Sampling and Measurement for Inorganic Gaseous Pollutants

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

Inorganic Gaseous Pollutants 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

Inorganic Gaseous Pollutants 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 NO 2 is avoided by using a filter coated with an oxidizing agent

Inorganic Gaseous Pollutants NDIR method Non dispersive infrared (NDIR) photometry is also commonly used for measuring CO and CO 2 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

Inorganic Gaseous Pollutants NO 2 monitors Several types of personal NO 2 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

Inorganic Gaseous Pollutants Palmes tube Tube is exposed to air by removing the cap Concentration of NO 2 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