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The design, construction and performance characteristics of an easily removable interface to couple a gas chromatograph (GC) to an inductively coupled plasma mass spectrometer (ICP-MS) for trace element speciation is described. The interface is based on the use of a heated metallic tube where the last part of the capillary GC column is inserted. This metallic tube is connected to a metallic T-piece where a flow of argon carrier gas is introduced perpendicularly and externally to the metallic tube, creating a high velocity flow of intermediate sheath gas, which prevents condensation of the analytes eluting from the column on the walls of the T-piece or on the connection tubing to the ICP-MS torch. A flexible non-heated PTFE tube is used to connect the exit of the T-piece to the ICP-MS torch. This new interface has been applied to the separation and detection of different organometallic compounds of Se, S, Pb, Hg and Sn.

For the analysis of biological and environmental materials by inductively coupled plasma mass spectrometry (ICP-MS), several quantification procedures can be used depending on the precision and accuracy required. Semiquantitative methods based on the molar response curve were compared with conventional external calibration and standard additions for the analysis of waters and sewage sludges. For the analysis of biological materials, where higher quality data were required, isotope dilution analysis using enriched isotopes was applied. It was observed that the molar sensitivity for different elements in ICP-MS was a simple function of the mass of the isotopes measured after normalization for ionization efficiency which could be fitted to a third-order polynomial equation. Element ionization adjustments for the third-order polynomial, using the Saha equation, allowed the calculation of the plasma ionization temperature and electron density. For the determination of trace metals in waters and sewage sludges, the samples were spiked with different internal standards, ionization corrections were performed and the results obtained agreed with those obtained by external calibration and standard additions within a factor of 2 but, on average, the agreement was within 20%. The determination of molybdenum in biological reference materials was performed by isotope dilution analysis taking into account possible sources of error in the measurements by ICP-MS such as mass discrimination, detector dead time, isobaric interferences and random error propagation. © 1997 by John Wiley & Sons, Ltd.