Part I: Development of Mass Spectrometry and Its Application in Biological Research
As a commonly used technology in biological research today, mass spectrometry is becoming increasingly important in biological research by quickly and efficiently measuring the advantages of complex biological macromolecules and small molecules.
Mechanism of Mass Spectrometry
Mass spectrometry analysis is a method of analyzing a sample by measuring and analyzing the mass-to-charge ratio of the sample ions. The mass spectrometer is roughly divided into three parts, ion source, mass analyzer, and detector. The mass analyzer is the core component of the mass spectrometer, which determines the sensitivity, resolution, ability to generate ion fragments, and accuracy of the mass spectrometer. Before the sample is analyzed, it is first ionized in order to bring a certain charge to the sample molecule. Next, the charged ions will first driven through an accelerated electric field and fly into an analytical electric or magnetic field. Due to the difference in the mass of the sample itself and the ionization charge, the trajectories of the sample ions in the analysis electric field are also different, so that different ions can be distinguished by analyzing the trajectories of the ions. In addition, the qualitative and quantitative measurements of the information, purity and other characteristics of the sample can also be perform.
The History of Mass Spectrometry
The first mass spectrometer, invented by J. J. Thomson, has been around for more than 90 years. It was mainly used for the determination of inorganic elements in chemical experiments. With the development of mass spectrometry technology and computer technology, mass spectrometer has gradually been applied in the analysis of more complex biomolecules, including amino acid, protein, lipids, sugar and so on. Although the history of mass spectrometry and the time it has been applied to biological research are much shorter than those of microscopes, the importance of mass spectrometry in biological research is irreplaceable as an accurate means of analyzing biomolecules.
Types of Commonly Used Mass Spectrometers
The subjects of biological research are generally complex macromolecules, including proteins, nucleic acids, sugars, lipids, and various small molecules. The nature of various types of biomolecules also varies widely. Therefore, various types of mass spectrometers are used in biological research. The common used ones for biological research include quadrupole mass spectrometer, time of flight mass spectrometer, ion trap mass spectrometer and ion cyclotron resonance mass spectrometer.
Quadrupole Mass Spectrometer
The mass analyzer of the quadrupole mass spectrometer consists of four rod-shaped electrodes. An alternating field is applied between the two pairs of electrodes. The set frequency field allows only a certain mass of ions to pass through the quadrupole to the detector. A section of ions is rapidly analyzed. It is characterized by simple structure and fast scanning speed, but the resolution is relatively low.
Time of Flight Mass Spectrometer (TOF)
The mass-to-charge ratio of ions determined by this type of mass spectrometer is derived by analyzing the time of flight of the ions in the vacuum flight tube. After continuous improvement, the TOF mass spectrometer has greatly improved in resolution and precision. The accuracy can reach PPM level after the post-correction procedure, and the detected ion mass range can reach several hundred thousand.