Chromogenic substance of pesticide residue detection reagent

 Pesticide residue detection kit products basically include acetylcholinesterase, chromogenic agent, substrate and buffer, in which chromogenic substances play an important role.

Yacoo Science has summarized several commonly used color-developing substances, which are acetylthiocholine iodide, 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and disodium 4-nitrophenylphosphate ( PNPP).

Acetylthiocholine iodide, CAS number is 1866-15-5, is often used together with the developer 5,5'dithiobis(2-nitrobenzoic acid) (DTNB) for rapid detection of pesticide residues. The principle as follows:

Acetylthiocholine iodide is hydrolyzed by acetylcholinesterase to produce thiocholine, and the reaction of thiocholine with the color reagent DTNB produces a yellow substance. Under certain conditions, organophosphorus and carbamate pesticides have an inhibitory effect on the activity of acetylcholinesterase, and the inhibition rate is positively correlated with the concentration of pesticides.

If the agricultural product does not contain organophosphorus pesticide residues or the residual amount is low, the activity of acetylcholinesterase is not inhibited or inhibited to a low degree, then the substrate acetylthiocholine iodide can be hydrolyzed, and the hydrolysate reacts with the addition of DTNB Produce yellow substance. Conversely, if the extract of agricultural products contains pesticides and the residual amount is high, the activity of acetylcholinesterase will be inhibited, the substrate acetylthiocholine iodide will not be hydrolyzed, and when DTNB is added, there will be no color or little change in color.

5,5'-Dithiobis(2-nitrobenzoic acid), referred to as DTNB, has a CAS number of 69-78-3. In the existing rapid detection method of pesticide residues, DTNB is used as a separate chromogenic reagent for detecting cholinesterase activity. After the pesticide and cholinesterase in the sample inhibit the enzyme activity, DTNB is added. The agent and the substrate were then placed on a pesticide residue detector to measure the activity of cholinesterase and calculate the inhibition rate of cholinesterase. DTNB can also be combined with cholinesterase to form a special reagent for pesticide residue detection.

Disodium 4-nitrophenylphosphate, pNPP for short, CAS:4264-83-9 . PNPP is widely used as a substrate for ELISA to detect alkaline phosphatase (AP). When pNPP reacts with AP, water-soluble yellow product is formed, and its absorption wavelength is 405nm. It can be used for the determination of thiamethoxam, fipronil, carbaryl, Triazophos and other pesticide residues.

Acetylthiocholine iodide, DTNB, and PNPP are all the superior products of Yacoo Science. Yacoo Science can guarantee its long-term stability and meet customers' application requirements in the field of food safety testing.

Related links: acetylcholine iodide, DTNB, PNPP