PerkinElmer TORION T-9, User Manual

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Troubleshooting Guide . 267
4. Bake out the injector and column (see the section called Bake out the GC Injection Port
and Column
in Chapter 8 “Maintenance”). If the problem persists, the injection port liner,
the septum, or the column may need to be replaced. To replace any of these components
contact your PerkinElmer Service Representative for help..
5. Bake out the vacuum chamber. Contact your PerkinElmer Service Representative for help.
GC peaks are asymmetric
Please Note: Chromatographic peaks during a PERFORMANCE VALIDATION run will look asymmetric and
will most likely have peak tailing. This is not indicating a problem.
1. Chromatographic peaks should be symmetric and Gaussian. Asymmetric and non-Gaussian
peaks typically result from an overloaded column, a degraded column, an incompatible
solute/column combination, or incorrect instrument parameters or operation.
2. Improving peak shape is important for the best confidence in identifying target chemicals;
however, asymmetric peaks will not necessarily prevent identification. Some compounds are
generally detected as asymmetric peaks, in which case the chemical agent library can be
calibrated to compensate.
3. Asymmetric peaks may indicate problems with sampling, delivery, separation, or ionization.
Fronting and tailing are useful indications of possible causes.
Observation Example Possible cause
Fronting The sample is too concentrated and is
saturating the column, allowing some of
the sample to elute faster than expected.
4. The following list provides possible solutions to correct for fronting.
a. Use the sample control radio buttons found on the home screen of the instrument.
(See
Sample Concentration
in Chapter 5 “Basic Operation”.)
b. Use a faster injection time by leaving the SPME fiber extended for a much shorter
time during the introduction of the sample. To do this, extend the SPME fiber when
prompted by the screen and then immediately retract the fiber and remove the
syringe without waiting for the additional prompts.
c. Collect the sample using the headspace method described in the section Using the
Custodion in Chapter 4 “Basic Custodion Operations” for obtaining a sample for
analysis.
d. Dilute the sample.
e. Use a sample solvent with less affinity for the SPME fiber. For example, replace
acetone with water if possible.