Two selected methods from “Methods for Chemical Analysis of Water and Wastes,” EPA-600/4-79-020 (1979) have been subjected to interlaboratory method validation studies. The two selected methods are for Thallium and Zinc. The following precision and recovery statements are presented in this appendix and incorporated into Part 136:

Method   279.2

For Thallium, Method 279.2 (Atomic Absorption, Furnace Technique) replace the Precision and Accuracy Section statement with the following:

Precision and Accuracy

An interlaboratory study on metal analyses by this method was conducted by the Quality Assurance Branch (QAB) of the Environmental Monitoring Systems Laboratory—Cincinnati (EMSL-CI). Synthetic concentrates containing various levels of this element were added to reagent water, surface water, drinking water and three effluents. These samples were digested by the total digestion procedure, 4.1.3 in this manual. Results for the reagent water are given below. Results for other water types and study details are found in “EPA Method Study 31, Trace Metals by Atomic Absorption (Furnace Techniques),” National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161 Order No. PB 86-121 704/AS, by Copeland, F.R. and Maney, J.P., January 1986.

For a concentration range of 10.00-252 µg/L

X = 0.8781(C) − 0.715

S = 0.1112(X) + 0.669

SR = 0.1005(X) + 0.241

Where:

C = True Value for the Concentration, µg/L

X = Mean Recovery, µg/L

S = Multi-laboratory Standard Deviation, µg/L

SR = Single-analyst Standard Deviation, µg/L

Method   289.2

For Zinc, Method 289.2 (Atomic Absorption, Furnace Technique) replace the Precision and Accuracy Section statement with the following:

Precision and Accuracy

An interlaboratory study on metal analyses by this method was conducted by the Quality Assurance Branch (QAB) of the Environmental Monitoring Systems Laboratory—Cincinnati (EMSL-CI). Synthetic concentrates containing various levels of this element were added to reagent water, surface water, drinking water and three effluents. These samples were digested by the total digestion procedure, 4.1.3 in this manual. Results for the reagent water are given below. Results for other water types and study details are found in “EPA Method Study 31, Trace Metals by Atomic Absorption (Furnace Techniques),” National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161 Order No. PB 86-121 704/AS, by Copeland, F.R. and Maney, J.P., January 1986.

For a concentration range of 0.51-189 µg/L

X = 1.6710(C) + 1.485

S = 0.6740(X) − 0.342

SR = 0.3895(X)− 0.384

Where:

C = True Value for the Concentration, µg/L

X = Mean Recovery, µg/L

S = Multi-laboratory Standard Deviation, µg/L

SR = Single-analyst Standard Deviation, µg/L

[77 FR 29833, May 18, 2012]