A Green Chemosensor for Colorimetric Determination of Phosphate Ion in Soil, Bone, and Water Samples Using Curcumin Nanoparticles

This article presents a sensitive and straightforward colorimetric chemosensor for the determination of phosphate ion utilizing curcumin nanoparticles (CUNPs) as the sensing system. The color of as-prepared CUNPs can be changed from yellow to orange upon adding iron(III) ions due to the formation of a complex with CUNPs. However, in the presence of phosphate ions, iron(III) ions prefer to bind to phosphate ions and, subsequently the color of CUNPs is selectively recovered because of releasing the iron(III) ions from the CUNPs-iron(III) complex. Therefore, in this work the selective color changing of the CUNPs-iron(III) system upon the addition of phosphate ions was used for the quantitative sensing of phosphate ions. Various factors, such as the pH, concentration of iron(III) and volume of CUNPs, were examined and the optimum conditions were established. A linear calibration graph over the range of 10 - 400 ng mL(-1) for phosphate (r = 0.9995) was achieved using the optimal conditions. The limit of detection (LOD) of the proposed method for phosphate was 7.1 ng mL(-1) and the relative standard deviation (RSD) for measuring 50 ng mL(-1) of phosphate was 3.7% (n = 8). The developed method was applied for the measurement of phosphate in water, soil, and bone samples. Satisfactory results were obtained.