RESUMO
An optimized capillary zone electrophoresis (CZE) method for the analysis of tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DXC) is described. Using fused-silica capillaries, the influence of the electrolyte composition, pH and concentration, as well as temperature and applied voltage were investigated. A factorial and central composite design was performed to optimize the method in a simple way. The optimal separation conditions were 50mmolL(-1) sodium carbonate+1mmolL(-1) EDTA, pH 10; voltage 13kV and temperature 23 degrees C. The method was validated for TC determination in pharmaceuticals through the following performance criteria: linearity and linear range, sensitivity, selectivity, intra-assay and inter-assay precision, detectability, accuracy and ruggedness. In comparison with the recommended HPLC method in the United States Pharmacopeia, this CZE-method exhibited the same performance as the official method, with the advantage that the same method could be used for the simultaneous determination of the different tetracyclines in pharmaceutical formulations.
RESUMO
Culinary utensils may release some inorganic elements during food preparation. Mineral migration can be beneficial for as long as it occurs in amounts adequate to the needs of the consumer or no toxicological implications are involved. In this study, the migrations of Fe, Mg, Mn, Cr, Ni and Ca, along seven cooking cycles were evaluated for two food preparations (polished rice and commercial tomato sauce, the latter as an acid food), performed in unused stainless steel, cast iron and soapstone pans, taking refractory glass as a blank. Minerals were determined by inductively coupled plasma optical emission spectrometry (ICP OES). The utensils studied exhibited different rates, patterns and variability of migration depending on the type of food. Regression analysis of the data revealed that, as a function of the number of cycles, the iron pans released increasing amounts of iron when tomato sauce was cooked (y = 70.76x + 276.75; R2 = 0.77). The soapstone pans released calcium (35 and 26 mg/kg), magnesium (25 and 15 mg/kg) into the tomato sauce and rice preparations, respectively. Additionally, the commercial tomato sauce drew manganese (3.9 and 0.6 mg/kg) and some undesirable nickel (1.0 mg/kg) from the soapstone material, whereas the stainless steel pans released nickel at a lower rate than steatite and in a diminishing fashion with the number o cooking cycles, while still transferring some iron and chromium to the food. We conclude that while cast iron and glass could be best for the consumer's nutritional health, stainless steel and steatite can be used with relatively low risk, provided acid foods are not routinely prepared in those materials.
Assuntos
Utensílios de Alimentação e Culinária , Análise de Alimentos , Ferro/análise , Óxido de Magnésio/análise , Dióxido de Silício/análise , Aço Inoxidável/análise , Oligoelementos/análise , Humanos , Oligoelementos/químicaRESUMO
O Instituto Nacional de Alimentaçäo e Nutriçäo (Inan) está propondo o uso, em nível nacional, de fórmula de alimentaçäo alternativa, denominada "Multimistura", à base de farelos de arroz, e/ou trigo, sementes de gergelim e abóbora, folhas de mandioca, beterraba, cenoura, verduras nativas e pó de casca de ovo, como soluçäo para combater a fome da populaçäo carente. Embora o crítico estado nutricional da populaçäo-alvo possa fazer qualquer questionamento técnico ou ético parecer por demais filosófico, uma série de consideraçöes nutricionais, toxicológicas e até de viabilidade prática sugerem que a posiçäo adotada pelo Inan deveria ser revista. A soluçäo da multimistura, talvez válida para situaçöes transitórias de extrema pobreza, carece de universalidade para ser utilizada, independentemente de faixa etária, estado nutricional e período de duraçäo da intervençäo.
