As mentioned above, the TOF mass analyzer works well with the MALDI ion source because both of them operate in the pulsed mode. A great advantage of MALDI-TOF MS is that the soft ionization process causes little or no fragmentation of analytes, allowing the intact biomolecules to be identified; this property is especially important for analysis of mixtures. In addition, MALDI-TOF MS analysis is sensitive, being able to detect molecules at the low femtomole level and even below. A spectrum that is the sum of many laser shots can be generated within seconds from each of the hundreds of spots where a mixture of sample and matrix have been dried on the MALDI target. Hence, the majority of high throughput proteomics, genomics, and glycomics analyses are carried out by MALDI-TOF MS. MALDI-TOF/TOF MS instruments also provide fragment ion information that can provide sequence information for biopolymers.
Recently, simple yet high-performance ESI-TOF MS systems that have mass accuracy below 10 ppm have become commercially available. Although they do not have MS/MS capability, these are very useful for accurate mass determination of single analytes and mixture profiling.
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