Sample introduction techniques for inductively coupled plasma mass spectrometry

Arc nebulization is employed as a sample introduction method for elemental and isotopic analysis of conducting solids and non-conducting powdered samples with an inductively coupled plasma mass spectrometer (ICP-MS). Detection limits are in the [mu]g g[superscript]-1 range and relative precision and accuracy are ~5% for elements studied. The precision for isotope ratio measurements of non-conducting powders is ~1% for major constituents;A simple liquid chromatographic method is described for the removal of some interferences for the ICP-MS determination of Cu, Zn, and Cd. Detection limits are 1 to 2 [mu]g L[superscript]-1. Isotope ratios for Cu, Zn, and Cd have also been determined with reasonable precision (1-2.5%) on eluting peaks. This observation indicates that it is possible to do quantitative elemental analysis by isotope dilution with liquid chromatography (LC) and/or flow injection (FI) sample introduction; Speciation measurements are demonstrated by LC separation of phosphorous and sulfur containing compounds with ICP-MS detection. The response factors for P and S are independent of the individual compound. Detection limits are 0.4-4 ng for P and ~7 ng for S despite the high background at m/z = 31 and m/z = 34;Potassium isotope ratios can be determined with an ICP-MS simply by adjusting the operating conditions to remove the interference peaks from Ar[superscript]+ and ArH[superscript]+. The precision is 0.3-0.9% relative standard deviation. These observations should permit use of ICP-MS for rapid isotope ratio determinations of potassium from humans or other biological organisms