Fluorescence Line-Narrowing Spectroscopy as an Off-Line Identification Method for Narrow-Bore Column Liquid Chromatography

Abstract

Storage of the effluent from a column liquid chromatograph (LC) on a thin-layer chromatography (TLC) plate was utilized to identify analytes with fluorimetric techniques in the absence of time constraints. As an example, the deposited LC trace of an impure 1-chloropyrene sample was studied in situ by conventional excitation/emission spectroscopy and by fluorescence line-narrowing (FLN) spectroscopy, a high-resolution laser-induced fluorescence technique requiring cryogenic conditions. Pyrene and several mono-, di-, and trichlorinated pyrenes, present in the 1-chloropyrene sample, were identified with the use of the fingerprint structure of the vibrationally resolved FLN spectra. Quantitation on the basis of the FLN signals was achieved by standard addition; compounds could be detected down to the low picogram level. Various TLC materials were used to study the influence of the matrix on the FLN spectra; although peak intensities and hole burning effects are matrix-dependent, the line positions are not influenced.