Oxine, analytical reagent

Hydroxyquinoline, whose chemistry has been reviewed (56CRV271), has found wide application as an analytical reagent, and is known as oxine . It forms insoluble complexes with a great many metal ions, coordinating at O and N, and can be used for the estimation of Mg, Zn, Al, Cu, Bi, Fe, Mn, Ni and others. 

Hydroxyquinoline (oxine, 6), one of the earliest analytical reagents, also is one of the most widely studied N—O bidentates. Its early coordination chemistry was reviewed by Phillips.19 Its use as an in vivo agent in microbiological systems has been reviewed by Schulman and Dwyer.20 The extensive use of oxine and substituted forms, and closely related bidentates, for the analytical solvent extraction and colorimeteric determination of metal ions has been comprehensively reviewed.21 An unusual bridged bonding mode for oxine has been reported in which N monodentate and O... 

By far the greatest number of analytically important organic reagents fall into class II. Examples are l-nitroso-2-naphthol for Co(II), dimethylglyoxime and 1,2-cyclohexanedionedioxime (nioxime) for Ni(II), and oxine and diphenylthio-carbazone (dithizone) for various heavy metals. 

Although oxine is a group reagent and reacts with many metals, the use of appropriate masking agents makes the method specific for aluminium. There are many variants of the oxine method, depending on the kinds of metals that accompany aluminium in the analyte... 

Hydroxyquinoline ( oxine ), mp 75°C, contains an intramolecular hydrogen bond and is used as a complexing and precipitating reagent for many metallic ions in analytical chemistry. It is obtained by a Skraup synthesis starting from o-aminophenol. 

A third technique which is somewhat less popular but still useful is application of surface adsorption reagents. Activated car n is generally used as the carrier after conversion of the metal ion(s) of interest to a suitable form. For example, iodide in ground water has been determined by this method after conversion to silver iodide [61]. Neutral 8-hydroxyquinoline complexes have been employed in which, again, the oxine complex is collected on activated carbon [62]. Use of activated carbon is particularly useful where PIXE is being employed as the analysis technique, since the resultant sample is ideal for direct presentation to the instrument [63]. Other preconcentration methods that have been employed in this area include electrodeposition [64], precipitation chromatography [65], liquid/liquid extraction, immobilized reagents [66], plus a variety of other techniques well known to the analytical chemist. 

---