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Chromatography of fat-soluble food dyes on thin starch layers with stationary non-polar phases

1964; Elsevier BV; Volume: 15; Linguagem: Inglês

10.1016/s0021-9673(01)82816-8

1873-3778

J. Davı́dek, G. Janíček,

Advanced Chemical Sensor Technologies

The chromatographic behaviour of azobenzene and fourteen of its derivatives was studied by reversed-phase high-performance liquid chromatography with a C18 stationary phase. The optimal composition of the mobile phase is 9:1 methanol—0.01 M aqueous sodium dihydrogen phosphate which is 0.0002 M in ethylenediamine-tetraacetic acid, with a pH of 4.5. The solutes can be detected spectrophotometrically, voltammetrically or polarographically. Spectrophotometric measurement in the visible range is more sensitive than in the UV range (detection limits of 0.04–0.1 ng at 410 nm compared with 0,3–0.5 ng at 265 nm). Voltammetric detection is highly sensitive for hydroxy and amino derivatives [detection limits 0.02–0.09 ng at +0.8 V (AgAgCl)], whereas for other substances the detection limits area few nanograms. Polarographic detection is the least sensitive [detection limits 4–8 ng at  0.6 V (AgAgCl)]. All the calibration graphs exhibit good linearity, but spectrophotometric detection yields a wider linear dynamic range. Voltammetric detection is more precise at low solute concentrations (relative standard deviations of the peak heights 0.5–1.0% and 1.0–1.5% for voltammetric and spectrophotometric detection, respectively, with amounts of solute from 1 to 10 ng).