This paper describes the evaluation of the total concentration of Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, K, Mn, Pb e Zn and the bioaccessible fraction of Ba, Cu, Fe, Mn, Pb and Zn in samples of grape skins from different cultivars (Vitis Viníferas Tannat and Cabernet Sauvignon) by MIP OES. For the determination of total concentration, acid decomposition with a reflux system adapted to the digestion tubes in the oxidizing medium of HNO3 and H2O2 were used. The accuracy of the method was verified by recovery tests, whose values ranged from 80 to 120%, as well as through a comparative method in closed system. Bi, Cd and Cr showed values for total content below the LOD or below the values acceptable for health while Pb is higher than 0.2 mg kg-1, for both cultivars. To evaluate the bioacessible fraction, the gastrointestinal system was simulated using an in vitro procedure, and its performance was assessed considering the bioaccessible fraction (supernatant) and the non-bioaccessible fraction, whose sum should be closed to the total concentration, and the results obtained were between 81 and 120%. Both cultivars showed similar values for the bioaccessible fractions (~13.5 – 53% of the total content).

This paper describes a sample preparation method for domestic ceramics, based on the acid decomposition assisted by ultrasound for further determination of Cu, Fe, Mg and Zn by Flame Atomic Absorption Spectrometry technique. The main optimized conditions were: particle size (25 µm); sample mass (25 mg) and the acid volume (0.5 mL of HNO3 and 0.5 mL of HF). The samples were placed in an ultrasonic bath for 2 hours at 40 ºC. The method was employed for eight commercial samples of domestic ceramic, which showed different concentrations for all analytes investigated, showing the existing variety of raw materials. The method showed good accuracy and precision, attested by the addition and recovery test, with values of 87 to 112% for all analytes and relative standard deviation lower than 3.0%.

Methanolic transesterification of oils and fats was carried out in a two steps procedure, under basic and acidic catalysis. Palm, soybean, canola, corn, rice, grapeseed, sunflower, peanut, pequi and olive oils, besides tallow and lard were used as feedstock. Specific gravity, relative viscosity, thin layer chromatography and gas chromatography were used to characterize the biodiesel. Biodiesel was obtained in high yield and purity. Results were used to discuss the following key-concepts: 1 - triglycerides, composition and properties; 2 - nucleophilic acyl substitution under basic and acid conditions, 3 - thin layer chromatography, 4 - gas chromatography and its quantitative methods.