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Rapid characterization of nonpolar or low‐polarity solvent extracts from herbal medicines by solvent‐assisted electrospray ionization mass spectrometry
Author(s) -
Zhang Qiang,
Su Yue,
Liu Xiaopan,
Guo Yinlong
Publication year - 2018
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.8036
Subject(s) - chemistry , electrospray ionization , mass spectrometry , solvent , chromatography , atmospheric pressure chemical ionization , electrospray , polarity (international relations) , ion mobility spectrometry , petroleum ether , analytical chemistry (journal) , chemical ionization , ionization , ion , organic chemistry , extraction (chemistry) , biochemistry , cell
Rationale The direct detection of nonpolar and low‐polarity solvent extracts of herbal medicine is difficult by conventional electrospray ionization mass spectrometry (ESI‐MS). This problem can be solved by solvent‐assisted electrospray ionization mass spectrometry (SAESI‐MS). With the help of assisted solvents (ESI‐friendly solvents) at the tip of the spray needle, compounds (especially the low‐polarity compounds) in nonpolar and low‐polarity solvent extracts can be ionized directly. Methods Herbal medicines were ultrasonically extracted with nonpolar or low‐polarity solvents, such as petroleum ether. Thereafter, the extracts were analyzed by conventional ESI‐MS, atmospheric pressure chemical ionization mass spectrometry (APCI‐MS) and SAESI‐MS. The mass spectra obtained from these three methods were compared and analyzed. Results Unstable ion signals, and even no ion signals, were observed when the nonpolar and low‐polarity solvent extracts were detected directly by conventional ESI‐MS. Better specificity, higher sensitivity or cleaner spectra were acquired from SAESI‐MS by comparing with the performance of conventional ESI‐MS. The ion signals generated by SAESI‐MS and APCI‐MS were observed in clearly different m/z ranges. A variety of potential compounds were detected in the petroleum ether extracts of Pogostemon cablin and Ligusticum chuanxiong . The relative abundances and signal intensities of the same ion signals from the stems, leaves and decoction pieces of Pogostemon cablin were significantly different by SAESI‐MS. Conclusions As a convenient and efficient method, SAESI‐MS can be used to directly detect compounds (especially the low‐polarity compounds) in nonpolar or low‐polarity solvent extracts of herbal medicines, providing abundant chemical information for pharmacological studies. SAESI‐MS allows the simultaneous qualitative analysis of multiple compounds in the same complex samples and is thus particularly suitable for the preliminary screening of compounds in complex samples. SAESI‐MS can be used to differentiate the different parts of herbal medicines.