Preconcentration of submicrogram amounts of metals from natural water for X-ray energy spectrometric determination using pyrrolidinecarbodithioic acid

A method was developed for the routine determination of several trace metals in natural waters by X-ray energy spectrometry following precipitation with pyrrolidinecarbodithioate. Preoxidation with persulfate eliminates interferences by organic matter. By optimizing carrier ion selection and measurement conditions, one may determine dithioate-reactive elements with Z less than or equal to 50 by means of their K X-rays, and some with Z greater than or equal to 80 by means of their L X-rays. Determinations are feasible for several elements at concentrations down to 250 ng L-1, or below. Recoveries are generally greater than 90%, although some exceptions are noted. Reproducibility with real samples averaged about 25% relative standard deviation for five representative elements at concentrations above 250 ng L-1. 24 references, 5 figures, 4 tables