A continuous‐flow probe high performance liquid chromatography interface to a liquid secondary‐ion time‐of‐flight mass spectrometer

Abstract

NEOPENTANE IN CI MASS SPECTROMETRYthese aged filaments would have burned out soon after switching to even higher emission current settings. The total "on" times for the filaments were 34 h 55 min in the presence of isobutane and 65 h 40 min when neopentane was used, indicating a doubling of lifetime.Sustained operation of coiled tungsten filaments in the presence of either gas resulted in increased brittleness, requiring careful handling during source cleaning. There was usually less observable carbon deposition on the ceramics and block adjacent to the filament with neopentane than with isobutane.In summary, replacing isobutane with neopentane as a chemical ionization reagent gas increases the lifetime of tungsten filaments significantly without compromising the quality of mass spectra and without significant additional cost. The possibilities for using the time-of-flight analyzer as a liquid chromatography detector are evaluated using a continuous flow probe and keV ion bombardment on a specially designed time-of-flight instrument.We recently the design and performance of a liquid secondary-ion time-of-flight mass spectrometer (liquid-SIMS TQF) for the analysis of large and/or thermally labile samples. The instrument incorporated the two-stage ion extraction and "time-lag focusing" design of Wiley and McLaren3 for simultaneous time, spatial and energy focusing. In this case, however, low voltage pulsed-ion extraction from a grounded ion source was employed, to be compatible with the introduction of a liquid sample matrix, to provide maximum spatial focusing for secondary ions desorbed from an irregular surface, and to permit the use of broad (1-10 ps), high flux (1-15 pA/cm2) primary ion pulses. Additionally, this configuration permitted the recording of analog signals during each time-of-flight cycle, so that complete mass spectra are obtained in several seconds by averaging the signal from several cycles at high repetition rate. Thus, this configuration was developed as a ~iiore appropriate analyzer for liquid SIMS than the constant field, high voltage extraction configurations employed in plasma desorption mass spectrometry (PDMS)4 and static SIMS' TQF instruments, where samples must be deposited as thin layers on an ' Author to whom correspondence should be addressed. equipotential surface and mass spectra are obtained through the accumulation of many time-interval measurements.6Holland et aL7 have noted that TQF mass spectrometry combined with gas chromatography may ultimately provide a method for GUMS analysis with very high sensitivity and low chromatographic distortion. Their approach, known as "time array" detection, relies upon the recording of analog data at very high repetition rate. In addition to high speed and high ion transmission, TOF mass analyzers are capable of recording ions over a wide mass range. Thus, it would appear that such analyzers would also be ideal for use as detectors for high performance liquid chromatography, employing soft ionization interfaces to permit the recording of mole...

Determination of bioactive peptides using capillary zone electrophoresis/mass spectrometry

“…(32), provides a powerful desorption/ionization source for the mass spectrometric analysis of polar, nonvolatile, and/or thermally labile analytes and has become the method of choice for the MS analysis of biopolymers. The coupling of FAB/MS with flowing liquid streams, developed by Ito et al as Frit-FAB/MS (33) and Caprioli et al as continuous-flow FAB/MS (34) has provided a potent interface for coupling LC with MS (2,5,10,11,(35)(36)(37)(38)(39)(40)(41)(42)(43).…”

Time-of-Flight Mass Spectrometry

“…The most promising approach to date, is that of Enke and his co-workers at Michigan State University (36) and will be discussed in detail later in this book. The coupling of a liquid chromatographic column via a continuous-flow interface to his liquid-SIMS/TOFMS system has been described by Cotter (37). An off-line sampling approach has been utilised by the Standing group in Manitoba (38).…”

Liquid chromatography/time-of-flight mass spectrometry with high-speed integrated transient recording

“…While the 100-MHz recording rate does not generally result in limitations on the mass resolution, the commercially available instruments are generally limited in repetition rate and downloading time. The 3500 SA signal averaging recorder and the 9400 digital oscilloscope manufactured by LeCroy (Spring Valley, NY) are 100-MHz 8-bit transient recorders that can digitize 8k 10-ns points in a single 80-µß transient and have both been used with our more recent instruments (23)(24)(25)(26). They are also integrating transient recorders that are capable of integrating up to 50 transients/s.…”