Barbiturates colour tests

Banistyl, 552 Banlin, 934 Banocide, 538 Banthine, 745 Baptitoxine, 507 Baratol, 683 Barb, 372 Barbaloin, 328 Barbamylum, 353 Barban, 82, 85 Barbital, 372 Barbitone, 372 (metabolite), 748 Barbitone sodium, 372 Barbitone, soluble, 372 Barbiturates, colour test, 147 gas chromatography, 15, 196 high pressure liquid chromatography, 216 infra-red spectra of, 247 published, 250 metabolism, 285... 

A colour test, specific for barbituric and thiobarbituric acids in amounts greater than 0-5 pg, uses pyridyl pyridinium dichloride as the colour reagent [111]. The quantitative determination of barbituric acid in the presence of several 5,5-disubstituted derivatives, by means of ultraviolet spectroscopic determinations and titrations in chloroform-methanol mixtures, has b n described [112]. 

The components of this reagent consist of 0.1 g of cobalt acetate in 10 ml of 0.2% glacial acetic acid in methanol (1) and 5% isopropylamine in methanol (2). Testing is carried out by adding a small amount of component (1) to the test substrate, followed by a few drops of component (2). A blue colour will develop if barbiturates are present in the sample. 

Other sensitive tests lor cyanide may be used, e,g. the pink colour produced with a mixture of chloramlne-T, barbituric acid solution and y-henzyl pyridine in acetone. 

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