The determination of GC-MS relative molar responses of benzene and biphenyl derivatives

The dependence of relative response factors on the carbon and chlorine atom number related to naphthalene has been investigated by using gas chromatography-mass spectrometry (GC-MS). The main goal of these investigations is to find some relationship between the GC-MS signal (peak area) and the test molecule chemical structure. By means of the knowledge of correlations of relative molar response, the quantitative analysis passes into easier and fewer reference materials are needed to investigate a sample having lot of component, because the sensitivities can be determined from the correlations studied in this paper. This is very important in daily analytical tasks, particularly for impurity profiling studies. Relative responses of some polychlorinated benzenes, polychlorinated biphenyls and n-alkylbenzenes are compared in the experiments. Linear correlation is found between the molecular structures of n-alkylbenzenes, i.e. the carbon atom number, and relative molar response. Relative molar responses of polychlorinated biphenyls also provided linear correlation taken as a function of chlorine atom number. Under given conditions, the increments of CH2 unit and chlorine atom number to the relative molar responses are 0.221 and 0.198, respectively. However, relative responses of polychlorinated benzenes showed diversity plotted against chlorine atom number, and their isomer compounds also gave various results according to the first ionization energy. The measurement conditions can influence the relative responses. The low injector temperature, the interface and the ion source temperature affected relative responses of high volatile compounds. However, when the parameters are kept under control, the results can become accurate and reproducible.