Measurement of the free concentration of octylphenol in biological samples with negligible depletion-solid phase microextraction (nd-SPME): analysis of matrix effects

A negligible depletion-solid phase microextraction (nd-SPME) method is presented to measure free concentrations of octylphenol in biological samples. Potential confounding factors, such as matrix effects, are studied as well. Fouling of the fibre appears to occur, but it does not seem to reduce or enhance the measured uptake of octylphenol. In the setup applied here, without any agitation, it has also been found that there is a large effect of protein presence on the kinetics of octylphenol uptake. In addition, an apparent affinity constant of octylphenol for bovine serum albumin was determined.