Spectrophotometric methods for the determination of tamoxifen citrate.
Three simple and sensitive spectrophotometric methods for the determination of tamoxifen citrate have been developed. They are based on the formation of an ion-association complex between the drug and a dye, Erioglaucine A, which is extractable into chloroform and has an absorption maximum at 625 nm (method A), oxidation with excess potassium permanganate and the determination of unconsumed permanganate using Fast Green FCF (method B), or by the formation of a coloured cobalt thiocyante coordination complex which is extracted into benzene and measured at 635 nm (method C). Beer's law limits for methods A, B, and C are 0.5-3.0 mug ml(-1), 1.0-6.0 mug ml(-1) and 100-500 mug ml(-1), respectively. No interference was observed from tableting additives and the applicability of the methods was examined by analysing tablets containing tamoxifen. The quantities determined were 99.0-100.03% of the exptected values.
A resonance light-scattering determination of proteins with fast green FCF.
The interaction of Fast Green FCF (FCF) with proteins (including bovine serum albumin (BSA), human serum albumin (HSA), pepsin (Pep) and alpha-chymotrypsin (Chy), and lysozyme (Lys)) was characterized by enhanced resonance light-scattering (RLS) measurements using a common spectrofluorometer. The enhanced RLS signals of FCF by proteins at 279.0 nm were obtained, and the mechanism of the RLS enhancement was considered in terms of the effects of the pH and ionic strength on the interaction. It was found that the enhanced RLS intensities were in proportion to the concentrations of proteins in the range of nanogram levels, displaying that the present assay is much more sensitive than the reported RLS methods, with the limits of determination being 4.54, 0.6, 22.8, 4.32 and 1.75 ng/ml for BSA, HSA, Pep, Chy, and Lys. respectively.
Determination of tamoxifen and metabolites in human serum by high-performance liquid chromatography with post-column fluorescence activation.
Sensitive and reproducible analyses were developed for assaying tamoxifen, monohydroxytamoxifen, N-desmethyltamoxifen, metabolite E [trans-1(4-hydroxyphenyl)1,2-diphenylbut-1-ene] and a new metabolite, metabolite Y [trans-1(4-hydroxyethoxyphenyl)-1,2-diphenylbut-1-ene] in human serum using high-performance liquid chromatography (HPLC). Three different systems were developed for specific purposes. All chromatography was performed using serum extracts made with hexane-butanol. Detection was by fluorimetry of phenanthrene derivatives formed by on-stream UV irradiation with a newly described device for post-column irradiation of the HPLC stream. This device may be of use in other HPLC systems requiring post-column photochemical reactions.