Development of Method for Detection of Rhodamine B Dye in Chilli Powder (Capsicum annuum L.)

Abstract

Background: Chilli is a major spice consumed all over the world. There are reports that chilli is commonly adulterated with Rhodamine B (Rh B) which is a fluorescent but carcinogenic and neurogenic dye. To detect the presence of Rhodamine B dye in chilli powder, fluorescent spectroscopic method was developed. Methods: Adulterated samples of chilli were prepared by spiking chilli powder with Rhodamine B dye at different concentrations. Effect of different solvents for extraction of dye was studied and fluorescent spectroscopy based method for quantitative detection of Rhodamine B dye in chilli powder was developed. Limit of detection, limit of quantification, linearity and recovery studies were carried out. Result: Rhodamine B dye showed maximum intensity at 577 nm emission wavelength. Solvent effect showed that among the studied solvents; the highest and lowest fluorescence intensity of dye was observed in methanol and water, respectively. Standard curve of Rhodamine B dye was prepared in the range of 0.4-2.4 µg/ml concentration. Under experimental conditions, limit of detection and limit of quantification for pure dye was 0.19 µg/ml and 0.63 µg/ml and for dye in chilli matrix was 0.42 µg/g and 1.47 µg/g, respectively. The developed method could detect Rhodamine B dye in spiked chilli samples with recovery limit of 93%. Fluorescent spectroscopy based developed method is sensitive and capable of detecting Rhodamine B dye in microgram concentration.