A protocol for the multelemential analysis of trace metals in food samples by flow injection coupled to ICP-MS

摘要

A protocol, based on microwave digestion, followed by flow injection coupled to inductively.coupled mass spectrometry (TI-ICP,MS) was developed (or the simultaneous determination of up to 17 metals present in food digests.A number of different signal acquisition methods were evaluated in terms of precision, accuracy, and detection limit. Studies were also carried out to assess the maximum number of isotopes that could be determined without degradation of the detection limits. The method, which involved a combined nitric acid-hyrogen peroxide microwave digestion step, was validated using an oyster tissue certified reference material (NIST 1566a). The results were in good agreement with the certified values. The applicability of the method to the determination of trace metals :in foodstuffs was tested by the multielemental analysis of mackerel, pig liver, and digestive biscuit digesrates. The developed procedure gave detection limits (defined as 3 times the standard deviation of the blank concentration) of: Al = 1.46, B = 1.97, V= 0.11, Cr = 1.36, Co = 0.15, Ni = 0.59, As =0.89, Sr = 0.08, Mo =0.44, Cd = 0.16, Sn = 0.39, Ba = 0.07 and Pb = 0.27 (all ng g~(-1)): These detection limits are comparable with a more time-consuming method using off-line dilution.