Abstract: A laser desorption ion source provides enhanced ion sampling efficiency and measurement sensitivity by using one or more ion guides to effectively capture ions in a plume emitted from the ion target and guide the ions through an aperture into a downstream vacuum chamber. In one configuration using two RF multipole ion guides, a first RF multipole ion guide disposed next to the ion target is selected to be sufficiently large to capture a substantial portion of the plume, while the second RF multipole ion guide disposed between the first multipole ion guide and the aperture has a smaller dimension to assist focusing of ions into the aperture. The first RF multipole ion guides the ions in the plume into the second RF multipole ion guide, which then focuses the ions so that they pass through the aperture into the downstream vacuum chamber.

Abstract: A mass spectrometry quantitation technique enables high-throughput quantitation of small molecules using a laser-desorption (e.g., MALDI) ion source coupled to a triple-quadrupole mass analyzer. The ions generated from the ion source are collisionally damped/cooled, and then quantitatively analyzed using the triple-quadrupole analyzer operated in the multiple-reaction-monitoring (MRM) mode. Significantly improved measurement throughput is obtained by applying the laser to each sample spot on the target for an irradiation duration significantly shorter than the time required to deplete the sample material in the sample spot. The irradiation duration may be set based on a determination of the MRM peak broadening caused by the ion optics.

Abstract: A laser desorption ion source provides enhanced ion sampling efficiency and measurement sensitivity by using one or more ion guides to effectively capture ions in a plume emitted from the ion target and guide the ions through an aperture into a downstream vacuum chamber. In one configuration using two RF multipole ion guides, a first RF multipole ion guide disposed next to the ion target is selected to be sufficiently large to capture a substantial portion of the plume, while the second RF multipole ion guide disposed between the first multipole ion guide and the aperture has a smaller dimension to assist focusing of ions into the aperture. The first RF multipole ion guides the ions in the plume into the second RF multipole ion guide, which then focuses the ions so that they pass through the aperture into the downstream vacuum chamber.

Abstract: A mass spectrometry quantitation technique enables high-throughput quantitation of small molecules using a laser-desorption (e.g., MALDI) ion source coupled to a triple-quadrupole mass analyzer. The ions generated from the ion source are collisionally damped/cooled, and then quantitatively analyzed using the triple-quadrupole analyzer operated in the multiple-reaction-monitoring (MRM) mode. Significantly improved measurement throughput is obtained by applying the laser to each sample spot on the target for an irradiation duration significantly shorter than the time required to deplete the sample material in the sample spot. The irradiation duration may be set based on a determination of the MRM peak broadening caused by the ion optics.