Determination method of meptyldinocap residues in plant food

Abstract

The invention discloses a determination method of meptyldinocap residues in plant food. The method comprises thefollowing steps: sampling; preservation; extraction: weighing 10.0 g of the preserved sample, adding 10 mL of ethyl acetate and 5.0 g of sodium chloride, performing homogenizing for 2 min at a centrifugal speed of 15000 rpm, performing centrifuging for 5 min at a centrifugal rotating speed of 9500 rpm, and leaving the mixture to stand; hydrolysis: taking 2 mL of a supernatant after extraction, performing nitrogen blowing to near dryness at 35DEG C, adding 1 mL of 1% ethanolamine solution, performing ultrasonic treatment for 15 min, and performing centrifugation at the centrifugal rotating speed of 9500 rpm for 5 min;purification; testing; determination: if chromatographic peaks appear in a mass chromatogram of sample liquid to be detected and a mass chromatogram of a standard working solution at the same retention time and the absolute value of the deviation of the two chromatographic peaks is lower than 2.5%, comparing the sample abundance ratio of selected ions in the to-be-detected sample liquid to the standard abundance ratio of the corresponding ions in the standardworking solution, and judging that the corresponding measured substances exist in the sample liquid to be detected if the relative difference value between the sample abundance ratio and the standardabundance ratio is within the allowable range; calculation: calculating the residues of meptyldinocap2,4-DNOPC.

Description

technical field [0001] The invention relates to the field of food safety, in particular to a method for determining the residual amount of anti-mite in plant food. Background technique [0002] Meptyldinocap (2,4-DNOPC, CAS No: 131-72-6) is a non-systemic acaricide and has a certain contact bactericidal effect. Anti-mite is one of the isomers with the highest biological activity isolated from the six isomers of the fungicide (mite) dinocap (CAS No: 39300-45-3). It is mainly used to control spider mites and powdery mildew in apples, citrus, pears, grapes, cucumbers, melons, watermelons, pumpkins, strawberries, roses and ornamental plants. It also has good control effects on mulberry tree powdery mildew and eggplant spider mites. The role of killing mite eggs. At present, the European Union has formulated the maximum residue limit (MRL, maximum residue limit) in various agricultural products. The MRL in strawberries is 3mg / kg. Hong Kong stipulates that the MRLs in grapes, ...

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Problems solved by technology

For example, the HPLC detection method adopts traditional organic solvent extraction, solid phase extraction purification, and separation by C18 chromatographic column, but the sensitivity of the method is low, and the detection limit, that is, the effective number of detection cannot meet the requirements of current regulations; , Hydroxylamine chloride is hydrolyzed, the extraction method is relatively simple, but the alkaline hydroxylamine solution needs to be prepared immediately before use, the solution needs to be stored in an ice bath, and the validity period is only 3h, which is not suitable for daily use; the liquid-liquid extraction detection method uses acetone: Methanol: 4N HCl (100:10:5, V / V / V), the extract was evaporated to near dryness, then added methanol and sodium hydroxide for hydrolysis, then adjusted the pH to neutral with hydrochloric acid, and then extracted with ethyl acetate, Extraction and purification after redissolving, and then detection by liquid chromatography-mass spectrometry (LC-MS) / (mass spectrometry) MS, this method is cumbersome to operate, uses a large amount of solvent, is not environmentally friendly, and uses sodium hydroxide or hydrogen When potassium oxide is hydrolyzed, the recovery rate is lower than 60%, and due to adding hydrochloric acid to adjust the pH value in the later stage, the formed inorganic salt will cause the ESI spray needle of the mass spectrometer to be blocked; use QuEChERS technology to extract, then take the purified solution, and hydrolyze it with ammonia water Carry out multi-extraction and purification of anti-mite, and then alkaline hydrolysis, but it needs to be derivatized for 12 hours, which is too long and not suitable for daily work

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