2000 MS Hardware Maintenance
148
Troubleshooting
Correction of Leading Sample Peaks (Reverse
Tailing)
Symptom Solution
Column overhead due to injection of
excessive amounts of a component
Dilute the sample, or perform a split injection.
Degradation of the stationary phase
Change the column.
Carrier gas velocity is too low
Increase the carrier flow rate.
Correction of Poor Resolution
1
Symptom Solution
Column temperature or program is
not optimized
Modify the method (e.g., slow the column ramp
rate) to improve the separation
Carrier gas flow is not optimized
Decrease the carrier gas linear velocity to
improve the resolution.
Column cannot separate certain
species, (e.g., those with similar
boiling points)
Use a more polar column.
Column stationary phase is
degraded, resulting in poor efficiency
Replace the column.
1
Peaks are not well separated, e.g., 2,6-dimethylphenol and
2-ethylhexanoic acid in the COLTEST mixture.
Lack of Reproducibility of Peak Size
Symptom Solution
Leaking or partially
plugged syringe
Visually check that the syringe is pulling up the sample.
Check that the nut is tight. Flush the syringe with solvent.
Heating the solvent in a hot injector may help if the syringe
is plugged; otherwise, replace the syringe.
Leak at the septum
Replace the septum regularly and ensure that the septum
nut is tight.
Improper installation of
column in the injector, or a
leak at the column inlet
Check the installation of the column in the injector.
Tighten the capillary column nut.
Sample is being absorbed
by active surfaces in the
injector or column
Change the injector insert. Remove the front 15 cm of the
column, or replace the column.
Incomplete vaporization of
sample in the injector
Increase the injector temperature (1077,1078 or 1079).
Or increase the maximum temperature to which the
injector is programmed (SPI or 1079).
1077,1078 or 1079 splits
too soon
Confirm that the switch time is chromatographically
optimized.
