Performance of a multiplexed chemical ionization miniature cylindrical ion trap array mass spectrometer

Chemical ionization(positive), Fragmentation mechanism, Instrument performance, Instruments, Ion trap.

The performance of a multiplexed array of miniature cylindrical ion trap (CIT) mass spectrometers composed of four identical sets of ion source/mass analyzer/detector channels is evaluated. Each miniature cylindrical ion trap (inner radius 2.5 mm) was coupled to an external chemical ionization/electron ionization (CI/EI) source and a miniature (inner diameter 2 mm) electron multiplier. The sample introduction system permits delivery of samples and reagent gases directly into any one or more of the ionization volumes. Experimental conditions were optimized as required for CI to occur in one or more ion volumes. The ion source potential was observed to affect the energy of [M + H]⁺ ions generated by self-chemical ionization in the external ion sources and, thus, the degree of fragmentation observed in resulting mass spectra. The versatility of this novel instrumentation permits two types of multi-channel experiments. In the first, different samples are analyzed at the same time in identical, parallel channels for high-throughput mass analysis using CI. In the second, the instrument is used for improved specificity in the analysis of a single sample by simultaneous measurements made with multiple methods of ionization, including EI and methane CI in adjacent channels of the instrument.