顶空低温液相微萃取技术分析水中杂醇油和啤酒挥发性成分

摘要

顶空液相微萃取(HS-LPME)存在溶剂稳定性不高,只能采用沸点较高的溶剂,容易干扰样品组分测定等缺点.顶空低温液相微萃取装置(HS-CLPME)以带有台阶形圆柱腔体的聚四氟乙烯小帽为萃取剂的载体,利用半导体制冷技术(TEC)将萃取剂冷却至最低-20℃,采用挥发性溶剂进行顶空液相微萃取(HS-CLPME),扩展了HS-LPME可选择溶剂的范围,减少了色谱图上萃取剂峰与挥发性样品峰的干扰,提高了顶空液相微萃取与气相色谱的兼容性.由于萃取剂处于相对低温,萃取性能得到提高.将HS-CLPME用于水中杂醉油的萃取分析,优化了萃取剂(乙腈)、离子强度(饱和NaCl浓度)、萃取剂体积(6 μL)和温度(-1℃)及样品温度(90 ℃),搅拌速度(800 r/min)和萃取时间(45 min)等条件,对杂醇油的检出限可达0.09～0.26 μg/L;富集倍数达78-198倍.将此技术用于啤酒样品中的杂醇油和其它挥发性物质的分析,获得了良好的结果.%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 inclu ding 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 μg/L to 0.26 μg/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.