24 February / March 2021
January 29, 2020. doi: https://doi. org/10.1101/2020.01.28.923938.
https://www.biorxiv.org/
content/10.1101/2020.01.28.923938v1.full
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A Wettable HPLC Phase Explained
Recently the Kromasil wettable phase was introduced for production-scale purification of polar substances like biomolecules under aqueous conditions. It is now also available in columns for analytical HPLC applications. Nominally, the wettable phase is a C18 phase. Normally, this is a highly hydrophobic phase. How can such a phase be ‘wettable’?
On a regular C18 phase, if 100% aqueous conditions are gradually applied, the mobile phase can keep fairly good contact with the stationary phase as long as the high pressure in the system is maintained. In this situation the pressure forces the mobile phase to be present in the stationary phase’s pores, despite the repealing force from the hydrophobic surface. If the pressure drops (i.e. at flow decrease or stop), the liquid is expulsed from the pores, dramatically reducing the interaction surface between stationary and mobile phases. For the chromatographic properties that means a severe loss in selectivity and coelution of sample components. The surface availability
can be restored in the column by switching back to normal phase conditions, though, but the actual chromatographic run can be considered as ruined.
To make the stationary phase wettable in fully aqueous conditions (avoiding dewetting as above), a polar component is introduced on the surface, like a mixed-mode phase. Some have added the polar groups at the root of the surface modifier. The Kromasil wettable phase has it as polar-embedded end-capping. This also allows for a better chemical stability of the phase under acidic conditions compared to other related purification phases on the market.
For more details about the chromatographic conditions for the illustration of this article, as well as learn more about this phase: properties according to the Tanaka test set, examples and current availability, please visit the wettable phase page on the Kromasil website.
More information online:
ilmt.co/PL/LK03 Automation-ready Sample Evaporator for Microplates
Porvair Sciences has launched a new second generation model of its Ultravap® Mistral - an automation-ready sample evaporator that offers throughput advantages to laboratories looking to optimise and accelerate sample preparation.
Designed to remove the traditional laboratory ‘bottleneck’ of solvent evaporation, industry-leading sample drying reproducibility has been achieved by recent advancements in gas injection technology. The new and improved Ultravap Mistral directly and consistently delivers heated gas up to 80°C in each microplate well or tube allowing most common chromatography solvents including dichloromethane, methanol, acetonitrile, hexane and water to be evaporated with speed and ease. A choice of straight or spiral needles allows users to choose between faster dry down (spiral) and better final drying in V-well plates (straight).
Highly intuitive software, and simple operation from up to 15 stored multi-step evaporation programs, means that even occasional users can gain the full benefits from an Ultravap® Mistral. For regular
users, the Ultravap® Mistral offers the versatility of fully flexible programming, for example enabling the evaporation stage to operate at an optimised rate for each solvent type being evaporated.
From the responsive colour touch screen display - gas temperature, pressure and flow rate can all be programmed individually and saved in stored programmes on the instruments controller. Each programme allows up to 5 distinct ramped phases, so that a fast initial drying period can be followed by a gentle final drying phase. Standard control commands stored on Ultravap® Mistral are compatible with drivers of most robot manufacturers making integration a seamless process.
The new Ultravap® Mistral is designed with a flat front profile and platform shuttle making interfacing with almost any liquid-handling robot even easier. The slim benchtop-friendly design of the 2021 version has built-in LED lights that provide great sample visibility.
More information online:
ilmt.co/PL/oDXy States and/or certain other countries.
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Echo and Echo MS are trademarks or registered trademarks of Labcyte, Inc. in the United States and other countries, and are being used under license.
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