Centre for Green Chemistry, School of Chemistry, Monash University, Wellington Road, Clayton 3800, Australia.
Anal Chem. 2011 Sep 1;83(17):6485-92. doi: 10.1021/ac200973z. Epub 2011 Aug 9.
A method is described that permits automated online enrichment of injected compounds in multidimensional gas chromatography by using a microfluidic heart-cut (H-C) device to direct target compounds into a cryogenically cooled internal trap (cryotrap, CT). By performing multiple injections of a sample, selected compounds or regions of a primary column separation can be collected in the CT. Remobilizing the trapped species allows elution and further resolution on the second column. Using a well-balanced H-C device, compounds can be fully excluded from the collection step or quantitatively transferred to the CT. Peak areas of the remobilized compound correlate well with the number of sample injections. Trapping on various column phases shows the method is suited to quantitative trapping of alkanes of mass greater than about dodecane and fatty acid methyl esters greater than the C8 homologue. Caffeine and menthol standards of concentration 100 μg mL(-1) gave peak area correlation coefficients for 1-10 and 1-50 replicate split injections of 1 μL volume of 0.999 and 0.996, respectively. Peak height correlations were less favorable as a result of peak broadening on the second column, presumably due to overloading at greater collected mass. The method was applied to 0.2% solutions of peppermint oil (menthol; a major component; 44%) and 1.0% lavender oil (α-terpineol and neryl acetate; minor components of 1.05 and 0.42% abundance). The minor components gave good area and height correlations, and good recovery around 90% was observed for menthol compounds recovered from 15 accumulations. Response amplification was further demonstrated for menthol from mint oil headspace sampling using solid phase microextraction. This approach should be a valuable adjunct for improved detection specificity, for detectors of low sensitivity, and when prior sample concentration provides insufficient response of selected target analytes.
描述了一种方法，该方法通过使用微流控心切（H-C）装置将注入的化合物自动在线富集到多维气相色谱中，从而将目标化合物引导到低温冷却的内部捕集阱（捕集阱，CT）中。通过多次进样样品，可以将主要柱分离的选定化合物或区域收集在 CT 中。重新移动捕获的物质允许在第二柱上洗脱和进一步分离。使用平衡良好的 H-C 装置，可以将化合物完全排除在收集步骤之外，或者将其定量转移到 CT 中。重新移动的化合物的峰面积与进样次数很好地相关。在各种柱相上的捕获表明该方法适用于大于约十二烷的烷烃和大于 C8 同系物的脂肪酸甲酯的定量捕获。浓度为 100μg mL（-1）的咖啡因和薄荷醇标准品，对 100μL 体积的 1-10 和 1-50 个重复分流进样，得到的峰面积相关系数分别为 0.999 和 0.996。由于第二柱上的峰展宽，峰高相关性不太有利，可能是由于在更大的收集质量上过载。该方法应用于薄荷油（薄荷醇；主要成分；44%）和薰衣草油（α-萜品醇和乙酸橙花酯；1.05%和 0.42%丰度的次要成分）的 0.2%溶液。次要成分的峰面积和峰高相关性良好，从 15 次积累中回收的薄荷醇化合物的回收率约为 90%。通过固相微萃取（SPME）对薄荷油顶空采样中的薄荷醇进行了响应放大。对于提高检测特异性、低灵敏度的检测器以及在选择的目标分析物的前体样品浓度提供的响应不足时，这种方法应该是一种有价值的辅助手段。
