Chlorination for efficient identification of polycyclic aromatic hydrocarbons by liquid chromatography-mass spectrometry

Utilizing liquid chromatography-mass spectrometry (LC-MS) for identification of polycyclic aromatic hydrocarbons (PAHs) has long been underrated, as the sensitivity for determination of PAHs directly by MS is very poor. In the present work a chlorination method for high-sensitive determination of PAHs by LC-MS is discussed. This method includes two steps: (1) chlorination of PAHs by the BMC method; (2) determination of the chlorinated PAHs by LC-MS. Interfaced by atmospheric pressure chemical ionization in negative ion mode, five representative perchlorinated PAHs producing from the languidly detectable parent PAHs (naphthalene C(10)H(8), acenaphthene C(12)H(10), phenanthrene C(14)H(10), pyrene C(16)H(10) and fluoranthene C(16)H(10)) have been LC-MS characterized in high sensitivity with determination limits in 10(-9)g/mL level. In addition, molecular compositions and polycyclic carbon-frameworks of unknown PAHs can be identified according to the isotopic pattern of the chloro-derivatives ions in the corresponding mass spectra. Our experiments demonstrate that the proposed chlorination-involving LC-MS method is efficient for the PAHs analysis, for example, in soot and soil samples.