[Determination of trace ammonia in indoor air by ninhydrin spectrophotometry].
OBJECTIVE
To develop a new spectrophotometric method to detect trace ammonia in indoor air.


METHODS
Ammonia in the air was absorbed by 0.01 mol/L sulfuric acid in a bubbling absorption tube. With 95 degrees C of water bath and pH 5.5-6.0 of buffer solution of acetic acid-sodium acetate, the ammonium in the solution reacted with ninhydrin at the presence of ascorbic acid to form a royal purple product which has a maximum absorbance at 568 nm.


RESULTS
This method produced a linear range of 0-8 microg/10 mL. The detection limit was 0.06 mg/m3. The recoveries of the method ranged from 96.2% to 102.3%, with 2.8%-6.8% of relative standard deviations.


CONCLUSIONS
The method is simple, rapid and safe. The common coexisting substances in the air do not interfere with the determination. The precision and accuracy can satisfy the requirements of the determination of trace ammonia in indoor air.
Li
Yang
Y
Department of Sanitary Technology, West China School of Public Health, Sichuan University, Chengdu 610041, China.
Liu
Yi
Y
Sun
Cheng-jun
CJ
D016902:Air Pollution, Indoor / Q000032:analysis*; D000641:Ammonia / Q000032:analysis*; D009555:Ninhydrin; D015203:Reproducibility of Results; D013053:Spectrophotometry / Q000379:methods*
D000641:Ammonia; D009555:Ninhydrin