Matrix separation by chelation to prepare biological materials for isotopic zinc analysis by inductively coupled plasma mass spectrometry

Abstract

Following an evaluation of three chelating resins [Chelex-100, poly(dithiocarbamate)(PDTC) and carboxymethylated poly(ethyleneimine)–poly(methylenepolyphenylene) isocyanate (CPPI)], a procedure was established with the last of these for the separation of Zn from biological matrix elements prior to ⁷⁰Zn: ⁶⁸Zn isotopic analysis by inductively coupled plasma mass spectrometry (ICP-MS). The method was verified by establishing Zn recoveries and by determining its effectiveness in removing Cl and Na from buffered test solutions. Calcium, Na, and Zn concentration data were determined by inductively coupled plasma atomic emission spectrometry. Chlorine was measured by electrothermal vaporization ICP-MS. The efficacy of the technique was demonstrated by the determination of zinc isotope ratios in bovine milk and human urine. Results compared favourably with those obtained using a previously established extraction procedure.