Mercury speciation using the capillary cold trap coupled with microwave-induced plasma atomic emission spectroscopy

In this paper the capillary cold trap (CCT) is presented as a novel sample introduction and separation system for microwave-induced plasma detection. The method is based on cryogenic trapping and gas chromatographic separatio n carried out within the same capillary. The device, which comprises a deri vatization step, on-line gas phase extraction, preconcentration and analyte separation, is semi-automated and all operational parameters are adjustabl e via an in-house developed control unit, regulating the selected parameter s throughout the analysis process. Detection was carried out using a 2.45 G Hz microwave-induced argon discharge sustained in a TM010 Beenakker cavity and emission lines were recorded by means of a ST6-UV CCD camera provided b y the Santa Barbara Instrument Group. The detection limits achieved were 6. 0, 0.95 and 1.25 ng L-1 for dimethylmercury, methylmercury and inorganic me rcury, respectively. A complete chromatogram could be obtained within 3 min , resulting in the duration of one whole analysis cycle of about 15 min. Th e proposed method was validated by the analysis of a reference material (BC R 710) and applied to mercury speciation in different sample matrices such as oyster, tuna fish and sediments after microwave-assisted extraction. The total mercury concentration in real samples was in the range of 0.2-11 mg kg(-1), of which up to 75% corresponded to organic mercury species.