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The determination of trace lead in a CaCO3 matrix by isotope dilution coupled anion-exchange and quadrupole-based inductively coupled plasma-mass spectrometry was established. The matrix of CaCO3 seriously affected the determination by clogging the cones of the instrument was removed by the anion-exchange resin column. Effects such as dead time, mass bias, dwell time and the amount of isotopic agent spiked were discussed and corrected. The detection limit estimated by 3× standard deviation of the procedure blank was 2.94 ng g−1. The results indicated that the lead concentration in all samples tested was far less than 3%, the legislated limit. The recovery mostly ranged from 90 to 110%. The relative standard deviation was found to be <1%. [Copyright &y& Elsevier]

Isotope dilution analysis method coupled with flow injection and inductively coupled plasma mass spectrometry (ID-FI-ICP-MS), enabled trace lead concentration in seawater to be determined and the high salt concentration in the matrix, such as Na+, Ca2+ and Mg2+, to be removed on-line. The operational parameters of the FI system including pH for the chelating reaction, concentration of 8-hydroxyquinoline-5-sulfonic acid (8-HQS), sample loading time and injection speed, washing time and speed, eluting acid concentration and eluting speed, and instrumental parameters for ICP-MS were optimized and selected. Accurate results could be achieved because the isotope ratios required can be precisely measured in the range of the eluting peak by means of ID-FI-ICP-MS. The 3σ detection limit was 0.204 ng ml−1. The trace lead concentration of seawater in south Xiamen, China was 0.988 ± 0.039 ng ml−1. The recoveries of spiked Pb standard in seawater and standard reference water (GBW 08607) were 97.9 and 101.0%, respectively, with a relative standard deviation of 0.98%. This method can be used to determine trace lead concentration in high salt matrix samples, and is especially useful when the eluting peaks do not have a Gaussian-distribution. [Copyright &y& Elsevier]

The purpose of this study is to investigate the amounts and characteristics of heavy metals (As, Hg) leachable from several Chinese medicinal materials (CMM) under conditions simulating stomach and intestine digestion and absorption. Analysis by inductively coupled plasma mass spectrometry (ICP-MS) was compared with that by hydride generation atomic fluorescence spectrometry (HG-AFS). Focused microwave assisted extraction (MAE) and Soxhlet extraction were carried out to compare with the conventional sequential extraction method. The CMM studied included two mineral drugs: realgar and cinnabar, and two formulated drugs containing the two minerals. The leachable amounts of the target elements into artificial stomach fluid, artificial intestinal fluid, and artificial intestinal fluid in 0.5% trypsin were compared. The last solvent gave the greatest amounts of leachable As (0.41%) from realgar and Hg (1×10−4%) from cinnabar, but otherwise no significant effect on the leachable amounts was observed upon changing the following parameters: temperature (37–60 °C), HCl concentration (0.5–6 M), and CMM sample particle size (74 and 250 μm). The low leaching efficiencies observed confirmed the presence of As and Hg as insoluble species (sulfides)in these mineral drugs. Sequential extraction schemes were used to determine the species of mercury and arsenic in formulated drugs containing the minerals. Trace amounts of organic forms of arsenic (0.43%) and mercury (2.9×10−4%) were observed which could be the transformation products derived from the original cinnabar or realgar minerals in drug formulation. [Copyright &y& Elsevier]