Naked-eye differentiable isocarbophos rapid colorimetric detection method

Abstract

The invention discloses a method for specifically detecting isocarbophos in a catalytically colorimetric mode through interaction of a random ssDNA sequence, Hemin and a target in a NaH2PO4 buffer solution. Reagents adopted for the method mainly comprise the random ssDNA sequence, Hemin, H2O2 and 3,3',5,'5-tetramethyl benzidine (TMB). When the random ssDNA sequence and Hemin are firstly incubated for a certain time, the random ssDNA sequence can cover the surface of Hemin, the activity of Hemin for catalytically oxidizing TMB is restrained temporarily, N atoms in substrate molecules lose one electron, the color of the system is remarkably changed into light blue or blue from colorless originally, and at the moment, characteristic absorption peaks of a product are 370 nm and 650 nm. If isocarbophos is added into the system to jointly act for a certain time, the catalytic activity of hemin is greatly enhanced, substrate TMB loses two electrons and is changed into a diimine structure, at the moment, the color of the system is changed into yellow from blue, the characteristic absorption peak exists at the position of 450 nm, and the change amplitude of the light absorption value at the position of 450 nm and the concentration of isocarbophos are in direct proportion.

Description

technical field [0001] The invention belongs to the field of detection of organophosphorus pesticide residues in agricultural products, and particularly relates to the use of colorimetry to measure the change of the characteristic absorption peak of the detection system at 450 nm in an aqueous buffer system, and to determine the detection of isocarbophos pesticide by naked eyes method. Background technique [0002] Isocarbophos is a fast-acting broad-spectrum organophosphorus pesticide, which has a good control effect on mites in Arachnida, Lepidoptera and Homoptera in Insecta. However, isocarbophos is a highly toxic pesticide and can cause poisoning through the esophagus, skin and respiratory tract. Article 27 of the "Regulations on Pesticide Management" and Article 29 of the "Regulations on Pesticide Management" and Article 29 of the "Regulations on Pesticide Management" clearly stipulate that highly toxic and highly toxic pesticides must not be used to prevent and contro...

AI Technical Summary

Problems solved by technology

Instrumental analysis methods mainly include gas chromatography (GC), high performance liquid chromatography (HPLC), ion chromatography and chromatography-mass spectrometry, etc. The disadvantage of instrumental analysis methods is that the required equipment is expensive and requires professionals operation, not suitable for rapid detection in the field

The disadvantage of the enzyme inhibition method is that its sensitivity and reproducibility need to be improved, and the sensitivity is not as good as that of the instrument method

The disadvantage of immunoassays is that they are prone to false positives

The disadvantage of the biosensor method is that the stability of many biosensor technologies is not high, resulting in problems such as short service life in practice.

The disadvantage of chemiluminescent technology is that it can only detect one kind of organophosphorus, and cannot detect the total amount of organophosphorus pesticides

Traditional colorimetry includes visual colorimetry and photoelectric colorimetry, wherein the standard series of methods are commonly used in visual colorimetry, but the disadvantage is that there are subjective errors in eye observation, and the accuracy is relatively low; photoelectric colorimetry is compared to Although visual colorimetry eliminates subjective errors and improves accuracy, the disadvantage is that photoelectric colorimeters are not as good as UV-Vis spectrophotometers in terms of measurement accuracy, sensitivity and application range.

In recent years, the colorimetric detection of organophosphorus pesticides by the enzyme inhibition method needs to be further improved in sensitivity, and the cost is relatively high.

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