Page:NIOSH Manual of Analytical Methods - 3704.pdf/4

 PERCHLOROETHYLENE (portable GC) in exhaled breath and air: METHOD 3704, Issue 1, dated 15 January 1998 - Page 4 of 5

obtained using conventional laboratory GC analysis by NMAM 1003 [2]. Sample bags should be analyzed as soon after collection as practical. Perchloroethylene (at concentrations of 5, 25, and 100 ppm) was found to be stable in Tedlar bagsfor more than 8 hours (loss of analyte <8%); storage for 24 hours resulted in a greater loss of analyte with increased concentration (20% loss of analyte at 100 ppm after 24 hours). Evaluation of this method, which uses a capillary column, indicated that perchloroethylene can be separated from acetone, isoprene, methanol, ethanol, acetaldehyde, carbon tetrachloride, chloroform, benzene, butane, styrene, toluene and xylenes. These compounds were selected for testing because they are either common human metabolites or substances which are frequently used in dry cleaning facilities with perchloroethylene. Most permanent gases, including water vapor, carbon monoxide, and carbon dioxide, are not detected using a photoionization detector, and therefore, do not interfere with the analysis. However, water vapor at very high concentrations in exhaled breath was considered likely to condense in the bags subsequent to collection. To prevent condensation, exhaled breath was dried by passing it through a desiccant before entering the sample bag. The use of desiccant during the collection of exhaled breath samples was shown to decrease the perchloroethylene concentration by 7.0% at 1 ppm and 9.6% at 10 ppm, for an average 8.3% loss of analyte as a result of drying. Correction can be made for this loss either mathematically by increasing the measurement proportionally or by passing the calibration gas through the drying tube prior to calibration of the instrument.

REFERENCES: [1] Sweet ND [1996]. A field method for near real-time analysis of perchloroethylene in end-exhaled breath [Dissertation]. Cincinnati, OH: University of Cincinnati, College of Medicine, Department of Environmental Health. [2] NIOSH [1994]. Hydrocarbons, halogenated: Method 1003. In: Eller PM, Cassinelli ME, eds. NIOSH Manual of Analytical Methods (NMAM), 4th ed. Cincinnati, OH: National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 94-113. [3] NIOSH [1996]. Volatile organic compounds (screening): Method 2549. In: Eller PM, Cassinelli ME, eds. th NIOSH Manual of Analytical Methods (NMAM), 4 ed., 1st Supplement. Cincinnati, OH: National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No.96-135. [4] Toutonghi G, Echeverria D, Morgan M, et al [1994]. Characterization of exposure to perchloroethylene, with biological monitoring, in commercial dry cleaning workers, submitted for publication in Scandinavian Journal of Work and Industrial Health.

METHOD WRITTEN BY: G. E. Burroughs, NIOSH, DPSE, and Nathan Sweet, University of Cincinnati

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition