ISQ User Guide - Write Frame of Mind

8 Troubleshooting
Investigating Peak Issues
Table 2. Troubleshooting Baseline Issues in Your Data, continued
Behavior Cause Characteristic Remedy
Noise
General Column is contaminated Condition or replace the column.
High-frequency
Mass spectrum is
electronically noisy
Mass spectrum is
chemically noisy
Investigating Peak Issues
Table 3. Troubleshooting Peak Issues in Your Data
Detector gas is contaminated
Check the purity of your gas and install appropriate
filters.
Electrometer is defective. Replace the electrometer.
Temperature of the detector is
higher than column’s maximum
allowable temperature
Reduce the temperature detector to the maximum
allowable temperature of the column.
Column fittings are loose Tighten connections accordingly.
Electrometer is not properly
zeroed or electrometer is
damaged
Column is dirty or MS is
contaminated
Behavior Cause Characteristic Remedy
Broadening General
Double Peaks General
Re-zero the electrometer.
Replace the electrometer, if necessary.
Reset the electrometer by powering the system off
and on.
Check for an air leak.
Find the source of chemical noise and fix it.
Check purity of carrier gas.
Check the cleanliness of your inline carrier gas filter.
Verify the GC liner, column and MS are free of
contamination.
Verify that the transfer line temperature is not set too
low.
Column flow is too high
Reduce the flow. Make sure vacuum compensation is
turned on.
Column flow is too low Increase the flow.
Split flow is too low for split
injection
Increase the flow to 40-50 ml/min.
Performance of the column has
degraded
Test the column at the optimum flow rate.
Injector is dirty Clean or replace the liner.
Temperature of the transfer line is
too low
Increase the temperature to 10 °C below the
maximum allowable temperature of the column.
Injection speed is too slow Inject more rapidly in a smooth motion.
Autosampler injection speed or
mode is incorrect
Increase the speed and reduce the post injection
dwell time.
92 ISQ User Guide Thermo Scientific