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August/September 2010 Foreword
Welcome to the eleventh edition of Chromatography Today, the theme for this edition is developments in high temperature separations
Temperature as a separation tool is not new to the separation community.
The Polymer industry realisedmany years ago that if itwas going to be able to controlmolecularweight distributions for the newer emerging polymers it would require instrumentation to be run at high temperature tomaintain sample solubility. The instrument companies responded to this demand and the first liquid chromatographs and columns - albeit for size exclusion chromatography, were developed with the capabilities of running up to 180C.
Similarly the Petrochemical industry-with its heavy dependency on gas chromatography as its core characterisation technique, indentified the need for even higher temperature instruments for the characterisation of high molecular weight distillates and latterly biodiesel. Thus GC’s and columns capable of operating temperature programmes to 450C emerged which like SEC systems have now been in routine operation for many years.
The mainstream HPLC community however has never seen a need to venture away from its tried and tested ambient systems. They have flirted with separation up to 60C - staying within the confines of the “silica column stability window”.We have seen SFC systems offering both a temperature and pressure alternative, and column media suitable for higher temperature operation being developed – carbon, zirconium and SDVB. But we have not seen the technology fully embraced for routine HPLC analysis.
This however now seems to be changing, driven by:
- The move to higher sample throughput with more information per sample (fuelled by the UPLC revolution).
- The pressures of “green chromatography”, looking to reducing solvent usage and/or the switch to benign mobile phase solvents.
It has long been known that increasing operating temperature can dramatically improve both the efficiency and speed in HPLC. Higher temperatures decrease the viscosity of the mobile phase such that higher flow rates are possible even when using existing “first generation instrument”. Diffusion and interaction of analytes within the stationary phase becomes faster and hence lowers overall retention, reduces peak tailing and generally improves separation efficiency. Temperature can also influence polarity- the polarity of water decreases markedly at high temperatures (150-200C) this enables solvent free separations, with the added benefit of increased HPLC detector options such as FID or NMR.
There have been concerns in the past about sample stability, but it has now been shown that this is not a great issue as we are not looking to long resident times in the column, and let’s not forget the drive is for faster analysis and hence even shorter resident times.
Alan Handley - President of the Chromatographic Society
As with UPLC there have been questions about column stability when running under “forcing” conditions. Non silica based packing have been available for years and we are now seeing the development of more robust silica based technologies.
Essential to this technology is the temperature control and accuracy. In the past few years we have seen the development and introduction of customdesigned oven units. These units can not only provide the required fast and effective temperature control, but now also offer the much needed provision of pre column heating and post column cooling.
Everything now seems in place to exploit such technology and with this in mind; the articles featured in this edition will hopefully give you an insight into the potential use and application of high temperature separations
Onto more general themes, The Chromatographic Society prides itself on putting together topical scientific meetings, in this edition we feature a report from one of our recent meetings - “Advances in High Resolution and High Speed Chromatography" held at AstraZeneca, Alderley Park, Cheshire
I would like to take this opportunity to formally thank AstraZeneca and the various analytical Instrument companies for their support in hosting the meeting.
Our next meeting titled “Oligonucleotides; The Next Big Challenge for Analytical Chemistry” is also previewed in this edition in the article by George Okafo & Chris Bevan.
The Chromatographic Society is currently planning its 2011 meetings program and we are always looking for suggestion for future topic areas (
alan.handley@lgc.co.uk).
We are also looking to further develop our student activities and have plans to introduce “The Chromatographic Society Student Awards” the details of these awards will be available shortly on the website
http://www.chromsoc.com.
Happy separations Alan. Next Issue November/December -
Electrophoretic Separations To be included call us on +44(0)1727 855574 or
info@chromatographytoday.com
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