TRACE GOLD DETERMINATION BY ONLINE PRECONCENTRATION WITH FLOW-INJECTION ATOMIC-ABSORPTION SPECTROMETRY

A reverse-phase extraction column method has been employed as an on-li ne preconcentration technique for trace gold analysis by flame atomic absorption spectrometry. Di(methylheptyl)methyl phosphonate (DMHMP) lo aded onto a macroporous resin was used as the immobilized phase. A thi ourea-HCl solution was found successful in eluting the gold. The exper imental parameters were optimized by Simplex Optimization, with 17 tes ts needed to obtain optimal conditions. Sensitivities of 5.2 mug/l. an d 2.3 mug/l., with sample frequencies of 45/hr and 48/hr, were obtaine d by using single and dual-columns respectively. The recoveries for mi xed composition samples were 93-110%.