Design and optimization of the VA-TV-SPME method for ultrasensitive determination of the PAHs in polluted water

This paper describes how a novel and reliable alternative approach was developed for conventional solid-phase microextraction (SPME) sampling by total-vaporization of a sample under vacuum conditions. SPME sampling consists two stages of the equilibrium process, which take place between the sample/headspace and the headspace/fiber coating. In the total-vaporization SPME (TV-SPME) strategy, the first stage is omitted and analytes are directly partitioned between the headspace and fiber coating. In this research, the TV-SPME strategy was implemented by the extraction of PAHs from aqueous media, using a polydimethylsiloxane (PDMS) coated SPME fiber. The most important variables were investigated and optimized. Optimal conditions were obtained at an extraction temperature of 55 degrees C, a vaporization time of 25 min, and a sample volume of 100 mu L. To achieve higher sensitivities in shorter times, the TV-SPME setup was coupled with the VA-SPME system, which resulted in a much lower extraction temperature and time, in comparison with the conventional TV-SPME method. Under optimal experimental conditions, the calibration curves were linear across the area of 0.015-2 mu g mL(-1) (R-2 > 0.996). The limits of detection (LODs) were obtained in the range of 0.3-5 ng mL(-1) and the relative standard deviations (RSDs, n = 6) were 6.1-7.5%. The developed vacuum-assisted total-vaporization SPME (VA-TV-SPME) technique, was coupled with GC-FID and successfully utilized for the determination of polycyclic aromatic hydrocarbons (PAHs) in river water samples. The data obtained was statistically in accordance with that achieved employing a validated approved method.