American Industrial Hygiene Conference and Exposition, May 13-16, 2006, Chicago, Illinois. Fairfax, VA: American Industrial Hygiene Association, 2006 May; :37
System-level evaluation of protective ensembles is increasingly being used to develop performance specifications. For example, the 2006 proposed revision of the NFPA 1994 standard requires particulate integrity tests for class 4 suits. While aerosol penetration tests exist, there is a continued need for better methods suitable for use with human subjects and capable of passively sampling trace levels of particulates at multiple body locations between the skin and the ensemble. Surveying aerosols with properties to facilitate passive sampling, we found iron (II,III) oxide, magnetite, attractive due to low toxicity and cost, availability in several particle sizes and sensitive analytical methods. Magnetite's magnetic susceptibility allows several isolation and detection schemes; most simply, collection with permanent magnets. However, a coating isolating the iron-containing magnet from the collected aerosol is required to prevent confounding the analysis. In this work, various coatings were evaluated for their compatibility with magnetic sampling and the analytical method. Collected magnetite was dissolved in acid, oxidized, and quantified by spectrophotometry. Method blank was determined to be 1.0 ug. Coatings alone results were silicone (2 ug), epoxy A (81 ug), polyethylene A (2 ug), polyethylene B (3 ug), polyperfluoroethylene (2 ug), and silicone (2 ug). Single coating on iron or magnet results were epoxy A (1,100 ug), epoxy B (> 3,600 ug), gold (575 ug), polyethylene A (3 ug), polyethylene B (3 ug), polyperfluoroethylene (2 ug), and silicone (660 ug). Incomplete coverage and delamination appeared responsible for magnet dissolution, which caused the high iron content in the extract. Double coatings results were epoxy A (10 ug) and silicone (1 ug). Polytetrafluoro-ethylene, silicone, and polyethylene A were selected for further analysis. Monitoring magnet strength and blanks after repeated use indicated that all of these coatings were acceptable. However, polyethylene A was selected for further development based on practical considerations.
American Industrial Hygiene Conference and Exposition, May 13-16, 2006, Chicago, Illinois