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Development of low-cost passive sampler from cow bone char for sampling of volatile organic compounds
Tala, W.; Chantara, S.; Thiansem, S. & Rayanakorn, M.
Abstract
A simple and low-cost passive sampler for collection
of volatile organic compounds, specifically benzene,
toluene, ethylbenzene and xylene (BTEX), from the
ambient air has been developed by using cow bone char
(CBC) as an adsorbent with desorption by solvent extraction
prior to analysis by gas chromatography–mass spectrometry
(GC–MS). The laboratory-made CBC was
prepared by calcination process in a partially oxidative
atmosphere. The developed passive sampler was tested for
a suitable amount of CBC used, diffusion tube type and
size, and sampling duration, in a closed chamber saturated
with each of the BTEX vapors. With the optimum amount
of 250 mg CBC packed in a glass bottle (82.6 mm
height × 11.1 mm i.d.) and the exposure time of 168 h,
detection limits (µg/m3) for BTEX determination using this
developed sampler together with GC–MS were 0.28 (benzene),
0.79 (toluene), 0.58 (ethylbenzene), 0.28 (p-xylene)
and 0.54 (o-xylene). The proposed method was applied to
sampling BTEX from selected petrol stations, traffic congestion
areas and a rural area in Chiang Mai Province,
Thailand. The BTEX concentrations detected were well
correlated with their sources as they were the highest at the
petrol station sites, lower at the traffic congestion area sites
and the lowest at the rural area site. The laboratory-made
passive sampler containing CBC has thus opened up a
possibility of having a simple and effective device for
sampling of BTEX in the ambient air.
Keywords
Benzene; Ethylbenzene; Gas chromatography–mass spectrometry; Toluene; Xylene
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