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Superficially Porous Particles” utilising a very striking video of the supercritical fluid. This solvent-free form of functionalisation had been used to make, for example, fluorinated phases. In a wide-ranging talk covering the work of his group since ~2002, Professor Glennon covered green issues,
functionalisation of silica hydrides, the use of mercaptopropyl silica, the importance of uniform surface coatings, the supercritical fluid preparation of a quinine CSP and the construction of nanostructures. The group have now moved on to prepare fused silica particles by building up layer by layer using seeded growth. This product has been named “EireShell”!
Continuing on the SFC theme, Dr Andy Aubin (Waters, USA) described “ Harnessing
the Power of Sub-2 µm Chromatographic Particles in Supercritical Fluid Chromatography”. Waters had taken over the Thar Technologies SFC operation but evaluating the Thar instruments in 2009 the
true benefits of sub-2 µm particles could not be observed because of the system volumes involved. Waters therefore set about designing a whole new SFC system based on similar concepts that had lead previously to the ground-breaking Acquity UPLC system. This new Waters UPSFC system can fully
utilise the benefits of sub-2 µm particles (although it was noted that this does not apply fully to chiral phases) and is being promoted as an alternative to NPLC. Aubin noted that increasing pressure from increasing flow rate has an effect on mobile
phase (CO2) solvating strength, even under constant back-pressure conditions (isobaric). This implies that if a van Deemter plot is constructed for a certain column and the flow rate is varied (retention factor is usually held constant by adjusting the % organic in the mobile phase), measurement of peak efficiency and thus H may not be representative. Waters suggested that a more appropriate measure might be to use isopycnic (constant mobile phase density) conditions to mitigate this effect.
Other presentations on SFC were from Dr Pilar Franco (Chiral Technologies, France) on “Super Critical Fluid Chromatography Screening Strategies for Chiral Separations” and from Dr Denis Berger (Chemputeam, Switzerland) on “Aurora SFC”. Dr Franco proposed that a primary chiral screen should utilise the IA, IB, IC and ID columns (all immobilised polysaccharide selectors) which are compatible with a much greater range of solvents than the older non-covalently bonded materials. A secondary screen would
Post-dinner the chromatographic conversations flowed into the night
include AD-H, AS-H, AY-H, AZ-H and the 'O' equivalents. Butylamine was proposed as an alternative to diethylamine (DEA) for optimisation of chiral amine separations. (Work on a similar theme to that of Dr Pilar’s talk is described in the paper “Preparative chromatographic resolution of racemates using HPLC and SFC in a pharmaceutical discovery environment” (L. Miller and M. Potter J. Chromatogr. B 875 (2008) 230-236). Dr Berger indicated that for most SFC systems, pumping less than 8% organic is still difficult for current SFC pumping technology (possibly also the case for the Aurora system). He highlighted 'SuperSep' instrumentation for recycling carbon dioxide in preparative scale separations.
Before the afternoon tea break Tony Taylor (Crawford Scientific, UK) provided a brief respite from SFC. Tony described the latest in stationary phase developments from Agilent in a talk entitled “Agilent Technologies Poroshell 120: Superficially Porous Particle Technology for Increased Sample Throughput and Resolution in a Diverse Range of Applications”. One of his
principle themes was that the assessment of efficiency per unit pressure was a good way to evaluate columns. He highlighted this by presenting examples with coupled columns.
After the break it was back to SFC but Dr John Langley (University of Southampton, UK) “Achiral SFC-MS and Small Molecules – An Analyst’s View” did provide something a bit different, as his title suggests. John discussed the need to use a T-piece in a make up flow of liquid prior to the source capillary to prevent freezing of the capillary due to carbon dioxide expansion. His group typically uses 5 mM ammonium acetate for the make-up flow (see J.D. Pinkston et al. J. Sep. Sci. 27 (2004) 115). He described phenomena whereby ionisation of analytes was observed with the MS CV turned off in both APCI and ESI modes, which is thought to be due to a 'sonic spray' process.
The final talk of the afternoon, “Remote Open Access – The Lab2Lab™ Advantage” was given by Dr Brian Everatt of the host company, Novartis, UK. Brian described an automated sample delivery and analysis
Delegates at symposium dinner
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