DETERMINATION OF CHROMIUM AND NICKEL IN HUMAN BLOOD BY MEANS OF INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY

The suitability of inductively coupled plasma mass spectrometry (ICP-M S) for the determination Cr and Ni in human whole blood was investigat ed. Strict criteria for blood sampling and sample treatment were set t o avoid contamination or loss of analytes. A wide concentration interv al of analytes was obtained by collecting specimens from subjects with a history of exposure to one of the two elements or both. A dynamic r ange of more than three orders of magnitude was achieved with operativ e detection limits of 0.03 and 0.04 mu g/l in the analytical solution for Cr and Ni, respectively. At 1.0 mu g/l and 0.5 mu g/l concentratio n levels for Cr and Ni, respectively, the instrumental precision, as r elative standard deviation (R.S.D.), was 2.6% and 3.8%, while for repr oducibility of the entire analytical cycle of analysis, including samp le pretreatment, values of 4.8% and 5.5% were obtained. The accuracy o f the method was verified by using the serum NIST 909 reference materi al for Cr and an in-house standard for Ni with mean recovery percentag es of 95.0% and 105%, respectively. These performance characteristics were obtained by careful evaluation and correction of the interference s at the masses used for determination. For the Cr-52 isotope the pres ence of (ArC)-Ar-40-C-12, due to the high concentration of C in the or ganic matter, exerted a dramatic influence. This was overcome only by reduction of the C content of the sample performing a full digestion c ycle in a microwave oven and by a suitable correction equation. For Ni measurements, mass 60 gave satisfactory results because of very scarc e influence of the main potential interferent ions, i.e., (CaO)-Ca-44- O-16 and (ClNa)-Cl-37-Na-23.