GC Columns

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AB Builtin - Guard
AB-CarboWax 20M
AB-PLOT MoleSieve
Undeactivated Tubing
Deactivated Tubing
Customized columns
AichromBond AQ
Aichrom Ion Exchange
Aichrom Chiral
Aichrom PAH
Aichrom Amino Acid
Column Care

Proper column care and use such as installing, storing and regenerating can enhance the lifetime of a column and its’ application success.

Column installation

1,Know your GC
Since most problems of GC analysis are not due to column itself instead the improper instrument or instrumentation, it is never over emphasized to know about your GC and its history prior usage.
Below is a list of our recommended checklist for your GC:
·GC condition: new or used
Recent change of the GC location
·GC idling duration
·Recent maintenance of the GC system and gas line change
·Abnormal GC column degradation
·Previous GC column performance record/logbook
·Carrier gas quality
If the results from the above testing behaved abnormally, giving signs of shortened lifetime, high bleed, ghost peak, peaking tailing, no signal or too high baseline signal…. The GC most likely has leaking problem, dirty inlet, gas flow or blockage of detector jet.

2, Have a good GC ready
If your GC displays one or more of the above mentioned symptoms, you can fix the problems by following the manufacturer’s recommendations or refer below for some common fixes:
 ·Use high purity gases including the column carrier gas and make up gas
·Setup proper gas flows for both the inlet and the detector
·Change seals (o-rings, inlet seals, ferrules, etc.), septum and the inlet liner
·Change the jet
·Condition the GC inlet and the detector at high temperature for hours 

3. Know your GC column
- A new column or a used column
- Column shelf time in lab
- Any column breakage
- A test chromatogram from the column manufacturer
- A previous analysis chromatogram of the column to be used


1. Carefully uncoil the column one half coils on both ends
2. Loosely hang the column inside the GC oven
3. Use known good and correct ferrules and column nuts
4. Install the column nuts and ferrules to each end of the column
5. Cut each column end neatly for 3 -5cm with a good column cutter. Do not hands break the column end tip
6. Thoroughly examine the cuts. Re-cut the column ends, if the cuts are not neat
7.A ttach the column end to the inlet. llow instrument manual on column end tip length to install the column , such as 2-3cm for split/split inlet, 1-2mm gap length from the end of the FID jet, etc. Make sure the column end not touch metal wall more than 3 times, as multiple touching may damage the column tip that affect
sample introduction into the column
8. Finger-tighten the column nut with another hand holding the column end position for proper insert length, then use proper size wrench to tighten the nut completely. Do not over tighten the nut, as it may smash the column. Make sure the column tip insert length is in the range of the GC manufacturer’s recommendation or specification

9. Stepwise setup the column pressure to establish the column flow or set up the proper column flow
10. Repeat the above steps to connect the detector
11. Securely hang the column inside the GC oven. Do not over uncoil the GC column at each end as it may become broken after thermal cycling. Coil the extra loosed column back to the column cage for securing
12. Adjust the column flow to the manufacturer’s specification. A general flow setting would be:

Column id (mm)
Column flow range (ml/min)
0.2 0.4—1.0

13. Check for any leak sign with Snoop technique or other proper leak detection technique
14. Set properly the inlet and the detector temperatures
15. Set the oven temperature around 50-100
16. Turn on the detector after both the temperature and the flows have been established
17. Check for the stabilized signal level. If the signal is too low or too high, it may indicate a leaking column connection or a broken column at connection ends. Redo the column installation as needed
18. Condition a column at a temperature which is 10-20 lower than the column’s upper temperature limit for minimum 30 minutes. Overnight condition is preferred.
19. Check for the detector signal. If it is too high, there may be a leaking problem, a dirty inlet/detector, or a bad column. Find leaking place and redo column installation, or clean the inlet/detector, or change another column
20. Adjust the column flow to analysis condition if necessary

Good column installation will help obtaining good and successful analysis results.

Column Storage
Idling inside GC oven
Maintain proper oven temperature, e.g., 100-150 under proper column carrier flow
Out side GC oven
Septum-seal both ends of a column, store the column in its original box. Avoid moisture or chemical vapor.
Causes of performance degradation
Many root causes can result in column performance degradation. The most causes are oxygen present in carrier gas stream (oxidation), thermal damage, and sample contamination. Check for instrumentation obvious before time-consuming troubleshooting. The following table lists general troubleshooting processes and some remedies.
Degradation Symptoms Root cause From Remedy
-High column bleed
-Column selectivity change/shift
-Retention time shift
-Chopping baseline profile
-Peak tailing
-Blockage of a detector jet and abnormal signal level
-Oxygen in carrier gas flow path
-A bad column
- Low grade carrier gas used
- Leak in the gas line connection
- Instrument leaking places:
  inlet, pressure regulator, valve
- Home gas plumb connection with dead or void volume in the flow path
-Change carrier gas grade
-Use traps
-Properly re-plumbing
-Fix instrument leaks
-Purge the column for longer time at low temperature
-Avoid high temperature chromatography
-Change the column
-Peak tailing
-Unstable or noisy detector signal
-Retention time shift
-Moisture present in gas stream line
-Sample contamination
-Thermal damage at temperature over column upper limit
-System off for long time
-Low grade carrier gas
-Large dirty Sample introduction
-Use trap in carrier gas line
-Bake instrument
-Do not turn off instrument unless necessary
-Good sample preparation
-Trim contaminated column ends by 0.1-0.5m
-Accelerated column bleed
-Significant column selectivity change
-Severely peak tailing
-Peak broadening
-Thermal damage -Oven temperature exceeding the column upper temperature limit
-The inlet or detector temperature is too high
-Combination of oxidation, duration time and column temperature
-Almost irreversible degradation
-Trim column each end by 0.5-1m
-Reduce used temperatures
-Switch the high grade carrier gas
-Column breakage -Human errors
-Instrumentation errors
-A bad column
-A bad column
-Gas pressure pulse
-Fast temperature ramping up/down
-Column nut tightened Too much
-Slowly setup carrier gas pressure with EPC
-Reduce temperature ramping
-Butt-connect the  broken  column
-Redo the column installation
Column regeneration

Condition or bake a column at isothermal temperature close to the column upper temperature limit with two times of the column working carrier flow for 2-24 hours. Avoid using programmable temperature profile to condition a column. This regeneration can be effective for sample contamination. But sometimes conditioning can result in accelerated degradation if oxygen is presented in carrier stream. Column surface may become active for many polar compounds after conditioning.

Multiple solvent injections
Injecting solvent multiple times into a column at 50-100 oven temperature may regenerate the column performance. Avoid using oven temperature below solvent boiling point as solvent condensation will wash out too much stationary phase at the inlet end. The column surface may become less inert or more active after multiple injections.
Trim both ends of column
Trimming both ends of the column by 0.1-1m could be an easy and effective way to regenerate the column performance. Trim longer length at detector end than at the inlet end. Adjust instrument condition (e.g., column flow) according to maintain retention time locking. After trimming, condition the column for 30minutes to 2hrs. Trimming column leads to shorter column length, and it may eventually make the column unusable.
Solvent rinse
In extreme case of offline solvent rinse:
  • Use high grad (HPLC or GC grade) solvent compatible to stationary phase, such as non-aqueous solvent for wax columns, hexane/toluene for polysiloxane columns.
  • A column should only be rinsed with 2-3 column volume solvent at low pressure.
  • Gas purge dry a column for 30minutes to one hour
  • Properly condition the column at its upper temperature limit for 2-10hours.

Note: Avoid rapidly pressure change, since it often causes the column breakage.