Patent ID: 9508540
Filing Date: 2016-11-29
CPC Classification: H01J

Claim Text:
1. A method of generating ions from a plurality of sample target regions on a MALDI sample plate in a mass spectrometer using a pulsed laser, each sample target region comprising matrix, the method comprising the steps of (1) designating and rastering a plurality of sample raster sites on the MALDI sample plate, wherein each of the sample raster sites corresponds to one of the sample target regions and has a single set of sample target coordinates, and the plurality of sample raster sites are designated and rastered in a non-random manner such that the sample target regions are arranged consecutively along the sample plate in rows, (2) dithering at each of said plurality of sample raster sites so as to generate ions from a plurality of discrete dither locations associated with each sample raster site, wherein each said plurality of discrete dither locations comprises discrete dither locations that are selected automatically with reference to the sample target coordinates of the associated sample raster site, each discrete dither location of each plurality of discrete dither locations corresponds to at least one distinct shot of the pulsed laser, and each discrete dither location of said plurality of discrete dither locations is selected randomly with reference to the sample target coordinates of the associated sample raster site, and (3) detecting at least some of the generated ions, obtaining mass data about the ions generated at each of the randomly selected plurality of dither locations, and processing the mass data to produce composition data relating to the composition of the sample at each of the plurality of sample raster sites, whereby said dithering reduces or eliminates the adverse effects on the mass data associated with defects in the matrix of the sample target region.