Abstract

Isotope ratios and concentrations for lead measured by ICP-TOF-MS in twenty different wines from the five continents are reported. Concentrations and ratios were measured following microwave-assisted nitric acid digestion of the wines and extraction of lead by diethyl dithiophosphate (DDTP) into hexane. The hexane was evaporated and the complexed lead was re-dissolved in 0.5% nitric acid. Lead concentrations in the wines were between 5 and 150 ng ml ⁻¹. Average relative standard deviations (RSD) of 0.1% RSD in the 0.04–0.16% range for ²⁰⁶Pb/ ²⁰⁷Pb and ²⁰⁸Pb/ ²⁰⁶Pb ratios were obtained in solutions containing approximately 1 ng ml ^-1 of lead. For the ²⁰⁶Pb/ ²⁰⁴Pb ratio, an average of 0.85% RSD was obtained in the 0.15–1.7% range. Mass bias was assessed by measuring the NIST SRM 981 at regular intervals. The isotope ratio results obtained by ICP-TOF-MS are compared with results from multi-collector (MC) ICP-MS and quadrupole (Q) ICP-MS for assessment of accuracy. The ICP-TOF-MS data compare well with those of MC-ICP-MS for the ²⁰⁶Pb/ ²⁰⁷Pb and ²⁰⁸Pb/ ²⁰⁶Pb ratios. The agreement between ICP-TOF-MS and MC-ICP-MS for the ²⁰⁶Pb/ ²⁰⁴Pb is worse. Data sets are corrected for isobaric overlap from ²⁰⁴Hg on ²⁰⁴Pb. The data obtained by Q-ICP-MS are not in agreement with the results obtained by ICP-TOF-MS or MC-ICP-MS.