sequential determination of cd, co, cu, fe, mg, mn, ni, pb, and zn in powdered refreshments by fs-f aas after a simple sample treatment

In this work, a procedure is proposed for the direct analysis of powdered refreshments by fast sequential flame atomic absorption spectrometry (fs-f aas), after a simple treatment of the sample. a full 23 factorial design was applied, and the variables chosen were as follows: acid concentration, acid type, and sonication time. optimization provided the best conditions considering a mass of powdered refreshment of about 0.18 g diluted to a final volume of 15 ml with 0.5 mol l−1 hcl. the matrix effect was investigated, and external calibration was feasible for the determination of cd, co, cu, fe, mg, mn, ni, pb, and zn. the limit of quantification (loq) obtained was between 0.6 (cd) and 25 mg kg−1 (pb). the analyte addition and recovery test were applied to evaluate the accuracy, and recovery percentage values ranging from 83.9 to 109.7% were obtained, which is considered adequate for quantitative analysis. precision was expressed as relative standard deviation (% rsd); it was less than or equal to 5.0% (n = 7) for all analytes. the procedure was applied to 21 samples of powdered refreshment commercialized in salvador (brazil) and buenos aires (argentina). the concentration range and average of the analytes in the samples (in mg kg−1) commercialized in brazil (bz) and argentina (ag) were as follows: co (bz < 6.4–9.94, average 8.85; ag < 6.4–10.3, average 9.92), fe (bz < 6.9–376, average 270; ag < 6.9–32.81, average 29.11), mg (bz < 8.9–363, average 140; ag 770–3139, average 1464), mn (bz < 3.2–4.88, average 4.24; ag < 6.9), and zn (bz < 1.4–1.68, average 1.68; ag < 1.4). the concentrations of cd, cu, ni, and pb were lower than the loq of the proposed analytical method. for refreshment samples commercialized in buenos aires (argentina), high concentrations of mg were found in their chemical composition, but mg had been used as anti-caking agent along with the other components.