Rapid assessment of volatile components in Baicao oils by headspace single drop microextrction coupled with gas chromatography

Abstract

A simple, fast GC method based on headspace single drop microextraction (HS-SDME) was used for the determination of menthol and methyl salicylate in Baicao oils. A special sample pretreatment method was performed by adding 10 microL the oil its methanol solution into 5 mL water in a caped 10 mL sample vial, a 1.5 microL microdrop of N,N-dimethylformamide with benzyl alcohol as internal standard was formed on the pinpoint of microsyringe needle, exposing 5 min at extraction temperature of 40 degrees C. After extraction, 0.5 microL of extract was directely injected into GC for analysis. The determination was carried out on a capillary column (0.53 mm x 30 m) with PEG as the stationary phase with FID as the detector. A temperature programm was employed. The excellent separation and detection of the target components was accomplished. The average recoveries varied between 95.4% and 99.2%, and relative standard deviations were less than 1.9%. The calibration curves were linear in the range of 1.26-80.5 mg x L(-1) for menthol (r = 0.999 0) and 2.49-1.59 x 10(2) mg x L(-1) for methyl salicylate (r = 0.999 1), respectively. The proposed method is proved to be simple, fast, accurate and low cost without complicated sample pretreatment HS-SDME is expected to be widely applied for the analysis of volatile components in traditional Chinese medicines.