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a b s t r a c tA method using Laser Induced Breakdown Spectroscopy (LIBS) for calcium (Ca) determination in breakfast cereals was evaluated. To perform the calibration curve, seven commercial cereals containing Ca in a range of 16.00-3734 mg kg À1 were considered. The Ca amounts provided by the manufacturers were evaluated by using inductively coupled plasma optical emission spectrometry (ICP OES). The precision of the LIBS measurements was of 8% and the accuracy, observed by using a corn bran standard reference material was higher than 99%. The method was successfully applied to predict the Ca concentration in a set of commercial samples dispensing the sample pre-treatment, with the potential to be used in production lines.

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Recebido em 3/10/07; aceito em 15/2/08; publicado na web em 13/8/08 CHROMIUM REDOX SPECIATION IN SOIL ACCIDENTALLY CONTAMINATED WITH SULPHOCHROMIC SOLUTION. Determination of Cr(VI) and Cr(III) was studied in soil samples accidentally contaminated with sulphochromic solution. Molecular absorption spectrophotometry based on the diphenylcarbazide method was used for the determination of Cr(VI) after its alkaline extraction. The total chromium concentration was determined using ICP OES. The quantification of Cr(III) was accomplished by subtracting the Cr(VI) concentration from the total chromium concentration. Regardless of the known contamination of the soil samples by sulphochromic solution, concentrations of Cr(VI) were below the detection limit. Addition and recovery experiments for Cr(VI) in soil samples with and without organic matter indicated its influence on the reduction of Cr(VI) to Cr(III).