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1 Scope of application
It is suitable for the determination of 16 sulfonamide residues in honey by liquid chromatography-tandem mass spectrometry
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Method detection limit: sulfamethizole is 1.
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2 Principle of the method
Sulfonamide residues in honey are extracted with phosphoric acid solution (pH=2), filtered, purified by cation exchange column and Oasis HLB or equivalent solid phase extraction column, eluted with methanol and evaporated to dryness, and the residue is acetonitrile +0.
1mol/ The L ammonium acetate dissolves
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The sample solution was measured by liquid chromatography-tandem mass spectrometer and quantified by external standard method
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3 Reagents and materials
Methanol, acetonitrile, sodium heptane sulfonate (C 7 H 15 SO 3 ·Na·H 2 O): chromatographically pure
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Phosphoric acid, ammonium acetate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate : pure superior grade
Phosphate buffer solution: 0.
2mol/L, pH=8
Sodium heptane sulfonate solution: 0.
5mol/L
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Weigh 11 g of sodium heptane sulfonate, dissolve in water, and dilute to 100 mL
Sulfaacetamide, Sulfamethoxazole, Sulfamethoxazole, Sulfachloropyridazine, Sulfadiazine, Sulfamethoxazole, Sulfathiazole, Sulfa-6-methoxypyrimidine, Sulfamethazine, Sulfamethoxazole Ortho-dimethoxine, sulfapyridine, sulfa-p-methoxypyrimidine, sulfamethoxine, sulfamethazine, sulfafenpyrazole, sulfamethoxine standard materials: purity ≥99%
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16 kinds of sulfa standard stock solutions: 0.
1mg/mL
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Accurately weigh an appropriate amount of each sulfonamide standard substance, and use methanol to prepare a standard stock solution of 0.
Sulfonamide mixed standard working solution: According to the sensitivity of each sulfonamide and the linear range of the instrument, a blank sample extract is used to prepare a mixed standard working solution of different concentrations (ng/mL).
The mixed standard working solution is stored at 4°C and can be used for 1 week
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Cation exchange column: benzenesulfonic acid type, 500mg, 3mL
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Treat with 5mL methanol and 10mL water respectively before use
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4 Apparatus and equipment
Liquid chromatography-tandem mass spectrometer: equipped with electrospray ion source
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Solid phase extraction vacuum device
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5 Sample pretreatment
(1) Sample preparation
For laboratory samples without crystals, stir them evenly
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For samples with crystals, place them in a water bath of no more than 60°C under airtight conditions, warm them, shake them, stir them after all the samples have melted, and cool to room temperature
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Separate 0.
5 kg as a sample
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The prepared sample is placed in a sample bottle, sealed, and marked
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Store the sample at room temperature
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(2) Extraction
Weigh 5g sample, accurate to 0.
01g
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Place it in a 150 mL Erlenmeyer flask, add 25 mL of phosphoric acid solution, and mix quickly on a liquid mixer for 1 min to completely dissolve the sample
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(3) Purification
Connect the glass reservoir with glass wool plug to the benzene sulfonic acid type cation exchange column, pour the sample solution into the glass reservoir, and make the sample solution pass through the benzene at a flow rate of ≤3mL/min under reduced pressure.
For the sulfonic acid type cation exchange column, after the sample solution has completely flowed out, wash the column with 5 mL phosphoric acid solution and 5 mL water respectively, and discard all the effluent
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Finally, it was eluted with 40 mL phosphate buffer solution, and the eluate was collected in a 100 mL flat-bottomed flask
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Add 1.
5 mL sodium heptane sulfonate solution to the eluent, and then adjust the pH to 6 with phosphoric acid
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Pass the pH-adjusted eluent through the Oasis HLB or equivalent solid phase extraction column according to the above method, adjust the flow rate to ≤3mL/min, and after the eluent has completely flowed out, wash the column with 3mL of water and discard all the effluent
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Under a negative pressure of 65kPa, drain under reduced pressure for 5 minutes, and finally eluted with 10mL methanol.
The eluate was collected in a 150mL chicken heart bottle
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Use a rotary evaporator to evaporate to dryness under reduced pressure in a 45°C water bath
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Accurately add 1.
0mL of mobile phase to dissolve the residue for determination by liquid chromatography-tandem mass spectrometer
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