Ionic liquid sensitized fluorescence determination of four isoquinoline alkaloids

The fluorescence spectra of berberine, palmatine, jatrorrhizine, and coptisine in ionic liquids were studied and found to increase significantly in ionic liquids, with [C8MIM][PF6] having the greatest increase. Further studies showed that these drugs could be extracted from an aqueous solution by [C8MIM][PF6] using the temperature-assisted ionic liquid dispersive liquid phase microextraction method. The enrichment factors were 81.8–82.3, and the extraction recovery was 98.5%, 98.1%, 98.3%, and 98.8% for berberine, palmatine, jatrorrhizine, and coptisine, respectively. Based on the [C8MIM][PF6] preconcentration, separation, and sensitized fluorescence for these drugs, a new selective and sensitive method for the determination of concentration of these four drugs in aqueous samples was presented. At optimum conditions, the linear relationship was obtained in the ranges of 0.8–130 ng mL−1, 0.9–160 ng mL−1, 0.7–140 ng mL−1, and 0.6–110 ng mL−1, respectively. The proposed method was successfully applied for the determination of the drugs in pharmaceutical preparations, urine, and plasma samples.