Cyanide Detection Techniques in Aqueous Media

Cyanide is a highly toxic anion with widespread industrial use and environmental impact. Its detection at trace levels in water is critical for environmental monitoring, public health and industrial process control. Current strategies encompass electrochemical sensors that exploit redox reactions at modified electrodes, spectroscopic methods including ultraviolet–visible and near-infrared absorption, and optical chemosensors based on colourimetric or fluorescent signal transduction. Advances in fluorescent probes have harnessed intramolecular charge transfer to achieve rapid and selective ‘turn-on’ or ‘turn-off’ responses, while ratiometric systems improve quantitative accuracy by comparing emission intensities at two wavelengths. Paper-based microfluidic devices and membrane-embedded materials extend detection into low-resource or field settings, offering portability and low cost. Integration with smartphone readouts further enhances accessibility and real-time data analysis. Emerging platforms such as metal–organic nanosheets enhance surface area and binding affinity, achieving limits of detection at or below regulatory thresholds. Together, these innovations address the global need for sensitive, selective and deployable cyanide assays in diverse aqueous matrices.

Research from Nature Portfolio

Recent studies have introduced an origami-folded paper microfluidic device for point-of-need determination of cyanide in acidic blood samples. The system acidifies blood to liberate HCN gas, which diffuses into a borate buffer and interacts with a platinum complex, producing a visible colour change captured by a smartphone app. Under optimised conditions, the device quantified cyanide over the 1.0–100 µmol L–1 range with a detection limit of 0.4 µmol L–1, demonstrating reliability in fire-survivor blood samples. Another investigation presented a dual-channel near-infrared sensor that employs internal charge transfer to produce distinct fluorescence and absorption signatures. By monitoring two emission ratios and multiple absorption bands, the probe achieved selective detection of cyanide and was further applied to measure β-glucosidase activity via released CN–, illustrating the potential for enzymatic assays in complex samples.

Cyanide Detection Techniques in Aqueous Media publication trend

The graph below shows the total number of articles in cyanide detection techniques in aqueous media across all publications each year (not limited to Nature Index journals).

Technical terms

Intramolecular charge transfer (ICT): electronic transition within a molecule upon analyte binding, causing a change in its optical spectrum.

Limit of detection (LOD): the lowest analyte concentration that can be distinguished from background noise with statistical confidence.

Ratiometric fluorescence: analytical technique comparing emission intensities at two distinct wavelengths to improve quantitative reliability.

Colorimetric detection: method relying on a visible colour change to signal the presence of an analyte.

Origami paper analytical device (OPAD): folded-paper platform that guides fluids through patterned channels for portable assays.

Metal–organic nanosheets (MONs): ultrathin two-dimensional materials composed of metal ions coordinated to organic ligands, offering high surface area and enhanced analyte interaction.

References

1. Cu-TCPP Metal–Organic Nanosheets Embedded Thin-Film Composite Membranes for Enhanced Cyanide Detection and Removal: A Multifunctional Approach to Water Treatment and Environmental Safety. ACS Applied Materials & Interfaces (2025).
2. A New Phenothiazine-Based Fluorescent Sensor for Detection of Cyanide. Biosensors (2024).
3. Chemosensors based on N-heterocyclic dyes: advances in sensing highly toxic ions such as CN − and Hg 2+. RSC Advances (2021).
4. Ratiometric and colorimetric near-infrared sensors for multi-channel detection of cyanide ion and their application to measure β-glucosidase. Scientific Reports (2015).
5. Origami paper analytical assay based on metal complex sensor for rapid determination of blood cyanide concentration in fire survivors. Scientific Reports (2021).
6. Quantifying cyanide in water and foodstuff using corrin-based CyanoKit technologies and a smartphone. Analyst (2018).