Faculty Publications


Detection and estimation of part-per-billion levels of formaldehyde using a portable high-throughput liquid absorption air sampler

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Environmental Science and Technology





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In view of the known adverse health effects of formaldehyde and its suspected carcinogenicity, a convenient and simple apparatus for its rapid detection is highly desirable. A portable high-throughput liquid absorption air sampler (PHTLAAS) was therefore evaluated for the rapid and ultrasensitive detection of formaldehyde. Controlled concentrations of formaldehyde in air were generated with a constant-drive syringe pump and mixing chamber apparatus and were either sampled by the PHTLAAS, at a rate of about 200 L/min, or fed to two series-connected liquid impingers. In either case, the formaldehyde was absorbed in a small volume of aqueous sodium bisulfite and measured by the chromotropic acid method. The reddish-purple color of the chromogen formed with chromotropic acid provides a sensitive test for the screening of low levels of formaldehyde in ambient air. Comparison of samples collected from the test sampler with those from the impingers before and after each test yielded PHTLAAS collection efficiencies of about 50 and 40% at formaldehyde concentrations of 16 and 45 ppb v/v, respectively, which translate to a lower detection level of about 1 ppb v/v with the chromotropic acid method. The PHTLAAS was also tested in parallel with a standard method for preconcentration and detection of formaldehyde vapor in an applied anatomy laboratory, with the results of the two methods showing fair agreement. The collection method is simple and fast, and should be applicable to the sampling and preconcentration of other hazardous air contaminants with suitable trapping solutions. However, at ambient temperatures below or above 20-24 °C, caution should be exerted in applying its laboratory-derived correction factors.

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