| The need for analytical laboratories to increase sample throughput has led to the development of fast gas chromatography (GC)/time-of-flight mass spectrometry (TOF-MS). Some recent applications of fast GC/TOF-MS in our laboratory include screening for drugs of abuse, characterization of pesticides, and direct analysis of synthetic and biopolymeric samples. Use of short narrow-bore capillary columns, high carrier gas velocities, and rapid temperature programming can decrease chromatographic separation times up to several orders of magnitude compared to conventional GC. The spectral scan rates of quadrupole or magnetic sector mass spectrometers are incompatible with high-speed GC. However, non-scanning mass spectrometers, such as TOF-MS, offer fast data acquisition rates (500 spectra/sec), and accurate peak information. The high quality TOF-MS spectra also enable deconvolution of overlapping peaks.;Two approaches for pyrolysis of synthetic and biological polymers have been investigated: heated filament, and laser pyrolysis. A laser pyrolysis instrument, coupled to fast GC/TOF-MS has been designed using a UV laser for fragmentation without prior sample pretreatment. Effects of experimental variables have been characterized to optimize system performance. Chemical markers for carbohydrates have been identified and employed for direct analysis of bacterial lipopolysaccharides.;In other work, multivariate data analysis has been applied to discriminate between mass spectra of xylene isomers. Data were generated from three different instrument configurations: quadrupole MS, mass-selective detector (MSD), and TOF-MS. The performance of principal component analysis (PCA) and canonical variate analysis (CVA) were compared to that of the NIST MS library for xylene isomer identification. |
