Quantification of andrographolide sodium bisulphite in urine after intravenous injection to rats by LC–MS/MS

A liquid chromatography–tandem mass spectrometry method for the determination of andrographolide sodium bisulphite (ASB) in rat urine was established and validated. To our knowledge, the analytical method is the first developed assay for the determination of ASB in urine samples. Dehydroandrographolide (DAG) was used as an internal standard. ASB and DAG were separated on a C18 column and detected at negative ion mode using the mass transitions of m/z 413.2 → 287.2 and m/z 331.2 → 303.3, respectively. Good linearity was obtained over the range of 50–5000 ng/mL and the correlation coefficient was better than 0.99. The intra- and inter-day accuracy at all levels fell in the ranges of 85.8–101.4% and 87.9–97.5%, and the intra- and inter-day precision (RSD) were in the ranges of 4.3–11.2% and 8.4–13.3%, respectively. The recovery ranged from 96.1% to 98.3% and the matrix effects from 96.2% to 98.1%. Good stability was found under tested conditions. The method was successfully applied to a urinary excretion study of ASB in rats following intravenous administration of 80 mg/kg ASB.