Mass spectrometry enhancement via small spots

A Microplotter was used to enhance the sensitivity of matrix-assisted laser desorption / ionization (MALDI) mass spectrometry. MALDI mass spectrometry is a technique used to analyze the molecular weights of unknown chemicals or biomolecules, even when the molecules of interest weigh more than 10 kDa (10,000 molecular weight). To do this, analyte and matrix are deposited onto a metal plate, called a target, and a pulsed laser beam is directed at the matrix. This ejects both the matrix and analyte from the surface and ionizes the analyte material. A spectrometer reads the mass to charge ratio of the ejected molecules, which allows researchers to identify the composition of the analyte.

A Microplotter was used to dispense spots with diameters ranging from 20 to 70 microns of both analyte and matrix. It was observed that the smaller the spot size, the sharper the resulting peaks in the mass spectrometer readout. Sharper peaks can lead to better identification of proteins with similar molecular weights, as one example.