Smartphone-based on-cell detection in combination with emulsification microextraction for the trace level determination of phenol index

Abstract

In this study, a simple and portable device based on smartphone detection was developed for the determination of ppb levels of phenol index. The method was a combination of emulsification microextraction and smartphone sensing. The device consisted of a pycnometer as both extraction vial and detection cell, and a smartphone as a detector and data processing unit. Phenol was reacted with 4-aminoantipyrine in the sample solution to produce a colored compound. The colored product was extracted through an emulsification microextraction approach. Then, analyte quantification was performed using smartphone-based on-cell detection. The effect of key experimental factors on the method sensitivity was studied. The optimized method showed a linear range of 5–100 µg L−1 with the detection limit and the quantification limit of 2 and 5 µg L−1, respectively. The method provided the accurate and reproducible determination of phenol index in water and wastewater samples. The recoveries higher than 89% with relative standard deviations lower than 7% were obtained. The method required no external power supply or any complicated instrument, which made it a portable device suitable for field analysis.