INFLUENCE OF PARTICLE SIZE ON THE QUALITY OF PAH CONCENTRATION MEASUREMENTS IN A CONTAMINATED SOIL

Abstract

The study of PAHs in soil requires optimized analytical methods that assess reliable concentration measurements. In this study, uncertainties in the analytical measurements of selected PAH concentrations from contaminated soil have been evaluated. Sample soil came from an old gaswork site. Chromatographic analyses were done by HPLC with a fluorescence detector and extraction procedures were optimized by studying sample load, extraction time, solvent volume and extraction solvent. PAH concentration was also studied in seven size fractions (< 0.05, 0.05–0.1, 0.1–0.2, 0.2–0.5, 0.5–1, 1–2, 2–4 and > 4 mm) in the contaminated soil. Relative abundance of ring grouped PAH showed different distribution patterns among particle size fractions in which light and heavy PAH were enriched in coarse and fine material, respectively. A comparison was performed between data obtained with and without grinding each particle fraction before analysis, which includes an evaluation of the main uncertainty components involved in the procedure. Relative uncertainties between 10 and 20% were estimated depending on the PAH studied, when ground and low grain size were investigated; uncertainty contributions were increased according to grain size increases for samples that were not ground. This behavior depended on the volatility of PAH measured.