Glyphosate is a non-selective, non-residue herbicide; glufosinate-ammonium can effectively remove most glyphosate-resistant weeds, and is favored by all walks of life because of its environmental protection and easy degradation. With the widespread use of these substances, problems such as livestock poisoning and environmental pollution caused by glyphosate and glufosinate are increasing year by year. Rice is the most commonly used food raw material in daily life. The national standard "GB 2763-2021" stipulates that the maximum residue levels (MRL) of glyphosate and glufosinate in rice are 0.1 mg/kg and 0.9 mg/kg respectively .

Glyphosate is a highly polar compound, insoluble in most organic solvents, and has poor volatility. These characteristics greatly increase the difficulty of analysis. The use of gas chromatography and liquid chromatography, including liquid chromatography mass spectrometry, will encounter difficulties such as peak tailing . Therefore, the detection of such substances generally requires derivatization before analysis. However, the derivatization process is often cumbersome and time-consuming. hour.

Based on the analytical method for highly polar pesticide residues in food (Quppe) developed by the European Union, this application center uses hydrophilic interaction chromatography column-tandem mass spectrometry (HILIC-MS/MS) technology to establish the presence of glyphosate and glyphosate in rice. Glufosinate ammonium detection method. The experiment examined the linearity, sensitivity, precision and accuracy of the method. Using a highly sensitive and anti-pollution LC-MS/MS system, sensitive and accurate quantitative detection of glyphosate and glufosinate-ammonium residues in rice can be carried out.

Keywords: LC-MS/MS, food, rice, glyphosate, glufosinate-ammonium, herbicide, HILIC, GB 2763-2021

Experimental part

instrument

Table 1 Liquid chromatography tandem triple quadrupole mass spectrometer

Table 2 Detection parameters of liquid chromatography tandem triple quadrupole mass spectrometer

Reagents and standards

Reagents: mass spectrometry grade formic acid (CNW), mass spectrometry grade ammonium acetate (CNW), chromatography grade methanol (Merck), chromatography grade acetonitrile (Merck); sodium citrate, sodium chloride, sodium acetate (Sinopharm Group); hydrogen citrate dihydrogen citrate Sodium, anhydrous magnesium sulfate (SIGMA)

Pure water: 18.2 MΩ·cm deionized water (25℃);

Standard products: glyphosate, glufosinate ammonium standard products (Tianjin Alta).

Sample preparation

This experiment is based on the analysis method for highly polar pesticide residues in food (Quppe) developed by the European Union, and uses a 50% methanol aqueous solution as the extraction solvent.

Weigh 1g (accurate to 0.01g) of homogenized rice in a 50mL centrifuge tube. ➡Add 9mL of water and an appropriate amount of internal standard, and let stand for 15min. ➡Add 10mL of methanol containing 1% formic acid, shake and mix for 1min. ➡Add 1mL of 10% EDTA aqueous solution. Mix on a shaker for 15 minutes and centrifuge ➡Take the supernatant and filter it with a 0.22μm nylon filter ➡Take 2mL of the filtrate and transfer it to a centrifuge tube containing 2mL acetonitrile, vortex for 1 minute, centrifuge ➡Transfer to a polypropylene injection bottle

The detection limit

Table 1 Detection limits and quantitation limits of glyphosate in rice

Figure 2 Quantitative ion chromatogram of 10 μg/L glyphosate and glufosinate-ammonium

Spiked recovery rate

The spiked concentration is 0.2 mg/kg

The spiked concentration is 2 mg/kg

Test Results

Conclusion

This application center uses ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry to establish a detection method for glyphosate and glufosinate in rice. The linearity, precision, sensitivity and spike recovery of the method were investigated. The results show that this method meets the detection requirements, the method sensitivity is good, and the instrument precision is good. Using a highly sensitive and anti-pollution LC-MS/MS system, sensitive and accurate quantitative detection of glyphosate and glufosinate-ammonium residues in rice can be carried out.

appendix

Equipment and consumables solutions

1. EXPEC 5210 configuration details

2. Standard products