ANSI IT4.43-1998 pdf download Effluents – Determination of Total Cyanide
Hydrogen cyanide gas and water vapor are evolved from boiling the sample solution and are separated by refluxing and by means of an air stream. The water vapor is returned to the disilling flask and the hydro- gen cyanide is carried over into a sodium hydroxide solution. The disilled cyanide ion is then determined colorimetrically using the Chloramine-T method or optionally determined by titration with silver nitrate if the cyanide content is greater than 1 mg/.
4 Reliability
4.1 Statistical reliability According to the American Public Health Association (APHA) Standard Methods [1],” the silver nitrate ti- tration for cyanide (CN”) levels above 1 mg/1 has a coefficient of variation (100o/x) of 2.0% for ditildl samples or for relatively clear samples without significant interferences. The data, though obtained using the referenced method with mercuric chloride, will also apply to the method described in this standard. Using this method on one simulated photographic processing efluent, one laboratory found 95% confi- dence limits of +0.1 mg/l at a level of 2 mg/, based on 26 pairs of data. The 95% confidence limits for six- teen standard samples (between 0.020 mg/l and 0.200 mg/l CN) were found to be approximately +0.010 mg/l CN”.
4.2 Interferences The EPA approved total cyanide method, ASTM D2036, is based on dilation of HCN with sulfuric acid and magnesium chloride catalyst into an alkaline receiving solution. The specified finishing step consists of either a silver complexometric titration, a Chloramine-T colorimetric measurement, or a specific ion electrode measurement. The method given in this standard is also based on the disilation of HCN with sulfuric acid and magnesium chloride catalyst into an alkaline receiving solution.
The ANSI method speci fies the Chloramine-T colorimetric finishing step or a potentiometric titration with silver nitrate. Recent studies [2, 6, 9] have shown that organic compounds can react with amines when present together in wastewater to form cyanide under distllation conditions. Simulated color developing and photo- graphic processing solutions were examined in one study [8]. Hydroxylamine sulfate and organic com- pounds such as EDTA, glycols, alcohols, acetic acid, and aromatic amines were mixed together. Cyanide was detected from both solutions using EPA disillation conditions even though it had not been added.
ANSI IT4.43-1998 pdf download
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