From: Robert J. Panetta (rj_panet$##$alcor.concordia.ca)
Date: Sat Jul 29 2006 - 09:39:28 EDT
Hi Marilyn,
I had my own adventures with polyprotic acids from marine systems with the aim
of measuring isotopes and we had tried several columns, and unfortunately the
truth is these things are just not volatile on their own. However, instead of
TMS, why don't you try methylation with mthanol/BF3? I never did it with lactic
acid, but methylated citric acid flew beautifully on a DB-5 column, and you'll
only be adding one, maybe two carbon atoms instead of the 6 added with TMS.
Good luck,
Robert
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> Today's Topics:
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> 1. bromination of substituted pyridine - correction (philip cherian)
> 2. lactic GC (Marilyn Vogel)
> 3. TMS of wax esters (Marilyn Vogel)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 27 Jul 2006 05:57:00 -0700 (PDT)
> From: philip cherian <philip_189$##$yahoo.com>
> Subject: ORGLIST: bromination of substituted pyridine - correction
> To: everybody$##$orglist.net
> Message-ID: <20060727125700.35926.qmail$##$web50510.mail.yahoo.com>
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>
> Hello everybody, i am sorry but i forgot to mention that i am using 0.1
> equivalent of AIBN as the free radical initiator. So the conditions for the
> reaction are:
> 1.1eqNBS/0.1eq AIBN/112C/ 10mins/microwave, reaction run in ethyl acetate.
> [ref, Green chemistry, 2003, 5, 470-474]
> [Original Query - i am trying to brominate the methyl group of
> 2-piperazine-6-methyl pyridine-4- carboxylic acid but i am always getting
> ring subsitution and not benzylic bromination]
> Philip.
>
>
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> Message: 2
> Date: Thu, 27 Jul 2006 11:57:56 -0700
> From: Marilyn Vogel <mvogel$##$mail.arc.nasa.gov>
> Subject: ORGLIST: lactic GC
> To: everybody$##$orglist.net
> Message-ID: <p06210202c0eebcb4d505@[143.232.119.152]>
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> >
> >
> >>Hi,
> >> Can anyone offer me advice or references on GC/MS methods for
> >>lactate? I need to measure the carbon isotopic composition of a
> >>lactate solution that I have used to grow bacteria but I am not
> >>familiar with GC methods for very small molecules (MWs < ~ 140 Da).
> >>I do have materials for silylation, but was hoping to avoid the
> >>procedure because of possible isotope fractionation effects. Any
> >>advice is welcome.
> >>
> >>Marilyn Vogel
> >
>
>
> --
> Marilyn Vogel, PhD
> ORAU Postdoctoral Fellow
> NASA Ames Research Center
> Exobiology Branch, MS239-4
> Moffett Field, CA 94035
> Ph: 650.604.6941
> Fax: 650.604.1088
> mvogel$##$arc.mail.nasa.gov
>
>
> ------------------------------
>
> Message: 3
> Date: Thu, 27 Jul 2006 12:17:19 -0700
> From: Marilyn Vogel <mvogel$##$mail.arc.nasa.gov>
> Subject: ORGLIST: TMS of wax esters
> To: everybody$##$orglist.net
> Message-ID: <p06210203c0eebd3ff5b9@[143.232.119.152]>
> Content-Type: text/plain; charset="us-ascii" ; format="flowed"
>
> I have another question about silylation of a wax ester fraction
> taken bacterial extracts (e.g. mostly membrane lipids). I have used a
> silylation method (pyridine + BSTFA, 1:1 vol/vol, 30 min @80C in a
> teflon sealed vial), on a wax ester fraction collected from a TLC
> plate and found TMS derivatives of carboxylic acids, methyl branched
> carboxylic acids as well as primary and secondary alcohols. I have
> check my TLC methods using standards so I am reasonably sure that I
> am achieving good separation between my wax esters and alcohols, and
> not combining material when I collect the fractions. Does anyone know
> if BSTFA reacts with keto, ester or other functional groups on long
> chain alkyl molecules?
>
> Thanks,
> Marilyn Vogel
> --
> Marilyn Vogel, PhD
> ORAU Postdoctoral Fellow
> NASA Ames Research Center
> Exobiology Branch, MS239-4
> Moffett Field, CA 94035
> Ph: 650.604.6941
> Fax: 650.604.1088
> mvogel$##$arc.mail.nasa.gov
>
>
> ------------------------------
>
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> End of Everybody Digest, Vol 23, Issue 13
> *****************************************
>
--
Robert J. Panetta
Dept. Chemistry and Biochemistry
Concordia University
rj_panet$##$alcor.concordia.ca
(514)848-2424 ext. 7972
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