Determination of aristolochic acids in medicinal plant and herbal product by liquid chromatography–electrospray–ion trap mass spectrometry

This paper describes a liquid chromatography–electrospray–ion trap mass spectrometry (LC–ES–ITMS) method for the determination of aristolochic acid I and II (AA-I and AA-II) in medicinal plants and Chinese herbal remedies. A reversed phase C18 column with gradient elution was utilized. The effects of mobile phase additives, acetic acid and ammonium acetate, on LC separation and ES ionization were investigated. For both AA-I and AA-II, the [M+NH4]+ ion was found to be the precursor ion for target MS/MS analysis. The MS/MS product ion, [M+H−44]+, was used for the quantitative measurement of AA-I and AA-II. The linearity was good from 0.03 to 5 μg ml−1 and good correlation (r2=0.999) over the range examined was determined for both AA. The detection limit based on a signal-to-noise ratio of three was 0.012 and 0.015 μg ml−1 for AA-I and AA-II, respectively. Various Chinese herbal remedies obtained from renal failure patients and medicinal plants were examined by this newly developed method.