a fast and green preconcentration method based on surfactant ion pair-switchable solvent dispersive liquid–liquid microextraction for determination of phenazopyridine in pharmaceutical and biological samples

Herein, a novel, fast, green and sensitive surfactant ion pair-switchable solvent dispersive liquid–liquid microextraction (sip-ss-dllme) method was developed for the preconcentration of phenazopyridine. protonated triethylamine bicarbonate is synthesized by the reaction of triethylamine and co2 in the presence of water. this protonated switchable solvent (soluble in water) easily converted to triethylamine which is insoluble in water. aliquat 336 was used as an ion-pair agent in this method, which results in the increase of the phenazopyridine extraction into the switchable solvent. variables affecting the performance of extraction were studied and optimized. the relative standard deviation (rsd) was 3.1% for five repeated determinations containing 20 µg/l of phenazopyridine. the linear range of the method for microextraction and determination of phenazopyridine was found to be 5–180 µg/l with a detection limit of 0.88 µg/l. the presented method was applied successfully for the determination of phenazopyridine in pharmaceutical and biological samples.