title: Evaluation of a real-time aerosol monitor (RAM-S) for inhalation studies.
abstract: Measurement of the aerosol concentration in inhalation toxicology studies is generally done by gravimetric and/or chemical analysis of filter samples taken over a known period of time at a fixed sampling flow rate. The value obtained represents the time-averaged concentration in an exposure chamber. However, the filter method does not provide information as to the stability of aerosol concentration in "real-time" nor as to the time required for the aerosol concentration to reach the target value during the start-up of exposures. In order to accomplish evaluation of aerosol stability and chamber rise and fall times, a direct measurement device is required. An available real-time aerosol monitor (RAM-S, GCA Corp., Bedford, MA) is a photometer which collects scattered light from an aerosol cloud at a 70 +/- 25 degrees angle. The output signal is 0 to 10 volt with three ranges corresponding to maximum aerosol concentrations of 200, 20, and 2 mg/m3. The performance of the RAM-S was evaluated in inhalation studies involving nickel sulfate hexahydrate, nickel oxide, nickel subsulfide, and azodicarbonamide. Several RAM-S units were calibrated by obtaining both filter samples and voltage readings of a RAM-S simultaneously. Results indicated that the response of the RAM-S instruments was linear. However, the voltage output per given aerosol concentration was different for each compound used. Furthermore, there was interinstrument variability in the voltage response to aerosol concentration of a given compound. At concentrations higher than 100 mg/m3, modification of the flow system in the RAM-S was made to increase the sheath air around the optical system and also to dilute the aerosol concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Inhalation Toxicology Research Institute, Lovelace Biomedical and Environmental Research Institute, Albuquerque, New Mexico 87185.
authors: Y S
authors: YS
authors: Cheng
authors: E B
authors: EB
authors: Barr
authors: J M
authors: JM
authors: Benson
authors: E G
authors: EG
authors: Damon
authors: M A
authors: MA
authors: Medinsky
authors: C H
authors: CH
authors: Hobbs
authors: T J
authors: TJ
authors: Goehl
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols; D005069:Evaluation Studies as Topic; D009532:Nickel / Q000032:analysis; D010316:Particle Size
chemical_list: D000336:Aerosols; C029938:nickel sulfate; D009532:Nickel