Aim: A rapid and reproducible microwave (MW)-assisted acid digestion protocol was developed to determine the elemental composition of grapevine bark samples using ICP-MS. A representative grapevine bark sample and a similar matrix Certified Reference Material (CRM) were used for method optimisation. The method was subsequently applied to a set of New Zealand vineyard grapevine bark samples consisting of seven different grape varieties. Methods: A homogenous bark sample and a CRM (ERMCD281) were treated with 16 different acid combinations and microwave digestion settings prior to ICP-MS analysis. 54 chemical elements were measured in the samples. Calibration standards were prepared in matrix matched solutions from single elements standards (Inorganic Ventures, USA). Results: The acid digestion combination of HNO3, H2O2, and HCl with a MW digestion of 15 minutes was shown to give optimal results. 48 elements could be measured in a representative grapevine bark sample using this procedure and 27 elements in a reference CRM sample. Ca was the most abundant element present in all grape variety bark samples. Conclusions: A method was developed and validated for an MW digestion of grapevine bark samples using ICP-MS. The application of this new method showed that bark from different grape varieties varies in elemental composition within a vineyard site. Acknowledgements: The authors wish to thank the Bragato Research Institute, New Zealand Winegrowers, and the Ministry of Business, Industry, and Employment (MBIE), for funding this work.
Authors: Alexandra Lowrey – University of Auckland, New Zealand,Bruno FEDRIZZI, University of Auckland Rebecca JELLEY, University of Auckland Stuart MORROW, University of Auckland
Keywords: icp-ms, grapevine bark, trace elements, microwave digestion