No thanks! I would like to know more about CHROMacademy

 Over 3000 E-Learning topics / 5000 Articles & Applications
 

GC Column installation

“The beginning is the most important part of the work.” - Plato, The Republic

A properly installed GC column is the most important beginning for your work. Follow our step by step guide below, and use the interactive animations, to ensure your column is correctly installed every time, giving you great chromatography, analysis after analysis.

GC columns need to be properly prepared to avoid issues such as high bleed and poor peak shape. Poor installation can lead to reduced efficiency (broad peaks), peak shouldering or splitting, and poor quantitative reproducibility.

 

Step 1

If your column was shipped with flame-sealed ends, be sure to trim at least 10 cm from each end to avoid high column bleed associated with the flame-sealing process.

Be sure that the column cuts are straight (that is, at 90° to the column outside wall), and not jagged. Angled cuts with rough column edges lead to peak tailing or splitting caused by polar analyte interactions with the excess of silanol groups exposed and the formation of turbulent eddies at the inlet, which holds up analytes from entering the column. Be sure to check the quality of the cut with a magnifying glass (a microscope is better), because the quality of the cut directly affects peak shape and therefore the reproducibility of your integration or quantitative data.

 

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player


Step 2

After you have properly cut the column, follow the manufacturer's instruction regarding insertion distances into both the inlet and detector.

A column installed too high in the inlet risks poor quantitative reproducibility, and when a column is installed too low, peak broadening can occur because of the extra dead volume created. At the detector, a column inserted too high will give rise to high baseline noise and spikes with flame-based detectors (as the polyimide column coating burns in the flame!) or again to broad peaks if installed too low. Each column type has a dedicated ferrule size or internal diameter, and gas chromatography–mass spectrometry (GC–MS) ferrules are made from different materials — are you using the correct type? Check with your manufacturer. Oh — and that funny little cup with insulation inside that stops you from getting to the column coupling so you just removed it— well that's probably just lost you some potentially vital plates and degraded the peak shape slightly, so make sure you put it back.

 

Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player

Step 3    

Column conditioning parameters differ with stationary-phase polarity and film thickness, so always check the side of the box for the maximum isothermal and gradient temperatures. But here's a tip to reduce your conditioning effort and save stationary phase — connect the column to the inlet (not the detector) and allow your carrier gas to flow through at ambient temperature for 10–15 min — this helps to purge dissolved oxygen from the stationary phase and significantly reduces conditioning time and subsequent phase loss. Then condition the column by raising the oven temperature at 10 °C/min to the gradient maximum and hold for the required period of time to subsequently obtain a stable baseline — this is almost never longer than 1 h in our experience and may be as short as 10 min for less-polar, thinner-film columns.

 

Once your column is correctly fitted you want to make sure you get the best possible results for as long as possible, so here are some final tips for extending your column lifetime.

  1. Fit carrier-gas traps close to the instrument (to remove oxygen and moisture) this is a great way to improve column lifetime and detection limits.
  2. Use the plate count of a test analyte to monitor column efficiency and set a column discard limit based on your knowledge of required plate counts for your types of analysis.
  3. Columns can often be miraculously restored to life by trimming 5% of the total column length from the inlet end — note that retention times may shift slightly after this operation, but efficiency may increase and peak shapes will improve.
  4. Consider using a guard column if your samples are particularly dirty.

 

You may also like:

 


loading data
loading data
loading data
loading data
loading data
 

group  subsCHROMacademy can deliver to corporate clients on a multi-user subscription basis.
Served up from secure servers to the corporate intranet or individual desktops.

  • Microsite - your own learning site powered by CHROMacademy
  • Your Landing Pages -with your logo and branding
  • Customized Assessments - Based on content agreed upon Certificate of Completion
  • Certification Programs - Offer your learners a goal to strive towards
  • LMS : Connect - Our Learning Management System is S.C.O.R.M. compliant and will connect to your system
  • Engagement Package - E-newsletter stimulation program derived from your content and ours
  • Full archive of Essential Guide webcasts & tutorials
  • 1000’s of eLearning topics - HPLC / GC / Sample Prep / Mass Spec
  • Ask the Expert - our experts will answer your chromatography questions within 24 hrs.
  • Assessments - test your knowledge
  • Application notes & LCGC articles
  • Troubleshooting and virtual lab tools

Request a quote

 

 Home | About UsContact Us | SubscribeTerms and Conditions | Advertise | Privacy Policy 

loading data

loading data

loading data

 

loading data


loading data