Targeted multidimensional gas chromatography for the quantitative analysis of suspected allergens in fragrance products

Two approaches are described and compared for the analysis of suspected allergens (SAs) in fragrance products, which are defined by the Scientific Committee of Cosmetics and Non-Food Products (SCCNFP). The first consists of a comprehensive two-dimensional gas chromatography (GC × GC) experiment using both a “conventional” non-polar/polar column combination and an “inverse” polar/non-polar column set. The second approach uses a targeted multidimensional gas chromatography (MDGC) system employing a Deans type pneumatic switch and a longitudinally modulated cryogenic system (LMCS). It was found that the conventional and inverse column sets complement each other well, providing identification of SAs present. Compounds well retained on the second dimension of one column set were the first to be eluted from the other. In some instances SAs co-eluting with matrix components on the second dimension for a given column set were clearly resolved on the other, although this has the disadvantage of requiring two analytical runs. Targeted MDGC with a non-polar/polar column set, successfully separated all SAs identified within a fragrance product. The instrument is set up in a similar fashion to a GC × GC system though with longer second dimension (2D) column, a cryogenic trap at the beginning of the second column, and a pneumatic switch coupling both columns. The data are easier to process than for a GC × GC experiment. The targeted MDGC method has the capacity to deliver far greater efficiency to targeted regions of a primary separation than a GC × GC experiment, whilst still maintaining overall run times similar to those of a conventional one-dimensional (1D) GC experiment. Cryogenic focussing at the beginning of the 2D column delivers enhanced sensitivity, accurate 2D retention times and narrow peak widths; these are responsible for an increased resolution obtained from the fast, relatively short (∼5 m) 2D column. The two column set GC × GC analysis provided a quick and effective means to qualitatively determine the presence of six SAs in a commercially available air freshener, however all were not adequately resolved from matrix components. In contrast, quantitation was straightforward using the targeted MDGC method.