Chapter 7 89
Troubleshooting
PROBABLE CAUSE CORRECTIVE ACTIONSYMPTOM
Improper gate values
Low range
Unswept dead volumes,
sample adsorption on
activated surfaces, sample
decomposition, or a leaking
injector septum
Crushed column at combus-
tor support
Normal elemental reaction
Ruined column
PFPD is too cold
Quenching
Verify that the correct mode and
gate values are being used.
Optimize gate and threshold
(trigger) level settings in the
Board/Channel Parameters
window of WinPulse.
Increase the gain by using a lower
range.
Check PFPD temperature to
ensure that the sample is not
condensing prior to elution into
the combustor and that the PFPD
temperature does not exceed the
recommended maximum tempera-
ture for the column.
Check the column end protruding
beyond the combustor support to
verify full flame propagation into
the combustor. Increase detector
temperature to prevent condensa-
tion in the detector body. Verify
proper operation of the injector
and column installation.
Peak tailing is normal in As, Sn,
and Sb detection. The tail is
reduced for these elements at high
PFPD temperatures. At low PFPD
temperatures, the tail may become
much longer but with a low
amplitude.
Replace the column. If dirty
samples are used, add a guard
column.
Increase the PFPD temperature to
300°C for phosphorus or sulfur/
phosphorus pesticides.
Replace the column with one with
better separation, inject less
sample, use a 3-mm combustor,
and increase air 1.
Severe peak tailing
Nonuniform
response
Reduced sulfur
response under
coelution with
hydrocarbons
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