An environmentally friendly hydrophobic deep eutectic solvent dispersive liquid liquid microextraction for spectrophotometric analysis of indigo carmine (E132)

This method was developed using ultrasonic-assisted hydrophobic deep eutectic solvent based dispersive liquid liquid microextraction (UA HDES DLLME) to determine trace levels of indigo carmine in food samples prior to analysis by UV Vis spectrophotometer at 610 nm. Some important analytical parameters such as pH, and sample volume and influence of foreign components were considered for optimization studies. A suitable extraction medium for indigo carmine was obtained at pH 3.0 and the mentioned above optimum conditions were determined. For instance, 15 mL sample volume, 1 mL final volume and a short centrifucation and ultrasonication time have been found. The limit of detection and limit of quantification were determined to be 2.79 ng mL−1, 9.31 ng mL−1 respectively. Moreover, the performed UA HDES DLLME process implemented to beverage, colored chocolate, chewing gum and nail polish samples. Analyte addition studies were carried out on an energy drink sample to demonstrate the accuracy of the method.