biocommaIntroduction
4-Methylimidazole (4-MI) is a contaminant of carcinogenicrisk that is commonly found in food as a by-product of theproduction of caramel coloring. Biocomma established a LCMS/MS method for detection of 4-methylimidazole in passionfruit juice and honey with good recovery and precision for yourreference.
Experiment
Extraction
Weigh 2.000 g of the sample into a 50 mL centrifuge tube.Add 2 % formic acid aqueous solution to 20 mL and mix well.Centrifuge at 10000 r/min for 5 min. The supernatant is readyfor purification.
Purification (Copure® MCX Cartridge, 200 mg/ 6 mL)
Activation: activate the Copure® MCX Cartridge by 5 mL ofmethanol, then 5 mL of water.
Loading: add 10 mL of prepared sample.
Washing: add 2 mL of 2 % formic acid aqueous solution, 5 mLof water and 5 mL of methanol in sequence.
Elution: add 8 mL of 5 % ammonia methanol and collect theeluate. Evaporate sample to near dryness at 45℃ . Add 1 mLof acetonitrile-5 mmol/L ammonium acetate (9+1). Vortex for 30s to dissolve the residue. After filter by 0.22 μm membrane, thesample is ready for analysis.
Preparation of Standard Curve Solution
Dilute the internal standard solution with acetonitrile-5 mmol/Lammonium acetate (9+1) solution to prepare series of standardconcentrations of 10 μg/L, 20 μg/L, 50 μg/L, 100 μg/L, 200 μg/Land 400 μg/L.
Instrumental Conditions
1.Chromatographic conditions
Instrument: UPLC-MS/MS (Thermo Fisher TSQ Endura)
Chromatographic column: GOWON HILIC (2.1 mm×100 mm,2.7 μm)
Mobile phase: A: 5 mmol/L ammonium acetate, B: acetonitrileFlow rate: 0.6 mL/min
Column temperature: 35 °C
Injection volume: 5 μL
Table 1. Gradient Elution Program
2.Mass Spectrometry Conditions
Ion source: HESI
Electrospray voltage: 3500 V
Sheath gas pressure: 40 arb
Auxiliary air pressure: 5arb
Ion exchange tube: 380 ℃
Auxiliary air temperature: 350 ℃
Table 2. Targes Characteristic Ions (*Quantifier Ion)
Result
Table 3. 4-Methylimidazole Spiked Recovery
Ordering Information
