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Thank you for your insights Nancy.  I have initially used a 60:40 v/v
hexane:isopropanol solvent based on a colleagues methods related to PAH
and other organic constituent collections and analyses but I will try
the methylene chloride:methanol solution next.

I appreciate the quick response!

Later, Anne
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Anne M. Cotter
U.S. Environmental Protection Agency
Mid-Continent Ecology Division
6201 Congdon Blvd
Duluth, MN 55804
218-529-5183
fax 218-529-5003
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  |Nancy Beavan <[log in to unmask]>                                                                                                     |
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  [log in to unmask]                                                                                                                |
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  |11/04/2009 12:36 PM                                                                                                                    |
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  |Re: [ISOGEOCHEM] select solvents for lipid removal                                                                                     |
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  |Stable Isotope Geochemistry <[log in to unmask]>                                                                                  |
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Hi Anne:

 I've used a dichloromethanol and methanol for lipid extraction to
prepare
fish muscle and liver for analysis, and also collected the lipids. It is
a
method slightly modified from Ruiz et al 2007, and it seems very
reliable
given my replicate results.

Dichloromethanol and methanol are made up into two solutions at 1:2 and
2:1 v/v. The freeze-dried, finely ground and screened tissues are first
steeped in the 1:2 v/v solution for two hours, then centrifuged and the
solution retained for extracted lipids. The sample is then steeped in
the
1:1 v/v solution for two hours, centrifuged, solution retained for
extracted lipids, then the de-lipidised material washed exhaustively in
deionized water.  I would suggest a preliminary rotary evaporation of
the
de-lipidised sample before freezedrying.

Ruiz, N., Dubois, N., Wielgosz-Collin, G., du Pont, T. R., Berge, J.-.P,

Pouchus, Y. F., Barnathan., G. (2007). Lipid content and fatty acid
composition of a marine-derived Trichoderma longibrachiatum strain
cultured by agar surface and submerged
fermentations. Process Biochemistry 42, 676?680

Dr. Nancy Beavan Athfield, Rafter Radiocarbon
National Isotope Center, GNS Science
PO Box 31 312, Gracefield, Lower Hutt
NEW ZEALAND

DD 64 4 570 4650
FAX 64 4 570 4657
http://www.rafterradiocarbon.co.nz





Fname Lname <[log in to unmask]>
Sent by: Stable Isotope Geochemistry <[log in to unmask]>
05/11/2009 07:06
Please respond to Stable Isotope Geochemistry


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        Subject:        Re: select solvents for lipid removal


While looking at the scientific literature, there seems to be quite a
spread of solvents used to extract lipids from tissues ultimately
analyzing the tissue for 15N & 13C.  New to this, I am trying to veer
from the chloroform/methanol solution.  Are there any other solvents
that people are happy using generating  accurate isotopic results?  I
ultimately plan on capturing the lipid fraction and analyzing 15N & 13C
as well as the lipid extracted muscle tissue.

Thanks, Anne

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Anne M. Cotter
U.S. Environmental Protection Agency
Mid-Continent Ecology Division
6201 Congdon Blvd
Duluth, MN 55804
218-529-5183
fax 218-529-5003
[log in to unmask]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~




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