Inductively coupled plasma mass spectrometry with a continuous-flow dialysis simulated gastrointestinal digestion for study of arsenic bioaccessibility in shrimp

Abstract

A hyphenated method of continuous-flow dialysis and on-line inductively coupled plasma mass spectrometry (ICP-MS), with and without the use of hydride generation sample introduction, was developed for the study of arsenic bioaccessibility in shrimp. The method was based on a simulated gastric digestion in a batch system followed by a continuous-flow intestinal digestion. The simulated intestinal digestion was performed in a dialysis bag placed inside a channel in a flowing stream of dialyzing solution (NaHCO 3). The pH of the dialysate was monitored on-line to ensure pH changes similar to the situation in the gastrointestinal tract. The concentrations of total arsenic and inorganic arsenic in the dialysate were determined by ICP-MS without and with hydride generation, respectively. With the parameters used in the hydride generation as follows: 8% (v/v) of HCl; 1% (m/v) of NaBH 4; and a pre-reduction solution (10% (w/v) KI in 5% (w/v) ascorbic acid), only inorganic arsenic can form arsine, implying that hydride generation-ICP-MS can be used to detect inorganic arsenic only. The method was applied for the estimation of arsenic bioaccessibility in shrimp samples, by which the bioaccessibility from shrimp was found to be approximately 55%, contributed from inorganic arsenic only 1% or 2%, and mostly from organic arsenic. Further, the effect of ascorbic acid and fruit juices on arsenic bioaccessibility was investigated which was found not to cause any significant changes in bioaccessibility.