Solid-phase microextraction and headspace solid-phase microextraction for the determination of polychlorinated...

A solid-phase microextraction (SPME) method has been developed for the quantification of polychlorinated biphenyls (PCBs) in water samples. Parameters such as sampling time, volume of water, volume of headspace, temperature, addition of salts, and agitation of the sample were studied. Because the time for reaching equilibrium between phases takes several hours or days, depending on the experimental conditions, it was necessary to work in nonequilibrium conditions to keep the sample analysis to a reasonable time. The possibility of sampling the headspace over the water sample (HSSPME), instead of immersing the fiber into the water (SPME), was also investigated, and despite the low partition of PCB into the headspace, HSSPME offered higher sensitivity than SPME at 100 °C. The adsorption kinetics for SPME at room temperature, SPME at 100 °C, and HSSPME at 100 °C were investigated and compared. The proposed HSSPME method exhibits excellent linearity and sensitivity. The detection limit was in the sub-ng/L level. This method has been applied to a real industrial harbor water and compared with liquid-liquid extraction. Both techniques offered similar results, but HSSPME was much more sensitive and considerably faster, by eliminating all the manual process intensive sample workup, and reduces solvent consumption entirely. The only drawback was that matrix effects were observed, but with the addition of deuterated surrogates to the sample or the use of a standard addition calibration, accurate quantification can be achieved.