An analytical method for the determination of Al, Ca, Cd, Cr, Cu, Fe, Hg, K, Mg, Na and Zn in breast of conventional, country and Christmas chicken and turkey samples using microwave induced plasma optical emission spectrometry (MIP-OES) technique was developed. Samples were decomposed in a digester block with a reflux system under conditions optimized using a central composite design as it follows: 2 g of sample, in 7.5 mL of HNO3 during 180 min at 160 °C. The accuracy was evaluated by the analysis of standard reference material SRM 1546 meat homogenate (94 to 108%) and also by addition and recovery tests (80 to 121%). The highest concentrations, in mg kg-1, of Al (2.77), Ca (88.3), Cu (1.99), Fe (3.65), K (3236), Mg (292.62) and Na (312.03) were found in the breast of conventional chicken sample. Zinc presented high value in the breast of turkey sample (10.6 mg kg-1). However, the found concentrations were lower than the daily consumption limit established by supervisory agencies and reference limits from Brazilian legislation. Cadmium, Cr and Hg presented values below limit of quantification. In this way, it is evident that chicken breast should be consumed in a complementary way in a healthy diet.

The objective of this study was to evaluate the concentration of Cu, Zn, Cr and Pb in different species of fish collected in the estuarine and limnic regions of the São Gonçalo channel, located in the Patos-Mirim lagoon complex in the coastal plain of Rio Grande do Sul State (Southern Brazil) during 2013 (autumn, winter and spring) and 2014 (summer). Fish samples were decomposed in a digester block with a reflux system under conditions optimized using a central composite design as it follows: 250 mg of fish sample, 5 mL HNO3, 2 mL H2O2 during 2 h at 150 °C. The concentrations obtained ranged from 6.7 to 12.0 mg kg -1 for Cu; 1.8 to 23.6 mg kg -1 for Zn; 37 to 487 µg kg -1 for Pb; and 40 to 1268 µg kg -1 for Cr. The highest concentrations of Cu, Zn and Pb, were observed in fishes collected at locations in the estuarine region and Cr showed high levels, especially in the limnic region. The samples of the species Loricariichthys anus (viola) showed the highest concentrations of all analytes investigated.

This paper describes the evaluation of simple and fast solubilization methods for the determination of Ca, Mg, and K in glycerin samples from biodiesel production by atomic spectrometry. The solubilization in water was compared with two other methods: solubilization in formic acid and solubilization in ethanol. Using solubilization in water, determination of the three analytes was possible; the values of limits of detection for Ca, K, Mg were 0.31, 0.06, and 0.16 mg kg−1, respectively. Because no adequate reference material was available, the accuracy was evaluated by assessing the recoveries tests with both solubilization methods; the evaluation ranged from 90% to 115%, with values of relative standard deviation >8%, indicating good accuracy of the measure. Four crude glycerin samples obtained from biodiesel plants of Rio Grande do Sul were analyzed after treatment with the different methods of solubilization, and the obtained results of Ca, Mg, and K concentration were in agreement with the values obtained from both solubilization methods. Therefore, solubilization in water is concluded to be a simpler, faster, and viable method for sample preparation of glycerin.