Anal. Chem. 2000, 72, 5881-5885
Internal Calibration on Adjacent Samples (InCAS) with Fourier Transform Mass Spectrometry Peter B. O’Connor* and Catherine E. Costello
Mass Spectrometry Resource, Department of Biochemistry, Boston University School of Medicine, 715 Albany Street, R806 Boston, Massachusetts 02118
Using matrix-assisted laser desorption/ionization (MALDI) on a trapped ion mass spectrometer such as a Fourier transform mass spectrometer (FTMS) allows accumulation of ions in the cell from multiple laser shots prior to detection. If ions from separate MALDI samples are accumulated simultaneously in the cell, ions from one sample can be used to calibrate ions from the other sample. Since the ions are detected simultaneously in the cell, this is, in effect, internal calibration, but there are no selective desorption effects in the MALDI source. This method of internal calibration with adjacent samples is demonstrated here on cesium iodide clusters, peptides, oligosaccharides, poly(propylene glycol), and fullerenes and provides typical FTMS internal calibration mass accuracy of
