DETERMINATION OF LEAD IN FRESH AND CANNED PINEAPPLE BY ISOTOPE-DILUTION MASS-SPECTROMETRY AND ISOTOPE SYSTEMATICS

Pineapple stored in welded and soldered can was analysed for lead to assess the extent to which it is contaminated during processing and storage. To avoid contamination during analysis the samples were prepared in clean laboratory using ultra-clean procedures. The lead concentration was determined by isotope dilution mass spectrometry and the sources of lead were identified by their isotopic signature and quantified by isotope systematics. The results showed that the lead concentration in pineapple stored in the soldered cans (ca. 150 ng g-1) was about 2.5 times that found in the welded cans and 60-80% of this lead was traced to the soldered joint using isotope systematics. The edible portion of a fresh pineapple contained < 0.85 ng g-1 lead, showing that even pineapple in welded cans may be contaminated 80 times more than the natural level. © 1990.