Laser-induced fluorescence/ion trap as a detector for mass spectrometric analysis of nanoparticles

A novel detector is developed for ion trap mass spectrometry of nanoparticles. The detector, composed of a laser, a photomultiplier, and a quadrupole ion trap, is designed specifically for probing nanoparticles that are intrinsically fluorescent or extrinsically labeled with dye molecules. Using this detector, we have been able to obtain the mass spectra of fluorescein-labeled polystyrene spheres of 27 and 110 nm in diameter with a home-built quadrupole ion trap mass spectrometer operating in the mass-selective instability and frequency scan modes. it represents advancement in mass spectrometric analysis of nanoparticles with m/z (mass/charge) beyond 10(6). In this article we describe in detail the characterization of the laser-induced fluorescence/ion trap as a nanoparticle detector. Important parameters such as q(z) and particle damping/dumping times are analyzed both experimentally and theoretically. The utility of this new ion detection method in mass spectrometric analysis of biological particles is discussed. (C) 2003 Elsevier B.V. All rights reserved.