Optimization of the coupling of multicapillary GC with ICP-MS for mercury speciation analysis in biological materials

The coupling between multicapillary gas chromatography (MCGC) and inductively coupled plasma mass spectrometry (ICP-MS) was optimized with the objective of minimizing the detection limits and time necessary for the species-selective determination of mercury compounds. The most critical parameters influencing the sensitivity were the position of the capillary inside the ICP injector, the makeup gas flow rate and the column temperature. The interface itself did not need to be heated. An absolute detection limit of 0.08 pg could be achieved and was controlled by the injection speed and the data acquisition rate of the quadrupole mass analyser. Using a previously developed automated purge-and-trap accessory, a method for the analysis of fish samples was developed and validated by the analysis of the DORM-1 and TORT-1 National Research Council of Canada (NRCC) certified reference materials. The experimental detection limit for methylmercury was 0.2 ng g –1 ; for Hg 2+ it was controlled by the reagent blank.