The national standard " GB23200.121-2021 Determination of 331 Pesticides and Metabolites Residues in Plant-Derived Foods by Liquid Chromatography-Mass Spectrometry" was approved by the National Health Commission, the Ministry of Agriculture and Rural Affairs, and the State Administration for Market Regulation in March 2021. Jointly released by the three departments. This standard is the first domestic liquid-quality national standard with the largest single-needle determination of pesticide residues . It is applicable to 10 major categories of agricultural products including plant foods, including edible fungi, fruits, vegetables, sugars, grains, and oils, and fully covers plant foods. . GB23200.121-2021 is applicable to the determination of 331 pesticides and their 44 metabolites (a total of 375 components) residues in plant foods and will be officially implemented in September 2021. The new standard has the same pretreatment method as GB23200.113-2018. The QuEChERS pretreatment method can be applied to both gas and liquid quality testing, greatly simplifying the pretreatment process and improving analysis efficiency.

This application center refers to "GB23200.121-2021 Determination of 331 Pesticides and Metabolites Residues in Plant-Derived Foods by Liquid Chromatography-Mass Spectrometry" and uses a liquid chromatography-triple quadrupole tandem mass spectrometer to determine the residues in vegetables. 331 pesticide residues.

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 formate (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℃);

Standards: 331 pesticide standards (20 mg/L) (Tianjin Alta).

Typical spectrum

The MRM superimposed chromatograms of 331 pesticide residues are shown in Figure 3 below, and the ion channel chromatograms of the linear minimum concentration (2 μg/L) of some pesticide residue compounds are shown in the figure.

Linear

Vegetables were treated with reference to "GB23200.121-2021 Determination of 331 pesticides and their metabolites in plant-derived foods by liquid chromatography-mass spectrometry", and the vegetable blank matrix was diluted step by step to obtain standard working solutions of 0.002 mg/L, 0.005 mg/L, 0.01 mg/L, 0.02 mg/L, 0.05 mg/L, 0.1 mg/L, 0.2 mg/L and 0.5 mg/L, and the samples were injected according to the above method. The linear results of some pesticides are shown in the table below. The linear correlation coefficients of the standard curves of 331 pesticides and their metabolites are all greater than 0.995, which meets the requirements of methodological validation. Some typical linear graphs are shown in the figure.

Repeatability

The 10ppb matrix standard was used for precision verification. Some pesticide linearity results are shown in the figure below. The peak area repeatability RSD of 331 pesticides and their metabolites were all less than 10%, meeting the methodological verification requirements.

in conclusion

After vegetable samples were pre-treated according to the national standard GB23200.121-2021, the LC-MS/MS system was used to determine the residues of 331 pesticides. This article examines the linearity and repeatability of the method. The results show that the pesticide components have good linearity within the measured concentration range, the correlation coefficient r is greater than 0.995, and the peak area repeatability RSD is less than 10%. Using the highly sensitive and anti-pollution EXPEC 5210 system, you can perform sensitive and accurate quantitative detection of pesticide residues in fruits and vegetables.

appendix

Equipment and consumables solutions

1. EXPEC 5210 configuration details

2. Standard products