Ninhydrin hydrazones

The spots were located by examination under UV light or spraying with one of following solutions (detection limits in yg) fluorescamine (0.5), ninhydrin (1), NBP followed by heating and treatment with a base (5) [51,63a], and 0.5% iodine in chloroform. Visualization using 4-pyridine-carboxaldehyde 2-benzothiazolyl hydrazone has been described under 5.2.1. 

Reaction of acetohexamide with 2,4-dinitrophenyl-hydrazine to produce the colored hydrazone was used by Amer and Walash (19) to determine the drug colorimetri-cally. The colored product was dissolved in KOH and determined at 480 nm. The accuracy of the method was claimed to be 100. A ninhydrin colorimetric method for some oral hypoglycemic agents was also reported (20b). 

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