Identification and quantification of atractylenolide I and atractylenolide III in Rhizoma Atractylodes Macrocephala by liquid chromatography-ion trap mass spectrometry.

Rhizoma Atractylodes Macrocephala (RAM) is an important traditional Chinese medicinal herb that is used for treatment of dyspepsia and anorexia. The active ingredients, atractylenolide I (AO-I) and atractylenolide III (AO-III), were identified by direct-injection ion trap-mass spectrometry (IT-MS) for collecting MS(n) spectra. The major fragment ions of AO-I and AO-III were confirmed by MS(n) both in negative ion mode and in positive ion mode. The possible main cleavage pathway of fragment ions was studied. The determinations of AO-I and AO-III were accomplished by liquid chromatography (LC) with UV and MS. The analytes provided good signals corresponding to the protonated molecular ions [M + H](+) and product ions. The precursor ions and product ions for quantification of AO-III and AO-I were m/z 249 → 231 and m/z 233 → 215, respectively, using selected ion monitoring by LC-IT-MS. Two methods were evaluated for a number of validation characteristics (repeatability, limit of detection, calibration range, and recovery). MS provides a high selectivity and sensitivity for determination of AO-III and AO-I in positive mode. After optimization of the methods, separation, identification and quantification of the two components in RAM were comprehensively tested by HPLC with UV and MS.