Development of Cellulosic Paper-Based Test Strips for Mercury(II) Determination in Aqueous Solution

Abstract

Titration method (dropping-on method) was introduced as an efficient approach for determining the mercury ion (Hg ²⁺) concentration in aqueous solution by using fabricated cellulosic paper-based test strips. In this study, dithizone used as a recognition reagent was physically loaded on cellulosic paper-based test strips for Hg ²⁺ selective recognition. The sensing mechanism was established on the spectral absorption rate of the coordination compound that was formed by dithizone and Hg ²⁺ under strong acidic conditions. The calibration curve was obtained by the absorbency of Hg ²⁺-dithizone complexes from different Hg ²⁺ concentration solutions, and the correlation coefficient ( R ²) reached 0.9971. The detection range of the test trip for Hg ²⁺ was obtained at 0.1  μg/mL to 30  μg/mL. Moreover, these superior cellulosic paper-based test strips have a rapid color-forming time (1.5 min) and low volume demand (3.7  μL samples at 0.0127 g/L dithizone recognition concentration). This portable paper-based test strip can give potential applications for field screening or on-site semiquantitative analysis.