Agilent Technologies 7890A Troubleshooting Manual page 26

3
Chromatographic Symptoms
Retention Times Not Repeatable
26
• Replace the septum.
• Check for leaks in the inlet, liner (as applicable), and
column connection. (See "Checking for Leaks".)
• Check for sufficient carrier gas supply pressure. The
pressure delivered to the GC must be at least 40 kPa
(10 psi) greater than the maximum inlet pressure
required at final oven temperature.
• Run replicates of known standards to verify the problem.
• Verify that you are using the correct liner type for the
sample being injected. (See Selecting the correct inlet
liner.)
• Consider if this is the first run. (Has the GC stabilized?)
• If using an FID or NPD and retention times increase
(drift), check the jet for contamination.
Troubleshooting