## HACH COMPANY

Validation Study Report for Hach Method 10206, TNTplusTM 835/836 Nitrate Using Dimethylphenol Chemistry - Measurement of Nitrate in Water and
Wastewater

Submitted by:
David MacDonald

November 2010Hach Company Validation Study Report Measurement of Nitrate in Water and Wastewater, Method 10206

2 Background

Purpose of Study The purpose of this study was to evaluate the proposed Hach Company Measurement of Nitrate in Water and Wastewater, Method 10206 against the USEPA reference nitrate methods (EPA Method 300.1 and SM4500-NO 3 - E) for approval and use in USEPA regulatory drinking water programs.

Method Summary The Hach TNTplus Nitrate chemistry follo ws classical electrophillic aromatic substitution in that nitrate in the presence of sulfuric acid yields a nitronium ion ( + NO 2 ) and HSO 4 - . Nitronium ions are el ectrophiles that attack t he aromatic ring of the dimethylphenol reagent to fo rm intermediate nitro-carbonium ions. The basic HSO 4 - ion then extracts a hydrogen ion from the nitr o-carbonium intermediate to yield a stable substitution product (o, or p-nitro-dimethyl phenol). The nitrodimethylphenol product is a highly colored (directly related to the nitr o functional group), quantif iable by its visible absorption spectra.

Method Justification

The current EPA reference methods for the measurement of nitrate nitrogen (NO 3 - -N) and total nitrate-nitrite nitrogen (NO 3 —NO 2 N) (EPA Methods 353.2, SM4500- NO3 — E and F, and ASTM D3867-99(A) (B)) are costly, and contain cadmium which is harmful to the environment. A “green” chemistry method that excludes the use of toxic metals is desirable that is equally effective in performance in the measurement of nitrate and nitrate-nitrite nitrogen.

Scope of Method The Method 10206 is applicable for use in drinking water, surface and saline waters, and domestic and industrial wastewat ers. The measurem ent range for this method is in the range from 0.020 to 13.5 mg/L NO 3 - - N.

Study Design and Objectives

The design and objectives of this validat ion study are detailed in the Validation Study Plan 1 appended to this report.

1 Revised Hach Validation Study Plan, August 2010Hach Company Validation Study Report Measurement of Nitrate in Water and Wastewater, Method 10206

3 Study Implementation

Study Sponsor The organizational sponsor responsible for managing this study is Hach Company.

Study Participants The participants, laboratories, and test matrices were selected from geographically diverse regions of the United States and are lis ted in the following table.

Matrix Facility Laboratory Source of Treated Test Water Watertown, Wisconsin Test America-Watertown Surface Water Cedar Falls, Iowa Test America-Cedar Falls Surface Water Phoenix, Arizona Test America-Phoenix Ground Water

Tier Study The validation study was perform ed under Tier II requirements.

Sample Collection and Distribution Matrix samples for this validation st udy were collected at the tap for each laboratory. Collection follow ed standard USEPA sampling procedures 2

.

Analysis Description The description of the type and number of analyses are described in the Validation Study Plan appended to this report.

Data Reporting and Validation

Data Collection, Laboratory Submission, and Validation For each laboratory performing analyses, results from each test measurement were read from a DR 2800 s pectrophotometer and manually tr ansferred to an electronic spread sheet. Each laboratory then submitt ed the electronic spread sheet to the Hach Study Director for review and statistical evaluation.

Results

Summary results of the validation study are listed in Tables 1-4.

2 40CFR 141.23Hach Company Validation Study Report Measurement of Nitrate in Water and Wastewater, Method 10206

4 Table 1 - City of Watertown Tr eatment Plant Summary Results
EPA 353.2 Hach Method 10206 Matrix Method Detection Limit (mg/L) Minimum Quantitation (mg/L) Method Detection Limit (mg/L) Minimum Quantitation (mg/L) Low Ionic Strength Reagent Water 0.06 0.20 0.10 0.30

High Ionic Strength Reagent Water 0.01 0.03 0.04 0.10

Initial Precision and Recovery Initial Precision and Recovery Average Percent (%)

Recovery Standard Deviation Average Percent (%)

Recovery Standard Deviation

Low Ionic Strength Reagent Water 108 0.01 100 0.01

High Ionic Strength Reagent 106 0.02 97 0.01

Matrix Spike Analysis Matrix Spike Analysis Average Percent (%)

Recovery % Relative Difference Average Percent (%)

Recovery % Relative Difference Watertown Tap

109 0.2 96.0 0.4Hach Company Validation Study Report Measurement of Nitrate in Water and Wastewater, Method 10206

5 Table 2 – Cedar Falls Treatment Plant Summary Results

Standard Method 4500- NO 3 - E Hach Method 10206 Matrix

Method Detection Limit (mg/L) Minimum Quantitation (mg/L) Method Detection Limit (mg/L) Minimum Quantitation (mg/L) Low Ionic Strength Reagent Water 0.01 0.02 0.09 0.30

High Ionic Strength Reagent Water 0.04 0.10 0.08 0.20

Initial Precision and Recovery Initial Precision and Recovery Average Percent (%)

Recovery Standard Deviation Average Percent (%)

Recovery Standard Deviation

Low Ionic Strength Reagent Water 99.0 0.05 99.1 0.01

High Ionic Strength Reagent Water 102 0.02 90.5 0.003

Matrix Spike Analysis Matrix Spike Analysis Average Percent (%)

Recovery % Relative Difference Average Percent (%)

Recovery % Relative Difference Cedar Falls Tap

97.4 3.2 94.3 0.4Hach Company Validation Study Report Measurement of Nitrate in Water and Wastewater, Method 10206

6 Table 3 – Phoenix Water Treatment Plant Summary Results

EPA Method 300.0 Hach Method 10206 Matrix Method Detection Limit (mg/L) Minimum Quantitation (mg/L) Method Detection Limit (mg/L) Minimum Quantitation (mg/L) Low Ionic Strength Reagent Water 0.02 0.10 0.03 0.10

High Ionic Strength Reagent Water 0.01 0.10 0.08 0.20

Initial Precision and Recovery Initial Precision and Recovery Average Percent (%)

Recovery Standard Deviation Average Percent (%)

Recovery Standard Deviation

Low Ionic Strength Reagent Water 104 0.003 98.6 0.003

High Ionic Strength Reagent Water 104 0.002 96.4 0.002

Matrix Analysis Matrix Analysis Average Percent (%)

Recovery % Relative Difference Average Percent (%)

Recovery % Relative Difference Phoenix

102 0.2 95.1 2.4

Development of QC Acceptance Criteria

Development of quality control acceptance crit eria for method detection limit (MDL) and initial precision and recovery (IPR) followed the criteria detailed in A ppendix D, Tier 2 of Section 9 of the guidance document for EPA approval of new methods 3 . A summary of the pooled quality control acceptance criteria is described in Table 4.

3 Protocol for EPA Approval of New Methods for Organic and Inorganic Analytes in Wastewater and Drinking Water, March 1999 EPA

‐ 821

‐ 98

‐ 003Hach Company Validation Study Report Measurement of Nitrate in Water and Wastewater, Method 10206

7 Table 4 – Pooled Statistical Results
Reference Methods Hach Method 10206 Matrix Method Detection Limit (mg/L) Rounded Minimum Quantitation (mg/L) Method Detection Limit (mg/L) Rounded Minimum Quantitation (mg/L) Low Ionic Strength Reagent Water 0.03 0.10 0.06 0.20

High Ionic Strength Reagent Water 0.02 0.10 0.05 0.20

Initial Precision and Recovery Initial Precision and Recovery Percent (%)

Recovery

Range Precision of Recovery 95% Confidence Percent (%) Recovery

Range Precision of Recovery 95% Confidence Lower Limit Upper Limit Lower Limit Upper Limit Low Ionic Strength Reagent Water 88 119 0.06

97 101 0.01

Lower Limit Upper Limit Lower Limit Upper Limit High Ionic Strength Reagent Water 95 112 0.03

81 108 0.01

Matrix Limit Percent (%) Recovery Range Matrix Limit Percent (%) Recovery Range Low High Low High

85.7 120 92.6 97.7Data Analysis/Discussion

MDL Results The range of results of the LI S matrix were 0.01 mg/L NO 3 - -N to 0.06 mg/L NO 3 - -N for the reference method and 0.03 mg/L NO 3 - -N to 0.10 mg/L NO 3 - -N for the Hach method. For the reference HIS matrix , the range was 0.01 mg/L NO 3 - -N to 0.04 mg/L NO 3 - -N and 0.04 mg/L NO 3 - -N to 0.08 NO 3 - -N for the Hach method.

The pooled method detection limit results of the LIS matrix yielded 0.03 mg/L NO 3 - -N for the reference method and 0.06 mg/L NO 3 - -N for the Hach Method. For the HIS matrix, the pooled method detection limit results yielded 0.02 mg/L NO 3 - -N for the reference method and 0.05 mg/L NO 3 - -N for the Hach Method. The rounded minimum quantitation limit, regardless of the ionic strength yielded 0.10 mg/L NO 3 - -N for the reference method and 0.20 mg/L NO 3 - -N for the Hach method.

Initial Precision and Recovery Results The range of recovery results of the LIS ma trix were 99% to 108% for the reference method and 91% to 100% for the Hach method. For t he reference HIS matrix, the recovery range was 102% to 106 % and 91% to 97% for the Hach method. For the LIS matrix, the range of precision (standard deviation) of the re ference method was 0.003 to 0.05 and 0.003 to 0.01 for the Hach method. Fo r the HIS matrix, the range of precision of the reference method was 0.002 to 0. 02 and 0.002 to 0.01 for the Hach method.

The pooled initial precision and recovery limits of the LIS matrix yielded a recovery range of 88% to 119 % and a precision of 0.06 for the reference method and 97% to 101% and a precision of 0.01 for the Hach method. The pooled initial precision and recovery limits of the HIS matrix yielded a recovery range of 95% to 112% and a precision of 0.03 for the reference method and 81% to 108% and a precision of 0.01 for the Hach method.

Matrix Spike Results The matrix spike percent relative standar d deviation (%RSD) results ranged from 0.13 to 2.9 for the reference method and 0. 29 to 1.8 for the Hach method.

The pooled range of recovery was 86% to 120% for the reference me thod and 93 to 98 for the Hach method.Hach Company Validation Study Report Measurement of Nitrate in Water and Wastewater, Method 10206

Conclusions

A validation study was conducted to comp are the performance of Hach Method 10206 for the measurement of NO 3 - -N in drinking water to that of the EPA approved reference method. The results of the study indicate that the Hach method (10206) is equally effective to the performanc e of the reference method.

9Hach Company Validation Study Report Measurement of Nitrate in Water and Wastewater, Method 10206

10 Appendices

Appendix A – EMMC formatted Hach Met hod 10206 (Hach Method 10206.pdf)

Appendix B – Supporting Data (Supporting Data.xls)