Gold Nanoparticle-Based Colorimetric Sensing of Arsenic(III) and Arsenic(V) in Groundwater

Overview

Kundu and Kar (2026) report an AuNPs-based colorimetric sensing approach for the simultaneous or sequential detection of both inorganic arsenic species — As(III) (arsenite) and As(V) (arsenate) — in groundwater. The method exploits differential affinity of gold nanoparticles for the two arsenic oxidation states, enabling visual or spectrophotometric discrimination.

Key numbers

Limit of detection (LOD): approximately 2.5 × 10^-3 mM for arsenic, equivalent to approximately 0.19 µg/L (0.19 ppb). This is well below the WHO guideline of 10 µg/L for arsenic in drinking water, making it analytically relevant for groundwater monitoring.

The method distinguishes As(III) from As(V), which is relevant for speciation purposes — though this is not the food-matrix speciation requirement (food matrices require HPLC-ICP-MS for iAs vs. organic arsenic species separation, not As(III)/As(V) separation per se). Validated in groundwater matrices only.

Methods (brief)

AuNPs colorimetric platform. Differential nanoparticle aggregation behavior for As(III) vs. As(V). Spectrophotometric or visual readout. Simple, low-cost design. Not validated in food matrices.

Implications

Testing: The sub-0.2 µg/L LOD is analytically relevant for drinking water monitoring. For food matrix arsenic testing, this approach would require adaptation given complex matrix interferences. The speciation note (As(III)/As(V)) is distinct from iAs/organic arsenic speciation in food; both axes matter for comprehensive arsenic risk assessment.

Wiki pages updated on ingest

• arsenic-methods

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