RESUMEN

A new MALDI probe has been designed that uses transmission geometry. This geometry allows the probe to be fashioned after typical EI/CI solid probes which enables it to be introduced into spatially constrained ion source regions such as encountered in quadrupole ion trap mass spectrometers. In the probe design demonstrated here, light from a fiber optic irradiates the backside of a sample through a small piece of quartz on which the sample has been directly deposited. The performance characteristics exhibited by utilizing this probe for MALDI on a quadrupole ion trap mass spectrometer are similar to those which can be obtained through the traditional methods of implementing MALDI. Spectra have been obtained from 50 fmol of total loading of bombesin, MS/MS has been performed on 5 pmol of des-Arg9-bradykinin, and the analyte ion signal is shown to last for over 2500 laser shots for 2 pmol of bombesin. Optical micrographs showing the crystal distribution of a sample containing 2 pmol of bombesin have been obtained as a function of the number of laser shots for a single sample loading. Although this probe was designed for use with the quadrupole ion trap, it can be adapted for use with all types of mass spectrometers. Thus, with only one laser, one fiber optic, and this probe, MALDI can be performed on multiple instruments in a lab.

Asunto(s)

Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/instrumentación , Bombesina/análisis , Bradiquinina/análogos & derivados , Bradiquinina/análisis , Técnicas de Sonda Molecular

RESUMEN

A method to help facilitate efficient implementation of pulsed ionization methods on a double-focusing sector mass spectrometer is described here. This method involves the addition of an inductive detector between the electric and magnetic sectors. The inductive detector will allow a crude, but complete time-of-flight mass spectrum to be acquired with as little as a single laser shot, thereby avoiding the necessity of sequentially compiling limited mass ranges as has been done previously. Mass analysis by the complete sector instrument can be performed simultaneously with the time-of-flight analysis.