Pressurized hot water extraction coupled on-line with LC-GC: determination of polyaromatic hydrocarbons in sediment.

Pressurized hot water extraction (PHWE) was directly combined with a LC-GC system for the determination of polyaromatic hydrocarbons (PAHs) in sediment. The sediment sample was first extracted with pressurized hot water, and the analytes were adsorbed into a solid-phase trap. The trap also functioned as a LC column, which removed most of the interfering matrix components. The 780-microL LC fraction containing the analytes was directly transferred to the GC using an on-column interface. The whole PHWE-LC-GC analysis took place in a closed system, and no sample pretreatment was required. The sensitivity of the method was excellent due to the efficient concentration in the LC-GC system. Sensitivity was approximately 800 times better than in traditional systems. In addition, only a small amount of sample (10 mg) was required for the analysis. The PHWE-LC-GC method proved to be linear in the concentration range of 0.01-2 microg/g, the limits of quantification were below 0.01 microg/g for all the analytes, and the relative standard deviations were between 3 and 28%. LC cleanup and the improved sensitivity made detection with FID sufficient for the determination of analytes. The results were comparable to those obtained in an interlaboratory comparison study as well as to the results obtained with off-line SFE-GC-MS.