Sensitive and rapid isocratic liquid chromatography method for the quantitation of curcumin in plasma

An HPLC assay was developed using three methods of plasma sample preparation in order to quantitate curcumin, the main constituent in the herbal dietary supplement turmeric. Each method involves simple and rapid processing of samples (either an ethyl acetate or chloroform extraction) with resulting different quantitation limits for curcumin. The assay was developed in an effort to quantify extremely low curcumin plasma concentrations observed in preliminary in vivo studies. The most sensitive assay can reliably detect concentrations down to 2.5 ng/ml. Plasma quantitation was precise and accurate based on both intra- and inter-day validations as indicated by low values for coefficients of variation and bias, respectively (< or =15%). The analytical validation was reproducible between different analysts. The resulting analytical method couples desired sensitivity with the ease of an isocratic system.