How do I troubleshoot my GC?
Inject less sample (dilute, use split injection, reduce injection volume). Minimize dead volume in the GC system; verify proper column installation, proper connectors, proper liners, etc. Verify injector and detector flow rates and adjust if needed. Verify make-up gas flow and adjust if needed.
What causes GC retention time shift?
A change in the temperature program often causes a retention time shift of all the peaks. A change in the initial temperature, the initial hold time, or the ramp rate can affect all of the peaks. Retention times increase with a lower initial temperature, longer initial hold time, or a slower ramp rate.
What causes peak splitting in GC?
Split peaks can show up in gas chromatography when our injection isn’t working right or things aren’t transferring from the inlet to the column correctly.
How do I get better peak separation in GC?
How do I improve early eluting peak shape for GC?
- Use a split injection. This limits the amount of solvent that gets onto the column and reduces how much analyte dissolves in pooled solvent.
- Decrease the injection volume.
- Use a pressure pulsed injection.
- Use a guard column.
- Increase the column film thickness.
What is purge flow in GC?
The purge flow acts to keep the injector clean by flushing the upper portion with a low flow of gas. A small amount of the more volatile portion of the sample may escape from the injector via the purge vent. The higher the purge vent flow, the greater the potential loss of the more volatile sample compounds.
What is the split ratio in GC?
The split ratio is calculated by dividing the column carrier gas flow rate into the split vent flow rate. This value is the relative amount of carrier gas flowing out of the split vent compared with the column flow rate.
How do you stop peak tailing in GC?
Try changing your stationary phase or solvent. If peak tailing is occurring only in peaks closest to the solvent front or major component peak, consider the Reverse Solvent Effect. Try a retention gap or guard column to correct this.
What is septum purge in GC?
Most modern gas chromatographs have a septum purge flow that is designed to flow across the inward face of the septum, sweeping most of the volatiles away from the column. In these cases, small septum particles can be cored from the body of the septum and fall into the inlet liner.
What factors affect GC separations?
Which factors influence the separation of the components?
- Vapor pressure.
- The polarity of components versus the polarity of stationary phase on column.
- Column temperature.
- Carrier gas flow rate.
- Column length.
- Amount of material injected.
- Conclusion.
How can I improve my GC results?
Increasing the carrier gas linear velocity will increase the speed of analysis. Loss of resolution can occur if the speed is increased much higher than the optimal velocity for the carrier gas. Using hydrogen and higher linear velocity will improve efficiency.
How to troubleshoot using the Agilent 7890 gas chromatograph manual?
Proceed with troubleshooting under the assumption that method(s) are working properly. This manual also includes common troubleshooting tasks as well as information needed prior to calling Agilent for service. How to troubleshoot using this manual Use the following steps as a general approach to troubleshooting:
Is there a GC troubleshooting video series on Agilent?
As part of our ongoing commitment to be your partner in chromatography, we have created this series of GC Troubleshooting videos.
What do you need to know about GC troubleshooting?
You will also learn the detailed steps to perform basic inlet maintenance, a vital process to ensure accurate GC performance. You will learn the causes and solutions for baseline disturbances, including inlet, column and detector contamination as well as septum degradation.
What kind of gas chromatograph does Agilent use?
Agilent 7890 Gas Chromatograph Troubleshooting Agilent Technologies Agilent 7890A Gas Chromatograph Troubleshooting Notices
