A dual-mode visual detector for toxic hydrazine

Hydrazine (N₂H₄) is one of the commonly used chemical reagents in numerous industries and applications but its toxicity to humans poses a need to develop simple visual detection methods. Herein, we demonstrate a novel dual-mode system to detect and simultaneously consume hydrazine in vapour and solution by using a small photoresponsive molecule that has altered optical response (both colourimetric and fluorescent) after reacting with hydrazine.

A small photoresponsive molecule changes colour from blue to colourless when exposed to hydrazine vapours. It also becomes emissive providing two convenient ways of detecting the presence of this toxic chemical.

A Colorimetric Approach towards Polycyclic Aromatic Hydrocarbon Sensing

The colorimetric detection of polycyclic aromatic hydrocarbons (PAHs) was achieved using photochromic compounds. This technique exploits the ability of the photochromic compound to reversibly change from a colourless to a coloured compound using ultraviolet light and visible light. In the presence of a PAH, this photoisomerization is inhibited. The degree of inhibition corresponded to the molar absorptivity and excitation wavelength of the PAH, and with a limit of detection in the micromolar range, the current method delivers a highly sensitive and selective technology. In addition, PAH mixtures were successfully identified using this method, providing a potentially fast in-field sensing technology for the identification of likely sources of spilled oil.

International Year of Light and Light-Based Technologies

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