Validation Study Plan for Proposed ATP Method Hach 10225 for the Colorimetric Measurement of Fluoride Ion Using SPANDNS Reagent and an Arsenite

- fr ee Interferent Reduction Option

Introduction

This validation study plan (Plan) follows in part, follows the guidelines set forth in the United States Environmental Protection Agency (EPA) document Protocol for EPA Approval of

Alternate Test Procedures for Organic and Inorganic Analytes in Wastewater and Drinking

W

ater

. 1 The Plan is part of the application f or requesting expedited approval of Hach Method

10 225 for the Colorimetric Measurement of Fluoride Using SPADNS and a n Arsenite

- free Interferent Reduction Option.

Method Justification

EPA reference method SM4500

- F D and ATP Hach Method 8029 are colorime tric

methods that use SPADNS chemistry for the measurement of fluoride. As part of the se method s
, sodium arsenite is used for the removal of residual chlorine, as it is an interferent in the analysis

for fluoride. Hach Method 10 225 for the Measurement of Fluoride uses the exact same core chemistry as the EPA reference and ATP methods cited above, but differs by replacing the sodium arsenite with a green non

- hazardous chlorine scavenger.

Program Use

This method is currently approved for use in 40 CFR pa rt 136 wastewater programs under section 136.6. It is being proposed as an alternative method under the EPA Office of Drinking Water Expedited Rule for 40 CFR 141 drinking water monitoring programs.

Single Laboratory Performance Data and Results

In the development of this test method, a single laboratory side

- by

- side study was performed with the EPA reference SM4500

- F D and ATP 8029 methods. The summary of the

results are listed in Table 1.

1 1 EPA

- 821

- B

- 98

- 002, March 1998.Table1. Summary of Results from Fluoride Side

- by

- side Study

Performance Test Reference Method Results

SM 4500

- F D/Hach 8029 Proposed ATP Method

Results Hach 10225

MDL

– 7 reps at 0.03 mg/L F - 0.014 mg/L F - 0.014 mg/L F QL

– 3.18 X MDL rounded up 0.05mg/L F - 0.04 mg/L F IPR

– 4 reps at 1.0 mg/L F Average 100 .3 % 99.8%

IPR

– 4 reps at 1.0 mg/L F Stdev 0.50 0.50

IPR

– 4 reps at 1.0 mg/L F -

%RSD 0.49% 0.50%

Matrix Spikes

– Duplicates at

5.0 mg/L Cl 2 Fall City, Washington spiked @ 1.0 mg/L F Duplicate Average 94.5% 97.0%

Duplicate %RSD 0.75 % 0.00% Sandy Springs, Georgia spiked @ 0.50 mg/L F Duplicate Average 90.0% 96.0%

Duplicate %RSD 3.14% 0.00% Dallas, Texas spiked @ 0.50 mg/L F Duplicate Average 92.0% 92.0% Duplicate %RSD 3.07% 0.00%

Proposed Validation Test Plan

T est Analyte

– Fluoride ion

Number of test matrices

– 3

Number of test laboratories

– 3

Geographic locations

– California, Colorado, Iowa

Reference Method

– SM4500

- F D/Hach 8029

ATP Method

– 10225Comparative Test

Validation performed by laborator ies in three geographically distinct regions (CA, CO, IA)

Calibration verification at 0.5 and 1.5 mg/L F MDL

– 7 replicates spiked @ 0.1 mg/L F - with low ionic strength water and a minimum

of 2

. 0 mg/L Cl 2 MDL

– 7 replicates spiked @ 0.1 mg/L F - with h igh ionic strength water * and a minimum of 2.0 mg/L Cl 2

IPR

– 4 replicates spiked @ 1.0 mg/L F - with l ow ionic strength water and a minimum of

2.0 mg/L Cl 2 IPR

– 4 replicates spiked @ 1.0 mg/L F - with high ionic strength water and a minimum of 2.0 mg/L Cl 2

Matrix

– 4 replicates of tap water with fluoride fortification levels of 0.5

– 1.0 mg/L F and residual chlorine levels of 0.02

– 2.00 mg/L Cl 2

One laboratory to distill matrix samples

* High ionic strength water was prepared by weighing 0.70 g sodi um bicarbonate, 0.74 g sodium sulfate and 0.77 g sodium chloride into a 1

- L volumetric flask and bringing to volume with reagent water. The stock solution was diluted by a factor of 10x and used for the analyses.