Evaluation of the accuracy of the determination of lead isotope ratios in wine by ICP MS using quadrupole, multicollector magnetic sector and time-of-flight analyzers

Different mass analysers [(quadrupole (Q), time-of-flight (TOF) and multico llector (MC) sector-field (SF)] of ions produced in an inductively coupled plasma were evaluated for the determination of lead isotope ratios in wine samples. A population of 20 wines of different origin including two referen ce wines from the EC Standards, Measurement and Testing Programme with conc entrations varying between 7-140 mug Ph l(-1) was investigated. Wines were analyzed directly by Q ICP MS and MC ICP MS. The poor sensitivity of the TO F instrument, further aggravated by matrix signal suppression, did not allo w the acquisition of data for wine samples that contained less than 50 mug l(-1) in the direct sample introduction mode. The separation and preconcent ration of lead were therefore required. The precision obtained for the Pb-2 06/Pb-207 and Pb-208/Pb-206 were similar and equal to 0.14-2.7% for Q ICP M S, 0.04-0.17% for TOF ICP MS and 0.01-0.12% for MC ICP MS. The precision fo r Pb-206/Pb-204 was 0.44-5.29, 0.15-1.7, 0.08-1.6%, respectively. On the le vel of accuracy, the data from TOF ICP MS and MC ICP MS were in good agreem ent. The accuracy of Q ICP MS data was judged satisfactory in comparison wi th the other techniques but their poor precision Ic as a significant obstac le on the way of using these data for the determination of the geographic o rigin of wine, (C) 2001 Elsevier Science B.V. All rights reserved.