A novel gas sensor of formaldehyde and ammonia based on cross sensitivity of cataluminescence on nano-Ti₃SnLa₂O₁₁

A credible method based on cross sensitivity of cataluminescence (CTL) on nano-Ti₃SnLa₂O₁₁ was proposed for simultaneously determining formaldehyde and ammonia in air. The experimental conditions satisfying the algebraic sum rule of the CTL intensities of formaldehyde and ammonia were ascertained. They are two analysis wavelengths of 575 nm and 675 nm, the surface temperature of sensing materials of 350 °C and the flow rate of air carrier of 300 mL/min. The limits of detection of this method were 0.06 mg/m³ for formaldehyde and 0.14 mg/m³ for ammonia. The linear ranges of CTL intensity versus analyte concentration were 0.17-51.5 mg/m³ for formaldehyde and 0.31-59.6 mg/m³ for ammonia. The recoveries of 10 testing standard samples by this method were 97.3-102.7% for formaldehyde and 97.6-102.4% for ammonia. Common coexistence matters, such as acetaldehyde, methylamine, benzene, toluene, ethylbenzene, ethanol, sulfur dioxide and carbon dioxide, did not disturb the determination. The relative deviation (RD) of CTL signals of continuous 150 h detection for gaseous mixture containing formaldehyde and ammonia was less than 3%, which demonstrated the longevity and steady performance of nano-Ti₃SnLa₂O₁₁ to formaldehyde and ammonia.