Mass Spectrometry

MALDI-MS is run in either linear or reflectron modes, with positive or negative ionization. Common uses/compound analyses are listed below. In Reflection mode, the monoisotopic masses are measured using 0.25-500 fmol of 750-4,000 Da peptides with an average mass accuracy (internal calibration on 1 fmol of bradykinin) of <50 ppm (parts per million). At masses >4,000 Da the instrument is run in linear mode and average masses are measured.

• Suitable for intact protein mass analysis up to 250K (mass resolution expected to be ±250 ppm)
• Analysis of DIGE protein spot digests with a sensitivity of ∼250 attomol routinely
• Comparative MALDI-MS mapping of control versus experimental digests
• MS and MS/MS analysis of beta peptides
• A variety of biomolecules can be analyzed including oligosaccharides, and gangliosides
• Best suited for simple protein mixtures of 1-3 proteins. More complex mixtures are analyzed by LC-MS/MS using either a single or MudPIT run.

Sample Preparation: Protein/peptide solutions in 10 μM volatile buffers can sometimes be analyzed directly while samples with higher salt concentrations require prior C18 or C4 ZipTip desalting