Determination of aromatic and polycyclic aromatic hydrocarbons in gasoline using programmed temperature vaporization-gas chromatography-mass spectrometry.

A sensitive method is presented for the fast analysis of three aromatic and six polycyclic aromatic hydrocarbons (biphenyl, 3-methylbiphenyl, 4-methylbiphenyl, fluorene, phenanthrene, fluoranthene, pyrene, 1,2-benz(a)anthracene and chrysene) in gasoline samples. The applicability of a GC device equipped with a programmable temperature vaporizer (PTV) and an MS detector is explored. Additionally, a modular accelerated column heater (MACH) was used to control the temperature of the capillary gas chromatography column. This module can be heated and cooled very rapidly, making total analysis cycle times very short. The proposed method does not require any previous analyte extraction and preconcentration step, as in most methods described to date. Sample preparation is reduced to simply diluting the gasoline samples in methanol. This reduces the experimental errors associated with this step of the analytical process. By using sampling injection in the solvent vent mode, and through choice of a suitable temperature, the lightest major components of the gasoline were removed. Moreover, use of a liner packed with Tenax-TA allowed the compounds of interest to be retained during the process. This working strategy could be extended to other groups of compounds through the choice of different venting temperatures. In this way, a large part of the gasoline components are eliminated, the life of the liner is prolonged, and it is possible to inject sample volumes that will not saturate the chromatographic column. The limits of detection ranged from 0.61 microg/L (pyrene) to 6.1 microg/L (biphenyl), and precision (measured as the relative standard deviation) was equal to or lower than 7.3%. The method was applied to the determination of analytes in gasoline samples and the results obtained can be considered highly satisfactory.