Varian 450-GC, User Manual

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Technical Tips Technical Tips
Page: Page: 458 458 User User Manual Manual 450-GC 450-GC Varian, Varian, Inc. Inc.
CHROMATOGRAP CHROMATOGRAPHIC HIC INTERPRETATIONS INTERPRETATIONS
The troubleshootin The troubleshooting procedures outlined in this g procedures outlined in this section are structured to section are structured to
accommoda accommodate deviations from known te deviations from known responses of a st responses of a st andard sample, andard sample,
including peak shapes, peak areas, retention times, including peak shapes, peak areas, retention times, baseline characteristics, baseline characteristics,
etc. etc.
In these cases, the general characteristics of the In these cases, the general characteristics of the chromatogram are well known chromatogram are well known
and even slight deviations can and even slight deviations can be discerned. be discerned.
A vast majority of g A vast majority of gas chromatog as chromatographic malfu raphic malfunctions will be in nctions will be indicated by o dicated by one or ne or
more of the following symptoms; inspect the chromatogram for all of more of the following symptoms; inspect the chromatogram for all of the the
symptoms: symptoms:
••
Change Change in p in peak eak size size (peaks (peaks of di of different fferent area, area, or h or height eight than than expected). expected).
••
Change Change in in retention retention times. times.
••
Change Change in in baseline baseline stability. stability.
••
Asymmetrical Asymmetrical peak peak shapes shapes (non-Gaussia (non-Gaussian, n, skewed, skewed, etc.). etc.).
••
Change Change from from expected expected peaks. peaks.
For overall troubleshooting of the capillary For overall troubleshooting of the capillary system based on the system based on the appeara appearance of nce of
the chromatogram, refer the chromatogram, refer to Table Capillary to Table Capillary Chromatograp Chromatographic Interpretations. hic Interpretations.
If a problem exists which cannot be If a problem exists which cannot be identified and/or corrected, call your identified and/or corrected, call your
nearest Varian Service Center for nearest Varian Service Center for assistance. assistance.
Sympto Sympto m m Cause Cause Reme Remedy dy
Multiple peaks from a single Multiple peaks from a single
compound
compound
Injection is too large. Injection is too large.
Initial temperature is too low.
Initial temperature is too low.
Reduce the size of the Reduce the size of the
injection.
injection.
Initial temperature should
Initial temperature should
be no more than 20°C
be no more than 20°C
below the solvent boiling
below the solvent boiling
point for samples greater
point for samples greater
than or equal to 1.0 mL.
than or equal to 1.0 mL.
Tailing Tailing Degraded Degraded column column or or sample sample
adsorption. adsorption.
Frit may be clogged.
Frit may be clogged.
Contamina Contaminated ted insert. insert.
Excess dead volume. Excess dead volume.
Injector not heating correctly. Injector not heating correctly.
Replace or recondition Replace or recondition
column.
column.
Replace purge frit or use Replace purge frit or use
needle valve.
needle valve.
Replace glass insert.
Replace glass insert.
Recheck Injector
Recheck Injector
assembly and column
assembly and column
connections.
connections.
Check make-up gas flow.
Check make-up gas flow.
Check Injector
Check Injector
heating/coo
heating/cooling ling functions. functions.
Peak Peak broadening, broadening, poor poor resoluti resolution on Degraded Degraded column. column.
Wrong carrier gas flow. Wrong carrier gas flow.
Replace or recondition Replace or recondition
column.
column.