Determination of Environmental Lead Using Continuous-Flow Microwave Digestion Isotope Dilution Inductively Coupled Plasma Mass Spectrometry

A commercial flow-through microwave system was successfully applied as an alternative sample preparation procedure for lead determinations using isotope dilution inductively coupled plasma quadrupole mass spectrometry. Sample is introduced as a slurry and then injected into a carrier stream which is continually flowing through the system. As configured, the sample dissolution is sequential, taking about 10 min/sample. This closed system is easy to use and produces low blanks, thus providing a viable alternative to the direct introduction of untreated samples, which can degrade analytical results. Leaves, air filters, urine, sludge, dust, and paint standard reference materials previously certified for lead using isotope dilution mass spectrometry (IDMS) were used to evaluate the accuracy of this automated sample preparation device. Lead concentrations in the nanograms to micrograms per gram range were accurately determined when compared with the certified value and previous IDMS results.