Fast determination of 18 synthetic colors in foods by high performance liquid chromatography

A HPLC method was developed for the simultaneous determination of 18 water soluble synthetic colors such as tatrazine, amaranth, indigotin, ponceau 4R, sunset yellow, rhodamine B, quinoline yellow, metanil yellow, basic orange Ⅱ, Auramine O, allura red, carmoisine, erythrosine, acid orange Ⅱ, basic orange 21, basic orange 22, brilliant blue, patent blue VF in colored foods.The sample was directly extracted by solvent, and separated by Venusil MP C18 column (4.6mm×250mm, 5μm) using methanol-acetotrile (1∶1) and 0.02mol/L ammonium acetate as mobile phase by gradient elution.The target compounds were detected by absorbance at different ultraviolet or visible wavelengths and identified by diode-array spectroscopy (wavelength range:200⁸00nm) .The external standard method was adopted for quantification of the analytes.Under the optimal conditions, the calibration curves of 18 synthetic colors showed good linearities in the range of 0.5 ²0.0mg/L, with their correlative coefficients more than 0.9980.The mean recoveries at 3 spiked levels of 3, 15, 40mg/kg ranged from 68.9% to 100.8% with RSDs (n=6) of 0.1%⁵.3%.The detection limits were in the range of 0.06³.75mg/kg.The method was used in detection of some colored foods on the market and the results showed that the method was simple in pre-treatment, good separation in chromatograph, suitable for detection of various synthetic colors in foods.The detection results also revealed that it was common for synthetic colors to be added in foods.