A MALDI source is interfaced to a modified LTQ Orbitrap XL instrument. This work gives insight into the MALDI source design
and shows results obtained with the MALDI source coupled to an accurate mass, high-resolution hybrid mass spectrometer. MALDI-produced
ions and fragment ions thereof produced in the mass spectrometer may be analyzed and detected by the Orbitrap analyzer at
a maximum mass resolution of 100,000 (FWHM) at m/z 400 with high mass accuracy. An accuracy of ≤2 ppm is achieved by internal mass calibration using lock mass functionality;
using external mass calibration, an accuracy of ≤3 ppm is routinely obtained. External mass calibration of the hybrid mass
spectrometer is performed using a standard calibration mixture of different peptides and matrix components. The instrumental
capabilities are demonstrated for analytical methodologies such as Protein ID using Peptide Mass Fingerprint (PMF) and MS/MS
analyses of small molecule samples. Stability of mass accuracy and signal-to-noise ratio for low samples loads (on plates)
are demonstrated as well as the experimental dynamic range using α-cyano-4-hydroxy cinnamic acid (CHCA) matrix.
These two authors contributed equally to this work.
Published online May 3, 2009