Optimization of Tenax extraction parameters for polychlorinated biphenyls in contaminated sediments

Tenax extraction is a chemical technique used to provide a rapid estimate of exposure to chemicals from contaminated sediments. However, an absence of standardization has limited the implementation of Tenax extraction in regulatory venues. In the current study, the operational parameters of extraction solvent volume, Tenax sorption rate from water, and Tenax:OC (organic carbon) ratios were investigated employing polychlorinated biphenyls (PCBs) as model compounds. The highest extraction efficiency of the analytes from Tenax resulted from a 10mL extraction volume. Recoveries of PCBs from spiked-sediment ranged from 79% to 100% with relative standard deviations between 1% and 9%. For the Tenax sorption rate from water, 0.01g of Tenax cleared >95% of the initial solution concentration of individual PCBs from 40mL of water in less than 30min. This Tenax mass is capable of clearing PCBs from the 40mL of water 413 times in 24h. Thus, a 24h single-point Tenax extraction would be sufficient to remove all of the desorbing PCBs from a contaminated sediment. Finally, the influence of the Tenax:OC ratio becomes more evident as the hydrophobicity of the compound and OC content (%) of the sediment increases. To obtain more reliable Tenax extractable concentrations, a minimum Tenax:OC ratio of 5:1 is suggested to conduct single-point Tenax extractions. In summary, a solvent volume of 10mL extracted the compounds efficiently from the Tenax, and the rapid sorption from water using at least the minimum Tenax:OC ratio should lead to good measures of rapidly desorbing compound and thus represent bioaccessibility.