1. Â Â Â INTRODUCTION OF MALDI-TOF-TOF MS/MS
Matrix-assisted laser desorption/ionization (MALDI) is one of soft ionization technique in mass spectrometry, allowing analysis of molecular weight for biomolecules (DNA, proteins, peptides and sugars) small (natural product and synthetic compound with molecular weight less than 1,000 Da) as well as large organic molecules (polymers, dendrimers, macro and supramolecules with molecular weight more than 1,000 Da). In MALDI, sample is firstly co-crystallized with a matrix compound on the top of conductive plate. When the UV laser interacts with this crystallized sample in matrix, it results in the vaporization of the matrix which carries sample with it. The resulting ionized matrix molecules will flight and then travel to the detector with different time (time of flight; TOF), depending on their mass. Therefore, the system is called as MALDI-TOF MS measurement.
In MALDI-TOF-MS measurement, analysis of samples must be characterized based on their molecular weights and monoisotope patterns. The successful measurement is depending of concentration of sample-matrix, crystallation, measurement mode (reflector or linear mode) and laser intensity. Morever, advance analysis of resulting molecular weight can be deeply characterized by fragmentation of suspected monoisotope patterns to do one more MS by applying high energy collision-induced dissociation (CID). Therefore, the system is MALDI-TOF-TOF MS/MS for determination of molecular weight including the monoisotope pattern in high resolution. Our MALDI TOF/TOF MS/MS is AB SCIEX TOF/TOFTM 5800 system with high resolution and accuracy.
2. Â Â APPLICATIONS
Biochemistry
MALDI TOF/TOF MS is used for rapid identification of proteins isolated by using gel electrophoresis: SDS-PAGE, size exclusion chromatography, affinity chromatography, strong/weak ion exchange, isotope coded protein labelling (ICPL),and two-dimensional gel electrophoresis. MALDI TOF/TOF MS is used to reveal amino acid sequence of peptides using post-source decay or high energy collision-induced dissociation.
Organic Chemistry
MALDI TOF/TOF MS is used for determination of molecular weight extending into the thousands or tens of thousands of some synthetic macro and supramolecules such as catenanes and rotaxanes, dendrimers and hyperbranched polymers. MALDI TOF/TOF MS can be also used for low molecular weight of organic compounds such as synthesized from carbon-carbon couplings and isolated from natural products.
Polymer Chemistry
MALDI TOF/TOF MS is used for determination of the molar mass distribution and repeating unit (monomer) of homopolymer or copolymerby using additional software.
Microbiology
MALDI TOF/TOF MS is used for identification of microorganisms such as bacteria or fungi. A colony of the microbe in question is smeared directly on the sample target and overlayed with matrix. The mass spectra generated are analyzed by dedicated software and compared with stored profiles. Species diagnosis by this procedure is much faster, more accurate and cheaper than other procedures based on immunological or biochemical tests. MALDI/TOF may become the standard method for species identification in medical microbiological laboratories over the next few years.
3. Â Â MALDI TOF/TOF MS/MS AB SCIEX TOF/TOFTM 5800 system
Sample plate loading
AB SCIEX TOF/TOFTM 5800 system