This standard specifies the determination method of gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry/mass spectrometry for multi-residues of chloramphenicols in animal-original food.
This standard is applicable to qualitative confirmation and quantitative determination of chloramphenicol, florfenicol and thiamphenicol residues in aquatic products, livestock and poultry products and byproducts.
2 Gas Chromatography-Mass Spectrography
2.1 Principle
Extract the sample with ethyl acetate, distribute and purify 4% sodium chloride solution and N-hexane solution-solution, purify through Florisil, and then take methylbenzene as reaction medium, use N, O BSTFA-TMCS (BSTFA+TMCS, 99+1) to silanize at 70℃, determine with gas chromatography/negative chemical ionization source mass spectrometry, and then quantify through internal standard working curve method.
2.2 Reagents and materials
Unless otherwise specified, only confirmed analytical reagent and secondary deionizer water or water with equivalent purity may be used in analysis.
2.2.1 Methanol: chromatographic pure.
2.2.2 Methylbenzene: pesticide residue.
2.2.3 N-hexane: pesticide residue.
2.2.4 Ethyl acetate.
2.2.5 Ethyl ether.
2.2.6 Sodium chloride.
2.2.7 Standard chloramphenicol (CAP), florfenicol (FF) and thiamphenicol (TAP): purity≥99%.
2.2.8 Standard m-chloramphenicol (m-CAP): purity≥99%.
2.2.9 Sodium chloride solution (4%): weight a right amount of sodium chloride to prepare 4% sodium chloride solution with water, store at ambient temperature, and use for 1 week.
2.2.10 Stock standard solution of chloramphenicols: accurately weigh a right amount of standard chloramphenicol, florfenicol and thiamphenicol (with the accuracy of 0.1mg), and prepare with methanol into stock standard solution with a concentration of 100μg/mL.
2.2.11 Internal standard working solution of m-CAP: accurately weigh a right amount of standard m-CAP (with the accuracy of 0.1mg), and prepare with methanol into 10ng/mL standard working solution.
2.2.12 Standard working solution of chloramphenicol substrate: select six portions of samples not containing chloramphenicols, respectively add 1mL internal standard working solution (2.2.11), use these six portions of extracting solutions to respectively prepare the solutions that the concentrations of chloramphenicol, florfenicol and thiamphenicol are 0.1ng/mL, 0.2ng/mL, 1ng/mL, 2ng/mL, 4ng/mL and 8ng/mL, extract according to this method (2.4.1) and purify (2.4.2), prepare into sample extracting solution, slowly dry with nitrogen, silanize, and then prepare into standard working solution.
2.2.13 Derivatization reagent: N, O BSTFA-TMCS (BSTFA+TMCS, 99+1).
2.2.14 Solid-phase extraction column: Florisil column (6.0mL, 1.0g).
2.3 Instruments and equipment
2.3.1 Gas chromatography/mass spectrometry chromatograph: equipped with chemical ionization source (CI).
2.3.2 Tissue blender.
2.3.3 Solid-phase extraction device.
2.3.4 Oscillator.
2.3.5 Rotary evaporator.
2.3.6 Vortex mixer.
2.3.7 Centrifuge.
2.3.8 Thermotank.
2.4 Determination procedures
2.4.1 Extraction
GB/T 22338-2008 The following standards are cited：
