Pete Gibbons

By Dr Pete Gibbons, Head of Reduced-Risk Product Analysis at Hall Analytical


Hall Analytical continues to advance the science of Reduced Risk Product (RRP) testing, through a combination of innovative method development by our dedicated R&D team, and ongoing investment in our custom-built analytical facility.


In a recent meeting of the R&D team, our senior GC method development scientist described a GC backflushing technique that has significantly improved method selectivity. The results were impressive, so we decided to write a brief technical update to share with you!

As many of you will know, one of the issues with Reduced Risk Product analysis is matrix interference. E-liquids for use in ENDS are formulated with propylene glycol and glycerol as the base ingredients, and tobacco sticks used with Heated Tobacco Products (HTPs) contain a significant quantity of glycerol as a humectant. Broad chromatographic peaks corresponding to propylene glycol and glycerol can interfere with the quantitation of trace HPHC analytes, particularly in aerosol analysis. Therefore, techniques to limit the amount of matrix on the GC column are advantageous.

For the development of a method to analyse Volatile Organic Compounds (VOCs) in HTP aerosols, we installed a 1m long pre-column with DB-1 stationary phase and connected this to a capillary flow technology splitter, prior to connection to the main GC analytical column. This GC instrument configuration allows for a short period of forwarding carrier gas flow prior to the pressure/flow being altered, and flow reversed in the DB-1 pre-column to eject the non-target analytes (PG, glycerol matrix) out of the GC split line.

The DB-1 column chemistry and 1-metre length proved ideal for this application, and other optimal column chemistries and lengths can be determined experimentally for further RRP analysis applications. We’ve found the backflush technique is particularly useful not only for improving selectivity and resolution of complex volatile analyte mixtures but also as a means of protecting GC analytical columns from becoming saturated with matrix and excess amounts of solvents.

We hope you’ve found this description of GC column backflushing of interest. Please get in touch to find out more details of our testing capabilities for RRPs.


R&D is integral to our success at Hall Analytical