Determination of vanillin and ethyl vanillin in milky tea by HS-SPME-GC/MS

A method for headspace solid phase micro extraction( HS- SPME) and gas chromatography mass spectrometry( GC / MS) was developed for the determination of vanillin and ethyl vanillin in milky tea. 75 μm carboxen / polydimethylsiloxane( CAR / PDMS) fiber was selected for extraction in this study. The parameters affecting extraction efficiency such as extraction temperature,extraction time and salt concentration were investigated.3',4'-( methylenedioxy) acetophenone was used as an internal standard for quantifying vanillin and ethyl vanillin.The results showed that the linear relationships between ratio of peak area and concentration of vanillin( R2= 0.9974) and ethyl vanillin( R2= 0.9987) were good enough from 0.5 to 25.0 μg.The limits of detection for vanillin and ethyl vanillin were 0.5 mg / kg and 0.3 mg / kg in solid samples,and they were 0.05 mg / kg and 0.03 mg / kg in liquid samples,respectively. The average recoveries of vanillin were 88.99% ~ 105.15%,and the relative standard deviations( RSDs) were 2.40% ~ 9.26%. The average recoveries of ethyl vanillin were 91.57% ~ 105.13%,and the RSDs were 2.35% ~8.49%.This method is convenient and reliable,and it is suitable for the determination of vanillin and ethyl vanillin in milky tea.