DETERMINATION OF INORGANIC AND ORGANIC MERCURY-COMPOUNDS BY CAPILLARYGAS-CHROMATOGRAPHY COUPLED WITH ATOMIC-ABSORPTION SPECTROMETRY AFTER PRECONCENTRATION ON DITHIZONE-ANCHORED POLY(ETHYLENE GLYCOL DIMETHACRYLATE-HYDROXYETHYLMETHACRYLATE) MICROBEADS

Poly(EGDMA-HEMA) microbeads were prepared by suspension polymerization of ethylene glycol dimethacrylate EGDMA) and hydroxyethyl methacrylat e (HEMA). Poly(vinyl alcohol), benzoyl peroxide and toluene were used as stabilizer, initiator, and diluent, respectively. A chelating ligan d, dithizone, was then attached. The microbeads were characterized by FTIR spectrometers and elemental analysis. The affinity microbeads con taining 118.9 mu mol dithizone g(-1) polymer were used for the adsorpt ion/desorption of inorganic mercury [Hg], methyl mercury chloride [CH3 HgCl] and ethyl mercury chloride [C2H5HgCl] from aqueous media at conc entrations in the range 5-1000 mu g l(-1) and various pH values (2.0-8 .0). Adsorption rates were high, and adsorption equilibria were reache d in about 30 min. The maximum adsorption of mercury species onto the dithizone-anchored microbeads from their individual solutions was 138 mg g(-1) for Hg(Tr), 221 mg g(-1) for CH3HgCl and 207 mg g(-1) for C2H 5HgCl. The same behavior was observed during competitive adsorption in the case of the adsorption from their mixture. The affinity order of mercury species was CH3HgCl > C2H5HgCl > Hg(II). Dithizone-anchored mi crobeads are suitable for repeated use for more than 5 cycles without noticeable loss of adsorption capacity. Speciation of organomercurials was performed using a Gas chromatography-atomic absorption spectromet ry coupled system. Detection limits were increased at least 120-fold w ith this preconcentration approach using the dithizone-anchored microb eads. (C) 1998 Elsevier Science B.V. All rights reserved.