A Headspace Cooled-liquid Phase Microextraction Technique and Its Application for Analysis of Fusel Oil in Water Samples and Volatile Compounds in Beer

A novel Headspace cooled-liquid phase microextraction (HS-CLPME) has been developed and demonstrated. A polytetrafluoroethylene vial cap with a two-step cylindrical cavity was used as solvent drop holder, and a cooling system based on thermoelectric cooler (TEC) was used to lower the temperature of solvent drop to subzero. Volatile solvents can be used as extractant in HS-CLPME, which extends the selection of extractant for HS-LPME, reduces the interference of the large solvent peak to the analytes peaks, and enhances the compatibility of HS-LPME with gas chromatograph (GC). Because of the relatively lower temperature of extractant, the extraction efficiency has been improved. HS-CLPME was applied to analyze the fusel oil in water. The operation parameters including the ionic intensity, the volume and temperature of extractant, the sample temperature, stirring rate, and extraction time were optimized. The limits of detections ranged from 0. 09 mu g/L to 0. 26 mu g/L for fusel oil, and the enrichment factors were from 78 to 198. The HS-CLPME was also applied to analyze volatile flavors in beer