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- Posts: 16
- Joined: Mon Apr 09, 2018 2:18 pm
I'm developing an application for PCB analysis of sanitary sewer wastewater by GC-ECD, and as such, there's a lot of clean-up to do before GC analysis to avoid chemical interferants. The first round of extract cleanup after evaporation to 1 mL hexane is EPA 3665A, which starts with reaction of the extract with concentrated (or 1:1 diluted) sulfuric acid. I'm finding that the wastewater samples I'm running require a total of 2-3 additions of 1 mL H2SO4 to yield a clean acid layer, which requires a lot of very careful pipetting of a hazardous reagent, both to avoid injury as well as to avoid discarding part of the sample extract.
Does anyone have any personal experience with this procedure and possibly some recommendations on how to better carry it out? One idea is implementing an automated liquid handling robot, though I think the sulfuric acid will be an issue with its viscosity and tendency to corrode metals. Another idea is supporting the sulfuric acid on a silica gel support, such that the cleanup could be done in a dSPE manner.
I'm unfortunately the only person I know of at my large company (~10K employees total) with domain knowledge on this type of analysis, and haven't been able to get any good suggestions other than "hire a student to help". I would like the method to be robust for others to perform, but as currently implemented is too tedious for the technician. I welcome any comments or suggestions, thank you!