SOLID-PHASE MICROEXTRACTION AND HEADSPACE SOLID-PHASE MICROEXTRACTIONFOR THE DETERMINATION OF POLYCHLORINATED-BIPHENYLS IN WATER SAMPLES

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 stu died. Because the time for reaching equilibrium between phases takes s everal hours or days, depending on the experimental conditions, it was necessary to work in nonequilibrium conditions to keep the sample ana lysis to a reasonable time. The possibility of sampling the headspace over the water sample (HSSPME), instead of immersing the fiber into th e water (SPME), was also investigated, and despite the low partition o f PCB into the headspace, HSSPME offered higher sensitivity than SPME at 100 degrees C, The adsorption kinetics for SPME at room temperature , SPME at 100 degrees C, and HSSPME at 100 degrees 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 result s, but HSSPME was much more sensitive and considerably faster, by elim inating all the manual process intensive sample workup, and reduces so lvent consumption entirely. The only drawback was that matrix effects were observed, but with the addition of deuterated surrogates to the s ample or the use of a standard addition calibration, accurate quantifi cation can be achieved.