A clean water standard must be analyzed with each sample set and the established criteria met for the analysis to be considered under control. These criteria must be met or exceeded before sample analyses can be initiated. Clean water acceptance limits are presented in paragraph 2(b)(2) below.
(1) Calculate clean water precision and accuracy in accordance with standard statistical procedures. sulfide standard prepared in distilled water (see paragraph 6 under “Reagents” above). (a) Perform four replicate analyses of a 20 mg./l. Before performing any analyses, the analyst must demonstrate the ability to generate acceptable precision and accuracy with this method by performing the following operations. Ongoing performance checks must be compared with established performance criteria to determine if the results of analyses are within precision and accuracy limits expected of the method.Ģ. The laboratory is required to maintain performance records to define the quality of data that is generated. The minimum requirements of this program consist of an initial demonstration of laboratory capability and the analysis of replicate and spiked samples as a continuing check on performance. Each laboratory that uses this method is required to operate a formal quality control program. of analytical reagent grade NaOH in 1 liter distilled water.ġ. Diluted working standards must be prepared fresh daily and their concentrations determined by EPA test procedure 376.1 (see 40 CFR 136.3, Table IB, parameter 66 ( 49 FR 43234, October 26, 1984, with correction notice at 50 FR 690, January 4, 1985)) immediately prior to use.ħ. reagent grade sodium sulfide in 1 liter of distilled water. Preparation of stock sulfide standard, 1000 ppm: Dissolve 2.4 g. 1 percent dimethylglyoxime in ethanol, and 0.5 ml. Preparation of ferrous dimethylglyoxime indicator solution: Mix 10 ml. barium chloride dihydrate in 1 liter of distilled water.ĥ. Preparation of 0.05M barium chloride solution: Dissolve 12-13 g. Store in a tightly stoppered container.Ĥ. 14M reagent grade ammonium hydroxide and make up to 1 liter with distilled water. ammonium chloride in approximately 500 ml. Preparation of 6M ammonium chloride buffer, pH 9.3: Dissolve 200 g. Normaility of Potassium Ferricyanide = ( ml of thiosulfate added ) ( normality of thiosulfate ) M 1 of K 3 Fe ( CN ) 6ģ.
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