Isogeochemist and especially Dr William J. Showers of North Carolina State
University


on our CEInstruments Elemental analyzer we used Helium and Oxygen as
utilities.

In the EA1108 the Oxygen is used for  Flash Combustion while Helium is used
as carrier gas and purge gas.
The function of purge is to eliminate the presence of air , therefore N,
over the tin container before dropping in the oxidation reactor.

In the CE 2500, Helium is carrier gas while Oxygen has double function :
oxidative gas and purge gas.
Using Oxygen as Purge gas, the blank value is reduced (10 time less): this
factor was very important for  trace elemental analysis
Consequently in CE2500 configuration, also the He consume , using only for
carrier , is riduced.

According to the autosampler used the Oxygen flows for purge in CE 2500
are the following:

AS200  40 - 50 ml/min
AS128   80 ml/min

while for EA1108, the Oxygen use for Oxidation gas  was 10 - 20 ml/min :
this is the reason of the different Oxygen  gas consume in EA1108 and CE2500.

Best regards



Guido Giazzi
Product Manager
CE Instruments - Rodano Italy
phone   ++39 02 95059336
fax     ++39 02 95059309