Sampling and Measurement for Inorganic Gaseous Pollutants.

Sampling and Measurementfor

Inorganic Gaseous Pollutants


Measuring Instruments

Measurement protocol depends largely on the objectives

Personal Carbon Monoxide monitors– COED I and COED II monitors(CO Exposure

Dosimeter)

– Originally developed for EPA by General Electric

– COED II was designed for use in a moving automobile


COED I monitors

• Capable of recording 1600 data points over a 24-hour exposure period

• Automatic data logging system• Works in the active mode by employing a small

pump installed in the monitor• CO laden air is continuously drawn into an

electro chemical cell which contains deionized water


COED I monitors

• CO reacts with water and changes its properties in a manner that is proportional to CO concentration

• Concentration of CO is directly read from the LCD display in ppm

• Interference from NO2 is avoided by using a filter coated with an oxidizing agent


NDIR method

• Non dispersive infrared (NDIR) photometry is

also commonly used for measuring CO and CO2

• Involves determining the difference in the

infrared energy absorption over all wavelengths

• Difference in the infrared energy absorbed is

proportional to the concentration of compound

in the sample gas


NO2 monitors

• Several types of personal NO2 monitors have been developed

• Most commonly used is known as Palmes tube– Works in a passive mode and works on the principle

of molecular diffusion

– Sampler consists of three stainless steel screens coated with triethanolamine

– One end of the tube is capped permanently while the other end has a removable cap


Palmes tube

• Tube is exposed to air by removing the cap

• Concentration of NO2 is determined from the intensity of resultant color by using a spectrophotometer

• A minimum amount of .05 mg must be collected on the wire screens to provide an accurate measurement

• Sampling time is approximately 24 hours

Sampling and Measurement for Inorganic Gaseous Pollutants.

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