One of the most effective ways to control the harm of pesticide residues to the human body is to strengthen the detection of pesticide residues in food. The detection and analysis of pesticide residues in the world today is developing towards multi-residue and rapid analysis. To ensure the accuracy of high-throughput detection methods, strict pesticide residue confirmation techniques are needed.
1. Folded gas chromatography-mass spectrometry (GC/MS)
GC/MS is the most widely used method for pesticide residue analysis. Using GC/MS for pesticide residue analysis, in order to pursue higher sensitivity and accuracy, selective ion mode (SIM) is often used, depending on retention time and characteristic ion and ion ratio to confirm the target. In the United States, it is generally required that the retention time of the target in the sample is less than 0.05 minutes compared with the standard; each target has at least 3 characteristic ions, and the relative ion ratio is within 10% of the absolute value of the standard; Other effects of the substrate on the target should be considered; the experimental recovery is generally between 70% and 120%. In the European Union, the use of SIM mode requires at least 2 characteristic ions larger than m/z 200 or 3 larger than m/z100 for each target; the characteristic ion ratio of the target is 70%-130% compared with the standard; the detection recovery rate is controlled between 60% and 140%, and the confirmation analysis needs to be between 70% and 110%.
2. Folding fast detection technology
However, the traditional GC/MS and other pesticide residue analysis technologies have high detection cost and long time. This has caused many inconveniences to the food safety supervision departments for the pre-production, mid-production and post-production supervision of agricultural products, which has also spawned a large number of rapid pesticide residue detection techniques, such as chemical rapid test, immunoassay, enzyme inhibition and in vivo detection.
(1). The chemical rapid test mainly uses the redox reaction, the hydrolysis product and the detection liquid to change color, which is used for rapid detection of organophosphorus pesticides, but has low sensitivity, limited use, and is susceptible to interference by reducing substances.
(2). Immunoassay, mainly radioimmunoassay and enzyme immunoassay, the most commonly used enzyme-linked immunoassay (ELISA), based on the specific recognition and binding reaction of antigens and antibodies, the preparation of artificial antigens for small molecular weight pesticides, in order to carry out an immunoassay.
(3). Enzyme inhibition method is the most mature and widely used rapid pesticide residue detection technology, mainly based on the specific inhibition reaction of organophosphorus and carbamate pesticides on acetylcholine.
(4). The in vivo detection method mainly uses the sensitive reaction of living organisms to pesticide residues, for example, feeding samples to house flies and observing the mortality to determine the amount of pesticide residues. The method is simple in operation, but has strict qualitative properties, low accuracy, and narrow application range to pesticides.
Folding and editing
1). Single Residue Methods
2). Multiresidue Methods
Selective multi-residue method: same type of pesticide
Multi-class multi-residue method: multiple types of pesticides
Pesticide residue testing procedures:
1). Sample collection: sampling, sample transport and storage;
2). Sample pretreatment: shrinking, rejecting or pulverizing the sample to become a test sample;
3).Sample preparation: extraction: the process of separating residual pesticides from the sample;
Purification: the process of separating pesticides from interfering substances in extracts;
4). Analytical determination
Selection of pesticide residue detection methods
1). The physical and chemical properties of pesticides, requirements for analytical tasks, properties of samples and source of samples;
2).Single residual or multi-residue method;
3). Maximum residue limit, method detection limit and total method error;
MRL and LOD/LOQ relationship, relative error (accuracy) + 2 relative standard deviation (precision)
4).The effectiveness of the analytical method;
5). Analyze time and expenses.
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