RadielloTM Type Passive Samplers versus ALPHA Type Passive Samplers
Nina Gartman, Christopher Lehmann, David Gay and Clyde Sweet
Central Analytical Laboratory
National Atmospheric Deposition Program
Champaign, IL 61820
Efforts to quantify and measure ammonia in the atmosphere are continuing within the NADP program. Currently 19 sites throughout the USA and Canada deploy passive devices that are impregnated with phosphoric acid and capture ambient ammonia gas. The NADP program is evaluating differences between passive ammonia devices at five of its 19 sites. ALPHA (Adapted low-cost Passive High Absorption) devices are being compared with RadielloTM devices. Both types of samplers work on diffusion theory, where ammonia is absorbed as ammonium ion by the interior cartridge.
Radiello™ cartridges are made of microporous polyethylene coated with phosphoric acid. Radiello™ cartridges are available with two types of diffusive bodies, one that is white in color and the other that is blue.
The cartridges loaded into the ALPHA devices must be impregnated with phosphoric acid at the Central Analytical Laboratory (CAL).
The passive samplers, once loaded with impregnated cartridges, have been deployed side-by-side in the field at five sites. After returning to the CAL, cartridges are removed, the ammonia is extracted in deionized water using sonication, and the extracts are analyzed within 24 hours by Flow Injection Analysis. The purpose of this study is to compare the precision, repeatability and reliability of two types of passive samplers. We should also determine whether there is a statistically significant effect between white- and blue-colored Radiello™ diffusive bodies.