Use of a continuous leaching method to assess the oral bioaccessibility of trace elements in seafood.

A continuous leaching method, coupled online with inductively coupled plasma mass spectrometry (ICP-MS) was used on seafood samples to assess the maximum bioaccessibility of several trace elements. The method indeed involves continuous leaching of the food sample by artificial saliva and gastric juice, successively, where this exposition of the food to fresh reagent drives the dissolution equilibrium to the right. Leaching with intestinal juice had to be omitted because it resulted in clogging problems. The experimental apparatus includes a mini-column of powdered sample, which is directly connected to the nebulizer of an ICP-MS instrument. The on-line approach allows a quick assessment of the maximum bioaccessibility of elements of interest by monitoring the real-time release of elements by a given reagent. The method was applied to determine the bioaccessibility of four toxic elements (Al, Cd, Hg, and Pb) and of four essential elements (V, Mn, Cu, and Zn) in certified reference materials and in actual seafood samples. In all cases, mass balance was verified by carrying out the total digestion of the remaining residue from the mini-column and the relationship between total concentration and bioaccessibility was examined.