Bromocresol green spectrophotometric determination

Erk developed a spectrophotometric procedure for the assay of atorvastatin, both for the bulk drug substance as well as for pharmaceutical formulations. The procedures are based on the reaction between the drug and bromocresol green, alizarin red, or bromophenol blue, which result in the production of ion-pair complexes (1 1). Beer s law was obeyed over the concentration ranges 5.0-53.0, 7.1-55.8, or 7.5-56.0 /ig/ml with bromocresol green, alizarin red, and bromophenol blue, respectively. The specific absorptivities, molar absorptivities, Sandell sensitivities, standard deviations, and the percent recoveries were evaluated. Atorvastatin was determined by measurement of its first derivative signal at 217.8 nm. 

J. M. Calatayud and P. C. Falco, Spectrophotometric Determination of Chlorhexidine with Bromocresol Green by Flow-Injection and Manual Methods. Anal. Chim. Acta, 189 (1986) 323. 

An other simple and sensitive spectrophotometric method based on color reaction with bromocresol green was studied by Zivanov-Stakic et al. (17) for the determination of colonidine hydrochloride in tablet form. 

Sakai, T., Extraction-spectrophotometric determination of benzethonium and benzalkonium salts with bromocresol green and quinine. Anal. Chim. Acta, 1983,147,331-337. 

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