顶空吸附萃取-气相色谱法分析小麦中部分风味物质

采用顶空吸附萃取法(headspace sorptive extraction, HSSE)建立了小麦中部分风味物质的分析方法。以硅橡胶为原料,采用溶胶-热空气硫化法,在模具中定型制得硅橡胶萃取棒。萃取棒的硅橡胶层体积约为87 μL,热稳定性好,耐热温度达到390 ℃。萃取棒吸附的风味物质经自制热解吸装置热脱附,被吹扫进入气相色谱仪进行分析。考察了萃取温度及时间、相比、热解吸条件对该方法萃取效率的影响。在优化条件下分析小麦粉标准样品,结果表明:方法的线性关系良好(r>0.9979),检出限为0.09～1.00 μg/kg,标准物质的平均添加回收率为95%～121%,相对标准偏差在2.2%～7.8%之间。对小麦粉实际样品进行分析,采用外标法得到了7种风味物质的绝对含量。该方法简便快捷,检出限低,适用于小麦中风味物质的快速定量分析。

Analysis of part of flavor compounds in wheat by headspace sorptive extraction-gas chromatography

A method has been established for the analysis of flavor compounds in wheat by headspace sorptive extraction (HSSE). The sorptive extraction bar was composed of a silicon rubber coating and a capillary glass with an inner iron rod. The silicon rubber coating was condensed inside a stainless steel mold from the silicon precursors with a sol-hot air vulcanization method. The coating of the extraction bar has a volume of about 87 μL and is thermally stable until 390 ℃. The flavor compounds extracted by the bar were desorbed in a homemade thermal desorption unit (TDU) and introduced directly into a pre-column in a gas chromatograph for analysis. Experimental parameters for the extraction efficiency were optimized including extraction temperature and time, phase ratio and thermal desorption conditions. The standard wheat flour samples spiked with seven flavor compounds were analyzed under the optimized conditions, and showed good linear relationships (r>0.9979), limits of detection (LOD) of 0.09-1.00 μg/kg, good recoveries (95%-121%) and repeatabilities (relative standard deviations, RSD, 2.2%-7.8%). By external calibration method, the absolute contents of the seven flavor compounds in a real wheat sample were determined. The method is rapid, simple with low limits of detection, and is applicable for the rapid quantitative analysis of the flavor compounds in wheat.