Bieri Stefan, Marriott Philip J
School of Applied Sciences, RMIT University, G.P.O. Box 2476V, Melbourne, Victoria 3001, Australia.
Anal Chem. 2006 Dec 1;78(23):8089-97. doi: 10.1021/ac060869l.
A method producing simultaneously three retention indexes for compounds has been developed for comprehensive two-dimensional gas chromatography by using a dual secondary column approach (GC x 2GC). For this purpose, the primary flow of the first dimension column was equally diverted into two secondary microbore columns of identical geometry by means of a three-way flow splitter positioned after the longitudinally modulated cryogenic system. This configuration produced a pair of comprehensive two-dimensional chromatograms and generated retention data on three different stationary phases in a single run. First dimension retention indexes were determined on a polar SolGel-Wax column under linear programmed-temperature conditions according to the van den Dool approach using primary alcohol homologues as the reference scale. Calculation of pseudoisothermal retention indexes in both second dimensions was performed on low-polarity 5% phenyl equivalent polysilphenylene/siloxane (BPX5) and 14% cyanopropylphenyl/86% dimethylpolysiloxane (BP10) columns. To construct a retention correlation map in the second dimension separation space upon which KovAts indexes can be derived, two methods exploiting "isovolatility" relationships of alkanes were developed. The first involved 15 sequential headspace samplings of selected n-alkanes by solid-phase microextraction (SPME), with each sampling followed by their injection into the GC at predetermined times during the chromatographic run. The second method extended the second dimension retention map and consisted of repetitive introduction of SPME-sampled alkane mixtures at various isothermal conditions incremented over the temperature program range. Calculated second dimension retention indexes were compared with experimental values obtained in conventional one-dimensional GC. A case study mixture including 24 suspected allergens (i.e., fragrance ingredients) was used to demonstrate the feasibility and potential of retention index information in comprehensive 2D-GC.
通过使用双辅助柱方法（GC×2GC），已开发出一种用于全二维气相色谱同时生成化合物的三个保留指数的方法。为此，借助位于纵向调制低温系统之后的三通分流器，将第一维柱的主流等分流至两个几何形状相同的微径辅助柱中。这种配置产生了一对全二维色谱图，并在一次运行中生成了三种不同固定相上的保留数据。根据范登杜尔方法，在极性溶胶 - 凝胶 - 蜡柱上，使用伯醇同系物作为参考标度，在线性程序升温条件下测定第一维保留指数。在低极性的5％苯基等效聚亚苯基/硅氧烷（BPX5）和14％氰丙基苯基/86％二甲基聚硅氧烷（BP10）柱上进行二维伪等温保留指数的计算。为了构建二维分离空间中的保留相关图，从中可以导出科瓦茨指数，开发了两种利用烷烃“等挥发性”关系的方法。第一种方法涉及通过固相微萃取（SPME）对选定的正构烷烃进行15次连续顶空采样，每次采样后在色谱运行期间的预定时间将其注入气相色谱仪。第二种方法扩展了二维保留图，包括在温度程序范围内递增的各种等温条件下重复引入SPME采样的烷烃混合物。将计算得到的二维保留指数与传统一维气相色谱中获得的实验值进行比较。使用包含24种疑似过敏原（即香料成分）的案例研究混合物来证明保留指数信息在全二维气相色谱中的可行性和潜力。
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