis dates and times (c) Analysis sequence/run chronology (d) Sample weight or volume (e) Sample volume prior to each cleanup step, if applicable (f) Sample volume after each cleanup step, if applicable (g) Final sample volume prior to injection (Section 11.0) (h) Injection volume (Section 11.0) (i) Dilution data, differentiating between dilution of a sample or modified sample (j) Instrument and operating conditions (k) Other operating conditions (temperature, incubation times, etc.) (l) Detector (operating condition, etc.) (m) Printer tapes, disks, and other recording of raw data (n) Quantization reports, data system outputs, and other data necessary to link raw data to the results reported

9.1.3 Analyses of matrix spike and matrix spike duplicate samples are required to demonstrate method accuracy and precision and to monitor matrix interferences (interferences caused by the sample matrix). The procedure and QC criteria for spiking are described in Section 9.3.

9.1.4 Analyses of blanks are required to demonstrate freedom from

contamination and that the com pounds of interest and interfering compounds have not been carried over from a previous analysis. The procedures and criteria for analysis of a blank are described in Section

9.4.Page 10 of 23 9.1.5 The laboratory shall, on an ongoing basis, demonstrate through the analysis of the LCS that the analysis sy stem is in control. This procedure

is described in Section 9.6.

9.1.6 The laboratory should maintain reco rds to define the quality of data that is generated. Development of accuracy statements is described in

Sections 9.3.8 and 9.6.3.

9.1.7 Accompanying QC for the determination of nitrate is required per analytical batch. An analytical batch is a set of samples analyzed at the same time, to a maximum of 10 samples. Each analytical batch of 10 or fewer samples must be accompanied by a laboratory blank (Section 9.4), an LCS (Section 9.6), and a matrix spike and matrix spike duplicate (MS/MSD, Section 9.3), resulting in a minimum of five analyses (1 sample, 1 blank, 1 LCS, 1 MS, and 1 MSD) and a maximum of 14 analyses (10 samples, 1 blank, 1 LCS, 1 MS, and 1 MSD) in the batch. If greater than 10 samples are analyzed at one time, the samples must be separated into analytical batches of 10 or fewer samples.

9.2 Initial demonstration of laboratory capability

9.2.1 Method Detection Limit (MDL)—To establish the ability to detect nitrate at low levels, the analyst shall determine the MDL per the procedure in 40 CFR 136, Appendix B using the apparatus, reagents, and standards that will be used in the practice of this method. An MDL less than or equal to the MDL listed in S ection 13.0 must be achieved prior to practice of this method. Calculate the MDL as follows:

MDL = (t) x (S)

Where, t = Student’s t value for a 99% confidence level and a standard deviation estimate with n-1 degrees of freedom (t = 3.143 for seven replicates), S = standard deviation of the replicate analysis. MDLs should be determined every 6 months , when a new operator begins work, or whenever there is a significant change in the background or instrument response.

9.2.2 Initial Precision and Recovery (IP R)—To establish the ability to generate acceptable precision and accuracy, the analyst shall perform the following operations:

9.2.2.1 Analyze four samples of the LCS according to the procedure beginning in Section 10.0.

9.2.2.2 Using the results of the set of four analyses, compute the average percent recovery (X) and the sta ndard deviation of the percent recovery (s) for nitrate. Use Equation 1 for calculation of the standard deviation of the percent recovery.Page 11 of 23 E QUATION 1

s =

where:

x = percent reco very in each sample n = number of samples s = standard deviation of the population

9.2.3 Compare s and X with the accepta nce criteria. If s exceeds the precision limit or X falls outside the range for recovery, system performance is unacceptable and the problem must be found and corrected before analyses can begin.

9.3 Matrix spike/matrix spike duplicate (MS/MSD)—The laboratory shall spike, in duplicate, a minimum of 10 percent of all samples (one sample in duplicate in each batch of ten samples) from a given sampling site.

9.3.1 The concentration of the spike in the sample shall be determined as

follows:

9.3.1.1 If, as in compliance monitoring, the concentration of nitrate in the sample is being checked against a regulatory concentration limit, the spiking level shall be at that limit or at 1 to 5 times higher than the background concentration of the sample (determined in Section 9.3.2), wh ichever concentration is higher.

9.3.1.2 If the concentration of nitrate in a sample is not being checked against a limit, the spike shall be at the concentration of the LCS or at 1 to 5 times higher than the background concentration, whichever concentration is higher.

9.3.2 Analyze one sample aliquot out of each set of ten samples from each site or discharge according to the procedure beginning in Section 11.0 to determine the background concentration (B) of nitrate.

9.3.2.1 Spike this sample with the amount of nitrate stock solution (Section 7.2.1) to produce a concentration in the sample of 1 mg/L. If necessary, prepare another stock solution appropriate to produce a level in the sample at the regulatory compliance limit or at 1 to 5 times the background concentration (per Section 9.3.1). 

### ∑ x 2



### - 

## ( ∑ x 

## ) 2



### n

____ n-1Page 12 of 23 9.3.2.2 Spike two additional sample aliquots with the spiking solution and analyze these aliquots to determine the concentration after spiking (A).

9.3.3 Calculate the percent recovery of nitrate in each aliquot using Equation

2.

E QUATION 2

P = 100 (A – B)

T

Where: P = Percent recovery A = Measured concentration of nitrate after spiking B = Measured background concentration of nitrate T = True concentration of the spike

9.3.4 Compare the spike recovery per centage to the QC acceptance criteria of 90 to 110%. If spike percent recovery is outside of the acceptance criteria, and the recovery of the LCS in the ongoing precision and recovery test (Section 9.6) for the analytical batch is within the acceptance criteria, an interference is present. In this case, the result may not be reported for regulatory compliance purposes.

9.3.5 If the results of both the MS/MSD and the LCS test fail the acceptance criteria, the analytical system is judged to be out of control. In this case, the problem shall be identified and corrected, and the analytical batch reanalyzed.

9.3.6 Compute the relative percent di fference (RPD) between the two spiked sample results using Equation 3.

E QUATION 3

RPD = ⏐ D 1 – D 2 ⏐ x 100

--------------- [D 1 + D 2 ]/2

where: RPD = Relative percent difference

D 1 = Concentration of nitrate in the spiked sample

D 2 = Concentration of nitrate in the spiked duplicate sample

9.3.7 The precision of the RPD for the MS/MSD should be less than 20%. If the RPD is greater than the acceptance criteria, the analytical system isPage 13 of 23 judged to be out of control, and the problem must be immediately identified and corrected, and the analytical batch reanalyzed.

9.3.8 As part of the QC program for the laboratory, method precision and accuracy for samples should be assessed and records should be maintained. After the analysis of five spiked samples in which the recovery passes the test in Section 9.3.4, compute the average percent recovery (P

a ) and the standard deviation of the percent recovery (s p ). Express the accuracy assessment as a per cent recovery interval from P

a – 3s p to P

a + 3s p . For example, if P

a = 100% and s p = 5% for five analyses, the accuracy interval is expressed as 85 – 115%. Update the accuracy assessment on a regular basis (e.g., after each five to ten new accuracy measurements).

9.4 Laboratory Reagent Blanks (LRB)—Laboratory reagent water blanks are analyzed to demonstrate freedom from contamination.

9.4.1 Analyze a reagent water blank initially and with each analytical batch. The blank must be subjected to th e exact same procedural steps as the samples.

9.4.2 If nitrate is detected in the blank at a concentration greater than the MDL, analysis of samples is halted until the source of contamination is

eliminated and a blank shows no evidence of contamination.

9.5 Calibration Verification—Verify calibra tion of the analytical equipment before and after each analytical batch of 14 or fewer measurements. (The 14 measurements will normally be 10 samples, 1 reagent blank, 1 LCS, 1 MS, and 1 MSD). This can be accomplished by analyzing the mid-range calibration standard and verifying that it is within +/- 10% of the true value. (The

concentration of the calibration verifi cation depends on the calibration range being used.) Failure to attain recove ries within the acceptance criteria requires recalibration of the analysis system.

9.6 Laboratory Control Sample (LCS)—To demonstrate that the analytical system is in control and acceptable precision and accuracy is being maintained with each analytical batch, the analyst shall perform the following operations.

9.6.1 Analyze a LCS with each analytical batch according to the procedure in

Section 11.0.

9.6.2 If the results for the LCS are within +/-10% of the true value, analysis of the batch may continue. If, however, th e concentration is not within this range, the analytical process is not in c ontrol. In this event, correct the problem, repeat the LCS test, and reanalyze the batch.

9.6.3 The laboratory should add results that pass the specification in Section 9.6.2 to IPR and previous LCS data and update QC charts to form a graphic representation of continued laboratory performance. ThePage 14 of 23 laboratory should also develop a statement of laboratory data quality for nitrate by calculating the average percent recovery (R) and the standard deviation of the percent recovery (s

r ). Express the accuracy as a recovery interval from R – 3s

r to R + 3s

r . For example, if R = 100% and

s r

= 5%, the accuracy is 85% to 115%.

9.7 Reference Sample—To demonstrate that th e analytical system is in control, the laboratory may wish to periodically test an external reference sample, such as a Standard Reference Material (SRM) av ailable from the National Institutes of Standards and Technology (NIST). Corr ective action should be taken if the measured concentration significantly diffe rs from the stated concentration.

10.0 Calibration and Standardization

10.1 Working Standards should be prepared as required to cover the range of analysis at a minimum of three standards and a blank. If analyzing samples not dissolved in pure DI water, dilute the working st andards with sample matrix solution.

10.2 Calibration should include a minimum of 4 standards and a blank. The linear correlation coefficient (r 2 ) should be greater than 0.995.

10.3 Prepare standard curve by plotting instrument response against concentration readings. A calibration curve may be f itted to the calibration standards response data using the computer. Acceptance or control limits should be established using the difference between the measure d reading of the calibration standards

and the “true” value concentration.

10.4 After the calibration has been accomplished, it must be verified by the analysis of a suitable Quality Control Sample (QCS). If measurement exceeds the +/-10% of the QCS true value the analysis should be terminated and the instrument

recalibrated. The new calibration must be verified before continuing analysis. Periodic reanalysis of the CCV is recommended as a continuing calibration

check.Page 15 of 23 11.0 Procedure

11.1 User parameter settings

11.1.1 Flow Cell

Standard 10 mm pathlength

11.2 Method Parameters

11.2.1 Method Parameters Range 0.001-0.150mg/LPage 16 of 23 11.2.2 Method Parameters Range 0.020-2.0mg/LPage 17 of 23 11.2.3 Method Parameters Range 0.050-10mg/LPage 18 of 23 11.2.4 Method Parameters Range 0.25-50mg/LPage 19 of 23 12.0 Data Analysis and Calculations

12.1 Report results to three significant figures for nitrate and/or nitrite concentrations above the MDL. Do not report results below the MDL unless required by the permitting authority or in the permit.

13.0 Method Performance

13.1 Performance data using aqueous standards

Test Range 0.050-10 mg/L N-NO3 Sensitivity at 10 mg/l as N 1.8 O.D. Reagent Absorbance 0.07

Linear Correlation Coefficient 0.999 Recovery ratio 10 ppm N-NO2 90-110% versus 10 ppm N-NO3 Method Detection Limit 0.011mg/L (determined according to 40 CFR 136, Appendix B)

Note: the above performance specifications we re developed with the exclusive use of genuine parts and consumables.

14.0 Pollution Prevention

14.1 Standards should be prepared in vol umes consistent will laboratory use to minimize the volume of expired standards to be disposed.

15.0 Waste Management

15.1 It is the laboratory’s responsibility to co mply with all federal, state, and local regulations governing waste management , particularly the hazardous waste identification rules and land disposal restrictions, and to protect the air, water and land by minimizing and controlling all releases from fume hoods and bench operations. Compliance with all sewage disch arge permits and regulations is also required.

15.2 Samples preserved with HCl or H 2 SO 4 to a pH<2 are hazardous and must be neutralized before being disposed, or must be handled as a hazardous waste.

15.3 For further information on waste manage ment, consult ”The Waste Management Manual for laboratory Personnel,” and “Less is Better: Laboratory Chemical Management for Waste Reduction,” both available from the American Chemical Society’s Department of Government Relations and Science Policy, 1155 16 th
Street, N.W., Washington DC, 20036.

16.0 ReferencesPage 20 of 23 16.1 Methods for the Determination of Inorganic Substances in Environmental Samples – Nitrate 353.2 Rev. 2.0 Determin ation of Nitrate-Nitrite by AutomatedColorimetry, U.S. EPA National Exposure Research Laboratory EPA600/R93/100 (NTIS PB 94-120821), 1993.

16.2 Grasshoff, K., Technicon International Congress.

16.3 “Handbook of Analytical Quality Control in Water and Wastewater Laboratories,”USEPA EMSL, Cincinna ti, OH EPA-600/4-79-019, March 1979.

16.4 “Carcinogens - Working With Carcinogens ,” Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, Publication No. 77-206, August

1977.

16.5 “OSHA Safety and Health Standa rds, General Industry,” (29 CFR 1910), Occupational Safety and Health Admi nistration, OSHA 2206 (Revised, January 1976).

16.6 “Safety in Academic Chemistry Labor atories,” American Chemical Society, Committee on Chemical Safety, 3rd Edition, 1979.

17.0 Tables, diagrams, and validation data

See Sections 7.0 and 13.0

18 The definition and purposes below are specific to this method, but have been conformed to common usage as much as possible.

18.1 Calibration Blank (CB): A volume of reagent water in the same matrix as the calibration standards, but without analyte.

18.2 Calibration Standard (CAL): A solution prepared from the primary dilution

standard solution or stock standard solu tions. The CAL solutions are used to calibrate the instrument response with respect to analyte concentration.

18.3 Clean Water Act (CWA): An act to provide for water pollution control in the

Public Health Services of the Federal S ecurity Agency and in the Federal Works Agency and for other purposes as specifi ed in the Federal Water Pollution

Control Act.

18.4 Chemical Abstracts Servi ce Registry Number (CASRN): The largest substance identification system in existe nce. When a chemical substance, newly encountered in the literature, is pro cessed by CAS, its molecular structure diagram, systematic chemical name, molecular formula, and other identifying information are added to the Registry and it is assigned a unique CAS Registry

Number.

18.5 Comprehensive Environmental Reso urce Compensation Liability Act (CERCLA): The 1980 Superfund statute established liability to the U.S.Page 21 of 23 Government for damage to natural res ources over which the U.S. has sovereign rights and requires the President to designate Federal officials to act as trustees

for natural resources.

18.6 Deionized Water (DI Water): The vast majority of dissolved impurities in modern water supplies are ions such as calcium, sodium, chlorides, etc. The deionization process removes ions from water via ion exchange.

18.7 Environmental Protection Agency (EPA): The mission of the Environmental Protection Agency is to protect human health and the environment.

18.8 Instrument Precision Check (IPC): Also known as a Continuing Calibration Verification (CCV) used to evaluate the performance of the instrument throughout the analysis.

18.9 Linear Calibration Range (LCR): The concentration range over, which the instrument response is linear.

18.10 Laboratory Reagent Blank (LRB): An aliquot of reagent water or other blank matrices that is digested exactly as a sample including exposure to all glassware, equipment, and reagents that are used w ith other samples. The LRB is used to determine if method analytes or other interferences are present in the laboratory environment, the reagents, or other apparatus.

18.11 Method Detection Limit (MDL): The EPA defines MDL as “the minimum

concentration that can be determined with 99% confidence that the true concentration is greater than zero.” This procedure is outlined in 40 CFR 136. Prepare a solution of the analyte that is one to five times the estimated detection. Test this solution seven or more times, then determine the standard deviation of the data set. The method detection limit is calculated according to the formula:

MDL = Student’s t value x the standard deviation.

18.12 Matrix Spike (MS): Also known as a Laboratory Spiked Blank (LSB). An aliquot of reagent water or other blank matrices to which known quantities of the method analytes are added in the laboratory. The MS is analyzed exactly like a sample, and its purpose is to determine whether the methodology is in control, and whether the laboratory is capable of making accurate and precise

measurements.

18.13 Matrix Spike Duplicate (MSD): Also known as a Laboratory Spiked Sample Matrix (LSM). An aliquot of an environmental sample to which known quantities of the method analytes are added in the laboratory. The MSD is analyzed exactly like a sample, and its purpose is to determine whether the sample matrix contributes bias to the analytical results.

18.14 Material Safety Data Sheets (MSDS): Written information provided by vendors concerning a chemical’s toxicity, health hazards, physical properties, fire, and reactivity data including st orage, spill, and handling precautions.Page 22 of 23 18.15 National Institute of Standards and Technology (NIST): Founded in 1901, NIST is a non-regulatory federal agency within the U.S. Commerce Department's Technology Administration. NIST's mission is to develop and promote measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life.

18.16 Occupational Safety and Health Administration (OSHA): OSHA's mission is to assure the safety and health of Amer ica's workers by setting and enforcing standards; providing training, outreach, a nd education; establishing partnerships; and encouraging continual improveme nt in workplace safety and health.

18.17 Quality Control Sample (QCS): Also known as a Laboratory Control Sample (LCS). A solution of method analytes of known concentrations that are used to verify stock standard solutions or spike an aliquot of MS or MSD. The QCS is obtained from a source external to the laboratory and different from the source of

the calibration standards. It is used to check laboratory performance with externally prepared test materials.

18.18 Resource Conservation and Recovery Act (RCRA): RCRA gave EPA the authority to control hazardous waste from the "cradle-to-grave." This includes the generation, transportation, treatment , storage, and disposal of hazardous waste. RCRA also set forth a framework for the management of non-hazardous

wastes.

18.19 Safe Water Drinking Act (SWDA): The Office of Ground Water and Drinking Water (OGWDW)
, together with states, tribes, and its many partners, protects public health by ensuring safe drinki ng water and protecting ground water. OGWDW, along with EPA's ten regional drinking water programs, oversees implementation of the Safe Drinking Wa ter Act, which is the national law safeguarding tap water in America.

18.20 Stock Standard Solution (SSS): A concentrated solution containing one or more method analytes prepared in the laboratory using reference materials or purchased from a reputable commercial source.Page 23 of 23 19.0 Consumables used for this method.

P/N Description Sales unit Estimated consumption

CUP-EASY-02 SAMPLE CUPS 2.0 ml Pk/500 500 tests

E/F25 FILTERS - SAMPLE PROBE CLE ANER Pk/25 1 pk per month

E/R18 REAGENT BOTTLES Pk/18 1 pk per 12 months

E/RZ24 REACTION CUVETTES Pk/100 2400 tests

E/T25 STOPPER - REAGENT BOTTLES Pk/25 1 pk per month E/K01 TUBE KIT EA 1 yearly E/K02 PROBES KIT EA 1 yearly E/LA01 SOURCE LAMP ASSEMBLY EA 1 yearly E/WT2X4-01 WASTE LINE TUBE meter 5m per year E/FC-10 EASYCHEM 10MM FLOWCELL EA 1 yearly