HiTyler,
First off, I agree with your concerns over the practical problems associated
with analysing brines using on line pyrolysis.
The sample that Francois alludes to in the paper is from a Cambrian age
aquifer and contains around 350gms per litre dissolved salts. The isotope
value obtained for it from multiple measurements within a single Chrome HD
batch run is correct and reproducible. It was measured in order to compare
the online result to the value obtained using a classical preparation and
measurement.
The aim of the micro distillation port mentioned was to establish a volume
within the injector packed with some material such as quartz wool that the
salts would nucleate onto to at an elevated temperature. Through a
combination of injection control and injector temperature it was hoped (and
still is)that the effects (predicted) of the salts and that you described
might be at least minimised.
Some work has been carried out on known waters with variable
salt(NaCL)concentrations.
There is not a lot else that can be said other than you might possibly be
interested in sending me some of your nasty but isotopically known samples
with a view to running them here blind using the version of injector I have
at the moment.
regards
John
-----Original Message-----
From: Francois Fourel [mailto:[log in to unmask]]
Sent: 21 February 2006 09:21
To: [log in to unmask]
Subject: Re: [ISOGEOCHEM] Gas Bench hydrogen measurements
Ty,
The paper mentions heating the injector port at 170°C and make it work
as a microdistillation port. That means a design close to what you have
in GC split splitless injectors where you have a liner easily removable
which you can use as a filter depending on what you analyse. The paper
also mentions that this was preliminary results. I don't have this
microdistillation port on my EA so I can't tell you more. I know John
Morrison had one on his, maybe he can further comment on that.
Regards,
--
François FOUREL
UMR CNRS 5125 PEPS
Université Claude Bernard Lyon 1
2 rue Raphaël Dubois - Bât. Géode
F-69622 VILLEURBANNE Cedex - FRANCE
Tél : +33 (0) 4 72 44 62 42
FAX : +33 (0) 4 72 43 16 88
Email : [log in to unmask]
Tyler B Coplen a écrit :
>
> Dear François,
>
> You have not made me rest any easier. Yes, there is a discussion about
> the ChromHD and brine samples in Morrison et al., but there is only
> discussion and no solution to the problem.
>
> I am still concerned about recommending the TC/EA technique or ChromHD
> technology for delta H-2 measurements to those who analyze ground
> waters, saline waters, or brines containing ions whose salts have water
> of hydration.
>
> Ty
>
>
>
> *Francois Fourel <[log in to unmask]>*
> Sent by: Stable Isotope Geochemistry <[log in to unmask]>
>
> 02/20/2006 10:13 AM
> Please respond to
> [log in to unmask]
>
>
>
> To
> [log in to unmask]
> cc
>
> Subject
> Re: Gas Bench hydrogen measurements
>
>
>
>
>
>
>
>
> Hello Ty,
> There is a discussion regarding ChromHD and brine samples in the paper
> we did with John Morrison:
> "On-line high precision stable hydrogen isotopic analyses on nanoliter
> water samples - J. Morrison, T. Brockwell, T. Merren, F. Fourel and A.M.
> Phillips - Analytical Chemistry Vol 73, Number15, Pages 3570-3575".
> I am not running brine samples here with my MultiPrep, but I remember
> from the numerous equilibration experiments we did with John, we
> sometimes had surprises with H2O-H2 equilibration reactions. If the
> water to equilibrate is not pure, the catalysts seem to be sometimes
> affected and the D/H numbers can become very erratic.
> We even had the case once on waters extracted from plants where
> equilibration got us nowhere whereas EA-ChromHD on the same waters gave
> beautiful numbers.
> Regards,
>
>
>
> --
> François FOUREL
>
> UMR CNRS 5125 PEPS
> Université Claude Bernard Lyon 1
> 2 rue Raphaël Dubois - Bât. Géode
> F-69622 VILLEURBANNE Cedex - FRANCE
>
> Tél : +33 (0) 4 72 44 62 42
> FAX : +33 (0) 4 72 43 16 88
> Email : [log in to unmask]
>
>
> Tyler B Coplen a écrit :
> >
> > Dear Paul and Wolfram,
> >
> > I was not issuing a concern about memory due to sample carryover in the
> > syringe from one sample to the next, which has been discussed on
> > ISOGEOCHEM, nor about analysis of precipitation samples.
> >
> > Rather, unless the proper precautions have been taken, I am concerned
> > about recommending the TC/EA technique or ChromHD technology for delta
> > H-2 measurements to those who analyze ground waters, saline waters, or
> > brines containing ions whose salts have water of hydration. Luckily
for
> > some laboratories, they never analyze such waters and this e-mail does
> > not apply to them.
> >
> > Unfortunately, many of the most interesting waters in geochemistry and
> > geology are saline waters or brines composed of salts having waters of
> > hydration. Some of these salts can be dehydrated. Calcium sulfate
> > dihydrate (gypsum) dehydrates completely at 163 degrees C. Calcium
> > chloride hexahydrate and magnesium sulfate septahydrate both dehydrate
> > completely at 200 degrees C. But some salts with waters of hydration
> > are more problematic. Magnesium chloride hexahydrate does not
dehydrate
> > with increasing temperature. Rather, it decomposes, giving off HCl at
> > 116 degrees C.
> >
> > One can imagine that putting calcium/magnesium chloride/sulfate waters
> > into a reactor can provide the opportunity for large between-sample
> > memory unless all salt formed during flash evaporation of a sample is
> > maintained above its dehydration temperature. The more samples that
are
> > analyzed, the larger the memory. What one would like to do is to
> > maintain the bottom of the septum and the injection volume at a
> > temperature greater than degrees C. In this manner, only magnesium
> > chloride will be a problem and most other salts will be dehydrated.
> >
> > What I am wondering is how Willi and Giorgio tackle this problem.
> >
> > I should mention that because we analyze such brines and saline waters,
> > we prefer dual-inlet Pt equilibration.
> >
> > Ty
> >
> >
> >
> > *Paul Brooks <[log in to unmask]>*
> > Sent by: Stable Isotope Geochemistry <[log in to unmask]>
> >
> > 02/17/2006 05:53 PM
> > Please respond to
> > Stable Isotope Geochemistry <[log in to unmask]>
> >
> >
> >
> > To
> > [log in to unmask]
> > cc
> >
> > Subject
> > Re: syringe memory
> >
> >
> >
> >
> >
> >
> >
> >
> > Ty,
> >
> > We were able to eliminate the memory effect of syringe injection on an
> > H/Device by using a dry ethyl ether rinse between samples. I think
> > since we started this others are now using alcohol or carbon
> > tetrachloride, but the principle is the same. Rinsing the syringe with
> > a dry compound that is an azeotrope and injecting the waste to a modest
> > house vacuum dries the syringe completely. We keep the ethyl ether in
a
> > vial with a septa to stop it evaporating, then inject to a waste
> > position that is a septa with the house vacuum on the other side of the
> > septa. Even as the syringe goes into the waste septa one sees the
ethyl
> > ether blow out of the syringe even before the plunger comes down.
> >
> > Having said that, the syringes we use gradually oxidize and have to be
> > replaced every 200 injections. I have also only run a few sets of sea
> > water, but saw no memory effect going from the sea water to the
> > standards in fresh water.
> >
> > I can provide more details if anyone is interested. Paul Brooks
> >
> >
> >
> >
> > At 09:35 AM 2/17/2006, you wrote:
> >
> > Dear François,
> >
> > With the ChromHD technology, how are you solving the between-sample
> > memory problem for brine and sea water samples?
> >
> > Ty
> >
> > *
> > Francois Fourel <[log in to unmask]>*
> > Sent by: Stable Isotope Geochemistry <[log in to unmask]>
> >
> > 02/17/2006 03:33 AM
> >
> > Please respond to
> > [log in to unmask]
> >
> >
> > To
> >
> > [log in to unmask]
> >
> > cc
> > Subject
> >
> > Re: Gas Bench hydrogen measurements
> >
> >
> >
> >
> > I'd like to add a few comments to Willi's email.
> > As far as D/H is concerned I fully agree that continuus flow is now
> > giving the best precision for water analyses. My experience is that a
> > Eurovector EA with ChromHD technology generates D/H precisions better
> > than 0.5permil which is better than what we get with our MultiPrep/DI
> > system (usually 1permil). As far as 18O is concerned our experience
here
> > is that we get reproducibilities better than 0.05permil using CO2-H2O
> > equilibration with our MultiPrep-DI system. For some applications going
> > from 0.1 to 0.05 can make a significant difference.
> > Another parameter to take into account when doing 18O with an EA is
that
> > as soon as you will mention the name "carbon monoxide", the health and
> > safety officer of your university will be on your back. Depending on
the
> > legislations, there are almost always solutions, but CO2 equilibration
> > is more "health and safety-friendly".
> > Our experience in short is that for best isotopic determinations with
> > waters we prefer D/H with an EA but 18O with DI equilibration.
> >
> > Regards,
> >
> > --
> > François FOUREL
> >
> > UMR CNRS 5125 PEPS
> > Université Claude Bernard Lyon 1
> > 2 rue Raphaël Dubois - Bât. Géode
> > F-69622 VILLEURBANNE Cedex - FRANCE
> >
> > Tél : +33 (0) 4 72 44 62 42
> > FAX : +33 (0) 4 72 43 16 88
> > Email : [log in to unmask]
> >
> > Willi A. Brand a écrit :
> > > Hi,
> > > I just would like to comment to Anindya's remark that "/certainly
TCEA
> > > cant be an alternative to more precise gas bench/". The daily
routine
> > > precision in our TC/EA is 0.5 per mill for D/H from water samples.
We
> > > run more than 200 injections per day with a net of 30 samples,
> each of
> > > them injected 3 times. The other half of the injections is standards
> > > (the sequences are optimized for performance, not throughput;
> given the
> > > precision we could afford to inject each sample only once,
increasing
> > > the net number of samples processed for D/H to 90 on a single mass
> > > spec). For 18O, precision is in general better than 0.1 per mill
with
> > > fewer injections due to the longer elution time of the CO. With a
> single
> > > glassy carbon tube we have made more than 3000 injections.
> > > My conclusion: This is my method of choice for the times to come.
> It is
> > > so much more convenient compared to all other techniques (I think
> I have
> > > tried them all) with zero compromise in precision.
> > > Willi
> > >
> > > Anindya Sarkar wrote:
> > >
> > >> Hi Penny
> > >> With a relatively new machine and gas bench we get typically 1.5
> %o SD
> > >> that is the kind of SD one gets in dual inlet as well. But we have
> > >> been able to bring it down to even 1 %o level also. I hope u are
> using
> > >> a fixed volume of water (we use 500ul and our experiments show
> that if
> > >> you go below 200ul, values systematically change). we also bake the
> > >> column after say about every 100 samples. But ur problem it looks
> more
> > >> with platinum catalyst. The sticks supplied by thermo are not like
> > >> hokko beads but a thin coating. we have reused each for at least 10
> > >> analyses and yet got very good results. but we also noticed that
from
> > >> some sticks coatings are peeling off. why not try with absolutely
new
> > >> sticks and run several of ur lab standards and see the
> > >> reproducibility? as i understand TCEA will have more errors than
gas
> > >> bench (~2%o) but we got ~3%o on limited analyses; possibility of
> water
> > >> evaporating in up part of furnace b4 it reacts. certainly TCEA
> cant be
> > >> an alternative to more precise gas bench.
> > >>
---------------------------------------------------------------------
> > >> Anindya Sarkar
> > >> Associate Professor
> > >> National Facility of Stable Isotope Geochemistry
> > >> Department of Geology and Geophysics
> > >> Indian Institute of Technology
> > >> Kharagpur 721302
> > >> West Bengal, INDIA
> > >> Tel.: 0091-3222-283392 (O) 283393 (R) 220184 (R)
> > >> Cell: 09434043377
> > >> Fax.: 0091-3222-282268
> > >> _http://anindya-sarkar.tripod.com_
> <http://anindya-sarkar.tripod.com/>
> > >> ------------------------------------------------------------------
> > >> ----- Original Message ----- From: "Penny Higgins"
> > >> <[log in to unmask]>
> > >> To: <[log in to unmask]>
> > >> Sent: Friday, February 17, 2006 3:57 AM
> > >> Subject: [ISOGEOCHEM] Gas Bench hydrogen measurements
> > >>
> > >>
> > >>> Hello Isotopers,
> > >>>
> > >>> We've been attempting to use our Gas Bench to do hydrogen
> analysis of
> > >>> waters using platinum catalysts and headspace equilibration at
about
> > >>> 32degreesC. When we started, we got acceptable numbers with good
> > >>> within analysis (10 peaks) standard deviations. Values plotted
> > >>> sensibly along (or very near) the meteoric water line. As time
went
> > >>> on, our standard deviations have gotten much worse (as much as 7
> > >>> permil) and our data very seldom plot reasonably close to the
> > >>> meteoric water line. Often, hydrogen data plot well above the
> > >>> meteoric water line. We have gotten great results from oxygen
> > >>> analyses of the same samples.
> > >>>
> > >>> We've just spent a great deal of time and effort to ensure that
our
> > >>> sample gas is totally dry before it enters the mass spectrometer.
I
> > >>> also let the catalysts sit in our oven (60degreesC) for two days
> > >>> before placing them into the vials with our water samples. We got
> > >>> better standard deviations for our analyses this time (between 2
and
> > >>> 3), but still have unreasonable scatter around the meteoric
> water line.
> > >>>
> > >>> Questions:
> > >>>
> > >>> 1) What is a generally acceptable standard deviation for d2H from
> > water?
> > >>>
> > >>> 2) Could the problem be with our catalysts? I thought that, by
> > >>> definition, catalysts were reusable .. but maybe not. We've only
> done
> > >>> about 5 analyses with each catalyst.
> > >>>
> > >>> 3) Are we going to have this same problem when we start running
> > >>> waters using our TC/EA instead? or are we going to be happy that
we
> > >>> made the change?
> > >>>
> > >>> If anyone out there in cyberspace has dealt with and corrected
this
> > >>> problem, we would love to hear from you!
> > >>>
> > >>> Thanks,
> > >>>
> > >>> ~Penny
> > >>>
> > >>>
*******************************************************************
> > >>> Dr. Pennilyn Higgins
> > >>> Research Associate
> > >>>
> > >>> "SIREAL"
> > >>> Stable Isotope Ratios in the Environment Analytical Laboratory
> > >>>
> > >>> Department of Earth and Environmental Sciences
> > >>> University of Rochester
> > >>> 227 Hutchison Hall
> > >>> Rochester, NY 14627
> > >>>
> > >>> [log in to unmask]
> > >>>
> > >>> Office: 209b Hutchison Hall Lab: 209 Hutchison Hall
> > >>> Voice : (585) 275-0601 Outer lab: (585) 273-1405
> > >>> FAX : (585) 244-5689 Inner lab: (585) 273-1397
> > >>>
> > >>> _http://www.earth.rochester.edu/SIREAL/index.html_
> > >>>
*******************************************************************
> > >>>
> > >>>
> > >>>
> > >>> --
> > >>> No virus found in this incoming message.
> > >>> Checked by AVG Anti-Virus.
> > >>> Version: 7.0.344 / Virus Database: 267.15.6/257 - Release Date:
> > >>> 2/10/2006
> > >>>
> > >>>
> > >>
> > >>
> > >
> > > --
> > >
.....................................................................
> > > Willi A. Brand, Stable Isotope Laboratory
[log in to unmask]
> > > Max-Planck-Institute for Biogeochemistry (Beutenberg Campus)
> > > Hans-Knoell-Str. 10, 07745 Jena, Germany Tel: +49-3641-576400
> > > P.O.Box 100164, 07701 Jena, Germany Fax: +49-3641-577400
> > > _http://www.bgc-jena.mpg.de/_
> > > _http://www.bgc-jena.mpg.de/service/iso_gas_lab/_
> > >
.....................................................................
> > > GASIR 2005 in Jena:
> > >
_http://www.bgc-jena.mpg.de/service/iso_gas_lab/gasir2005/index.shtml_
> > >
.....................................................................
> > >
> >
> > --
> > François FOUREL
> >
> > UMR CNRS 5125 PEPS
> > Université Claude Bernard Lyon 1
> > 2 rue Raphaël Dubois - Bât. Géode
> > F-69622 VILLEURBANNE Cedex - FRANCE
> >
> > Tél : +33 (0) 4 72 44 62 42
> > FAX : +33 (0) 4 72 43 16 88
> > Email : [log in to unmask]
> >
> > Center for Stable Isotope Biogeochemistry
> > Valley Life Science Building Room 3060
> > Integrative Biology - MC3140
> > Berkeley CA-94720
> > Phone: (510)-643-1748
> > Fax: (510)-643-1748
> >
>
> --
> François FOUREL
>
> UMR CNRS 5125 PEPS
> Université Claude Bernard Lyon 1
> 2 rue Raphaël Dubois - Bât. Géode
> F-69622 VILLEURBANNE Cedex - FRANCE
>
> Tél : +33 (0) 4 72 44 62 42
> FAX : +33 (0) 4 72 43 16 88
> Email : [log in to unmask]
>
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