SORPTION OF PAR-METAL COMPLEXES ON ACTIVATED CARBON AS A RAPID PRECONCENTRATION METHOD FOR THE DETERMINATION OF CU, CO, CD, CR, NI, PB AND V IN-GROUND WATER

A simple, rapid and field-oriented preconcentration method is describe d for the determination of Cu, Co, Cd, Cr, Ni, Pb and V in ground wate r samples by flame AAS. The method is based on sorption of trace eleme nts as metal-pyridyl azo resorcinol (M-PAR) complexes on activated car bon (AC) at pH 5.5 +/- 0.5. The effects of various parameters for quan titative sorption of M-PAR chelates on AC are discussed. The trace ele ments are desorbed from AC simply by treating AC with 1.6 M nitric aci d, thus avoiding the tedious and time consuming operation of ashing AC . An enrichment factor of 200 or greater is easily achievable. The tra ce elements could be determined down to 1 ppb (V at 5 ppb) with +/-15% relative error. The RSD of the method is +/-15% at the practical dete rmination limit of 1 ppb with an enrichment factor of 200. The major a dvantage of the method is the possibility of performing the preconcent ration at the sampling site and hence a small preconcentrated volume c ould be sent for instrumental analysis, thus preventing sorption on a container during storage. The method has been applied to numerous grou nd water samples for the determination of these trace analytes at ppb levels in connection with the hydrogeochemical exploration for uranium . (C) 1998 Elsevier Science B.V. All rights reserved.