Bases in GC analysis solution.

Chromatography Forum: GC Archives: Bases in GC analysis solution.
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Thursday, December 12, 2002 - 06:21 am:

Can anybody suggest me about the reliability in usage of sodium hydroxide in diluent for Gc analysis. Can we use such bases in dissolving sample and do they cause any deterioration of teh column stationary phase under direct injection technique.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Thursday, December 12, 2002 - 07:13 pm:

Sodium hydroxide will react destructively with any silicone based liquid phase. They will not react in most cases with a carbon based phase or support, but may be a source of all sorts of problems unless removed.

The use of a packed precolumn is highly recommended.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Friday, December 13, 2002 - 05:14 am:

I'm using HP-5 column. this means the column may get damaged?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Friday, December 13, 2002 - 07:09 am:

yes


Top of pagePrevious messageNext messageBottom of pageLink to this message  By ScottF on Friday, December 13, 2002 - 05:25 pm:

25 years ago I used a pre-column packed with KOH/NaOH coated on the solid support to do an on-column clean-up.

The analytical column was a packed column, the detector an ECD. I ran it during the summer for 2-3 years with no problems.

If you absolutely must use NaOH, a pre-column might work. But Anon is right--you can wreck things, so don't be surprised when it happens.

A compound that requires NaOH to dissolve it doesn't sound like it would work on GC, anyway. You probably need to extract the analyte with organic solvent after dissolving the sample. I'm currently working on a compound that I extract from pH 12 water with methylene chloride. That technique is time-tested--no problems from the base.


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