Photometric determination of trace silver with dithizone-benzene

A small amount of silver in 8N sulfuric acid is extracted with dithizone-benzene, and the silver dithizonate is decomposed with sodium chloride solution. It is reextracted with dithizonebenzene, the excess of dithizone is washed out with dilute aqueous ammonia, and silver is determined by mono-color method. Alternatively, the excess of dithizone in the first extract is washed off and the complex is treated with sodium chloride solution. The liberated dithizone is photometrically determined to give an indirect measure of silver. The reextraction is unnecessary in the latter procedure. Good results were obtained by applying the method for determination of a small amount of silver in alloyed steel or in large amount of copper. The use of EDTA for masking of copper in the presence of iron should be avoided since it also hinders the extraction of silver.