Stable Isotope Geochemistry


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Stephanie Ewing <[log in to unmask]>
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Stable Isotope Geochemistry <[log in to unmask]>
Wed, 6 Jul 2005 14:40:53 -0700
text/plain (48 lines)
The HCl will be hard on your freeze dryer unless
you have an effective trap.  There's been lots of
discussion of various alternate acids on this
list.  I've used 100% phosphoric, which has the
benefit of low vapor pressure, but makes
subsequent dehydration challenging.


>We're trying to separate siderite from soil/clay samples so that we may
>analyze the organic components of the soil for d13C, d15N and CN ratios.
>The refs I've come across focus on 'carbonate' removal and indicate that
>siderite is less soluble. I found I can dissolve siderite in 6 molar HCl at
>50C overnite, or soaking in 6 molar HCl at 25C for several days. To
>remove excess HCl I plan to freeze dry the samples and not pour out any of
>the acid in case some of the organics have also gone into solution (I think
>this is the same idea as vapour removal).
>Any comments or suggestions regarding possible effects others have observed
>using this method, or better methods before I follow the tedious path of
>sample preparation testing? The first line of testing I was going to do was
>to dose IAEA-C5 (wood) with siderite and see if THIS pretreatment affected
>its d13C values.
>Thanks in advance for saving me time,
>Toti Larson Ph.D.
>Los Alamos National Laboratory
>Earth and Environmental Sciences                505.667.9894 (lab)
>Los Alamos, New Mexico 87545            550.667.8006 (office)

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