Laser Two-Photon Ionization for Determination of Aromatic Molecules in Solution

A laser two-photon Ionization technique has been successfully applied to the trace determination of aromatic molecules such as pyrene, tetraphene, chrysene, anthracene, anthracene derivatives, N-phenyl-1-naphthylamlne, benzophenone, and 4,4‴-bis[(2-butyloctyl)oxy]-p-quaterphenyl in solution. Cell design and factors affecting the sensitivity of the photoionl-zation detection have been investigated and optimized to improve the sensitivity substantially. The detection limit of pyrene is 6 ng/L. This technique is quite useful for weakly or nonfluorescent molecules; the detection limits of halogenated anthracenes and benzophenone are on the order of 0.1 and 100 µg/L, respectively. The detection limit is correlated with the molar absorptivity.