A potentiometric detector for hydrogen cyanide gas using silver dicyano complex

Area of Science:

• Electrochemistry
• Environmental Science
• Analytical Chemistry

Background:

• Hydrogen cyanide (HCN) is a highly toxic gas with significant environmental and health implications.
• Accurate detection of HCN at low concentrations, such as the threshold limit value (TLV), is crucial for safety and monitoring.
• Existing detection methods may lack sensitivity or real-time capabilities.

Purpose of the Study:

• To develop and present a sensitive electrochemical method for detecting hydrogen cyanide gas in the atmosphere.
• To establish a method capable of detecting HCN at its threshold limit value (TLV).
• To characterize the performance and linearity of the developed sensor.

Main Methods:

• Utilized a sensor comprising two silver electrodes separated by a solution of silver dicyano complex at pH 11.5.
• One silver electrode served as a reference (concealed), while the other was exposed to ambient air for sensing.
• Measured the potential difference generated between the electrodes upon exposure to hydrogen cyanide gas.

Main Results:

• A linear relationship was observed between the potential difference and the logarithm of hydrogen cyanide concentration (0.66–42.3 mg/m³).
• The sensor exhibited a slope close to 120mV and a high regression coefficient (R² ≈ 0.997).
• The minimum detectable limit was determined to be 0.66 mg/m³, with a standard deviation of 6% (n=4).

Conclusions:

• The developed electrochemical sensor demonstrates high sensitivity and accuracy for detecting hydrogen cyanide gas.
• The method is suitable for monitoring hydrogen cyanide at its threshold limit value.
• The sensor's performance is consistent across various concentrations of the silver dicyano complex solution.