A time-of-flight mass spectrometer has been developed using a reflectron in which the voltages placed on the lens elements correspond to a function describing the arc of a circle. This curved-field reflectron enables acquisition of focused product-ion mass spectra at a single reflectron voltage. In this paper, we present results from this instrument for the amino acid sequencing of several peptides and describe the method of mass calibration.

It is possible to trap and mass-analyze ions that have been laser desorbed from a probe within the Ion storage volume of a quadrupole ion storage mass spectrometer. A Finnigan ion trap detector was modified to enable a C02 laser pulse to strike a probe tip that passed radially through the ring electrode. Molecular and fragment ions from a variety of organic and biochemical compounds have been obtained. These Ions are typical of C02 laser desorption (LD) processes, while the instrument Itself retains tuning characteristics typical of the original electron Impact (El) Ionization performance. Because the El filament assembly was left Intact, it has been possible to operate In LD/EI mode and produce additional fragment ions.

The design and performance of a new time-of-flight mass spectrometer is reported. The instrument combines the advantages of a pulsed drawout TOF analyzer with a liquid secondary ion source. Differences from commercially available pulsed TOF analyzers (Wiley/McLaren type) are discussed with regard to operation with ion desorption from a liquid matrix.

High-performance liquid chromatography (HPLC) has been interfaced to a time-of-flight mass spectrometer. The interface is a continuous flow probe and ions are desorbed from the liquid matrix by energetic ion bombardment. Pulsed and delayed ion extraction from the source permits the use of broad ionization times, results in the production of analog signals in each time-of-flight cycle, and provides both energy and spatial focusing. A high-speed integrated transient recording system has been developed and is also reported. This instrument is the prototype for development of a high-speed, high-mass range LC detector with high duty cycle. Its performance is demonstrated for the separation of several mixtures of small peptides.

Conversion of Wiley-McLaren type TOF instruments for laser desorption is described, including laser optics, timing circuitry, postacceleration detection for high mass and data acquisition. Results are shown to illustrate signal averaging capabilties, detection limits and high mass measurements. 93 Copyright© 1987 bv Marcel rvn-er i--Downloaded by [Nanyang Technological University] at 19:48 07 June 2016 94 OLTHOFF ET AL.