Dear Wolfgang, are you shure that these methods are suitable to measure arginine. This
is one of the most critical AA in GC-C-IRMS. Other critical ones are glutamin
/glutamate and asparagine/aspartate. Has anyone a satisfying derivatisation method to
get them all. For 15N and 13C.
Thanks gerd gleixner

Wolfram Meieraugenstein schrieb:

> Dear Sergine,
>
> > I would like to measure the d15N of the aminoacids Arg and Gly (separately)
> > in a mixture of several aminoacids, and possibly other nitrogeneous
> > compounds. I guess this is possible with the GC-C-IRMS technique, but I
> > have never used it.
>
> You guess correctly.
>
> > I would be very grateful to anybody who could ask one or several of the
> > following questions :
> >
> > - is it possible or do I have to purify Arg and Gly from my mixture before?
> > - what is the minimum amount of matter needed per measurement?
> > - who does this kind of analyses and how much does it cost?
>
> There is a good chance that you can inject your AA mixture (protein
> hydrolysate?) straight on to the GC, after the usual clean-up and
> derivatisation steps.
>
> The question about minimum amount on column per individual amino acid
> necessary depends whom you speak to. Instrument manufacturers are
> like Microsoft, they give you the minimum amount under the best
> possible conditions (downhill with the wind in your back). It is
> possible to do d15N analysis with 1 nmol (and less) per amino acid
> injected (splitless) on to the GC but I wouldn't recommend using this
> as a goal post. Unless you have to because your original sample can't
> be larger than X (e.g. human samples such as blood, tissue etc.).
>
> I would aim to inject at least 2 nmol per individual AA, preferably 4
> nmol, to ensure that 250 pmol to 1 nmol of N2 actually end up in the
> ion source (this is assuming 100% conversion and no N-oxides plus a
> split of 1:4 prior to the ion source).
>
> For references as to sample preparation, derivatisation,
> GC-conditions and all that sort of apple sauce have a look at:
>
> C.C. Metges et al., J. Mass Spectrom., 31, 367-376 (1996)
>
> C.C. Metges and K.J. Petzke, Anal. Biochem., 247, 158-164 (1997)
>
> T. Preston et al , Br. J. Sur.,. 82, 229-234 (1995)
>
> C.L. Williams et al., FEMS Immunol. Med. Microb, 13, 87-94 (1996)
>
> I.A. Simpson et al., Archaeol. Prospect., 4, 47-152 (1997)
>
> W. Meier-Augenstein, LC-GC, 15, 244-263 (1997)
>
> W. Meier-Augenstein, J. Chromatogr. A, 842, 343-363 (1999)
>
> and my webpage on AA derivatisation (for URL see below).
>
> Hope this helps.
>
> Regards,
>
>                          Wolfram
>
> ****************************************************
> Dr. W. Meier-Augenstein, CChem MRSC
> Senior Research Fellow
>
> University of Dundee, Dept. of Anatomy & Physiology,
> OMS, Small's Wynd, DUNDEE  DD1 4HN, United Kingdom
>
> Tel.: +44-(0)1382-34/5124, /4574, /4968
> Fax:  +44-(0)1382-34/5514
>
> e-mail: [log in to unmask]
>
> URL: http://www.dundee.ac.uk/anatphys/wma/wolfram.htm
>
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