Validation of an LC–MS/MS assay of terpene trilactones in Ginkgo biloba extracts and pharmaceutical formulations through standard addition method

A chromatographic column packed with 1.8 microm particle size octadecyl modified silicagel was used to separate terpene trilactones from Ginkgo biloba extracts/pharmaceutical formulations. Gradient elution was applied, using acidic methanol and water as mobile phase components (0.1% formic acid addition). No specific sample preparation is needed, except dissolution/extraction in methanol of the solid material. Baseline separation of bilobalide and ginkgolides A, B, C and J is obtained within 4 min. The gradient profile is needed to elute the remaining matrix from column. A separation cycle takes 7 min, including column re-equilibration. MS/MS detection with positive electrospray ionization and triple quadrupole mass analysis was used. Multiple reaction monitoring mode was applied for data acquisition, taking protonated molecular ions as precursors. In order to generate reproducible ionization conditions, the standard addition method was considered. The assay of terpene trilactones obtained under such conditions was validated according to guidances in place. Method intermediate reproducibility corresponds to a relative standard deviation of less than 10%. Accuracy, expressed in terms of absolute percent bias ranged from 90% to 110%. Spectral confirmation of target analytes was also included in the validation procedure.