Jo Boden
Carlos VargasThis Information Applies To: Agilent GC Systems
Issue
A shift in retention time can occur for single, multiple or all peaks.
Other chromatographic problems are identified in Basic Troubleshooting for GC Systems . Regular maintenance of your instrument in accordance with the recommended maintenance schedule will reduce the incidence of chromatography problems.
Background
Retention time (RT) shifts can be the result of changes analytical conditions, sample concentrations, column, or injector problems (Figure 1):
Figure 1. Retention time shift
1. Normal retention time, 2. Retention time increased (all analytes)
| Possible cause of retention time shift | Solution |
| Overloading from a large change in analyte concentration | Dilute the sample |
| Septum leak | Replace the septum |
| Injection technique | Check that the syringe plunger is moving freely. The solution should be pulled into the syringe body, and moving freely and fast when plunger is depressed. Use an autosampler |
| Leak in the injector | Leak check the injector How to Run and Interpret the Inlet Leak and Restriction Test for the Agilent 7890/8860/8890 GC Systems |
| Change in carrier gas flow rate (all peaks similar RT shift) | Check the carrier gas flow rate. Carrier gas flow rate can be measured with an unretained compound |
| Sample solvent incompatibility (splitless injections) | Change the sample solvent or use a retention gap |
| Change in column temperature | Check any changes in the method column temperature |
| Change in column dimension |
Verify that the installed column matches the configured column in the instrument and the method column. |
If these procedures have not resolved the retention time shift problem, contact Agilent Technical Support.
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Learn how to effectively troubleshoot your Agilent GC System:
GC-0GEN-1040z - Practical Steps in GC Troubleshooting
GC-0GEN-2040zs - GC Troubleshooting Series e-learning courses available from Agilent education |
