INJECTORS
&
GASYALYES
Thermal Desorber Soil Sample Preparation
Chapter:
Topic:
(
!
I
i
~~-------------------------~)
Glass
woo]
plugs
DONor COMPACf
SAMPLE!
-----t
,:!
7
Glass woolplug
'20
iso-_.••_._ .. _..
J
so
80
70
ec
50
40
Sample preparation
in
beaker
2.5- (6.35cm)
10 gms.
soil sample
~._
...
_
...
_
...
_
...
_--
I
PIacement of
glass
wool
in
desorption
tube
prior
to
sample insertion
Diagramof assembled sample desorption
tube
containing
0.5
gms
of soil - Na:zS04
sample
mixture
t-
I=:;;:::::===~
/
Borosilicate desorption
tube
I) To ensure that the soil sampleanalyzed is
representative of the site sample, mix the soil
in
the sample container completely. Then weigh 10
grams of soil from the sample container into a
150
ml
beaker.
3) Roll a small amount of glass wool
into
a ball
with your fingers, then insert it into one end of
the glass desorption tube so that
it
remains
in
place. Then place the
tube
on a tared balance.
Record the tare weight,
4)
Load
approximately 0.5 grams of the
soil-sodium sulfate mixture
into
the desorption
tube.
2) Add 10grams of granular
sodium
sulfate
(NaozS0.) to thebeakerand
mix with
a stirring
rOO
or
spatula.
The granular
sodium
sulfate,
when
mixed
with thesoil, absorbs most of the
moisture from thesoil, allowing clay soils
to
be
ground into smaller particles.
This
is
important
because dense clay
will
not fully desorb. The
mixture of soil and
NAzSO.
should be of a
granular
consistency with small
uniform
particles.
5)
Insert
another plug of glasswool
into
the
desorption
tube
to
hold the sample
in
place.
Do
notcompact the sample when inserting the glass
wool or the sample may not desorb thoroughly.
When properly loaded and plugged, the
tube
should resemble the diagram
to
the rigbt.
6)
Place the loaded desorption
tube
on the
balance and record the undesorbed weigbt. After
desorption, allow the
tube to
cool
and
re-weigh
to
obtain the desorbed weigbt. The hydrocarbon
content can then
be
calculated hased on either the
desorbed weigbt of the sample or the undesorbed
weigbt (wet weigbt) of the sample. The
difference between the two weights represents
theamount ofmoisture left
in
the sample
following the mixture with
sodium
sulfate.
