Evaluation of a method for soluble silver on air filter samples.
Airmon 2005, Fifth International Symposium on Modern Principles of Air Monitoring, June 12-16, 2005, Loen, Norway. Oslo, Norway: National Institute of Occupational Health, 2005 Jun; :O-50
Several occupational exposure limits and guidelines exist for silver, but the values for each depend on the form of silver as well as the individual agency making the recommendations. For instance, the American Conference of Governmental Industrial Hygienists has established separate threshold limit values for metallic silver (0.1 mg/m3) and soluble compounds of silver (0.01 mg/m3). On the other hand, the permissible exposure limit (PEL) set by the Occupational Safety and Health Administration and the Mine Safety and Health Administration and the recommended exposure limit by the National Institute for Occupational Safety and Health are 0.01 mg/m3 for all forms of silver. It generally was not possible, without process knowledge, to distinguish soluble silver from insoluble silver compounds following collection of air samples. Therefore, analytical results were typically reported as total silver. Laboratory work was conducted at NIOSH to evaluate a method to differentiate between the quantity of water-soluble silver compounds and total silver collected on filters. The following work is a modification of the International Organization for Standardization (ISO) method 15202 - Determination of metals and metalloids in airborne particulate matter. The study design incorporated experiments to determine analytical recovery and stability, filter selection, and storage stability. Teflon (PTFE) filters (2 um, 37 mm) in opaque cassettes were either spiked with known amounts of silver nitrate or contained a known mass of solid silver nitrate. The samples were placed in a shaker bath for 60 minutes at 37 degrees C. The extractant was filtered, acidified, and analyzed by inductively coupled plasma - mass spectrometry (ICP-MS). The results showed that over 90% of the silver was recovered from the filters. Recoveries were in accordance with the NIOSH Guidelines for Air Sampling and Analytical Method Development and Evaluation.
Silver-compounds; Air-filters; Air-samples; Air-sampling; Occupational-exposure; Exposure-limits; Laboratory-work; Laboratory-testing; Metals; Metalloids; Airborne-particles
National Institute for Occupational Safety and Health, Spokane Research Laboratory, 315 E. Montgomery Ave., Spokane, WA 99207, USA
Abstract; Conference/Symposia Proceedings
Airmon 2005, Fifth International Symposium on Modern Principles of Air Monitoring, June 12-16, 2005, Loen, Norway