Formic acid extractions of Brazil nut and babassu coconut samples were undertaken prior to determination of Al, As, Ba, Co, Cr, Cu, Mn, Mo, Ni, Pb, Se, Sr, V and Zn in their meat and oil portions by inductively coupled plasma mass spectrometry (ICP-MS) in an effort to accomplish a first order fractionation of the trace elements between these two components. An optimized full factorial design was applied to establish the best conditions for extraction. Microwave-assisted nitric acid digestions of samples and fractions along with analysis of certified reference material TORT-2 established the efficiency of recovery of the trace elements as well as provided a verification of accuracy. The multiple responses were analyzed using a desirability function wherein the recovery of the trace elements by extraction was compared with the determination of the total content as determined by nitric acid digestion. Although most trace elements presented a recovery higher than 85% using a formic acid extraction, Al suffered consistently low results for all samples (40-50%). Except for Al and Cr, the majority of the trace elements were present in the defatted fraction of both samples, i.e., Al (50 and 10%), Cr (86 and 60%), Ni (30 and 10%) and Sr (8 and 20%) in Brazil nut and babassu coconut oil fractions, respectively.

A spectrophotometric method for the determination of AlIII in hemodialysis water employing alizarin red S complexing agent in the presence of polyvinylpyrrolidone 40 surfactant is described. The complex, formed in pH 4.5 buffered media, is detected at 510 nm. Optimal concentrations of all reagents were investigated as well as the appropriate detection wavelength. A linear analytical curve in the range of 5.0-320 µg L-1 was obtained, providing a limit of detection (3s, n = 7) of 2 µg L-1 and quantification limit of 5 µg L-1. Results were compared with those generated using inductively coupled plasma mass spectrometry (ICP-MS) as an independent technique and method validation was also demonstrated by analysis of AccuStandard certified reference material QCS‑02-R1-5, appropriately diluted to 10 µg L-1. Equivalent results (t-test at a 95% confidence level) with a relative standard deviation of 4% were obtained. Real samples, spiked at a level of 10 µg L-1 to conforme to Brazilian legislated limits, showed recoveries between 90-110%. The procedure is simple and fit-for-purpose with sufficient detection power to screen for Al at trace levels in hemodialysis water without pre-concentration of the samples.