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Microwave induced plasma optical emission spectrometry (MIP OES) was employed to determine the concentrations of macro and micronutrients (Ba, Ca, Cu, Fe, K, Mg, Mn and Na) in products derived from sugarcane: sugars (refined, crystal, demerara and brown) and derived products (molasses and brown sugar candy) produced in the southern region of Brazil. The sample preparation was performed by acid decomposition with a reflux system under optimized conditions: 1000 mg of sample and 5.0 mL of concentrated nitric acid for 4 hours at 150 °C and addition of 1.0 mL of hydrogen peroxide. At the end we obtained a procedure that provides analytical solutions in accordance with the established parameters of acidity and dissolved solids as per the MIP OES spectrometer manufacturer's recommendations. The accuracy was evaluated by the analyte addition tests (80 to 119%). The limits of detection, in mg kg−1, were 0.03 (Ba); 0.03 (Ca); 0.04 (Cu); 0.08 (Fe); 0.18 (K); 0.03 (Mg); 0.02 (Mn) and 0.26 (Na). The concentrations of the analytes in the different samples varied according to the degree of processing, since higher values appeared for the less processed samples, i.e. brown sugar, molasses and brown sugar candy.

A method for the simultaneous determination of As, Hg, Se and Sn in sediment slurries using chemical vapor generation (CVG), in situ trapping electrothermal vaporization inductively coupled plasma mass spectrometry, is proposed. The vapors produced by the reaction of the sample slurry with the reducing agent are transported to the vaporizer and trapped at 150 °C in a graphite tube, treated with Ir as a permanent modifier, before vaporization at 2000 °C and transport to the plasma. The accuracy of the method was assured by the analysis of certified reference sediment samples, using external calibration with aqueous solutions, prepared in the same medium and subject to the same CVG and trapping procedure as the slurries. The obtained concentrations were in agreement with the certified values, using the t-Student test for a confidence level of 95%. The detection limits, in ng g−1, were: 0.8 for Hg, 0.04 for As, 0.01 for Se and 0.30 for Sn.

The aim of this study was to present three sample preparation methods for the determination of Cd, Pb and Sn in meat by Graphite Furnace Atomic Absorption Spectrometry (GFAAS): acid digestion, solubilization with tetramethylammonium hydroxide and formic acid. For the digestion with HNO3, a conventional open system with a cold finger was used. This system helped to avoid losses of analytes and reagents by volatilization, permitting to operate at high temperatures applied at a digester block and reducing the digestion time (∼1 h). Solubilizations were performed at room temperature. The slurry was left standing overnight and remained closed until achieving complete solubilization. The temperature program of the graphite furnace was optimized for each element in the different means of preparation samples using a mixture of Pd–Mg. The figures of merit were similar for all sample preparation methods evaluated. The limits of detection obtained for the acid digestion procedure were 0.0006, 0.0164 and 0.0520 μg g−1 for Cd, Pb and Sn, respectively. In order to evaluate the accuracy of the results obtained by the three sample preparation methods, recovery tests for four real meat samples were performed and the recoveries ranged from 93.7 to 109%, supporting the accuracy of the method. Also, different certified reference materials of meat were analyzed and the results obtained were in agreement with the certified value at 95% of confidence (t-test). The best results were obtained by the acid digestion procedure with the cold finger system. This procedure is faster, the system is semi-closed with no significant contamination or loss of analytes by volatilization and it provides a better signal/noise ratio.

A new procedure based on exposure of ethanol biofuel samples to UV radiation in the presence of low molecular weight organic acids was developed for the determination of total Hg (inorganic and organometallic species: Hg2+, CH3Hg+ and CH3CH2Hg+) by photochemical vapor generation coupled with atomic absorption spectrometry (photo-CV-AAS). For each species, the optimum conditions for photochemical generation were investigated, including the effects of medium composition, exposure time to the UV radiation and transfer gas flow rate. The accuracy was evaluated by assessing the recoveries of species-specific spikes (91–107%) as well as by assessing recovery from a mixture of all species of the mercury added to the ethanol biofuel samples based on calibration standards prepared in high purity bidistilled ethanol. The limits of detection ranged from 0.05 to 0.09 μg L−1 for all addition and recovery tests, enabling the determination of total Hg. The proposed method is sensitive, simple (no sample pretreatment) and provides a direct approach to the generation of mercury vapor from ethanol biofuel samples while promoting “green” chemistry.

A very simple procedure is proposed for the determination of total and inorganic Hg in biological materials. Organic Hg (methylmercury) can be obtained from the difference. After treating the sample at room temperature with tetramethylammonium hydroxide (TMAH), inorganic Hg is obtained by cold vapor atomic absorption spectrometry (CV-AAS), keeping the quartz cell at room temperature, while total Hg is obtained by the same technique, heating the quartz cell in an air–acetylene flame. By analyzing several biological certified materials, it was evident that the difference between the mentioned concentrations corresponds to methylmercury. Cold vapor graphite furnace atomic absorption spectrometry (CV-GF-AAS) with retention of the vapor in a heated Au-treated graphite tube was used to optimize the vapor generation conditions and also to determine total Hg. In a general way, the concentrations obtained by both techniques were in agreement with the certified values or with differences of the certified values for total, Hg2+ and CH3Hg+, according to the t-test for a 95% confidence level. Total Hg results obtained by the two techniques were also in agreement. The relative standard deviations were lower than 10% for most of the results. The detection limits in the sample were: 0.13 μg g−1 for total Hg and 0.025 μg g−1 for Hg2+ by CV-AAS. The detection limit for total Hg by CV-GF-AAS was 0.001 μg g−1. It is amazing how this very simple method is able to provide very important information on mercury speciation.