Analysis of undigested honey samples by isotope dilution inductively coupled plasma mass spectrometry with direct injection nebulization (ID-ICP-MS)

Undigested honey samples were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) using direct injection nebulization (DIN). Samples were diluted 25-fold using dilute HNO3 to which Triton X-100 was added. Isotope dilution (ID) was used to quantify Ba, Cu, ph and Zn in these natural matrix samples. DIN parameters were optimized to obtain a stable transient signal enough to determine multiple isotope ratios. The Ba, Cu and Zn isotope ratios were measured in a single sample injection of 50 mul diluted honey and the Pb isotopes in a separate injection. The analysis was characterized by precisions given by R.S.D. values from 0.20 to 1.24% for Ba, 0.49-1.23% for Cu, 0.61-2.28% for Pb and 0.50-1.51% for Zn. The results were in agreement, at the 95% confidence level, with those obtained by analyzing digested samples using external calibration. Using this direct method, 30 real honey samples per hour could be analyzed. (C) 2001 Elsevier Science B.V. All rights reserved.