Abstract: An apparatus and method is disclosed for reducing contamination in a mass spectrometer instrument system. The system includes an ion source at a first pressure for generating ions by laser desorption/ionization and an inlet aperture to a vacuum chamber at a second, lower pressure than the first pressure of the ion source. A sample plate within the ion source supports a sample deposited thereon and a laser can be configured to generate laser pulses striking at least a portion of the sample at an angle of incidence from about 0 to about 80 degrees to the center line of a first ion optical axis of a mass analyzer, producing a plume. A combination of the angle of incidence of the laser pulses and the distance between the sample plate and the inlet region aperture can reduce neutral contaminants in the plume from being drawn into the inlet aperture.

Abstract: An apparatus and method is disclosed for reducing contamination in a mass spectrometer instrument system. The system includes an ion source at a first pressure for generating ions by laser desorption/ionization and an inlet aperture to a vacuum chamber at a second, lower pressure than the first pressure of the ion source. A sample plate within the ion source supports a sample deposited thereon and a laser can be configured to generate laser pulses striking at least a portion of the sample at an angle of incidence from about 0 to about 80 degrees to the center line of a first ion optical axis of a mass analyzer, producing a plume. A combination of the angle of incidence of the laser pulses and the distance between the sample plate and the inlet region aperture can reduce neutral contaminants in the plume from being drawn into the inlet aperture.

Abstract: A method of collecting cells from a specimen and plating such cells onto a slide to create a monolayer. A suspension of cells is filtered to remove unwanted material and monitored to determine if a desired quantity of cells are collected. If insufficient cells are present in the filtered sample, additional suspensions of cells are serially added to the sample and filtered until a desired quantity of cells have been obtained. Devices for collecting samples of cells, for isolating a quantity of cells, and for microscopic examination of a monolayer of cells are also disclosed.