Highly sensitive zero-order emission system - fluorescence detection-liquid chromatographic method for simultaneous estimation of two banned phenyl xanthene dyes in bottled chili sauce

ABSTRACT. A zero-order emission system was applied to address the variation in emission wavelengths between analytes. Also, it assists to compensate for the drop in emission intensity resulted from the changes in analyte excitation wavelength. So, a high performance liquid chromatography-fluorescence detector (HPLC-FLD) with zero order emission mode was used for the simultaneous estimation of rhodamine B (RhB) and eosin Y (EsY) based on their native fluorescence. The presented method is considered the first fluorescence method for simultaneous determination of RhB and EsY. The efficiency of the developed method was tested by determining the two dyes in a high matrix sample, chili sauce. Under the optimum condition, a linear calibration graphs for RhB and EsY in range of 0.5 -300 ng/mL 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. RhB was detected only in one chili sauce sample at a concentration of 0.388 ng/mL while EsY was not found in any sample. KEY WORDS: Rhodamine B, Eosin Y, HPLC-FLD, Zero-order emission mode, Solid phase extraction Bull. Chem. Soc. Ethiop. 2023, 37(6), 1315-1323. DOI: https://dx.doi.org/10.4314/bcse.v37i6.2