A specific and reliable HPLC-MS/MS method was developed and validated for the simultaneous determination of four dicaffeoylquinic acids (DCQA): 3,4-DCQA, 1,5-DCQA, 3,5-DCQA and 4,5-DCQA. The analytes were separated on a C₁₈ column (150 mm × 2.1 mm, 1.8 μm) and a triple-quadrupole mass spectrometry equipped with an electrospray ionization (ESI) source was applied for detection. The plasma sample was prepared by a liquid-liquid extraction method and the recovery for the four analytes was around 80%. The calibration curves were linear over a concentration range of 10.6-1060.0 ng/mL for 3,4-DCQA, 19.2-1920.0 ng/mL for 1,5-DCQA, 14.0-2900.0 ng/mL for 3,5-DCQA, 9.7-970.0 ng/mL for 4,5-DCQA. The intra-day and inter-day precision was less than 15% and the relative error (RE) were all within ±15%. The validated method was successfully applied to a pharmacokinetics study in rats after oral administration of the extracts of Ainsliaea fragrans cham (a traditional Chinese herb).
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