Accurate Mass Measurement Mass Spectrometry

With the development of high-resolution mass spectrometry (HMS) and its instruments, the qualitative and quantitative analysis of compound quality determination has received more and more attention and been widely used by researchers. Accurate quality determination is an important biochemical method for the qualitative and quantitative analysis of drugs. The accurate mass measurement method can determine the accurate quality of a compound ion, perform qualitative and quantitative analyses of protein composition, perform quantitative analyses of amino acid structure, examine the composition of metal compounds, and can also be used for the qualitative detection of the majority of small molecule drugs. It is speculated that the composition of small molecule compounds, the formula for determination of compound saturation, and the identification of compound isomers.

Accurate quality determination is a powerful means to solve the difficulty of conventional GC-MS qualitative analysis. The difference between the accurate mass of a molecule ion and the accurate mass of a 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

Matrix-assisted laser desorption/ionization mass spectrometry

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 spectrometry.

FT-ICR MS

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 find out things like the molecular weight, the type of fine isotope peak, the fragments of a multistage mass spectrometer, 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 the 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), and sustained off-resonance irradiation collision-induced dissociation (SORI CID), dissociative debris such as function can be selected according to the sample cracking method. Then you can get the most comprehensive structural information.

(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, which can be quickly and accurately used to obtain a series of quasi-molecular ion peaks of the surfactant and its associated ion peak, adjust the signal by adding salt ions, the signal has no effect on the next sample, and play the advantages of being pollution-free and 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 quickly derived 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.