Quantitation method of N ,N ′-disalicylidene-1,2-propanediamine by comprehensive two-dimensional gas chromatography coupled to a nitrogen chemiluminescence detector

Determination of nitroalkanes in mainstream cigarette smoke by heart-cutting multidimensional gas chromatography system coupled with mass spectrometry detection

In this paper, heart-cutting two-dimensional GC/MS (GC-GC/MS) method in combination with a simple sample collection procedure was developed for the determination of 6 nitroalkanes in mainstream cigarette smoke. The method could remove large amounts of impurities on-line in the first polar column by heart-cuts and separate from the left interferences in a second mid-polar column. And the target compounds could be focused at the inlet of the second column by cryo-concentration. Compared to conventional GC/MS, GC-GC/MS achieved a lower noise level and sensitivity at least an order of magnitude higher. Furthermore, the GC-GC/MS method could avoid the false negative and false positive results that appeared in the compared conventional GC/MS analysis. By trapping the vapor phase of 20 cigarettes smoke, the LODs and LOQs of the nitroalkanes were 1.3 to 9.8 and 4.3 to 32.6ng/cigarette, respectively, and all linear correlation efficiencies were larger than 0.999. The validation results also indicate that the method has high accuracy (spiked recoveries between 84% and 102%) and good repeatability (RSD between 7.2% and 9.4%). The developed method was applied to analyze 1 Kentucky reference cigarette (3R4F) and 10 Chinese commercial brands of cigarettes. The research results indicated that nitromethane, nitroethane, 2-nitropropane and 1-nitro-n-pentane were detected in mainstream cigarette smoke, but 1-nitro-n-butane and 2-nitropropane, which were reported by one previous study, were not detected in all cigarette samples.

Multidimensional gas chromatography methods for bioanalytical research

Multidimensional gas chromatography (MDGC) methods are high-resolution volatile chemical separation techniques, and comprise classical heart-cutting MDGC and its more recent incarnation, comprehensive 2D GC. Although available for a long period, MDGC approaches are still not widely practiced in the field of bioanalysis, possibly reflecting the general preference for regular GC versus MDGC approaches. With the recent introduction of ‘-omic’ techniques that emphasize global nontargeted profiling of metabolites within living systems, it is evident that MDGC is gaining momentum as a separation tool, since it offers very high resolution. By untangling metabolites within highly complex biological matrices, and expanding the metabolic coverage, MDGC plays a frontline role in ‘-omics’ based studies. This review highlights state-of-the-art MDGC approaches, and summarizes the recent developments in bioanalytics.

Trace analysis of alkaline flavors in cut tobacco by heart-cutting multidimensional GC-GC-MS

Tobacco is a complex chemical matrix. The analysis of trace alkaline flavors in tobacco is very difficult because of the limited peak capacity of monodimensional GC. In the present study, a home-assembled twin-oven GC-GC-MS system, with MS detection in both dimensions, has been applied to the analysis of 20 alkaline volatiles in a variety of cut-tobacco samples. By transferring nine and six heart-cuts from the first apolar column to the second polar column in two separate runs, the potential mutual interference of adjacent isomeric targets and the complex matrix could be removed. For comparative purposes, a systematic comparison of both quantification and qualification results for the cut-tobacco sample as quality control was conducted between GC-GC-MS and GC-MS. The results showed that GC-GC-MS provided higher accuracy in peak assignment and quantification. And in GC-MS, the interferences of co-elution had caused both low matched similarity in peak assignment and false-negative/-positive results in quantification for some targets. Advantages of the developed GC-GC-MS method in the analysis of alkaline flavors are its high resolving power, reliability, and simplicity.