biocommaQuinol, a growth-promoting pharmaceutical additive, isbanned as a feed supplement due to its cumulative toxicity,teratogenicity in animals, and potential health risks. Itquickly metabolizes in the body, leaving behind a stablemetabolite, 3-methyl-quinoxaline-2-carboxylic acid (MQCA),recognized as a residual marker by the International CodexAlimentarius Commission.
Biocomma developed an LC-MS/MS method for MQCA inBeef with good recovery and stability for your reference.
Experiment
Extraction
Weigh 5.00 g of ground Beef into a 50 mL centrifuge tube.Add 10 mL of 0.6% formic acid and mix well. Place in a 47℃ shaking water bath and shake for 1 h. Add 3 mL of 1.0mol/L Tris solution and mix well, then add 0.3 mL of 0.01g/mL protease solution and mix well. Place in the 47 ℃shaking water bath for 16-18 h for enzymatic hydrolysis.Cool to room temperature, then add 20 mL of 0.3 mol/Lhydrochloric acid solution. After shaking for 5 min, centrifugeat 10,000 r/min for 5 min at 10 ℃ . Filter the supernatant forpurification.
Purification (Copure® MAX Cartridge, 60 mg/ 3 mL)
Activate the Copure® MAX Cartridge by 3.0 mL of methanol,then 3.0 mL of water. Add the prepared supernatant tothe cartridge. Add 30 mL of 0.05 mol/L sodium acetate- methanol (19+1) to the centrifuge tube, then pipetteto the cartridge. Drain the cartridge. Wash the cartridgesequentially by 30 mL of 0.05 mol/L sodium acetate -methanol (19+1), 3×3.0 mL methanol, 3.0 mL water, 3×3.0mL 0.1 mol/L hydrochloric acid solution, 2×3.0 mL methanolwater solution (1+4), and 2.0 mL ethyl acetate. Drain thecartridge. Add 3.0 mL of 2% formic acid in ethyl acetate andcollect the eluate. Evaporate sample to about dryness at 45℃ . Reconstitute with 1.0 mL of methanol with 0.1% formicacid (19+1). After vortex and filter by 0.22 μm filtermembrane, the sample is ready for analysis.
Instrumental Conditions
1.Chromatographic conditions
Instrument: UPLC-MS/MS（Thermo Fisher TSQ Endura）Chromatographic column: SuPersil AQ-C18 (2.1 mm×100mm, 3 μm)
Mobile phase: A: 0.1 % formic acid in water, B: methanolFlow rate: 0.3 mL/min
Column temperature: 30 ℃
Injection volume: 10 μL
Table 1. Gradient Elution Program
2.Mass spectrometry conditions
Ion source: HESI
Electrospray voltage: 3500 V
Sheath gas pressure: 40 arb
Auxiliary gas pressure: 2 arb
Ion exchange tube: 380 ℃
Auxiliary air temperature: 350 ℃
Table 2. Targets, Retention Times and Characteristic Ions(Quantitative Ion)
Results
Table 3. Results of MQCA Spiking Recovery
Ordering Information
