Effect of sample flow rate and sampling duration on the absorption of NO2 in the sodium arsenite monitoring method.
The effect of the two most critical parameters, the sample flow rate and sampling duration, on the absorption efficiency of NO2 in the sodium arsenite method of nitrogen dioxide determination in ambient air was studied. Laboratory experiments showed a high sensitivity to these parameters, which were subjected to variation during actual field monitoring. The reported NO2 absorption efficiency of the method of 82% at a flow rate of 0.2 l min-1 was found to be as low as 33% at a flow rate of 1.0 l min-1 for a sampling duration of 24 h. Similarly, a considerable decrease in absorption efficiency with increasing sampling duration from 2 to 24 h was observed at a particular flow rate. Correction factors for the absorption efficiency were evolved that can be used to update the existing database, as well as future NO2 data generated using this manual monitoring method.
National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur 440 020, India. svapgoyal@rediffmail.com
S K
SK
Goyal
D000042:Absorption; D018053:Arsenites / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods; D004791:Enzyme Inhibitors / Q000737:chemistry; D009585:Nitrogen Dioxide / Q000032:analysis*; D010083:Oxidants, Photochemical / Q000032:analysis*; D015203:Reproducibility of Results; D017670:Sodium Compounds / Q000737:chemistry; D013048:Specimen Handling; D013439:Sulfhydryl Reagents / Q000737:chemistry
D018053:Arsenites; D004791:Enzyme Inhibitors; D010083:Oxidants, Photochemical; D017670:Sodium Compounds; D013439:Sulfhydryl Reagents; C017947:sodium arsenite; D009585:Nitrogen Dioxide