Study of the long-term stability conditions of cyanide ion standard solutions

Abstract

Cyanide ions (CN⁻) are highly toxic and pose significant environmental and health risks. This study quantitatively evaluates the temperature-dependent decomposition kinetics of cyanide ion standard solutions under long-term storage conditions and explores implications for analytical calibration. The decomposition rate constants were determined at temperatures ranging from −18 °C to 25 °C, revealing a strong correlation between temperature and degradation rate. Freezing (−18 °C) maintained stability for approximately one year (rate change: −0.0005%), whereas at 25 °C, daily degradation reached −0.1032%. A predictive equation for estimating original cyanide mass fractions based on storage time and temperature was developed (r² > 0.999). And, this is the first time that it has been demonstrated that a cyanide ion standard solution is stable for more than one year when stored in a refrigerator. Additionally, effects of mass fraction and pH conditions of the cyanide ion standard solution were assessed. These findings provide guidance for preparing and storing traceable cyanide solutions and suggest future research on other toxic anions such as thiocyanate and cyanate. Additionally, preliminary tests on environmental water matrices were conducted.