Basic Troubleshooting for GC Systems

Answer

This Information Applies To: Agilent GC Systems

Issue

Several problems can be identified in GC chromatograms, and each of these problems can have various different sources.

Regular maintenance of your instrument in accordance with the recommended maintenance schedule will reduce the incidence of chromatography problems. 

Steps to follow

The most common gas chromatography problems identified in a chromatogram include: 

• Ghost peaks or carryover (Figure 1). 
  See Source of Ghost and Carryover Peaks in GC 

  
  Figure 1. Ghost and carryover peaks
  1. Clean blank run (no injection), 2. Contaminated run with ghost peaks and carryover
  
  

• Excessive baseline noise (Figure 2).
  See   Excessive Background Noise in GC 

  
  Figure 2. Excessive baseline noise
  1. Normal background with peaks visible, 2. Excessive background with peaks partially obscured
  
  

• Baseline instability or disturbances (Figure 3).
  See Baseline Instability in GC 

  
  Figure 3. Baseline instability
  1. Stable baseline, 2. Unstable baseline
  
  

• Fronting peaks (Figure 4).
  See  Peak Fronting in GC 

       
  Figure 4. Fronting peaks
  1. Normal symmetrical peak, 2. Fronting asymmetrical peak, 3. Overload
  
  

• Tailing peaks (Figure 5) 
  See Peak Tailing in GC Systems 

  
  Figure 5. Tailing peaks
  1. Normal symmetrical peak
  
  

• Split peaks (Figure 6).

  See Peak Splitting in GC 

  
  Figure 6. Split and broadening peaks
  
  

• Retention time shift (Figure 7).
  See Peak Retention Time Shift in GC 

  
  Figure 7. Retention time shift
  1. Normal retention time, 2. Retention time increased
  
  

• Change in peak size (Figure 8). 
  See Peak Size Changes in GC 

     
  Figure 8. Change in peak size
  1. Some peaks change size, 2. All peaks change size
  
  

• Loss of resolution (Figure 9). 
  See Loss of Peak Resolution in GC

  
  Figure 9. Loss of separation
  1. Normal retention time separation, 2. Separation, 3. Peak width
  4. Decrease in separation, 5. Increase in peak width

Learn how to effectively troubleshoot your Agilent GC System: GC-0GEN-1040z - Practical Steps in GC Troubleshooting e-learning course available from Agilent education