Development of a validated HPLC-PAD-APCI/MS method for the identification and determination of iridoid glycosides in Lamiophlomis rotata

An HPLC-photodiode array detector (PAD)-APCI/MS method was developed for the identification of iridoid glycosides in Lamiophlomis rotata (Benth.) Kudo. The regularities of characteristic ions of iridoid glycosides obtained in APCI-MS were analyzed and used to deduce the structure of iridoid glycosides. Compared with the literature on ESI-MS, the deprotonated molecular ions were more outstanding in APCI-MS. Five major active constituents, namely, 8-O-acetylshanzhiside methyl ester, loganin, 8-deoxyshanzhiside, phloyoside II, and shanzhiside methyl ester, were simultaneously determined in ten samples by HPLC. A comprehensive validation of the method included tests of sensitivity, linearity, precision, and accuracy. The linear regressions were acquired with r > 0.999. The precision was evaluated by intra- and inter-day assays, after which relative standard deviation (R.S.D.) values were reported within 2.5%. The recovery studies for the quantified compounds were observed in the range of 95.6-101.2% with R.S.D. values less than 2.1%. The overall procedure may be suitable for the qualitative and quantitative analyses of iridoid glycosides in L. rotata and its preparations.