Assay of xanthene dyes in lipsticks by inverse supercritical fluid extraction and HPLC

An inverse supercritical fluid extraction (SFE) procedure has been develope d for the efficient isolation of six of the most common xanthene dyes (fluo rescein; 4 ' ,5 ' -dibromofluorescein; 2 ' ,4 ' ,5 ' ,7 ' -tetrabromofluore scein; 2 ' ,4 ' ,5 ' ,7 ' -tetrabromo-4,5,6,7-tetrachlorofluoroscein; 4 '5 ' -diiodofluorescein and 2 ' ,4 ' ,5 ' ,7 ' -tetraiodofluorescein) from lip stick matrices. A rapid high-performance liquid chromatographic method is a lso presented for the separation of the six dyes on a cyanopropyl-bonded si lica column eluted with acetonitrile-methanol-acetate buffer Extraction of the lipstick with supercritical CO2 at 350 aim and 40 degreesC for 10 min e xclusively removed the matrix components, whereas the xanthene colorants re mained in the extraction vessel. After treatment with CO2i the target analy ses were quantitatively recovered > 96.8%) by dispersion of the sample in e thanol under sonication. The inverse SFE method was compared with conventio nal liquid-liquid extraction on commercial lipstick products. The two metho ds produced comparable recoveries. However; inverse SR was superior in term s of precision and speed of analysis and gave cleaner extracts.