Filter paper-based optical sensor for the highly sensitive assessment of thorium in rock samples

Abstract

Filter paper-based optical sensors (FPOS) offer rapid and sensitive quantification of analytes. Herein we report, a simple, sensitive, selective and low-cost FPOS for Th(IV) determination. Filter paper strips, impregnated with Morin reagent are reacted with Th(IV) yielding an intense yellow complex whose RGB (red/green/blue) color intensities made the basis of the assessment. A plot of the blue channel color absorbance versus Th(IV) concentration was linear up to 4.0 µg mL− 1 with a detection limit of 0.1 µg mL− 1. The proposed method was accurate, precise and reliable for analyzing complex certified rock samples in excellent compliance with the certified values.