Mass spectrometry is an analytical technique that is used to identify the mass of molecules or ions based on their mass to charge ratio. It has applications in several fields including chemistry, biology and medicine. Among the various types of mass spectrometers, quadrupole time-of-flight (Q-TOF) mass spectrometer has emerged as a powerful high resolution mass analyzer in recent years. This article aims to discuss the components, working principle and major applications of Q-TOF mass spectrometer.
Components of Q-TOF Mass Spectrometer
A Q-TOF mass spectrometer consists of the following major components:
Ion Source: The ion source is used to convert analyte molecules into gaseous ions. Common ionization techniques used are electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). ESI is useful for polar, thermally labile molecules dissolved in liquid solvents while MALDI is used for large biomolecules.
Quadrupole mass filter: It consists of four parallel metal rods that allows only ions of a certain m/z value to pass through, while destabilizing all other ions. Ions are filtered based on their stability in an oscillating electric field produced by the rods.
Time-of-flight mass analyzer: It is used to separately detect ions based on their time-of-flight. Ions entering the TOF get accelerated with same kinetic energy. But their velocity depends on m/z ratio, with lighter ions reaching the detector faster than heavier ones.
Detector: It detects the ions reaching the end of the flight tube and generates current pulses corresponding to each ion. Commonly used detectors include microchannel plates and multichannel plates.
Working Principle of Q-TOF mass spectrometer
The working involves:
1) Ionization of analyte using ESI or MALDI
2) Pulse extraction of ions from ion source into quadrupole mass filter
3) Mass selection by quadrupole that allows only specific m/z ions to pass
4) Acceleration of ions into the flight tube using electric pulse
5) Separation of ions based on m/z as they travel towards detector
6) Detection and recording of flight times that are inversely related to m/z
7) Generation of mass spectrum using the time-tagged data
Major Applications of Q-TOF Mass Spectrometry
Proteomics and Protein Analysis: Q-TOF MS enables identification and characterization of proteins from complex biological mixtures like plasma, cells or tissues in bottom-up and top-down proteomics studies.
Metabolomics and metabolite profiling: It is useful to profile small molecule metabolites, discover biomarkers and understand metabolism in cells/biofluids using untargeted and targeted metabolomics approaches.
Structural characterization: Q-TOF MS provides accurate mass measurement and structural information through MS/MS fragment analysis for identification of novel compounds, drug metabolites, post translational modifications etc.
Food analysis: Applications include authentication of food products, detection of adulterants, allergens, toxins, pesticide and veterinary drug residues in food.
Environmental analysis: It is employed to monitor environmental pollutants, identify degradation products of chemicals, study fate and transport of contaminants in ecosystems.
Forensics: Q-TOF MS finds use in forensic drug analysis, toxicological screenings, firearms residue analysis, identification of unknown substances and materials in criminal cases.
Conclusion
In summary, Q-TOF mass spectrometer combines the qualities of quadrupole for robust analysis with excellent mass accuracy and resolution of time-of-flight for complex mixture analysis. It has transformed biomedical research areas like proteomics and metabolomics owing to its high sensitivity, speed and specificity. With continued technical innovations, Q-TOF MS promises to play a pivotal role in pharmaceutical, clinical, food, environmental and forensic applications in future.
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- Source: Coherent Market Insights, Public sources, Desk research
- We have leveraged AI tools to mine information and compile it
