IMPROVED DETECTION LIMITS FOR ELECTROSPRAY-IONIZATION ON A MAGNETIC-SECTOR MASS-SPECTROMETER BY USING AN ARRAY DETECTOR

Array detection was compared with point detection for solutions of hen egg-white lysozyme, equine myoglobin, and ubiquitin analyzed by electrospray ionization with a magnetic sector mass spectrometer. The detection limits for samples analyzed by using the array detector system were at least 10 times lower than could be achieved by using a point detector on the same mass spectrometer. The minimum detectable quantity of protein corresponded to a signal-to-background ratio of approximately 2:1 for a 500 amol/muL solution of hen egg-white lysozyme. However, the ultimate practical sample concentrations appeared to be in the 10-100 fmol/muL range for the analysis of dilute solutions of relatively pure proteins or simple mixtures.