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- Posts: 3475
- Joined: Mon Jan 07, 2013 8:54 pm
- Location: Western Kentucky
I noticed that the extract is mostly Acetone, since you elute with 2ml acetone, then 5 ml Methylene Chloride then another 5ml Methylene Chloride then concentrate at 40C with nitrogen flow. This leaves an extract that is mostly acetone due to the higher boiling point. I have noticed the most stable extracts are the ones I have blown down to about 0.5ml or a little less while I have trouble with ones that I stop at about 0.9 ml. Could o-Toluidine react with acetone? I can leave the standards which are prepared in methylene chloride on the instrument for days at room temp and not see any loss of analyte, but even when kept in the cooler the sample extracts will lose surrogate concentration.
Just wondering if anyone else has had a similar problem.