Hello  Gurumurthy G P,
If it is just for DOC concentrations, then the simplest is to use GF/F
filters
(
http://www.fishersci.com/wps/portal/PRODUCTDETAIL?productId=610584&catalogId=29101&pos=1&catCode=SE_SC&fromCat=yes&keepSessionSearchOutPut=true&brCategoryId=null&hlpi=y&fromSearch=Y).
In North America the main manufacturer (I think) is Whatman, possible to
order through Fisher (the link above). Just be sure they are binder-free,
and if you don't care about measuring carbonates, the best preservation is
by acidifying with 6N HCl (100 uL for 30 mL water is what works for the St.
Lawrence river- 3 years and counting!). We also combust them at 500 degC for
a few hours to ensure no contamination with soluble organics.
Good luck!

On Thu, Apr 2, 2009 at 1:51 PM, Gurumurthy G P <[log in to unmask]>wrote:

>  Dear all members,
>
>
>
> Greetings from Manipal, India
>
>
>
> Could you please suggest me which membrane filter are preferable for
> measuring dissolved organic carbon in river water???? I would appreciate if
> you direct me to website of suppliers.
>
>
>
> Anticipated thanks
>
>
>
> Yours sincerely
>
>
>
> Gurumurthy G P
>
> *
> -----------------------------------------------------------------------------------
> *
>
> *Gurumurthy G P - Junior Research Fellow, Department of Civil Engineering,
> *
>
> *Manipal Institute of Technology, Manipal University, Manipal 576 104.
> INDIA*
>
> *
> -----------------------------------------------------------------------------------
> *
>
> *Tel - +91 820 2924724, Fax - +91 820 2571071, Cell - +91 9742353385 *
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-- 
Robert

"I have not failed. I've just found 10 000 ways that won't work" -T. Edison