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Tuesday, January 15, 2013

Unknown precipitate identified with FTIR


In late December, 2012 a Kolthoff Hall lab noticed a problem with white precipitate on bottles stored under a fume hood just after a new unopened bottle was added.  The bottle was removed and the precipitate was cleaned.  The bottle was placed back under the hood and the precipitate reappeared.

Chemicals stored under the hood.

White precipitate on bottles in the hood.

The pH testing of the solid was not helpful.  Tests for peroxides were not conclusive.

An MCE 5um filter was attached to a 15 liter per minute pump and used to vacuum the precipitate from the bottles onto the filter.  This did not work very well.  The edges of the plastic filter were then used to gently mechanically scrape the precipitate off the bottle while the pump was running. 

A 3mm diameter portion of the precipitate was analyzed on the Smith FTIR.  A very clean IR peak was produced but it did not match the chemicals in the library data base.  DEHS sent the .SIR and the .spc files to Reach Back ID service at Smith's Detection system.

The spectrum submitted, WAS consistent with DIISOPROPYLAMINE HYDROCHLORIDE, as shown in the attached JPEG (ReachBackID_20130110 UMN_1.JPG).  DIISOPROPYLAMINE HYDROCHLORIDE is used as  as a reagent in organic synthesis.


After cleaning and decontaminating and isolating each bottle a cap was found to be loose on diisopropylamine.  As the bottle had not been used, this may have been a problem with capping at the manufacturer.