Organophosphorus cholinesterase inhibitors, first

Organophosphorus compounds—inhibition of cholinesterase. To each of two tubes add 3 ml of dithiobisnitrobenzoic acid solution, 0.1 ml of 5% acetylthiocholine iodide solution, and 20 ml of normal serum to the first tube add 0.2 ml of water and to the second tube add 0.2 ml of the filtered sample and allow to stand for 2 minutes. Any significant difference in colour between the tubes is suggestive of the presence of an organophosphorus compound or other cholinesterase inhibitor. 

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