Agilent Knowledge Portal
Carlos VargasThis Information Applies To: Agilent GC Systems
Issue
Loss of peak resolution can be a combination of decrease in separation and increased peak width. Loss of resolution can impact on analytical reproducibility and accuracy.
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
Loss of resolution can be caused by decreasing separation between peaks or an increase in width of peaks (Figure 1):
Figure 1. Decrease in peak separation and peak broadening
1. Normal retention time separation, 2. Retention time difference, 3. Peak width at half height
4. Decrease in separation, 5. Increase in peak width
| Possible cause of decrease in separation | Solution |
| Change in column temperature (all peaks) | Check the column temperature |
| Change in column dimension | Verify that the installed column matches the configured column in the instrument and the method column. Trimming the column many times over its lifetime will change the effective column length, and impact retention times. Adjust instrument set column length every time the column is trimmed |
| Coelution with another peak | Improve peak separation. Change column temperature or stationary phase |
| Possible cause of increase in peak width | Solution | ||
| Overloading from a large change in analyte concentration | Dilute the sample | ||
| Change in sample concentration (higher concentrations have wider peaks) | Check if new standards have been recently prepared. Changes may also be caused by preparation error, degradation, evaporation, or variances in sample temperature or pH | ||
| Column contamination | Bake out the column. Bake-out for 1 to2 hours or until baseline is stable
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| Column activity (active compounds) | Irreversible. Replace the column | ||
| Change in carrier gas flow | Check the carrier gas flow rate | ||
| Change in the injector settings | Check injection volume, purge activation time (splitless only), split ratio, septum purge flow, column temperature | ||
| Improper solvent effect, lack of focusing (splitless) | Lower initial oven temperature, choose a different solvent, sample phase polarity match, use a retention gap |
If these procedures have not resolved the resolution 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 |
