A novel sample introduction system for microwave-induced plasma optical emission spectrometry

A newly developed micro-sampling technique using a discrete sample introduction system (DSIS) has been demonstrated for simultaneous multi-element analysis by microwave-induced plasma optical emission spectrometry (MIP-OES). A microliter volume of sample solution (20 μl) is manually inserted into a Teflon microsampling device and subsequently pumped at low solution uptake rates of <100 μl min−1 to a Meinhard-type concentric nebulizer and then into a 250-W helium plasma. The performance of DSIS-MIP-OES was demonstrated by the determination of major (Na, K, Ca, Mg), minor (Cu, Fe, Zn) and trace (Sr) elements in two clinical standard certified reference materials (serum, hair). Standard microaddition procedures were used to minimize possible matrix interference. The detection limit (3σ) obtained was 10, 30, 50, 100, 10, 5, 20 and 40 ng ml−1 for Ca, Cu, Fe, K, Mg, Na, Sr and Zn, respectively. The method offers relatively good precision (RSD ranged from 5 to 14%) and microsampling capability. Agreement between analytical results and certified values for the test elements was good. The method could be useful as a routine clinical laboratory procedure.