Simple method for estimating polychlorinated biphenyl concentrations on soils and sediments using subcritical water extraction coupled with solid-phase microextraction

Abstract

A rapid method for estimating polychlorinated biphenyl (PCB) concentrations in contaminated soils and sediments has been developed by coupling static subcritical water extraction with solid-phase microextraction (SPME). Soil, water, and internal standards are placed in a sealed extraction cell, heated at 250°C for 15 to 60 min, cooled, and the PCB concentrations in the extractant water determined by SPME and GC–electron-capture detection. When PCB 103 and 169 (not found in contaminated samples) are used as internal standards to calibrate for the soil/water and water/SPME equilibria, quantitative results for individual PCB congeners typically agree within 80 to 130% of the concentrations based on Soxhlet extraction and conventional GC analysis. The reproducibility of replicate subcritical water extraction/SPME determinations is typically 10 to 15% relative standard deviation. Analysis of water extracts stored for 24 h agrees with fresh extracts, demonstrating that extracts can be stored for later SPME analysis without significant loss of the PCBs from the extractant water. The method is simple to perform, uses field-rugged and inexpensive apparatus, and generates no organic solvent waste.