Immersed solid phase microextraction to measure chemical activity of lipophilic organic contaminants in fatty tissue samples

It is known that solid phase microextraction (SPME) fibers can be equilibrated directly within environmental matrices such as water, sediment and soil slurries. Here it is shown that this method can also be applied to biological tissue. SPME extraction of biological matrices reportedly causes lipophilic fouling of the fiber. However, we found no significant measurement bias when combining equilibrium sampling with fiber surface cleaning. The uptake of lipophilic organic pollutants from the tissue and into the SPME fiber coating was characterized by fast equilibrium partitioning without sample depletion and without impacting the sorptive properties of the fiber. The precision of the method when applied to hexachlorobenzene and several PCB congeners in harbor porpoise blubber was 15%, which includes the variation between SPME samplings, manual injections and the instrumental analysis. A good correlation (r(2)=0.95) was obtained between SPME measurements of PCB 153 in blubber and concentrations obtained via a traditional analytical approach. These results indicate that SPME is a promising technique for measuring chemical activity in biological tissue, which would make it a useful tool for studying chemical distribution in organisms as well as biodilution and biomagnification phenomena.