The modulation ratio in comprehensive two-dimensional gas chromatography: a review of fundamental and practical considerations
Marriott, Philip John; Mühlen, Carin von
Palavras-chave: Modulation ratio, comprehensive two-dimensional gas chromatography, quadrupole mass spectrometry, quantification.
Resumo: This paper presents a discussion on the implications of the modulation ratio (MR ) in comprehensive two-dimensional gas chromatography (GC×GC) separations. Concepts are discussed in a tutorial manner, which is essentially in the form of a review. The MR is defined as the ratio of the width of a peak as it elutes from a first dimension (1 D) column, to the modulation period used in GC×GC operation; it is a dimensionless number. As demonstrated here, there are many parameters of GC×GC that depend on or can be interpreted by considerations of the MR value. These include, but are not limited to, the peak amplitude enhancement, the number of modulated peaks that are observed, detectivity of each of these peaks, the effect of chromatographic peak shape on the distribution of modulated peaks and how peak retention time on the first column can be derived from this distribution. Also considerations of the physical dimensions and phase coating of the second (2 D) column that is used in GC×GC (these control the total retention time of the peaks on the 2 D column) can be interpreted based on the MR ,and how knowledge of this parameter can assist in interpretation of the separation of isomers.
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