HPLC DETERMINATION OF RHODAMINE-B (CI-45170) IN COSMETIC PRODUCTS

A method is proposed for the extraction, separation, identification an d quantitative measurement of rhodamine B in cosmetics samples The col our is extracted with a solution of orthophosphoric acid in either wat er or DMF (depending on the type of cosmetic) adsorbed on a polyamide column, and then eluted with water and methanol. Further clean-up of t he extract is performed by means of a Bond Elut C-18 cartridge, from w hich rhodamine B is eluted with methanol-water (8:2). The final eluate is examined by HPLC. Chromatography is performed on a C-18 column wit h a gradient elution from 50:50 to 70:30 of acetonitrile-water, contai ning 0.1 M sodium perchlorate, in 15 min. A diode-array detector enabl es peak purity analysis. The method gives recovery values of approxima tely 90 %, or better, and the reproducibility is within 4 %.