Sub-part-per-trillion detection of polycyclic aromatic hydrocarbons by laser induced molecular fluorescence.

Abstract

Laser-induced molecular fluorescence is shown to be a sensitive and selective means for determining representative polycyclic aromatic hydrocarbons (PAH) in aqueous solutions. The limits of detection of benzene, naphthalene, anthracene, fluoranthene, and pyrene were found to be 19 ppB, 1.3 ppT (parts-per-trillion), <44 ppT, 1.0 ppT, and 0.5 ppT, respectively. All the PAH fluorescence exhibits a linear dependence on concentration, sometimes extending over six orders in magnitude. Improvements in second harmonic generation and UV lasers should result in even lower minimum detectabilities, especially for anthracene.