Chapter:
PURGE-AND-TRAP
Diagnostic Flowchart
..
Topic:
Troubleshooting Purge and Trap Contamination (continued)
Page 2
of
2
From page 1
Call SRI
for
further
assistance.
Dirty
tubing.
New
tubing
was
the
fix.
Replace
the
traps
with
blank tubes. Perform2
more blank
runs.
15
the
contamination still
a
problem?
set
the trap temperature
to
250
0
C.
/5
the
contamination still a
problem?
It
appears
that the
traps
that were in use are
defective
and
retaining
contaminants. Replace
the
traps
to eliminate
the
problem.
• prior
10
removing
the
rotor, note the
~n
of a letter stampedon oneend
Of
the metal
tin
protruding
from
the
lOp. This
letter
indiCates
the
rotor
temperature
rating,
but
also assists
In
()(lentlng
the
tin
j:rOperty
dlXing
reinstallation
01
the
rotor
attar cleaning. Much Uke a automotive
disb'tllJtO(. the
rotor
can
be
reinserted
1SOo
wrong. resulting invalve ranee.
Replace
all
1/16·
stainless
steel
purge
and
trap
tUbing
around
the
gas
sampling valve.
15
contamination still
a
problem?
The
traps
were
retaining analyte.
Spent
traps
may
tend to retain
analyte.
Replacement
maybe
indicated.
Remove"
and
clean
the sampling valve
rotor. Clean the rotor
seat. Perform2 blank
runs.
Is contamination
still
a problem?
Wrth
a
clean
test
tube, sparge
and
carrier gas flowing and
the gas sampling valve in the INJECT position, bake
out
the
traps
for 15minutes. Activate relays C
and
F with trap
setpoints
of
300° C.
In the INJECT position, the traps
will
exhaust
to the column (raise the column temperature).
Perform 2 blanks. Is the contamination still a prcoem?
Remove
trap
heating events
(relays C
and
F on) from
event
table.
Perform two
moreblank runs. Is
the concentration
of
contamination
still
a problem?
GrapMe is
adsorbent.
It
is possible that the
ferrules could adsorb
analyte
if
exposed to a
high concentration.
New ferrules
eliminated the high
contamination
level.
The sampling valve rotor
and
I
or
seat
was
contaminated.
Cleaning
the
rotor area surfaces eliminated the
problem. Further cleaning may be
necessary as contaminaJ:ion works
through the valve
body.
The sampling valve rotor
and
I
or rotor seat
appear
to have
been
contaminated. Cleaning
the area eliminated the
contamination problem.
Dirty
tubing.
New
tubing
was
the fix.
Use this troubleshooting
flowchart
if
you are
experiencing difficulty
with contamination when
performing purge and
trap analyses.
Begin on page
1.
Replace the graphite ferrules securing the
traps and the column. Clean the
fittings.
Look
for graphite shavings in
trap
and
column
ends.
Remove shaving
if
found. Thenperfocm a
blank analysis. Are
thecontamination peaks
still
a proolem?
Remove"
and
clean the gas
sampling valve rotor. Clean
the rotor
seat.
Reinstall the
rotor. Is contamination still a
problem?
Replace the
stainless
steel
tubing around
the gassampling
valve.
Is the
contamination
stili a problem?
Call
SRI
for
tech.
support
