On-line mercury and methylmercury pre-concentration by adsorption of theirdithiophosphoric acid diacyl ester chelates on a C-18 column and cold-vapor atomic-absorption detection

The pre-concentration of mercury(II) and methylmercury by adsorption of the ir dithiophosphoric acid diacyl ester (DDTP) chelates on a C-18 column, the n detection with cold-vapor atomic-absorption spectrometry was investigated . Conditions such as sample pH, reductant and chelating agent flow and conc entration, and eluent and carrier gas flow were optimized. Optimization was performed by use of evolutionary operation with a proper factorial design. At a sample flow of 5.3 mL min(-1) and a loading time of 4.5 min, column a dsorption efficiency ranged from 88 to 93% for both species. Detection limi ts down to 10 ng L-1 were obtained at a sample throughput of 12 h(-1). Ther e was good agreement between found and certified values in the analysis of certified reference materials after their microwave-assisted mineralization with HNO3 and H2O2.