Geochemical and instrumental fundamentals for accurate and precise strontium isotope data of food samples: Comment on Determination of the strontium isotope ratio by ICP-MS ginseng as a tracer of regional origin (Choi et al., 2008)

The strontium isotope composition of food samples has been successfully used to trace the provenance of both herbal and animal agricultural products. Adequately accurate and precise Sr-87/Sr-86 ratios, however, are key to unravel environmental and anthropogenic strontium contributions of specific growing areas. In a recently published analytical method in Food Chemistry by Choi et al. (2008) a demonstrably inadequate protocol for the determination of Sr-87/Sr-86 ratios of ginseng is presented. Based on well established geological and analytical fundamentals the Sr-87/Sr-86 ratios presented by Choi et al. (2008) are too inaccurate and imprecise to be used to trace the origin of the ginseng. Appropriate wet chemical separation techniques and mass spectrometric instrumentation enables the generation of Sr-87/Sr-86 data with very low expanded uncertainties (<0.05%, k = 2). Those high quality data allow the identification of even small strontium contributions of source reservoirs or physical and anthropogenic processes if diagnostic isotope compositions are present. (C) 2010 Elsevier Ltd. All rights reserved.