Rapid analysis of trace pollutants using laser mass spectrometry

Organic pollution has been gaining more and more attention. Yet, at present the determination of virtually all of them, including polycyclic aromatic carbons (PAHs), the largest single class of chemical carcinogens known today, is made via pre-purification and pre-concentration, The major problems are complexity and time-consuming, thus, no ideal real-time on-line monitoring can be done. Laser mass spectrometry combines UV spectroscopy and time-of-flight mass spectrometry (TOF-MS) through resonance-enhanced multiphoton ionization (REMPI). It is characteristic of high sensitivity, high selectivity and rapidity. In this paper, after its principles, a small mobile laser mass spectrometer, in which a mini-excimer (KrF, 248 nm) laser was used, is introduced. Real-time analysis of vehicle exhaust gas was made using this instrument, and the results showed some advantages over traditional methods: multicomponent detection, including benzene, toluene, xylene, C₃-benzene, naphthalene, and methyl-naphthalene; high sensitivity (100 ppb); high time-resolution (0.1 s); and no need for prepurification or pre-concentration of samples.