The Application of Lead Isotope Ratios to the Determine the Contribution of the Tin-Lead to the Lead Content of Wine

¹ CSIRO Division of Exploration Geoscience, P.O. Box 136, North Ryde, N.S.W. 2113, Australia
² The Australian Wine Research Institute, P.O. Box 197, Glen Osmond, S.A. 5064, Australia
³ Gelnhauser Strasse 15, D-6463 Freigericht 1, Germany.

The lead isotope fingerprinting method has been used to determine whether soluble lead compounds produced by reaction of wine with the tin-lead capsule are drawn back through and/or around corks to give an apparently elevated lead content in wine. Lead isotope abundance and precise lead concentration have been measured in wines, corks, and capsules for over 50 Australian and a few German wines. The lead content and isotopic values of the wine and cork are critically dependent on the sampling procedure. When sampled rigorously, the lead content of Australian wine is generally low in the range from 0.020 to 0.060 mg/kg. Furthermore, no correlation was found between the lead isotope value in the wine and the capsule, and there is little difference in the isotopic values of wine from lead-capsuled and uncapsuled (or plastic capsuled) bottles of the same vintage. Such data provide strong evidence that there is no migration of lead corrosion products back into the wine. Nevertheless, the isotope data confirm that corrosion products from the lead capsule, if present especially in the case of leaking corks, can be dissolved during pouring and that the lead content of the wine in the bottle can be increased if the cork is pierced during its removal.

Key words: lead, wine, cork, capsules, isotope ratios

Submitted on May 8, 1991