Novel calibration procedure for improving trace element determinations in ice and water samples using ICP-SMS

Abstract

Matrix-induced loss of accuracy was observed during the determination of 19 trace elements (Ag, Al, Ba, Bi, Cd, Co, Cr, Cu, Fe, Mn, Pb, Rb, Sb, Sc, Sr, Tl, U, V, Zn) in ice and water samples at fg g⁻¹ to µg g⁻¹ concentrations using ICP-sector field mass spectrometry (ICP-SMS) equipped with a guard electrode. The accuracy of the results was considerably improved by utilising the Ar dimer at m/z 80 measured in the medium resolution mode (m/Δm 4000) as internal standard. This innovative correction was carefully evaluated using the certified water reference material SLRS-4. The correction approach applied here during the determination of trace elements in ice samples by ICP-SMS adequately compensates for potential matrix effects in individual samples as well as for long-term drifts in sensitivity. Thus, the ArAr correction is as good as conventional internal standards such as In or Rh, respectively, but does not require addition of an “internal standard element”, which risks contamination of the clean ice samples.