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I believe Bullister and Weiss (1988) " Determination of CCl3F and CCl2F2",
Deep-Sea Research, v.35, n5, p.839-853, used a packed 10' x 1/8" Porosil C
column at -30oC for separation of CFC-11 and CFC-12, by purge and trap.
This packing is available from Alltech Associates.

We are currently analyzing CFC-11 and CFC-12 for age-dating using a
modified vacuum extraction procedure described by Markus Hofer and Dieter
Imboden (1998) "Simultaneous Determination of CFC-11, CFC-12, N2, and Ar in
Water", Analytical Chemistry, v. 70, n. 4, p.724-729. Their method utilizes
a 10'x 1/8" Supelco 5% Flurocol 60/80 mesh Carbopak B column to separate
the CFC's with nitrogen carrier at 30mL/min and temperature programed
gradient.

When we built our system, however, we chose to go with a capillary column,
first using a 30 m x 0.53 mm x 3.0 um HP-624 at 15oC  and then switching to
a 30 m x 0.32 mm x 5.0 um GS-GASPRO from J and W (now part of Agilent). The
GASPRO give better separation of the lighter CFCs and helps with co-eluting
compounds. Either of these columns can be used for CFCs at room
temperature. We are doing cryo-cooling so that we can separate Ar and O2 on
an HP-Molesieve duing the same run.

Daniel D. Snow, Ph.D.
Water Sciences Laboratory
Department of Agronomy and Horticulture
Institute of Agriculture and Natural Resources
University of Nebraska-Lincoln
Lincoln, NE 68583-0844
((402) 472-7539





                    R D DESHPANDE
                    <[log in to unmask]       To:     [log in to unmask]
                    RNET.IN>              cc:
                    Sent by: Stable       Subject:     [ISOGEOCHEM] Requesting information about readymade columns
                    Isotope                available for              separation of CFC-11, CFC-12 and CFC-113
                    Geochemistry
                    <ISOGEOCHEM@LIS
                    T.UVM.EDU>


                    11/08/01 05:18
                    AM
                    Please respond
                    to Stable
                    Isotope
                    Geochemistry






Dear All,
                I am trying to setup a Gas Chromatography laboratory for
analysing dissolved CFCs(11,12 and 113) in natural waters using following
analyitical configuration.

Trace GC-2000/ ECD/purge and trap/Packed column/Ar-CH4 carrier
gas/Nitrogen stripping gas.

Separation column: 3m of 1/8" OD SS column packed with 80/100 mesh Porasil
C in a coil.

Precolum: 15 cm length of tube with same material in coil.

Preconcentration column:  20 cm length of 1/8"(O.D) SS tubing packed with
Porasil C -Porapak T and glass bids.

I WOULD BE OBLIDGED IF SOME ONE CAN GUIDE ME WHICH ARE THE READY MADE
COLUMNS best suited for this application and AVAILABLE IN MARKET FOR
SEPARATING cfcs (11,12 and 113). Also I would appreciate if you can share
your experience about purge and trap system of separating CFCs from water,
the precautions to be taken and improvised techniques in practice.


Regards


R.D.Deshpande

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