Pre-treatment Solutions for N-Nitrosodimethylamine Detection

Nitrite in cured meat is converted to nitrosamine compounds, which can easily form carcinogenic substances:N-nitrosamines. Under suitable conditions, nitrite reacts with amines to undergo nitrosation, eventually forming N-Nitrosodimethylamine.

N-Nitrosodimethylamine is widely present in foods and environments such as beer, meat products, and fish pickles. It is soluble in water, ethanol, ether, and dichloromethane, and is used to manufacture dimethylhydrazine. It is an internationally recognized toxic pollutant with hepatotoxicity and carcinogenicity.

On September 25, 2023, the National Health Commission released 85 national food safety standards and 3 amendment documents (Notice No. 6 of 2023), including GB5009.26-2023 for the "Determination of N-Nitrosamine Compounds in Food."

The new standard adds the QuEChERS-GC-MS/MS method (Method II). Compared with other pretreatment methods, the QuEChERS method is simpler to operate and easier for batch pretreatment, uses fewer reagents, and is more environmentally friendly.

Sample Pretreatment Steps

Extraction

• Weigh 5g of dried product into a 50mL centrifuge tube (RC-50004M, 50mL conical bottom)

• Add 5mL of water and shake to mix (for fresh samples, weigh 10g and place in a 50mL centrifuge tube)

• Add 50μL of internal standard (1μg/mL), then accurately add 10mL of acetonitrile

• MTV3000 multi-tube vortex mixer at 2500rpm, vortex for 2min, place in a-20℃ freezer for 20min

• After taking out, add1 ceramic homogenizer (RC-5003C) and an extraction salt packet (RC-50106M, containing 4g of magnesium sulfate and 1g of sodium chloride) Place in V20 vertical oscillator, oscillate at 1300rpm for 2min

• Place in a refrigerated centrifuge at 9000r/min, centrifuge at 10℃ for 5min

• Supernatant is ready for purification

Purification

• Measure 5mL of water into a 15mL purification tube (RC-15164M containing 150mg HLB-2 powder or RC-15165M containing 1g Holipid)

• Place in MTV 3000 multi-tube vortex mixer, vortex at 2500rpm to mix, immediately add 5mL of supernatant and vortex for 1min

• Remove and place in a refrigerated centrifuge, centrifuge at 9000r/min,10℃ for 5min

• Ready for dehydration

Dehydration

• Add the previously purified supernatant to a15mL dehydration purification tube (RC-15166M containing 1.6g of magnesium sulfate and 0.4g of sodium chloride)

• Place in MTV3000 multi-tube vortex mixer and vortex at 2500rpm for 2min
  

• Place in a refrigerated centrifuge at 9000r/min, centrifuge at 10℃ for 5min

• Filter the upper organic phase through a 0.22μm micropore filter membrane

• Analyze by instrument

Recommended Instruments and Consumables for Pretreatment

RayKol  V20 Vertical Oscillator

• Oscillation mode: Vertical oscillation

• Oscillation speed: 500-1800rpm

• Amplitude: 32mm

• Sample capacity: 50mL*20,15mL*38,100mL*10,2mL*52, etc., 96-well plates*6, customizable

• 7-inch color touch screen, real-time display of speed, work time, and countdown

• Reservation start, reservation time 0-840min

RayKol MTV3000 Multi-tube Vortex Mixer

• Oscillation mode: Eccentric oscillation

• Oscillation speed: Maximum speed 3000rpm

• Simple operation, compatible with various tube racks

• 7-inch color touch screen, real-time display of speed and working time and countdown, etc

Consumables