Smartphone-based colorimetric determination of triclosan in aqueous samples after ultrasound assisted-dispersive liquid–liquid microextraction under optimized response surface method conditions

Abstract

In the present study, a simple and low cost methodology based on ultrasonic assisted-dispersive liquid–liquid microextraction (UA-DLLME) followed by smartphone-based colorimetric measurement was introduced for the separation and determination of Triclosan (TCS) from contaminated waters. This method is based on the formation of an azo compound from the alkaline reaction of TCS with a diazonium ion, resulting from the reaction of sodium nitrite and p-sulfanilic acid in an acidic medium. The orange-brown color product was extracted into a low volume of organic phase by UA-DLLME method and RGB values were recorded with free Android app Color Grab. The effective parameters in this procedure, namely solution pH, p-sulfanilic acid and nitrite concentration, reaction time and volume of the extraction solvent were investigated and optimized by response surface methodology (RSM) based on a Box-Behnken design (BBD) model. Under optimum conditions, the calibration graph was linear in the range of 3.0 and 200 μg L-1 of TCS. The limit of detection (LOD) and limit of quantification (LOQ) were 0.8 and 2.7 μg L-1, respectively. The proposed method was successfullyused for the analyses of triclosan in several water and wastewater samples and satisfactory results were obtained.