Feasibility of internal standardization in the direct and simultaneous determination of As, Cu and Pb in sugar-cane spirits by graphite furnace atomic absorption spectrometry.

Bismuth and Sb were evaluated as internal standards (IS) to minimize matrix effects on the direct and simultaneous determination of As, Cu, and Pb in cachaça by graphite furnace atomic absorption spectrometry using W-coated platform plus Pd-Mg(NO(3))(2) as modifier. For 20microL injected sample, calibration within the 0.5-10microg L(-1) As, 100-1000microg L(-1) Cu and 0.5-30microg L(-1) Pb intervals were established using the ratios As absorbance to Sb absorbance, Cu absorbance to Bi absorbance and Pb absorbance to Bi absorbance versus analytes concentration, respectively. Typical linear correlations of 0.998, 0.999 and 0.999 were, respectively, obtained. The proposed method was applied for direct determination of As, Cu and Pb in 10 commercial cachaça samples and results were in agreement with those obtained by inductively coupled plasma mass spectrometry at 95% confidence level. The found characteristic masses were 30pg As, 274pg Cu and 39pg Pb. The useful lifetime of the graphite tube was around 760 firings. Recoveries of As, Cu and Pb added to cachaça samples varied, respectively, from 98% to 109%, 97% to 108% and 98% to 104% with internal standards and from 48% to 54%, 53% to 92% and 62% to 97% without internal standards. The limits of detection were 0.13microg L(-1) As, 22microg L(-1) Cu and 0.05microg L(-1) Pb. The relative standard deviations (n=12) for a spiked sample containing 20microg L(-1) As, Pb and 500microg L(-1) Cu were 1.6%, 1.0%, and 1.8% with IS and 4.3%, 5.2%, and 5.5% without IS.

Sealing ability of MTA, Super EBA, Vitremer and amalgam as root-end filling materials

Este estudo avaliou a capacidade de selamento do agregado trióxido mineral (MTA Angelus), de um cimento de óxido de zinco e eugenol reforçado (Super EBA), de um cimento de ionômero de vidro reforçado por resina (Vitremer) e de um amálgama sem zinco (GS-80) (controle). Os canais radiculares de oitenta molares inferiores humanos foram acessados, limpos, modelados e obturados. Os ápices foram seccionados, e as cavidades, preparadas. Os dentes foram divididos em 4 grupos de 40 cavidades, retrobturados com os materiais e imersos em azul de metileno por 72 h a 37ºC. As raízes foram então seccionadas transversalmente a cada milímetro e avaliadas sob aumento, observando-se a penetração de corante a cada corte. Os dados foram avaliados usando-se o teste de Kruskal-Wallis (5%), que mostrou diferenças entre todos os materiais (p < 0,001). A ordem crescente de infiltração marginal foi MTA < Vitremer < Super EBA < amálgama. Níveis mais altos de infiltração foram observados nos cortes de primeiro milímetro de amálgama, Vitremer e MTA, quando comparados com o terceiro milímetro (p < 0,05).

Bismuto compuesto y preparados

1.Bolivia que es el primer pais productor de bismuto del mundo debe convertirse en gran laboratorio abastecedor de productos y preparados bismuticos, 2.Los vehículos las bases bismuticas para preparados inyectables deberan tener absoluta pureza y no ser alterados por la esterilizacion y conservación, 3.Las suspensioones inyectables deben ser preparadas con cuidado siguiendo las reglas de la técnica respectiva para evitar abcesos bismuticos o reaccion inflamatoria local, 4.Los preparados galénicos son numerosos e insustituibles en la terapéutica corriente