In situ generation of Co(II) by use of a solid-phase reactor in an FIA assembly for the spectrophotometric determination of penicillamine

[EN] A flow injection analysis (FIA) manifold for the determination of penicillamine in pharmaceutical preparations is proposed. The manifold includes a solid-phase reactor for the in situ production of the derivatizing reagent, Co(II) ion, which forms a coloured complex with penicillamine in an alkaline medium. The reactor is prepared by natural immobilization of cobalt carbonate on a polymer matrix, which endows it with a high mechanical and microbiological stability. The cobalt released by passage of a 5 x 10(-4) Mol l(-1) sulphuric acid stream at a flow-rate of 2.3 ml min(-1) is merged with a volume of 314 mu l of sample containing penicillamine in ammonium-ammonia buffer at pH 9.5 to measure the absorbance at 360 nm. Beer's law is obeyed over the penicillamine concentration range 5-60 mg l(-1). The limit of detection (LOD) of the method is 1 mg l(-1) and its throughput 70 samples h(-1). (c) 2005 Elsevier B.V. All rights reserved.Gómez-Taylor Corominas, B.; Pferzschner, J.; Catalá Icardo, M.; Lahuerta Zamora, L.; Martínez Calatayud, J. (2005). In situ generation of Co(II) by use of a solid-phase reactor in an FIA assembly for the spectrophotometric determination of penicillamine. Journal of Pharmaceutical and Biomedical Analysis. 39(1-2):281-284. doi:10.1016/j.jpba.2005.02.044S281284391-

A tandem-flow assembly for the chemiluminometric determination of hydroquinone

A direct chemiluminescent procedure for determination of hydroquinone based on the emergent flow methodology known as multicommutation or tandem-flow is presented for first time. The manifold was based on a set of three channels and three solenoid valves; and, the determination was performed at 60degreesC and at flow-rate of 7.5 ml min(-1). The complete cycle lasted 35 s, which resulted in a sample flow trough of 103 h(-1). The chemical process was the hydroquinone oxidation with the system sulphuric acid-potassium permanganate; and the light emission was clearly enhanced by the presence of quinine sulphate and benzalkonium chloride reaching a detection limit of 30 Rg l(-1). The dynamic interval was over the range 0.1-15.0 mgl(-1) and a large list of interferents were assayed; the chemical robustness was also tested. The method was applied to different type of samples: namely, pharmaceutical formulations, a photographic solution and irrigation and residual superficial waters. (C) 2004 Elsevier B.V. All rights reserved.Gómez-Taylor Corominas, B.; Catalá Icardo, M.; Lahuerta Zamora, L.; García Mateo, JV.; Martínez Calatayud, J. (2004). A tandem-flow assembly for the chemiluminometric determination of hydroquinone. Talanta. 64(3):618-625. doi:10.1016/j.talanta.2004.03.031S61862564

Emitting species in chemiluminescence reactions with acidic potassium permanganate : a re-evaluation based on new spectroscopic evidence

The reaction of acidic potassium permanganate with a wide range of compounds is known to produce a broad red emission, and there is strong evidence for an excited manganese(II) emitting species. Nevertheless, numerous researchers have proposed other emitters for reactions with acidic potassium permanganate, particularly for systems where fluorescent compounds were present, either as enhancers or reaction products. We have examined many reactions of this type and found that, in most cases, the same red emission was produced. There were, however, some exceptions, including the oxidation of dihydralazine, certain thiols and sulphite (each in the presence of an enhancer).<br /