Sample Retentivity Properties of Passive Organic Vapor Samplers and Charcoal Tubes Under Various Conditions of Sample Loading, Relative Humidity, Zero Exposure Level Periods and a Competitive Solvent

The effects of samples loading, relative humidity, the presence of a competitive solvent and zero solvent exposure level periods on sample retentivity of two organic vapor passive samplers and the charcoal tube were investigated. The passive samplers and charcoal tubes were exposed to high levels of organic solvents followed by periods of 10,55 and 70% relative humidities with and without the presence of toluene as a competitive solvent. Significant sample losses occurred for the passive samplers loaded with methyl chloroform, methy lene chloride and isopropanol when the samplers were left in an atmosphere of 70% relative humidity and zero level of organic solvent vapor for 1 to 6 hours. For methyl chloroform, sample losses from the passive samplers were as high as 50% for a sample loading of 5 mg and 70% for a loading of 15 mg. Sample loss increased with increasing zero exposure time and higher relative humidity. Both samplers showed additional sample losses when toluene as a competitive solvent was introduced into the atmosphere during the zero test solvent exposure periods at 70% relative humidity. At 10% relative humidity no significant sample losses occurred with either passive sampler. For one sampler significant sample losses were observed during zero exposure periods at 10% relative humidity when toluene was introduced as a competitive solvent. No sample losses of toluene and methyl isobutyl ketone were observed during zero concentration periods of 3 hours at 70% relative humidity following initial loading of the passive samplers.