Vacuum ultra violet spectroscopy as a complementary detection system to mass spectrometry for one- and comprehensive two-dimensional gas chromatography.

Abstract

Vacuum ultraviolet (VUV) radiation and light sources are a common part of detection systems for gas and liquid chromatography. In most cases their ability to ionize molecules (photoionization) is used to generate charged ions which could be either quantitatively detected due to the induces current between two electrodes (e.g. Photoionization Detector, PID) or they could be further separated by their mass in combination with a mass spectrometer (e.g. single photon ionization mass spectrometry, SPIMS or atmospheric pressure photoionization, APPI). Even though in both cases only a small fraction of the adsorbed light is used for ionization or dissociation, the sensitivity of the overall detection system is sufficient for many applications. Compared with this, direct spectroscopic applications in chemical analytical laboratories have only rarely been reported in literature due to the peculiarity of VUV radiation and normally accompanied by an extensive instrumental setup. The recently introduced VGA-100 detector overcomes most of the instrumental obstacles and enables the direct coupling of a VUV spectrometer with gas chromatography. Probing of electronic and vibrionic states in the VUV range results in very distinct spectra as well as low detection limits compared to common UV absorption spectroscopy. The sensitivity and selectivity of the detector allow the application in fields where mass spectrometry is normally used. The ability for deconvolution of coeluting compounds based on spectral features as well as for quantification makes VUV spectroscopy a complementary detection system next to mass spectrometry