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Thanks, Robert.

We are running GC-irMS for dD of n-alkanes. I'd love to see how you go
about setting up your sequences, just to get an idea of how others tackle
this.

I will look into the references you provided.

Best,

On Fri, Oct 14, 2016 at 2:59 AM, Geldern, Robert <[log in to unmask]>
wrote:

> Hi,
>
> a couple of years ago, AirrLiquide had a product (called “IsoTop") that at
> least allowed for a selection of the range of the d2H values (so if the d2H
> lecture bottle is more to the high or low side). Inside you typically found
> also a “certificate” that gave you a precise of value of your particular
> bottle, but as others already pointed out this is not of much use. Not sure
> if it still available.
>
> With respect to the sequence layout: Yep - correct normalization,
> linearity, drift and QA/QC need a lot of lines in your sequence. Finally,
> you have to find a balance between sample throughput and
> calibration/quality control. Not always an easy task and it also varies
> from device to device. What analysis are we talking about? I can send you
> some of our master templates to give you an idea.
>
> But two point reference materials, drift, linearity (if applicable) and
> unknowns are mandatory on a daily basis. Depending on the device this will
> reduce, of course, your sample throughput. But: Always decide for better
> data quality than for more numbers. It is always better to include a
> standard twice if in doubt than to optimize your sequence for fast analysis.
>
> You also might find some ideas for setting up a sequence in the
> publications below.
>
> regards,
> Robert
>
> Werner and Brand (2001), Referencing strategies and techniques in stable
> isotope ratio analysis, RCM, 15, 501, 10.1002/rcm.258
> Wassenaar et al. (2013), Approaches for Achieving Long-Term Accuracy and
> Precision of δ18O and δ2H for Waters Analyzed using Laser Absorption
> Spectrometers, Environ. Sci. Technol. 2014, 48, 1123−1131,
> dx.doi.org/10.1021/es403354n
> van Geldern, R. and Barth, J.A.C. (2012) Optimization of instrument setup
> and post-run corrections for oxygen and hydrogen stable isotope
> measurements of water by isotope ratio infrared spectroscopy (IRIS).
> Limnology and Oceanography: Methods 10, 1024-1036.
>
>
>
> Am 14.10.2016 um 02:07 schrieb Jeff Salacup <[log in to unmask]>:
>
> > Thanks everyone for the thoughtful replies. I learn so much important
> info from this community on a daily basis.
> >
> > While we are interested in having some H2 of known dD in house, we do
> not plan to use it for standardization to VSMOW or any other scale. We
> routinely use two point scale anchors based on standards provided by Arndt
> et al. And then use this normalized scale to calibrate a third standard
> from Arndt to see how close we are getting to accepted. We are generally
> within a few permil, very close to 'within error'.
> >
> > One question we've been asking ourselves though is how often we need to
> perform a 2 point anchor... every sequence table (in other words, daily),
> weekly, every new reactor (3-4 weeks)? If I run 2 anchor standards 3-5
> times in every sequence, plus the other 'unknown' standard 3 times, that's
> 9-13 sequence lines. Then you've got to add in drift standards to make sure
> the run as a whole stays 'level'. You run out of room for samples! My
> goodness! So I'd be interested in hearing if there is an accepted protocol,
> and if not, if folks would be willing to share their experience with
> balancing the needs of quality assurance with those of the lab (data
> production).
> >
> > Thanks again, for any and all info.
> >
> > Best,
> >
> > On Thu, Oct 13, 2016 at 4:37 PM, Wolfram Meier-Augenstein (aps) <
> [log in to unmask]> wrote:
> > Even a lecture bottle of H2 with a “calibrated” value represents still
> only a single point of “reference” and does not do away with the need for
> proper scale calibration using two scale anchors spanning a d2H value range
> similar or identical to that covered by VSMOW/SLAP.  Anybody can verify
> this for themselves quite easily.  Use VSMOW(2) to dial in (aka “calibrate)
> the d2H value of your H2 cylinder. Once you are happy with the result, use
> the cylinder gas d2H value thus obtained to run SLAP or even GISP against
> it and see what the difference is between cylinder gas “calibrated” vs.
> accepted.
> >
> >
> >
> > Besides, it is impossible to correct for scale compression effects using
> merely 1 single point of scale reference. The need for a 2 point scale
> calibration, especially for 2H but also for other light element isotopes
> has covered extensively in the literature and in fact forms part of IUPAC
> guidelines for stable isotope ratio measurements and reporting results
> thereof.  Recommended reading on this subject includes Chapter 1
> (specifically pages 34 and 35), Chapter 40 and Chapter 41 in Pier de
> Groot’s Handbook of Stable Isotope Analytical Techniques (Vol. I); Figure
> 41.2 is reason alone to read Chapter 41.
> >
> >
> >
> > Another good and instructive read on this subject (using 34S analysis as
> example) is Appendix B of Zach Sharp’s book Stable Isotope Geochemistry.
> >
> >
> >
> > While of course a convenient way to generate measured (‘raw’) d2H
> values, as Arndt has already pointed out the use of a cylinder gas to
> “calibrate” H2 generated from sample conversion that on top has entered the
> ion source via a separate (different) gas train does not meet the identical
> treatment requirements.
> >
> >
> >
> > Using a dialled in H2 cylinder to generate measured d2H values has of
> course its advantages.  It helps writing SOPs with regard to acceptance /
> rejection criteria for measured d2H values of one to two QC materials on
> the basis of which one decides whether to continue with or abort a sample
> batch run sequence.
> >
> >
> >
> > Best,
> >
> >
> >
> > Wolfram
> >
> >
> >
> >
> >
> > From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On
> Behalf Of Paul Eby
> > Sent: 13 October 2016 20:57
> > To: [log in to unmask]
> > Subject: Re: [ISOGEOCHEM] Hydrogen Refgas of know value
> >
> >
> >
> > You can get this from Oztech (Chuck Douthitt). He has lecture bottles of
> pure H2, calibrated with a variety of isotopic values. Contact him by email
> at: [log in to unmask]
> >
> >
> >
> > Paul Eby
> >
> >
> >
> >
> >
> > Water Management
> >
> > Alberta Innovates - Technology Futures
> > Vancouver Island Technology Park
> > 3 - 4476 Markham St., Victoria, BC, Canada V8Z 7X8
> >
> > Phone: 250-483-3290 | Fax: 250-483-1989
> > [log in to unmask]
> > AlbertaTechFutures.ca
> >
> >
> >
> >
> >
> >
> >
> > From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On
> Behalf Of Jeff Salacup
> > Sent: October-13-16 11:36 AM
> > To: [log in to unmask]
> > Subject: [ISOGEOCHEM] Hydrogen Refgas of know value
> >
> >
> >
> > Greetings!
> >
> >
> >
> > Can one purchase a bottle of hydrogen gas with a know dD ratio? If so,
> where, and is it worth the cost?
> >
> >
> >
> > Best!!
> >
> >
> >
> >
> >
> >
> >
> > --
> >
> > Jeff
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Two things are infinite: the universe and human stupidity; and I'm not
> sure about the universe. - Einstein
> >
> >
> >
> >
> >
> > __________________________________________________________________
> > Jeff Salacup, Ph.D.
> >
> > Stable Isotope & Biogeochemistry Lab Manager
> >
> > UMass-Amherst
> >
> >
> >
> >
> >
> >
> >
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> >
> > --
> > Jeff
> >
> >
> >
> >
> > Two things are infinite: the universe and human stupidity; and I'm not
> sure about the universe. - Einstein
> >
> >
> >
> > __________________________________________________________________
> > Jeff Salacup, Ph.D.
> > Stable Isotope & Biogeochemistry Lab Manager
> > UMass-Amherst
> >
>
> --
> PD Dr. Robert van Geldern
> Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) | GeoZentrum
> Nordbayern
> Schlossgarten 5 | 91054 Erlangen | Germany
> [log in to unmask] | www.gzn.uni-erlangen.de
> fon: +49-9131-85-22514 | fax: +49-9131-85-29294 | room: O 2.112 (office)
>



-- 
Jeff




*Two things are infinite: the universe and human stupidity; and I'm not
sure about the **universe. - Einstein*




*__________________________________________________________________**Jeff
Salacup, Ph.D.*
*Stable Isotope & Biogeochemistry Lab Manager*
*UMass-Amherst*