Determination of flavonoid compounds from Saussurea involucrata by liquid chromatography electrospray ionisation mass spectrometry.

Saussurea involucrata produces several bioactive flavonoids that are derived from the phenylpropanoid pathway. To determine these flavonoids, a sensitive high performance liquid chromatography electrospray ionisation mass spectrometry method (LC-ESI-MS) was developed. Chromatographic separation was then performed. The gradient elution was optimised to give high recoveries and satisfactory chromatographic resolution. Flavonoid detection was carried out using an ion trap as mass analyser. Parameters of the mass analyser were optimised. We used the validated LC-ESI-MS method to verify the identities of bioactive compounds, namely apigenin, luteolin, hispidulin, luteolin-7-O-glucoside and rutin. Calibration curves for these five flavonoids were linear in ranges between 5.0 and 500 microg mL(-1). The limit of detection ranged from 1.5 x 10(-4) (for hispidulin) to 6.1 x 10(-3) mg mL(-1) (for rutin). Precision was well within the acceptable range (RSD < 3.0%) and the recovery rate was between 75.3 and 89.8% for each flavonoid. A method validation study showed that the LC/MS technique was a powerful analytical tool for detecting trace amounts of the flavonoid compounds in extracts of S. involucrata.