N,S-Doped Carbon Quantum Dots from Rice Straw for Fluorescence Detection of Mercury(II)

Overview

Nguyen et al. (2026) synthesize nitrogen and sulfur co-doped carbon quantum dots (N,S-CQDs) from rice straw waste biomass as a precursor, and use these as a fluorescence-quenching probe for the selective detection of Hg2+ in water samples. The use of rice straw as a zero-waste, green synthesis precursor is highlighted as an environmental sustainability contribution.

Key numbers

Limit of detection (LOD): 0.148 mM (approximately 29.7 µg/L, or ~30 ppb) for Hg2+. This LOD is above the WHO drinking water guideline for mercury (6 µg/L) and significantly above food-matrix regulatory levels, making this approach a screening-level rather than compliance-level tool for water.

Validated in water matrices only. No food matrix validation.

Methods (brief)

N,S-CQDs synthesized hydrothermally from rice straw and a nitrogen/sulfur source. Fluorescence quenching mechanism in the presence of Hg2+. Simple synthesis route; green chemistry appeal. LOD of 0.148 mM (~30 ppb) is not competitive with ICP-MS for food or regulated water testing, but demonstrates the rice-straw-to-sensor concept.

Implications

Testing: The LOD is too high for most food or drinking-water regulatory applications. This paper is primarily a materials chemistry contribution rather than a method ready for food monitoring. Of note for the wiki’s synthesis of low-cost sensor approaches to Hg detection.

Wiki pages updated on ingest

• mercury-methods

Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.