Rapid Determination of Methyl Salicylate and Menthol in Activating Collaterals Oil by Near Infrared Spectroscopy

The near infrared spectra of 10 kinds of commercial collaterals oil samples were collected by liquid transmission analysis module, and the contents of methyl salicylate and menthol in collaterals oil were determined by gas chromatography-mass spectrometry (GC-MS). The quantitative analysis model of methyl salicylate content (model 1) and menthol content (model 2) was established by correlating spectral information with measured values by partial least square method (PLS) in chemometrics. Model 1 was used to detect the content of methyl salicylate in activating oil. The predicted results showed that the absolute error was in the range of -0.098~0.082%, and the relative error was in the range of -9.986~8.195%. Model 2 was used to detect menthol in activating collaterals oil. The predicted results showed that the absolute error was in the range of -0.173~0.194%, and the relative error was in the range of -7.25~9.69%. A new method for rapid and accurate determination of methyl salicylate and menthol in activating collaterals oil was established.