RESUMO
Spectrophotometric determination of cobalt(II) was accomplished with vanillilfluorone (VF) in the presence of dimethylbenzyltetradecylammonium chloride (Zephiramine, Zep). In the determination of cobalt(II), Beer's law was obeyed in the range of 24-470 ng/ml, with an effective molar absorption coefficient (at 575 nm) and relative standard deviation of 1.35×10(5) l mol(-1) cm(-1) and 0.66% (n=5), respectively. The composition ratio of the colored complex was determined by the mole ratio and continuous variation methods, and it was found to be Co(II) : VF : Zep=1 : 2 : 4. Analysis of cyanocobalamin by the same procedure showed that cyanocobalamin could be determined in the concentration range of 0.5-0.11 µg/ml using the proposed method.
Assuntos
Benzoquinonas/química , Cobalto/análise , Espectrofotometria/métodos , Vitamina B 12/análise , Compostos de Benzalcônio/química , Benzoquinonas/síntese química , Concentração de Íons de Hidrogênio , Tensoativos/químicaRESUMO
A simple, reliable and sensitive spectrophotometric method for the determination of copper(II) was established with o-bromophenylfluorone (OBPF), a novel chemical probe, in the presence of poly(N-vinylpyrrolidone). Beer's law was obeyed in the range of 8-160 ng ml(-1), with an apparent molar absorptivity at 570 nm, the relative standard deviation being 3.64 x 10(5) dm3 mol(-1) cm(-1) and 0.72% (n = 5). This method was applied to the recovery tests of copper(II) in human urine, bovine serum and tap water; the results were satisfactory.