MULTIELEMENT DETECTION FOR SUPERCRITICAL FLUID CHROMATOGRAPHY BY INDUCTIVELY COUPLED PLASMA MASS-SPECTROMETRY

The feasibility of multi-element detection using supercritical fluid chromatography (SFC) with inductively coupled plasma mass spectrometry (ICP-MS) has been investigated for organomercury and organolead compounds. Since a quadrupole mass spectrometer is a sequential instrument. multi-element detection of transient signals presents difficulties; therefore, detection is usually performed in a single-ion monitoring mode. The applicability of utilizing time-resolved acquisition (TRA) software for quantitative determinations using SFC was investigated and compared with results obtained for single-ion monitoring modes. Detection limits were found to be approximately 5-10 pg for diethylmercury (DIEM) using TRA detection and 3 pg using single-ion monitoring detection. The detection limits of tetrabutyllead (TTBL) and tributyllead (TRBL) acetate were found to be 0.7-3 and 50-100 pg, respectively, for the TRA acquisitions, and 0.5 and 10 pg for single-ion monitoring measurements. The calibration graphs were linear over three decades for DIEM and TTBL, and two decades for the TRBL. The precision of the technique was between 1 and 5% relative standard deviation for 5 ng injections of the compounds of interest. The accuracy of the SFC-ICP-MS single-ion monitoring technique was demonstrated by analysis of a National Institute of Standards and Technology (NIST) standard reference material (SRM) 2715 Lead in Reference Fuel, giving a concentration of 785+/-9.71 ppm of tetraethyllead, with the SFC-ICP-MS system, compared with the certified value of 784+/-4.00 ppm at the 95% confidence level.