Optimizing your GC for the analysis of permanent gases and light hydrocarbons

The energy and chemicals industries are increasingly demanding analysis methods that are rugged and efficient and gas chromatography (GC) systems are therefore required to enable more samples to be run with reduced instrument downtime and maintenance costs. The analysis of permanent gases and light hydrocarbons requires the use of specialized GC columns as they are difficult to retain chromatographically due to their very low boiling points.
PLOT (porous layer open tubular) columns are the GC column of choice thanks to their excellent selectivity and retention characteristics. However, their routine use can be challenge because PLOT stationary phases are generally unstable as the adsorbents that are immobilized on the inner surface of the fused silica column can lead to particle shedding.


A number of problems can occur in the GC flow path when particles become dislodged from the column and flow downstream. Flow path restrictions or plugging can occur which results in analytical system downtime or even damage to rotary valve systems caused by abrasion of critical surfaces. This results in costly, unscheduled instrument maintenance. In addition, detector contamination results in spikes in the detector signal which interferes with the ability to identify and quantify compounds
Despite advancements in Bonded PLOT stationary phase coating techniques, particle shedding can still be problematic and these issues have limited the use of PLOT columns in GC/MS analysis to avoid the risk of damage or contamination to these highly sensitive systems. In order to overcome these issues, many end users have resorted to inconvenient workarounds such as installing particle trapping devices, using a press fit or other union connectors and associated fittings or using inline filters to trap particles. However, these measures by no means provide an ideal solution as the installation can be a time consuming procedure. In addition, glass press-fit unions are a source of potential leaks and inline filters are prone to clogging and flow restriction.


PLOT columns with integrated particle traps prevent PLOT stationary phase particles from moving downstream in the GC flow path and are ideal for the analysis of permanent gases and light hydrocarbons using GC or GC/MS systems. Agilent J&W PLOT PT GC columns provide convenient, leak-free operation by using built-in particle trapping technology that eliminates the difficult job of connecting separate traps. Integrated particle traps are incorporated into the column on both ends in one continuous length of fused silica tubing. These integrated traps increase GC system up time by protecting column switching valves and capillary flow technology devices, and eliminating the need for inline particle filters.
Because selectivity and performance of the column is similar with and without the particle traps, method transfer is a simple process with little or no method adjustment required. In addition, PLOT PT columns offer greater stability over conventional PLOT columns, resulting in reproducible flow restriction and retention, making them a more reliable choice for GC applications. Click here to watch our video on how to protect your GC system from PLOT column particle shedding and enjoy worry-free operation.

Agilent PLOT PT columns are ideally suited for multi column valve switching applications where techniques such as heart cutting, backflush, deans switch etc. are commonly used. By having particle traps on both ends of the column, any stationary phase particles shed from the column are trapped in the forward flow and reverse flow directions which helps to increase uptime for the instrument and reduced downtime for maintenance. Find out more by downloading the application note “Analyze Permanent Gases and Light Hydrocarbons with Agilent J&W Particle Trap Columns” .


To make sure you get the most out of your PLOT PT columns make sure you follow our six top tricks for using PLOT PT columns :

  • Use Ultra Inert liners and UltiMetal Plus deactivated tubing to prevent problems of tailing and signal loss
  • Install Gas Clean moisture filters to prevent moisture levels affecting retention and selectivity
  • Use particle traps to protect flow path components such as valves and detectors
  • GC systems are only as good as their connections so don’t forget to invest in the right connections
  • Choose the right size sample loop for your concentration level
  • Don’t exceed column temperature limits as this will reduce column lifetime

PLOT PT GC columns enable users to perform more robust analysis of energy and chemicals samples by setting a trap for particles that interfere with GC or GC/MS analysis.

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