Week 2 was spent reading up on MALDI-TOF mass spectrometry. MALDI-TOF stands for matrix-assisted laser desorption/ionization time-of-flight, which actually pretty much spells out how it works.
When performing mass spec using MALDI, your analyte is first mixed with matrix solution on a metal plate before being loaded into a vacuum chamber. Here, the matrix solution crystallizes along with the analyte and is hit with pulses from a nitrogen laser. The purpose of the matrix solution is to absorb energy from these pulses, thereby transferring it to the analyte and causing its desorption. This releases a plume of ions which can then travel through an electrostatic mirror and to a detector (ergo, “matrix-assisted laser desorption/ionization”.)
This is where the time-of-flight bit comes in to play, as the ionized analyte flies through the mirror and on to the detector based on good ole KE=(1/2)mv^2. In the case of my research, the analyte will be digested collagen: small peptide chains whose lengths differ based on the animal source. Depending on the size of the peptides and their ionization, they will hit the detector at different times and the mass spectrometer will spit out a spectra. This spectra, which is described by intensity and mass-to-charge ration (m/z), can be compared to an online database for identification!
We were also able to make contact with the lab at UW-Oshkosh this week, and we’ll continue communicating there about using their MALDI later on. Week 3, now, will be all about reading some papers by Buckley et al which further describe peptide mass fingerprinting.