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EPA Finds Twister a Valuable Extraction Technique

From the EPA Report:

Conclusions and Future Work

The results from the tests indicate that some compounds can be extracted from water samples no matter how the sample was modified, while other compounds are very particular and succeed with only one type of modifier. Generally, the compounds that have Log Ko/w values of at least 2.5 performed well, and those compounds with values less than 2.5 could sometimes get improved results with “salting out” the sample. Several benefits of this technique versus the liquid/liquid extraction were realized. Method detection limits were lower in all compound classes by a factor of 10 compared to the liquid/liquid extraction technique. Many classes of compounds can be analyzed in the same sample simultaneously. The process was fast and efficient, resulting in a fast turn-around capability for screening unknown aqueous samples. The process eliminated hazardous solvents and tedious bench work, reducing staff time and strain. Opportunities exist to further evaluate Twisters ™ for environmental compounds. Many other classes of compounds such as other organochlorine pesticides, aroclors, PCB congeners, and a more extensive list of brominated flame retardants could be tried. The detection limits can be pushed even lower by increasing both the sample volume and extraction time, as was demonstrated with the BFRs using 100 mL and a 24-hour extraction.