ABSTRACT
A novel method based on cross sensitivity of cataluminescence (CTL) on nano-Ti3CeY2O11 was proposed for simultaneous determination of formaldehyde, benzene and sulfur dioxide in air.The relations between the concentrations of formaldehyde, benzene and sulfur dioxide and their CTL intensities were respectively ascertained at three wavelengths.The accurate concentrations of formaldehyde, benzene and sulfur dioxide can be calculated by superimposed total CTL intensities.The three analysis wavelengths are 420 nm, 535 nm and 680 nm.The surface temperature of the sensitive materials is 280℃.The carrier gas flow rate is 130 mL/min.The detection limits (3σ) are 0.04 mg/m3 for formaldehyde, 0.05 mg/m3 for benzene and 0.10 mg/m3 for sulfur dioxide, respectively.The linear ranges of CTL intensity versus analyte concentration are 0.08-75.60 mg/m3 for formaldehyde, 0.1-101.40 mg/m3 for benzene and 0.3 to 115.00 mg/m3 for sulfur dioxide.The recoveries of 12 testing standard samples by this method are 96.4%-103.7% for formaldehyde, 97.8%-102.5% for benzene and 97.2%-103.3% for sulfur dioxide.Common coexisting substances, such as acetaldehyde, toluene, hydrogen sulfide, ammonia, methanol, ethanol and carbon dioxide, do not disturb the determination.The relative deviation of CTL signals of continuous 200 h detection for gaseous mixture containing formaldehyde, benzene and sulfur dioxide is less than 2%, which shows the longevity of the nanometer composite oxide to formaldehyde, benzene and sulfur dioxide.This method makes full use of the cross sensitive phenomenon, and can realize the on-line analysis of formaldehyde, benzene and sulfur dioxide in air.
ABSTRACT
A novel method based on cross sensitivity of cataluminescence (CTL) generated on the surface of a nanometer composite oxide was proposed for simultaneous determination of benzene and trimethylamine (TMA) in air. A variety of nanometer composite oxides based on Y2 O3 that showed catalytic activity to many gas molecules were synthesized. For the fabrication of the detector, nanometer composite oxide was directly coated on the ceramic rod to form a 0. 1-0. 15 mm thick layer. The ceramic rod with nanometer composite oxide was inserted into a quartz tube with an inner diameter of 10 mm. The temperature of nanometer composite oxide was controlled by the digital heater. When gas samples passed through the nanometer composite oxide in the quartz tube by the air flow, the CTL was generated during the catalytic oxidation on the surface of the nanometer composite oxide. The CTL signals were respectively recorded by two ultra weak chemiluminescence analyzers. The CTL intensity and selectivity for the determination of benzene and TMA on nano- Zr3 Y2 O9 which was characterized by TEM were bigger and better than those on other nanosized composite oxides. The optimum experimental conditions were tested. Selective determination was achieved at a wavelength of 440 nm for benzene and 540 nm for TMA. The surface temperature of the nanometer materials was about 313 ℃. The flow rate of air carrier was about 140 mL/ min. The limit of detection of this method was 0. 30 mg / m3 for benzene at 440 nm and 0. 70 mg / m3 for TMA at 540 nm. The linear range of CTL intensity versus concentration of benzene at 440 nm was 0. 8-105. 0 mg / m3 , benzene at 540 nm was 3. 0-130. 0 mg / m3 , TMA at 440 nm was 2. 5-232. 0 mg / m3 and TMA at 540 nm was 1. 2-156. 0 mg / m3 . The recovery of 5 testing standard samples by this method was 96. 8% -102. 3% for benzene and 97. 6% -103. 4%for TMA. Common coexistence matters, such as formaldehyde, ethanol, acetone, ammonia, sulfur dioxide and carbon dioxide, did not disturb the determination. The relative standard deviation (RSD) of CTL signals of a continuous 200 h detection of gas mixture of 50 mg / m3 benzene and 50 mg / m3 TMA was 2. 0% , which demonstrated the longevity and steady performance of nano-Zr3 Y2 O9 to benzene and TMA under this experimental conditions.