Identification of components in Zhi-Zi-Da-Huang decoction by HPLC coupled with electrospray ionization tandem mass spectrometry, photodiode array and fluorescence detectors

High-performance liquid chromatography (HPLC) coupled with electrospray ionization (ESI) tandem mass spectrometry (MS) in positive and negative ion mode and photodiode array (PDA) and fluorescence detectors (FD) was applied to simultaneously characterise thirty active components in Zhi-Zi-Da-Huang decoction (ZZDHD). The analysis was preformed on a Lichrospher C18 column (4.6 mm × 250 mm, 5 μm) using a binary eluent (0.1% aqueous acetic acid (A) and methanol (B), 1 ml/min) under gradient conditions. Based on the retention times (tR), UV spectral data, fluorescence characteristics, results of extracted ion current (EIC), information of molecular weight and mass fragmentation behaviours, 17 flavonoids, five anthraquinones, two coumarins and six iridoids were detected and identified. The ESI-MS/MS fragmentation behaviour of iridoids, flavonoids, anthraquinones, coumarins was also proposed. The fragmentation patterns proposed could be extended to the components mentioned above but in different herbs and prescriptions. The method was useful for the identification of unknown components in the herbal system and other complex samples, especially for which standards are unavailable.