Cw were lower than Cnom for BACs with alkyl chain lengths of C12-16, particularly at low concentrations (Figure , Table ). The lower Cw compared to Cnom for C12-16-BACs is partially due to sorption of the chemicals to glass vessels. Figure shows the measured recoveries for BACs from water and the glass beaker in the spiking toxicity test. Losses from 7% to 60% of the total mass due to sorption to the glass beaker were observed for C12-16-BACs. The sorption affinity for the glass beaker increases with increasing alkyl chain length of BACs, which agrees well with previous studies on sorption of BACs to glass/plastic surface. The greater loss to the glass surface at lower concentrations suggests limited sorption sites on the glass surface, which may be saturated at relatively high concentrations. At low concentrations of C12-16-BACs, 20-40% of the added mass was not recovered from either the water or glass wall, indicating the presence of another loss process. It is possible that the loss was due to the glass pipette during water sampling, even after five times aspirating and dispensing in order to equilibrate the pipette surface. Furthermore, up to 140% recoveries (water + beaker wall) of C16-and C18-BACs at high concentrations were observed for an unknown reason.