With the development of high-resolution mass spectrometry (HMS) and its instruments, the qualitative and quantitative analysis of compound quality determination has been paid more and more attention and widely used by researchers. Accurate quality determination is an important biochemical method for qualitative and quantitative analysis of drugs. Accurate mass measurement method can determine the accurate quality compound ion, qualitative quantitative analysis of protein composition, quantitative analysis of amino acid structure, examine the composition of metal compounds, and It can also be used for the qualitative detection of the majority of small molecule drugs, speculated that small molecular compound composition, the formula for determination of compound not saturation, identify compounds isomers.
Accurate quality determination is a powerful means to solve the difficulty of conventional GC-MS qualitative analysis. The difference of the accurate mass of molecule ion and the difference of the accurate mass of fragment ion can be used to determine the accurate quality. Accurate quality measurement can reduce the scope of mass spectrometry retrieval, make the retrieval targeted and improve the analysis efficiency. At the same time, some qualitative errors are avoided and the analysis results are more accurate and reliable.
Various Forms of MS instrument
- Electrospray ionization mass spectrometry
a. Reflector time-of-flight (TOF)
b. Tandem TOF
c. Triple quadrupole or linear ion trap
- Matrix-assisted laser desorption / ionization mass spectrometry
d. Quadrupole time-of-light
e. Ion trap
f. Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS)
Different types of accurate mass determination mass spectrometers
The quality identification method associated with high resolution mass spectrometry is mass spectrometry based on Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer.
FT-ICR MS is a mass spectrometer that measures the ion charge ratio according to the cyclotron frequency in a given magnetic field. It can accurately determine the molecular weight, fine isotope peak type, multistage mass spectrometer fragments, and so on.
(1) The working principle of FT-ICR MS
Firstly, the signal generated in a high magnetic field by the movement of a charged particle in a cyclotron resonance motion caused by the induction current changing with time was detected. Then, the Fourier transform of the signal was converted into the frequency of cyclotron motion of a charged particle. Finally, the ratio of mass-charge charged particles was obtained.
(2) Multi-heavy ion fragment function
In source dissociation, Collision induced dissociation (CID), Electron capture dissociation (ECD), Sustained Off-Resonance Irradiation Collision induced dissociation (SORI CID) dissociative debris such as function, can select the most appropriate according to the sample cracking method. Then you can get the most comprehensive structure information.
Composition of FT-ICR MS
(3) Application fields of FT-ICR MS
(4) Case analysis
Fatty alcohol polyoxyethylene ether to conventional analysis methods (HPLC, HPLC/ESI - MS) there is a long time, to analysis the instrument, sample residue pollution serious shortcomings, such as using MALDI/FT - ICR - MS can be quickly and accurately obtain a series of quasi molecular ion peaks of the surfactant and its associated with ion peak, adjust the signal by adding salt ions, the signal has no effect on the next sample, play the advantages of its pollution-free, resistant to salt. The distribution of the component elements, the length of the alkyl chain and the polymerization degree of ethylene oxide in the surfactant can be derived quickly from the relevant information.
A health product company commissioned the detection and analysis of the chemical components of a Chinese medicine. Ft-icr MS was used to detect and analyze the extract of this traditional Chinese medicine, and the obtained excimer ion peak and secondary mass spectrometry fragment information were compared with the information reported in the literature, and 42 compounds were identified.
1. Hongmei Ai. Application of two quality standards in quality management of biochemical detection. International Journal of Laboratory Medicine, 2014, 35 (10) 1329-1330.