DEVELOPMENT OF A MINIATURIZED GAS-CHROMATOGRAPH MASS-SPECTROMETER WITH A MICROBORE CAPILLARY COLUMN AND AN ARRAY DETECTOR

A miniaturized focal plane mass spectrograph with an array detector is demonstrated to measure multiple mass spectra from narrow GC peaks eluted from a short microbore capillary column (50-mu-m i.d., 3 m in length). The GC peaks of dichlorodifluoromethane, chloromethane, bromomethane, and chloroethane from a mixture of compounds are found to have full width at half-maximum in the range 200-300 ms and are separated by approximately 700 ms. The simultaneous measurement of all ions by the array detector enables mass spectral measurements of these peaks possible without affecting the GC resolution and the sensitivity of the mass spectrograph. The system is shown to possess high sensitivity (e.g., 7.5 x 10(-14) g for benzene) and a linear dynamic range of > 10(3). A microbore capillary column requires an extremely small carrier gas flow rate (approximately 0.05 atm cm3 min-1 for helium) and drastically reduces the weight and power needs of the mass spectrograph. The combination of such a column with a miniaturized focal plane mass spectrograph is thus uniquely suited for the development of a field-portable, high-performance GC-MS system.