[Coral-List] Organics in Sand Sample

Hajime Kayanne kayanne at eps.s.u-tokyo.ac.jp
Mon Nov 3 05:40:29 EST 2003

Dear Shane,

You had better acidify samples by vapor and measure C contents in the remnants,
or you acidify samples by liquid HCL in a cup and measure C contents for 
the whole remnants.
In both methods, you need to use a CHN analyzer for measurement.

If you apply "ash test" (low temperature combustion), you will obtain 
higher organic C contents as a portion of carbonate is also combust even at 
low temperatures.
More popular and precise procedure is "wash-out method", in which carbonate 
is acidified and removed through filters. However, this method 
underestimates the organic contents, as a portion of organic matter is also 
washed out.
The errors in the above methods are usually small for silici-clastic 
samples in which carbonate content is small.
However, the errors are critically large for carbonate samples in coral 
reefs with high percentage of carbonate and low one of organic matter.

Please refer to Yamamuro and Kayanne (1995) in Limnol. Oceanogr., 40, 


>I am working on a project where I need to be able to quantify the percent
>organics bound in a sample of sand taken from a marine location.  Are there
>any standard procedures for determining the organic content of a sand
>sample?  At this point all I'm interested in obtaining is what percent of
>the sample is inorganic and what percent is organic.  In my mind a simple
>ashing test seems to be the most logical test for this end result.  If
>anyone has any procedures for determining this (or tips), I would greatly
>appreciate it.
>Thank you in advance,
>Shane Graber
>Sr. Research Chemist
>Coral-List mailing list
>Coral-List at coral.aoml.noaa.gov

---- Hajime KAYANNE ----
Department of Earth & Planetary Science,
University of Tokyo
Hongo, Tokyo 113-0033 Japan
Tel: 81-3-5841-4573
Tel & Fax: 81-3-3814-6358

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