Pesticide Residue Testing

The development of agricultural industrialization makes the production of agricultural products increasingly dependent on foreign substances such as pesticides, antibiotics and hormones. According to the World Health Organization (WHO), more than 1,000 pesticides are used all over the world. Although the use of pesticides helps fight diseases and increase agricultural productivity, their residues may remain on food and be transported to the air, soil, and water.

The unreasonable use of these substances will inevitably lead to excessive pesticide residues in agricultural products, affecting consumer safety, and in severe cases, it will cause consumers to become ill, develop abnormally, and even directly lead to poisoning and death. Excessive pesticide residues will also affect the trade of agricultural products. Countries around the world attach great importance to the issue of pesticide residues, and increasingly stringent limits are imposed on pesticide residues in various agricultural and sideline products.

Pesticide residue refers to the general term of pesticide precursor, pesticide residue hazard derivatives, metabolites, degradation products and impurities remaining in the environment, organisms and food after pesticide use. The main cause of excessive vegetable pesticide residues is the organophosphorus pesticides and carbamate pesticides that some countries banned in vegetable production, such as methamidophos, omethoate, phorate, parathion, methyl parathion. Eating food containing a large amount of highly toxic and highly toxic pesticide residues can cause acute poisoning accidents in humans and animals. Long-term consumption of agricultural and sideline products with excessive pesticide residues will not cause acute poisoning, but may cause chronic poisoning of humans and animals, cause disease, induce cancer, and even affect the next generation.

Organophosphates, carbamates and pyrethroids are currently the three main types of insecticides on the market, especially organophosphorus insecticides still play a leading role in production, and they are the first type of insecticide used by vegetable farmers. For organophosphorus and carbamate pesticides, scientists have done a lot of research on the rapid detection technology of pesticide residues, and made great progress.

Pesticide Residue Detection Method

Folded Gas Chromatography-Mass Spectrometry

GC/MS is the most widely used method for pesticide residue analysis. In order to pursue higher sensitivity and accuracy, GC/MS often chooses ion mode (SIM) to confirm the target substance based on retention time, characteristic ions and ion ratio relationships. 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; at the same time Other effects of the matrix on the target should be considered; the experimental recovery rate is generally between 70% and 120%. In the European Union, using the SIM mode requires at least 2 characteristic ions greater than m/z200 or 3 characteristic ions greater than m/z100 for each target; the ratio of characteristic ions of the target is 70%-130% compared with the standard; daily The detection recovery rate is controlled at 60%-140%, and the confirmation analysis needs to be between 70%-110%.

Folding rapid detection technology

However, traditional GC/MS and other pesticide residue analysis techniques are expensive and time-consuming. This has brought a lot of inconvenience to the supervision of agricultural products before, during and after production by the food safety supervision department. The detection techniques for pesticide residues commonly include chemical rapid detection method, immunoassay method, enzyme inhibition method and in vivo detection method.

The chemical rapid measurement method is mainly used for the rapid detection of organophosphorus pesticides based on the oxidation-reduction reaction and the effect of the hydrolysate and the detection solution. However, the sensitivity is low, the use is limited, and it is easily interfered by reducing substances.

Immunoassay methods, mainly radioimmunoassay and enzyme immunoassay, the most commonly used is enzyme-linked immunoassay(ELISA), based on the specific recognition and binding reaction of antigens and antibodies, artificial antigens need to be prepared for small molecular weight pesticides. Before the immunoassay can be performed.

The enzyme inhibition method is mainly based on the specific inhibition of acetylcholinease by organophosphorus and carbamate pesticides.

The in vivo detection method mainly uses the sensitive response of living organisms to pesticide residues, such as feeding samples to house flies and observing the mortality rate to determine the amount of pesticide residues. The method is simple to operate, but the qualitative is rough, the accuracy is low, and the scope of application to pesticides is narrow.