Ion-Pair Extraction and “One-Drop” Flame Atomic Absorptiometric Determination of Silver in Sargasso

摘要

Ion-pair extraction of silver with 3,6-dithiaoctane in the presence of a univalent anion into a small volume of chloroform at pH less than 6 was studied. Univalent anions tested were 5 inorganic and 9 colored organic anions and 2 cobalt complex anions. Of these anions, perchlorate, tetraphenylborate and picrate anions and three alkyl oranges, Bromocresol Green, Bromothymol Blue, 5-Br-PAPS and cobalt-dihydroxyazobenzene complex gave a quantitative extraction (99%) of silver. The direct nebulization of 50 μL of the chloroform extract into a fuel-lean air-acetylene flame gave a highly sensitive signal intensity without any background correction from chloroform. The present method was applied to the determination of silver in a certified botanical sample, NIES-CRM No. 9 Sargasso. The results were very satisfactory and reproducible.