Analysis of 23 polynuclear aromatic hydrocarbons from natural water at the sub-ng/l level using solid-phase disk extraction and mass-selective detection

An Empore disk extraction method for the analysis of 23 polynuclear aromatic hydrocarbons (PAHs) in natural waters at ng/l levels is described. Experimental variables investigated include determination of solvent type, extraction number, preconditioning requirements, breakthrough and the use of an in-line drying agent. The stability of PAHs stored extracted on Empore disks compared to samples left unextracted is demonstrated. Disks stored at -19 degrees C for 60 days had higher recoveries than samples left in sampling bottles unextracted at 4 degrees C. In general, less decomposition of the target analytes occurred when extracted and stored on the disks. The accuracy of the method was evaluated through the use of certified reference material analyzed as blind samples. The Empore disk extraction method achieved equivalent or better detection limits, used significantly less amounts of solvent, and was faster to use than traditional liquid-liquid methods. Method detection limits for the 23 PAHs ranged from 9 to 56 ng/l.