Hi Paul:  We have been using the method listed below to remove carbonate
from samples for a few years.  It is easy to use but does slightly (or
sometimes not-so-slightly!) alter the d15N and %N for many types of
samples.  So we analyze the d15N and %N of really critical samples on
unacidified samples.

Anybody got a better method?

--Carol

     Yamamuro M, Kayanne H. 1995. Rapid direct determination of organic
carbon and nitrogen in carbonate-bearing sediments with a Yanaco MT-5 CHN
analyzer. Limnol. Oceanogr. 40: 1001-1005.

*******************************************************************************

Carol Kendall                                                        tel:
1-650-329-4576
USGS, 345 Middlefield Road, MS 434           fax: 1-650-329-5590
Menlo Park, CA 94025 USA                    email:[log in to unmask]



                    Paul Brooks
                    <[log in to unmask]        To:     [log in to unmask]
                    KELEY.EDU>                  cc:
                    Sent by: Stable             Subject:     Re: soil carbonate removal
                    Isotope Geochemistry
                    <[log in to unmask]
                    .EDU>


                    05/01/01 02:47 PM
                    Please respond to
                    Stable Isotope
                    Geochemistry





Dear list members,

I have just had a query from some one preparing soils for 15N and 13C
analysis by CN analyzer/IRMS.  They want to remove carbonate prior to
analysis.  Does the addition of HCl work, or does leave so much HCl residue
that Cl becomes a problem in the combustino tube?  Is there an accepted
published method?  I seem to recall one method using HCl vapor instead of
the acid directly on the soil itself, but I cannot find the reference.

Thanks in advance,

Paul Brooks.



Paul D. Brooks,
Dept. ESPM-ES,
147 Higard Hall MC 3110,
UC Berkeley, Ca. 94720-3110.

phone (510)643-1748,
FAX (510)643-5098.