Resorcinol, complexes

Uranium has been determined in process liquids by ion chromatography using an ammonium sulphate sulphuric acid element. Uranium was determined in the eluant. Uranium was determined in the eluate spectrophotometrically at 520 mm as the 4(-2-pyridylazo) resorcinol complex [36],... 

Cineol (179) occurs widely (there is, for example, up to 50% in laurel oil ) and it is of interest to isolate it commercially. A new method consists of isolation of the mixture of 1,4-cineol and 1,8-cineol as the resorcinol complex. This mixture, when treated with thiourea, yields an addition compound (m.p. 172 °C)... 

Extinction coefficients have been determined for Ta -oxalate-4-(2-pyridylazo)-resorcinol complexes. ... 

Figure 12.1.34. Optical micrograph of PEO-resorcinol complex. [Adapted, by permission, from M Dosiere, Macromol. Symp., 114, 51 (1997).]...

Pd(II), Rh(III), Ru(III), and Pt(II) were baseline resolved as their 4-(5-nitro-2-pyridylazo)resorcinol complexes using a C g column (A = 536nm) and a 50/10/40 methanol/ethyl acetate/water (lOmM acetate buffer at pH 4.0 with lOmM tetra-butylammonium bromide and 0.01 mM sodium EDTA) mobile phase [155]. Separation was complete in 20 min and detection limits of - 1 ng/mL were reported. A plot of k versus percent methanol ranging from 40% to 90% with no ethyl acetate present was given. The k for some complexes exceeded 9 when the mobile phase contained <50% methanol, so this is probably not an effective system to use. Ethyl acetate was used to enhance the selectivity of the separation. Levels of 4% to 20% ethyl acetate were used to generate baseline separation. 

The separation of Rh(lII), Ru(II), Pd(II), and Pt(II) as their 4-(5-nitro-2-pyridy-lazo)resorcinol complexes was achieved on a C g column (A = 536nm) using a 50/10/40 methanol/ethyl acetate/water (lOmM acetic acid buffer pH 4.0 with lOmM tetrabutylammonium bromide and lOmM sodium EDTA) mobile phase [155]. Elution was complete in <20 min. Peaks were baseline resolved. The detection limits were reported to be between 0.5 and 2.6ng/mL (ion dependent) and linear working concentrations were generated from 2 to lOOng/mL for all analytes. The authors note that ethyl acetate levels between 4% and 20% were effective for this separation but do not state that ethyl acetate is responsible for the selectivity obtained. 

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