DETERMINATION OF SELECTED NICKEL ISOTOPES IN BIOLOGICAL SAMPLES BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY WITH ISOTOPE-DILUTION

The bis-(1-pyrrolidinecarbodithioato) nickel(II) complex was extracted from acid-digested samples of blood, urine and faeces into 4-methylpe ntan-2-one. The organic extracts were evaporated to dryness and dissol ved in 2.8% v/v HNO3 prior to analysis by inductively coupled plasma m ass spectrometry (ICP-MS). The extraction procedure freed m/z 60, 61 a nd 62 from polyatomic interferences, allowing Ni-61 and Ni-62 to be us ed for combined isotope dilution (ID) and tracer studies. Satisfactory recovery was obtained for naturally abundant Ni added to serum (97.1 +/- 1.9%) and urine samples (100.8 +/- 2.8%) using ID with Ni-62. Aver age recovery of Ni-62 added to plasma, serum, red blood cells, faeces and urine, determined using ID-ICP-MS with Ni-61, was 99.8 +/- 3.2%.