A Simple and Rapid Analytical Method of Polynuclear Aromatic Hydrocarbons in River Sediment

Abstract

We have devised a simple and rapid method for analysing polynuclear aromatic hydrocarbons (PAH) in river sediment. This method consists of the following 4 procedures ; drying of a sediment sample, ultrasonic extraction of PAH from the dry sample, separation of PAH into each component by one dimensional dual band thin-layer chromatography (TLC), and identification and determination of PAH by spectrofluorometry. A sediment is passed through a screen of 28 mesh and then dried. PAH in the dry sample are extracted with a mixed solution of ethanol and benzene by ultrasonification. After centrifugation, a known volume of the extracted solution are evaporated just before dryness under a reduced pressure, and dried up by standing it in a room for 10-20 min. The residue is dissolved in benzene, and subjected to TLC. [Thin-layer plate : Kieselguhr G (5×20, cm)-(26% Acetylated cellulose + Avicel SF) (95 : 5, w/w, 15×20, cm). Developer : Ethanol-Methanol-Ether-Water (2 : 2 : 4 : 1, v/v). Detection : Fluorescence under UV ray.]. Each spot on the TLC plate is scrapped off into a small centrifuge tube, and extracted with dimethylsulfoxide by ultrasonification. After centrifugation, PAH in the solution are identified by comparison of the excitation and emission spectra of the solution with those of a PAH reference solution. Quantitative determination of PAH is done spectrofluorometrically with the narrow base line method. In this method, 7 PAH [benzo [a] pyrene, chrysene, benzo [k] fluoranthene, benz [a] anthracene, perylene, pyrene and benzo [ghi] perylene] in a river sediment can be analysed in a short time. Recoveries of PAH in this method were good. Furthermore, it was proved that PAH contents in several sediments determined by this method agreed well with those by soxhlet extraction instead of the ultrasonic extraction.