Normal phase LC coupled with direct analysis in real time MS for the chiral analysis of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and jasmonic acid

Normal phase chiral LC (NPLC) has been proved to be powerful and efficient for chiral separation. However, the combination of NPLC with ESI or atmospheric pressure chemical ionization MS is restricted by the poor ionization efficiency and thermal fragmentations of analytes to some extent. Direct analysis in real time MS (DART‐MS) is an ambient ionization technique that shows high ionization efficiency of the analytes in the normal phase mobile phase. In this work, we coupled chiral NPLC to DART‐MS for the chiral qualitative and quantitative analysis of 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol and jasmonic acid enantiomers. Satisfactory results for the enantiomers of 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol operating in the positive mode were obtained in terms of linearity (2.5–250 μg/mL, R2, 0.999–1.000) and repeatability (25 μg/mL, RSDs, 4.7–5.6%). Moreover, chiral NPLC‐DART‐MS resulted in the simultaneous chiral separation and detection of jasmonic acid enantiomers, which are very difficult to be analyzed by NPLC‐ESI‐MS and NPLC‐APCI‐MS. Compared with the coupled techniques of NPLC‐ESI‐MS and NPLC‐APCI‐MS, NPLC‐DART‐MS showed advantages in increasing the ionization efficiency and reducing the in‐source thermal fragmentation of analytes.