Field portable Cr2O3 nanozyme based paper sensors for on-site screening of arsenic and cadmium in quality control of herbal products

초록

The aim of this work was to develop a colorimetric sensor that is specific to arsenic (As3+) and cadmium (Cd2+) ions and is stable, sensitive, selective, and affordable. For the quantitative detection of As3+ and Cd2+, a dual platform (filter paper-based and UV-Vis approach) was utilized. Herein, we synthesized chromium oxide nanoparticles (Cr2O3 NPs) using co-precipitation method and characterization was done using FT-IR, FESEM/ SEM, AFM, UV-Vis, and XRD which confirmed the successful synthesis of NPs. The crystalline structure, abundance of binding sites, and large surface area of the NPs contributed to its increased suitability for sensor development. These nanoparticles act as nanozymes in colorimetric sensing of As3+ and Cd2+ ions. Numerous parameters were optimized, such as the incubation period (12 min), concentration of TMB (3 and 4 mg/mL), concentration of H2O2 (100 mM), and the concentration of NPs (3 mg/mL). This sensing probe showed exceptional sensitivity over a relatively wide linear range, with a lower detection limit (LOD) of 26 nM and 0.41 mu M in UV-Vis spectrophotometry and filter-paper, respectively for As3+ and in case of Cd2+ detection limit is 81 nM and 1 mu M in UV-Vis spectrophotometry and filter-paper, respectively. Testing against multiple interfering species was used to determine selectivity and real sampling on herbal products (Dmaghi, Maqbood, Safoof-e-tabkir) to check practical applicability in which recovery rates validate the technology for use in practical settings. The developed colorimetric sensor demonstrated remarkable selectivity and sensitivity in identifying heavy metals, such as As and Cd, even at low concentrations, according to the results.

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