A Field Comparison of Volatile Organic Compound Measurements Using Passive Organic Vapor Monitors and Stainless Steel Canisters

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• 作者：Gregory C. Pratt ; Don Bock ; Thomas H. Stock ; Maria Morandi ; John L. Adgate ; Gurumurthy Ramachandran ; Steven J. Mongin ; and Ken Sexton
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：May 1, 2005
• 年：2005
• 卷：39
• 期：9
• 页码：3261 - 3268
• 全文大小：874K
• 年卷期：v.39,no.9(May 1, 2005)
• ISSN：1520-5851

文摘

Concurrent field measurements of 10 volatile organiccompounds (VOCs) were made using passive diffusion-based organic vapor monitors (OVMs) and the U.S. FederalReference Method, which comprises active monitoringwith stainless steel canisters (CANs). Measurements wereobtained throughout a range of weather conditions,repeatedly over the course of three seasons, and at threedifferent locations in the Minneapolis/St. Paul metropolitanarea. Ambient concentrations of most VOCs as measured byboth methods were low compared to those of otherlarge metropolitan areas. For some VOCs a considerablefraction of measurements was below the detection limit ofone or both methods. The observed differences betweenthe two methods were similar across measurement sites,seasons, and meteorological variables. A Bayesiananalysis with uniform priors on the differences was applied,with accommodation of sometimes heavy censoring(nondetection) in either device. The resulting estimates ofbias and standard deviation of the OVM relative to theCAN were computed by tertile of the canister-measuredconcentration. In general, OVM and CAN measurementswere in the best agreement for benzene and other aromaticcompounds with hydrocarbon additions (ethylbenzene,toluene, and xylenes). The two methods were not in suchgood agreement for styrene and halogenated compounds(carbon tetrachloride, p-dichlorobenzene, methylene chloride,and trichloroethylene). OVMs slightly overestimatedbenzene concentrations and carbon tetrachloride at lowconcentrations, but in all other cases where significantdifferences were found, OVMs underestimated relative tocanisters. Our study indicates that the two methods arein agreement for some compounds, but not all. Weprovide data and interpretation on the relative performanceof the two VOC measurement methods, which facilitatesintercomparisons among studies.