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WP7 Biomimetic Passive Sampling Devices for Predicting Bioavailability
(462) Purification of the triolein to be used in SPMDs.
Lebo, J1, Almeida, F2, Cranor, W1, Petty, J1, Huckins, J1, Rastall, A3, Alvarez, D1, Mogensen, B4, Johnson, B1, 1 USGS, Columbia Environmental Research Center, Columbia, MO, USA2 Instituto de Quimica, UNICAMP, Campinas, SP, Brazil3 Chemistry Laboratory, Hygiene Institute, Heidelberg, Germany4 National Environmental Research Institute, Roskilde, Denmark
ABSTRACT- Analyses of triolein-containing semipermeable membrane devices (SPMDs) have sometimes been impeded by interferences caused by impurities endemic to triolein that codialyze with the analytes. Oleic acid and methyl oleate have been the most troublesome of these impurities because of their relatively high concentrations in triolein and because significant residues of both can persist even after size exclusion chromatographic (SEC) fractionation. These residues, particularly oleic acid, have also been blamed for false-positive signals during bioindicator testing of SPMD dialysates. To circumvent these problems, a simple, cost-effective procedure was developed for purifying the triolein for use in SPMDs: the bulk triolein is repeatedly (6X) partitioned against methanol. Tests of the procedure show that oleic acid is completely removed from the triolein. After SEC fractionation, dialysates of standard-size SPMDs made with the purified triolein contain less than 5 micrograms of methyl oleate as compared to sometimes more than 500 micrograms for dialysates (also after SEC) of SPMDs made with unpurified triolein. Gas chromatographic analyses with flame ionization and electron capture detection show that the purification treatment also greatly reduces the number and size of peaks caused by unidentified contaminants in triolein. Microtox Basic assay and yeast estrogen screen (YES) testing of dialysates from SPMDs fabricated with unpurified and purified trioleins show that those made with the purified triolein have lower acute toxicities than dialysates of SPMDs made with unpurified triolein, and that the purification process removes all background estrogenic activity.
Key words: oleic acid, methyl oleate, dialysate, microtox
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