Role of a microbore capillary column in the development of a portable gas chromatograph‐mass spectrometer

Abstract

AbstractFor the development of a portable gas chromatograph‐mass spectrometer (GC‐MS) system, drastic reduction in the carrier gas load is necessary in order to minimize the pumping requirements of the mass spectrometer. Two approaches were investigated for achieving this. The first involved the use of a palladium‐hydrogen interface and was found not to be viable due to its chemical reactivity. The second utilized a short microbore capillary column (3−m × 50−μm i.d.). The small cross‐sectional area of the column reduced the gas load into the MS and yielded sharp chromatographic peaks possessing full‐widths at half‐height in the range of 200–600 ms from a mixture of priority pollutants. Good column efficiency (> 2.3 × 104 theoretical plates/meter for k of 10) and resolution were observed, and analyses were completed within a few minutes. Mass spectral measurements were performed with a miniaturized focal plane mass spectrograph having an integrating array detector. Because this system detects (integrates) ions of all masses simultaneously and continuously, short data acquisition times can be used to measure several spectra per gas chromatographic peak without loss in sensitivity. Such time‐resolved mass spectral measurements were applied to the separation and identification of benzene and carbon tetrachloride which coeluted from the column. Our results show that a short microbore capillary column in conjunction with a miniaturized mass spectrograph and an array detector is eminently suited for the development of a field portable GC‐MS system of high performance.