Liquid Chromatography Electrospray Ionization Mass Spectrometry Analysis of Camphor and Menthol

Helium is an inactive gas that has been used as a carrier gas in gas chromatography (GC). Due to a recent helium shortage of last several years, a method transfer from GC to high-performance liquid chromatography (HPLC) has been increasingly considered. Here, camphor and menthol, which are used in many pharmaceutical products and have been widely analyzed by GC, were determined by reversed-phase liquid chromatography (LC) coupled with electrospray ionization single quadrupole mass spectrometry (ESI/MS). An excellent linearity was confirmed in the concentration range of 0.5-500 mu g/mL for camphor and 1-1000 mu g/mL for menthol. Diluted, commercially available eye drops were analyzed with the developed LC-MS method, where both of these compounds were successfully quantitated with a good precision as well as excellent accuracy. The developed LC-MS method can be applied as a promising alternative to the analysis of similar classes of volatile compounds in GC.