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7 Selection of analysis conditions
(1) Optimization of sample pretreatment method
The focus is on the comparison of trichloromethane extraction, silica gel column purification; Na 2 EDTA-Mcllvaine buffer solution extraction, Oasis HLB solid phase extraction column purification; acetonitrile extraction, alumina column purification and acetonitrile extraction and then using n-hexane to remove fat.
An extraction and purification system
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Experiments have found that when chloroform is used for extraction, more fat is extracted, and the recovery rate of sulfonamides is very low after passing through a silica gel column
Therefore, this method selects acetonitrile to extract, and then prepares the sample by using n-hexane to remove fat
(2) Optimization of mass spectrometry conditions
A syringe pump is used for direct sample injection, and each 5 uL/mL sulfonamide standard solution is injected into the ion source at 5 μL/min, and each sulfonamide is subjected to--stage mass spectrometry in the positive ion detection mode (Q1 scan) , To obtain the molecular ion peak of each sulfonamide, perform the secondary mass spectrum analysis (product ion scan) on the quasi-molecular ion peak of each sulfonamide to obtain fragment ion information, and then decluster the obtained secondary mass spectrum of each sulfonamide The voltage (DP), collision gas energy (CE), electrospray voltage, atomization gas and curtain gas pressure are optimized to maximize the ion pair intensity generated by the molecular ions of each sulfonamide and the characteristic fragment ions.
Select the qualitative ion pair and quantitative ion pair of each sulfonamide from Figure 2-2, connect the liquid chromatograph and tandem quadrupole mass spectrometer online, and then optimize the ion source temperature and auxiliary gas flow rate to make each type of sample liquid The ionization efficiency of sulfonamide is the best
Figure 2-2 The secondary mass spectra of 18 sulfonamides