Gradient elution liquid chromatography mass spectrometry determination of acetylcorynoline in rat plasma and its application to a pharmacokinetic study.

1. Acetylcorynoline is the major alkaloid component derived from Corydalis bungeana herbs. A sensitive and selective liquid chromatography mass spectrometry method for determination of acetylcorynoline in rat plasma was developed over the range of 5-1000 ng/mL to characterize the pharmacokinetic properties. 2. Chromatographic separation was achieved on a C18 (2.1 mm× 150 mm, 5 μm) column with acetonitrile 0.1% formic acid in water as mobile phase with gradient elution. The flow rate was set at 0.4 mL/min. After addition of carbamazepine as internal standard (IS), protein precipitation by acetonitrile-methanol (9:1, v/v) was used as sample preparation. An electrospray ionization source was applied and operated in positive ion mode; selective ion monitoring mode was used for quantification using target ions m/z 410 for acetylcorynoline and m/z 237 for the IS. 3. Mean recoveries of acetylcorynoline in rat plasma were in the range of 72.3-87.6%. Matrix effects for acetylcorynoline were measured to be between 88.7% and 93.5%. Coefficient of variation of intra-day and inter-day precision were both <13%. The accuracy of the method ranged from 95.8% to 112.1%. The analyte was stable under auto-sampler, room temperature, freeze-thaw and long-term (20 days), the bias in concentration was within ±15% of their nominal values. 4. The LC-MS method for the determination of acetylcorynoline in rat plasma utilizing 100 µL of plasma with an LLOQ of 5.0 ng/mL developed and validated, it was sensitive, selective and simple. This method was successfully applied in pharmacokinetic study of acetylcorynoline after intravenous administration of single dosage 3 mg/kg in rats.