We currently have three mass spectrometers, a Micromass LR MALDI-TOF, an ABI 4000 QTRAP, Thermo LTQ and an ABI QSTAR XL. The QSTAR is equipped with both MALDI and ESI sources and has the ability to acquire both MS and MS/MS data. Molecular weight information is obtained in MS mode, while MS/MS provides sequence information. We offer services for peptide sequence identification, post-translational modification site analysis, quantification using iTRAQ and AQUA peptides, and accurate mass measurement of proteins, peptides and oligonucleotides. 

MALDI stands for Matrix Assisted Laser Desorption/Ionization. Analyte is mixed with a matrix and dried onto a plate. Matrix and analyte desorb together when a laser hits the sample and a portion of the analyte is eventually charged. Singly charged ions are dominant.

ESI stands for Electrospray Ionization. In the electric field, sample solution sprayed out a needle forms droplets with excess charges. Analyte is charged as solvent within the droplet evaporates. Multiply charged ions are dominant, especially for macro-biomolecules.

The choice between MALDI-MS or ESI-MS depends on the nature of the analyte and the type of data required. Useful information can be found in the Sample Preparation Notes. We are also happy to discuss your experimental design at any time.

Please fill out the Mass Spectrometry Request Form and bring it with the sample.