Accuracy and precision of lead isotope ratios in wines measured by axial inductively coupled plasma time of flight mass spectrometry

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 hex ane. 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 Pb-206/Pb-207 and Pb-208/Pb-206 ratios were obtained in so lutions containing approximately 1 ng ml(-1) of lead. For the Pb-206/Pb-204 ratio, an average of 0.85% RSD was obtained in the 0.15-1.7% range. Mass b ias was assessed by measuring the NIST SRM 981 at regular intervals. The is otope ratio results obtained by ICP-TOF-MS are compared with results from m ulti-collector (MC) ICP-MS and quadrupole (Q) ICP-MS for assessment of accu racy. The ICP-TOF-MS data compare well with those of MC-ICP-MS for the Pb-2 06/Pb-207 and Pb-208/Pb-206 ratios. The agreement between ICP-TOF-MS and MC -ICP-MS for the Pb-206/Pb-204 is worse. Data sets are corrected for isobari c overlap from Hg-204 on Pb-204. The data obtained by Q-ICP-MS are not in a greement with the results obtained by ICP-TOF-MS or MC-ICP-MS.