PURGE-AND-TRAP ISOTHERMAL MULTICAPILLARY GAS-CHROMATOGRAPHIC SAMPLE INTRODUCTION ACCESSORY FOR SPECIATION OF MERCURY BY MICROWAVE-INDUCED PLASMA-ATOMIC EMISSION-SPECTROMETRY

A compact device based on purge-and-trap multicapillary gas chromatogr aphy was developed for sensitive species-selective analysis of methylm ercury and Hg2+ by atomic spectrometry. The operating mode includes in situ conversion of the analyte species to MeEtHg and HgEt2 and cryotr apping of the derivatives formed in a 0.53-mm-i.d. capillary, followed by their flash (<30 s) isothermal low-temperature separation on a min imulticapillary (22 cm) column. The very low detection limits obtained (0.01 pg mL(-1) of Hg for methylmercury) are due to the narrow inject ion band and reduced peak broadening in a bundle of 0.038-mm capillari es at high flow rates (>60 mL min(-1)) compatible with an MIP AES dete ctor (no dilution with a makeup gas is required). Developments regardi ng each of the steps of the analytical procedure and effects of operat ional variables (sample volume, purge now, trap temperature, separatio n conditions) are discussed. The device allows speciation of MeHg+ and Hg2+ down to 5 pg g(-1) in urine and, after a rapid microwave-assiste d hydrolysis, down to 0.1 ng g(-1) in solid biological samples with a throughput of 6 samples/h, The analytical protocols developed were val idated by the analysis of DORM-1 (dogfish muscle), TORT-1 (lobster hep atopancreas), and Seronorm urine certified reference materials.