Sensitive and Specific Analysis of Two Banned Phenyl Xanthene Dyes in Bottled Chili Sauce by High Performance Liquid Chromatography- Fluorescence Detection

Abstract

Abstract The risk of human exposure to phenylxanthene dyes is widely documented. Preliminary analysis of bottled chili sauce samples revealed the presence of two banned phenyl xanthene dyes (rhodamine B and eosin Y). Therefore, a simple, specific, and sensitive approach was implemented for the simultaneous estimation of rhodamine B (RhB) and eosin Y (EsY) in bottled chili sauce. The first high performance liquid chromatography-fluorescence detector (HPLC-FLD) was used for the simultaneous estimation of RhB and EsY, based on their native fluorescence. In addition, to overcome the difference in the excitation and emission wavelengths between the two dyes and maintain their sensitivity, a zero-order emission mode was selected in the fluorescence detector (FLD) unit. The excitation wavelength was adapted at 530 nm in mobile phase composed of 0.1% formic acid in ultrapure water (A) and methanol (B) at ratio of 30:70 v/v). Furthermore, using the Sep-Pak® C18 cartridge for solid-phase extraction method, interference from the chili sauce matrix was eliminated. Under the optimum condition, a linear calibration graphs in the range of 0.5- 300 and 0.5- 300 of RhB and EsY with r = 0.9994 and 0.9991, respectively were acquired. The limits of detection for RhB and EsY were 0.344 ng/mL (0.355 ng/g) and 0.215 ng/mL (0.222 ng/g), respectively. The recovery percentage and relative standard deviation of two analytes were obtained in the range of 98.38-101.86% and 0.83-1.66 % respectively. According to the results, the presented method offers specificity, convenience and sufficient sensitivity for the simultaneous estimation of RhB and EsY in wide variety of food matrices.