AUTOMATION OF MATRIX-ASSISTED LASER DESORPTION IONIZATION MASS-SPECTROMETRY USING FUZZY-LOGIC FEEDBACK-CONTROL/

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is a sensitive and versatile method for biomolecular analysis which ha s potential for high-throughput screening in many applications. To obt ain mass spectra of optimal quality, however, laser fluence is continu ously adjusted during data acquisition to be close to the threshold le vel of ion production, requiring a skilled operator and several minute s of acquisition time per sample, Using real-time fuzzy logic control of the laser fluence, we here demonstrate that the acquisition of MALD I spectra can be automated without reduction of data quality, The cont rol algorithm evaluates signal intensity and mass resolution of the ba se peak, Tit then regulates the laser fluence to keep the ion signal i ntensity within the dynamic range of the data acquisition hardware whi le maintaining high mass resolution. This fuzzy logic control system a llows unattended data acquisition using either static ion extraction o r delayed ion extraction MALDI. Even for difficult samples such as fem tomole-level peptide mixtures, no significant reduction in data qualit y is observed, as compared to manually obtainer: spectra, Automated an alysis of 78 chromatographic fractions with high mass accuracy demonst rates the utility of the method, The control algorithm has been combin ed with other software modules to completely automate database identif ication of proteins by their peptide mass maps. The success of fuzzy l ogic in MALDI automation suggests wider uses of this technique in mass spectrometry.