Talanta 53 (2001) 749–760 Preconcentration and separation of total mercury in environmental samples using chemically modified chloromethylated polystyrene-PAN (ion-exchanger) and its determination by cold vapour atomic absorption spectrometry M.A.H. Hafez *, I.M.M. Kenawy, M.A. Akl, R.R. Lashein Department of Chemistry, Faculty of Science, Mansoura Uniersity, El -Mansoura 35516, Egypt Received 15 March 2000; received in revised form 24 July 2000; accepted 25 July 2000 Abstract The use of chemically modified chloromethylated polystyrene-PAN, CMPS-PAN (ion-exchanger) for the precon- centration and separation of total mercury after digestion in preparation for determination by cold vapour atomic absorption spectrometry (CVAAS) was described. The effects on the percentage of recovered mercury by mass change of ion-exchanger, stirring time, pH of the solution samples and eluent concentration were studied. The distribution coefficient K d is 10 6.6 ml g -1 . The interfering effects of some foreign ions were described. The metal complex formed between CMPS-PAN ion-exchanger and mercury was characterized by IR spectroscopy, pH-metric titration and thermal analysis. The method is simple and rapidly applicable for the determination of total mercury (ng ml -1 ) in natural water, milk and urine. © 2001 Elsevier Science B.V. All rights reserved. Keywords: Mercury determination; CVAAS; Water analysis www.elsevier.com/locate/talanta 1. Introduction Over the last two decades, the need has in- creased for the determination of extremely low concentrations of mercury in various samples be- cause it accumulates in living tissues, thereby causing many harmful effects [1 – 3]. Cold vapour atomic absorption spectrometry (CVAAS) has been reported as a very efficient technique for the determination of sub-g ml -1 concentrations [4], in addition to graphite furnace atomic absorption after amalgamation [5,6], emission spectroscopy after electrodeposition [7] and determination by CVAAS [8 – 10]. The most important parameters for the ultratrace determination of mercury have been previously described [11,12]. A gold – plat- inum gauze has proven to be the most effective collector for mercury [11,12]. In later work, Welz and Schubert-Jacobs [13] also successfully em- * Corresponding author. Fax: +20-50-346781. E-mail address: sinfac@mum.mans.eun.eg (M.A.H. Hafez). 0039-9140/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved. PII:S0039-9140(00)00524-5