چكيده لاتين :
Background: Benzene, toluene, ethylbenzene and xylene (BTEX) compounds are components of motor vehicle fuel. BTEX
are released from exhausts of vehicles and also evaporation from the fuel tank, carburetor and crank case of engines. BTEX
are dangerous chemicals that participate in photochemical reactions and produce secondary air pollutants such as ozone,
peroxyacethyl nitrate, free radicals and nitrogen oxides. BTEX in ambient air of metropolitan areas has been the subject of
concern in many studies through elaborate "Environmental Protection Agency" (EPA) method. Level of BTEX in the ambient
air of major Iranian cities, has not been measured in concentration range of part per billion (ppbv) due to the inadequate
sensitivity of available gas chromatography systems. The aim of this study was to improve the sensitivity of gas
chromatography by using a special sampler and thermal desorber (Micro-Packed Injector).
Materials and Methods: Our sampler consisted of a 5-centimeter stainless steel tube one millimeter in diameter packed with
carbopacked B heat-conditioned samplers utilized for sampling atmospheric BTEX. It was subsequently injected to a custommade
thermal desorber (225°C) which was assembled onto the injection port of a gas chromatography device for analysis.
Results: BTEX standard atmospheres were analyzed with a gas chromatograph flame ionization detector (GC-FID) with
linear range detection of 27.5-275ppb, 23.1-223.6ppb, 20-320-ppb, and 20-320ppb respectively.
Conclusion: The Micro-Packed Injector (MPI) installed on ordinary GC-FID improved linear range detection of BTEX from
previous ppm detection to ppb range. (Tanaffos 2008; 7(3): 47-52)
