The continuous on-line leaching method coupled to inductively coupled plasma mass spectrometry for risk assessment of food safety and for sourcing of elements: a tutorial review

Abstract

When conducting a risk assessment, measuring bioaccessibility using an in vitro method is well accepted for determining the amount of an element that is extracted from the sample by gastrointestinal fluids. Conventional batch methods measuring bioaccessibility utilize inductively coupled plasma mass spectrometry (ICPMS) for their elemental analyses, but involve many steps and long extraction times. The continuous on-line leaching method (COLM) couples directly to ICPMS and COLM-ICPMS offers unique features. When compared to validated batch methods for measuring bioaccessibility, COLM-ICPMS results fall within accepted control limits and are directly comparable to the methods used by the United States Environmental Protection Agency and Bioaccessibility Research Group of Europe. For food safety, COLM-ICPMS has determined the bioaccessibility of a number of potentially toxic elements in samples of corn bran, bread, rice, seafood, wheat, and miswak (a natural toothbrush). In many cases, the results for all gastrointestinal fluids were obtained in 15 min, as opposed to over 4 h with a conventional batch method that however allows many samples to be processed in parallel. The dynamic kinetic information exclusively afforded by COLM-ICPMS provided, for the first time, source information of Pb in samples of corn bran, bread, soil, and miswak. This sourcing indicates that tetraethyl lead (a globally historical additive to gasoline) was likely a source of the Pb in some of these samples. Conventional batch bioaccessibility methods would not be able to elucidate this information, as it is only possible with the dynamic information provided by COLM-ICPMS. With the ability to incorporate automation, Pb reference standards, and on-site sampling techniques, the use of COLM-ICPMS for food safety and element sourcing will allow for more efficient, robust, and better-informed bioaccessibility risk assessments in the future.