Room-temperature fluorescence spectroscopy of monohydroxy metabolites of polycyclic aromatic hydrocarbons on octadecyl extraction membranes

Abstract

Urine analysis of monohydroxy metabolites is recognized as an accurate assessment of human exposure to polycyclic aromatic hydrocarbons. Despite the sophisticated arsenal of analytical tools, monitoring of monohydroxy metabolites via simple, cost effective and direct methods of analysis still remains a challenge. This article evaluates the analytical potential of solid-phase extraction room-temperature fluorescence spectroscopy for the problem at hand. Extraction membranes serve the dual purpose of sample pre-concentration and solid substrate for RTF measurements. The potential of our proposition is demonstrated with the analysis of 2-hydroxy-fluorene, 1-hydroxy-pyrene, 3-hydroxy-benzo[a]pyrene and 9-hydroxy-phenanthrene in synthetic urine samples. Signal reproducibility is improved with the aid of a sample holder specifically designed for the manual optimization of luminescence signals. Background correction of solid substrates is carried out with the aid of Asymmetric Least Squares. Recovery values for the studied metabolites varied from 99.0 ± 1.2% (3-hydroxy-benzo[a]pyrene) to 99.9 ± 0.05% (1-hydroxy-pyrene). With only 10 mL of urine sample, the limits of detection varied from 57 pg mL -1 (2-hydroxy-fluorene) to 2 pg mL-1 (1-hydroxy-pyrene). Additional figures of merit include a simple experimental procedure for routine screening of numerous samples and compatibility with portable instrumentation for field analysis. Because of the non-destructive nature of fluorescence measurements, membranes can be brought to the lab for subsequent elution and confirmation of compounds via high-resolution techniques.