Determination of selected nickel isotopes in biological samples by inductively coupled plasma mass spectrometry with isotope dilution

Abstract

The bis-(1-pyrrolidinecarbodithioato) nickel(II) complex was extracted from acid-digested samples of blood, urine and faeces into 4-methylpentan-2-one. The organic extracts were evaporated to dryness and dissolved in 2.8% v/v HNO3 prior to analysis by inductively coupled plasma mass spectrometry (ICP-MS). The extraction procedure freed m/z 60, 61 and 62 from polyatomic interferences, allowing 61Ni and 62Ni to be used 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 62Ni. Average recovery of 62Ni added to plasma, serum, red blood cells, faeces and urine, determined using ID-ICP-MS with 61Ni, was 99.8 ± 3.2%.