Wednesday, October 13, 2010

ANALYSIS OF PPB LEVELS OF PHOTOCHEMICAL SMOG COMPONENTS IN AIR WITH A PORTABLE ANALYZER

J.N. Driscoll and J.L. Maclachlan
PID Analyzers LLC
Abstract Number: 180 - 18P
Session 180 - New Developments in Analytical Instrumentation and Software
Day and Time: Sunday, March 13, 2011

5:30pm-7pm Room 412A Georgia World Congress Center

A number of cities in the US have problems with high levels of Ozone and/or photochemical smog including LA, Denver, Houston and even Boston. This phenomenon, while observed in the LA Basin area since the 1950’s, is still not well understood. Fixed monitoring stations have been established for several decades but this has not helped understand the ozone/photochemical smog formation problem. A portable analyzer could provide more valuable data to help solve the problem.....
We have developed a portable analyzer  for monitoring three of the pollutants that contribute to photochemical smog formation. namely: VOC’s, O3, ,NO2. The analyzer incorporates a photoionization detector (PID) that measures VOC’s down to 1 ppb, and electrochemical sensors for ozone (10 ppb) and nitrogen dioxide (20 ppb).
The VOC’s & NO2 were calibrated with permeation tubes. Toluene was used as the calibration gas for VOC’s. A zero gas generator was used to remove ppb levels of VOC’s, NO2 & Ozone from the ambient air for calibration. The ozone sensor was calibrated with an ozone generator. The analyzers were accurately calibrated over the range from low ppb to 1,000 ppb
The analyzer can store up to 20,000 points of data For 3 channels taken every 5 seconds for 24 hours this is 864 data points or 23 days of data. The normal operating time on a continuous basis is about 12 hours. If we could switch the PID duty cycle to 10 %, and increase the size of the battery, we could get nearly three weeks of operation off a full charge. Thus the analyzer could be used to spot check, leave for 12 or even three weeks.
We will evaluate the precision & accuracy in the lab and field as well as comparisons with a continuous monitoring networked for the same pollutants. 

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