Fingerprint analysis of Oxytropis falcate using ultra-performance liquid chromatography–electrospray ionization tandem mass spectrometry (UPLC-ESI-MS)
An efficient, accurate and reliable chromatographic fingerprint based on ultra-performance liquid chromatography coupled with photodiode array detection and electrospray ionization mass spectrometry (UPLC-PDA-ESI-MS) was developed for the identification and quality control of Oxytropis falcate Bunge. The method was validated for precision, repeatability, stability, and specificity. The RSD values of retention times and peak areas of the common peaks were 0–0.7% and 1.0–3.6% for within-day precision, while 0–0.5% and 1.5–6.1% for between-day precision. For repeatability, the values were lower than 0.5% and 2.6%, respectively, and for stability (24 h), the values were lower than 0.9% and 3.3%, respectively. Twenty-one batches of O. falcate obtained from different regions were analyzed by employing the developed method. Several multivariate statistical analysis including similarity analysis (SA), hierarchical clustering analysis (HCA) and principal component analysis (PCA) were applied to cluster and evaluate the O. falcate samples according to their collection sites. The results showed that the quality of O. falcate did not merely depend on the geographic origin. Thirty common peaks were found in the chromatographic fingerprints of O. falcate and eleven of them were identified by comparing the retention time, the ultraviolet spectrum and the molecular ion peaks (obtained from selective ion recording mode) with the reference compounds. This method with high precision, reliable stability and good repeatability can provide a reference for the quality evaluation of O. falcate.