In vitro human bioavailability of major, trace and ultra-trace elements in Chilean 'natural' wines from Itata Valley.

In vitro human bioavailability of elements in 'natural' wines from Chile's Itata Valley has been assessed using an in vitro dialyzability approach. The red wines (fifteen samples) were of the Cinsault, Cabernet sauvignon, Carmènére, Malbec, and Pinot noir varieties. All white wines (three samples) were of the Muscat of Alexandria variety. Inductively coupled plasma-mass spectrometry was used for determination. Elements such as Ag, As, Be, Cd, Cr, Hg, Mo, Ni, Pb, Sb, Se, Sn, Ti, Tl, and V were not found to be bioavailable (concentrations lower than the limit of detection in the dialysates). Elements such as Al, Co, and Fe showed low bioavailability ratios (lower than 20%), whereas B, K, Li, Mg, and Mn were found to be of moderate bioavailability (bioavailability ratios within the 20-79% range for most wine samples). Ca, Cu, and Sr bioavailability was moderate (higher than 20%) in some wines, but most of the samples showed Ca, Cu, and Sr bioavailabilty ratios lower than 20%. No differences were found regarding bioavailability ratios among red and white wines, or among the grape varieties.

Use of enzymatic hydrolysis for the multi-element determination in mussel soft tissue by inductively coupled plasma-atomic emission spectrometry.

A systematic evaluation of different variables affecting the enzymatic hydrolysis of mussel soft tissue by five enzymes, three proteases (pepsin, pancreatin and trypsin), lipase and amylase, has been carried out for the determination of trace elements (As, Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Enzymatic hydrolysis methods offers advantages such as a less species alteration, safer laboratory conditions and a less contaminant wastes. The enzymatic hydrolysis was performed in an incubation camera Boxcult with orbital and horizontal shaker. Variables affecting the enzymatic hydrolysis process were simultaneously studied by applying a Plackett-Burman design (PBD). For a confidence interval of 95%, the significant factors for all enzymes and for most of the elements were the pH, the incubation temperature and the ionic strength. These significant factors were optimized later by using a central composite design (CCD), which gave optimum conditions at pH of 1, incubation temperature of 37 degrees C and ionic strength fixed by sodium chloride at 0.2M when using pepsin. For pancreatin, trypsin, lipase and amylase there were found two different optimum condition sets. The first one involves the use of a 0.5M phosphate buffer (ionic strength), at a pH of 6 and at an incubation temperature of 37 degrees C, which allows the quantitative extraction of Al, Cr, Mn, Pb and Zn. The second conditions set employees a 0.1M phosphate buffer (ionic strength), a pH of 9 and an incubation temperature at 37 degrees C, and it results adequate to extract As, Cd, Cu, Fe and Ni. Analytical performances, repeatability of the over-all procedure and accuracy, by analyzing DORM-1, DORM-2 and TORT-1 certified reference materials, were finally assessed for each enzyme. Good agreement with certified values has been assessed for most of the elements (As, Cd, Cr, Cu, Mn, Ni, Pb and Zn) when using trypsin, pepsin and/or pancreatin, except for Cd and Pb in DORM-1 and DORM-2 because of the certified contents in such certified reference materials are lower than the limit of detection (0.10 and 0.16mugg(-1) for Cd and Pb, respectively, for the use of trypsin).