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Abstract: In common with all gas chromatography (GC) methods, comprehensive two-dimensional gas chromatography (GC×GC) has the potential to provide both qualitative and quantitative analysis. There are fundamental differences in the way one-dimensional (1D-GC) and GC×GC results are interpreted for these parameters. Since 1D-GC produces a single measured peak in the chromatogram, there is a single retention time, and associated with this a single peak response (either area or height). Peak area and height are related by peak width. GC×GC produces a series of modulated peaks at the detector. Thus, the peak metrics of retention, area and height for one component are now not simple single values for one peak, but rather are derived from the multiple peak distribution generated by the modulation process. The peak retention is interpreted in terms of two-dimensional coordinates in a retention plane. In this study, a brief background review to quantification in GC×GC is provided. Previous reviews cover aspects of quantitative GC×GC studies up to the year 2005, including different approaches to quantification, and reports of quantitative analysis with different detectors, for different compounds classes, and in different matrices. Other studies have developed chemometric approaches based on multivariate analysis to provide quantitative reporting of individual compounds. The coverage of the earlier reviews has been updated to include material that has been presented since 2005 and includes considerations of valve-based modulation. Recently the modulation ratio (M R) concept was proposed and intended to clarify the meaning of modulation number (n M) in GC×GC, which was shown to be a rather poorly defined parameter. Based on the prior studies that introduced this concept, the role of quantitative analysis is investigated here through calculation of the peak areas and peak area ratios of selected series of modulated peaks in GC×GC. The application of isotopically labelled reference compounds for polycyclic aromatic hydrocarbon (PAH) analysis is used here to develop the quantitative metric approach. It is shown that by selecting the two or three major modulated peaks for solutes and internal standards, comparing the response ratio with the sum of all modulated peaks and also with the reference non-modulated result, quantification is statistically equivalent. Thus, adequate quantitative analysis and calibration can be accomplished by using selected major modulated peaks for each compound. This may simplify quantitative interpretation of GC×GC data. [Copyright &y& Elsevier]

Abstract: In many studies of nonlinear or preparative chromatography, chromatographic signals must be recorded for relatively concentrated solutions and the detectors, that are designed for analytical applications and are highly sensitive, must be used under such experimental conditions that their responses are often nonlinear. Then, a calibration curve is needed to derive the actual concentration profiles of the eluates from the measured detector response. It becomes necessary to derive a relationship between the concentration of the eluent and the detector signal at any given time. The simplest approach consists in preparing a series of solutions of known concentrations and in flushing them successively through the detector cell, recording the height of the plateau response obtained. However, this method requires relatively large amounts of the pure solutes being studied and these are not always available or they may be most costly, although these solutions can be recovered. We describe and validate an alternative procedure providing this calibration from a series of peaks recorded upon the injection of increasingly large pulses of the studied compound. [Copyright &y& Elsevier]