Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS)

Purpose
Determination of the molecular weight of oligosaccharides, glycopeptides, glycoproteins, and other glycoconjugates.

Amount of Sample Required for Analysis
If the sample is a singly purified glycoprotein, we need a minimum of 500 pmol of material to produce a clear result, more if the sample is a crude protein.

General Criteria for Sample Preparation
Your sample should be pure, soluble in water or volatile organics, and free of non-volatile salts, buffers, and detergents. MALDI-MS can be performed on samples up to about 150 kDa. MALDI is a soft ionization method in which a sample solution (protein, peptide, and carbohydrate) is mixed with a matrix solution, applied to the sample plate, and dried. The matrix, usually an aromatic carboxylic acid, is used to protect the sample from decomposition by the strong laser beam and also to help vaporization and ionization. Once the sample is ionized, the ions are introduced into the mass spectrometer and the masses of the ions are determined by measuring the time it takes them to reach the detector.