We are not aware of any systematic studies with respect to the impact of flow rate on HILIC separations. Our concern would be that as you move to higher flow rates, you might observe peak shape issues due to the slow kinetics of IEX and adsorption mechanisms. If the retention mechanisms for a given system are partition dominated, this should be of less concern. It will be a case by case cause and effect.
53946-U
Ascentis® Express 90 Å HILIC (2.7 μm) HPLC Columns
L × I.D. 15 cm × 2.1 mm, HPLC Column
Sinónimos:
Core-shell (SPP) Fused Core Si HPLC column
About This Item
Productos recomendados
Nombre del producto
Ascentis® Express HILIC HPLC Column, 2.7 μm particle size, L × I.D. 15 cm × 2.1 mm
Materiales
stainless steel column
Nivel de calidad
Agency
suitable for USP L3
Línea del producto
Ascentis®
Características
endcapped: no
fabricante / nombre comercial
Ascentis®
envase
1 ea of
Parámetros
≤100 °C temp. range
600 bar max. pressure (9000 psi)
técnicas
HPLC: suitable
LC/MS: suitable
UHPLC-MS: suitable
UHPLC: suitable
L × D.I.
15 cm × 2.1 mm
superficie
135 m2/g
impurezas
<5 ppm metals
Matriz
Fused-Core particle platform
superficially porous particle
grupo activo de la matriz
silica phase
tamaño de partícula
2.7 μm
tamaño de poro
90 Å
pH operativo
1-8
aplicaciones
food and beverages
técnica de separación
hydrophilic interaction (HILIC)
normal phase
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Categorías relacionadas
Descripción general
Visit the Ascentis Express home page for more information on this new column technology.
Información legal
Producto relacionado
cartucho de precolumna
obligatorio pero no suministrado
Código de clase de almacenamiento
11 - Combustible Solids
Clase de riesgo para el agua (WGK)
WGK 3
Punto de inflamabilidad (°F)
Not applicable
Punto de inflamabilidad (°C)
Not applicable
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Artículos
For separation of polar compounds including polar neutrals, polar acids, and polar and non-polar basic amines use our Ascentis® Express HILIC column.
For separation of polar compounds including polar neutrals, polar acids, and polar and non-polar basic amines use our Ascentis® Express HILIC column.
For separation of polar compounds including polar neutrals, polar acids, and polar and non-polar basic amines use our Ascentis® Express HILIC column.
For separation of polar compounds including polar neutrals, polar acids, and polar and non-polar basic amines use our Ascentis® Express HILIC column.
Protocolos
We offer the tools for the analysis of the metabolites; including certified reference standards, enzymes, substrates, and chromatographic products.
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How does the flow rate influence the water layer on the column?
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In HILIC separations, what happens if the sample is an aqueous matrix? Does it always have a negative effect?
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Yes, it would be highly preferential (especially in this case where you want partitioning to dominate) to inject in high organic. That said, you can 'get away' with it if the injection volume can be kept small - much like we can inject low volumes of stronger solvents in RP mode, if needed. What you will want to do to minimize impact is to get as much retention on the analytes of interest as you can, this helps give the sample solvent some time to dissipate and negate the effects.
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Why is it recommended to run isocratically for HILIC methods?
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When running in HILIC mode, both isocratic and gradient practices result in instability. If you keep the re-equilibration times constant, gradient should not be a problem, but changing this parameter can have a significant impact. It is not so much that it is bad as it is different than we are used to in reversed phase. Usually, we assume that once equilibrated (5, 10, 15 min, etc.), we can leave the system for any time period and come back to the same results. This does not appear to be the case in our studies of HILIC. Knowing that the re-equilibration time has an impact, you should get in the habit of making several injections with known re-equilibration times prior to making any development decisions. To get around this, isocratic runs are recommended. Attached are two posters; the first was presented at HPLC 2013 (Amsterdam) and the second was presented at Balaton Symposium on High Performance Separation Methods 2013 (Hungary). Both show 'reproducibility' at any set re-equilibration time is good but both show that if you change the re-equilibration time; then retention, peak shape and selectivity can change especially where ionic interactions are prevalent.
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Would you advise addition of a buffer when using diol or amide stationary phase?
1 answer-
Yes. if possible you should always have at least a small amount of buffer in a HILIC system to help mediate/control IEX and other polar interactions that are bound to be present (even if at a low level). It is not so much the "buffering capacity" that is important, but the presence of the competing ions. We have found that their presence helps with day to day and column to column reproducibility. There are times when you need to eliminate the buffer, but aside from special circumstances, our recommendation is to include them.
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How should I store the Ascentis Express HILIC column?
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Long-term storage of silica-based columns is best in 100% acetonitrile. Columns may be safely stored for short periods (up to 3 or 4 days) in most common mobile phases. However, when using buffers, it is best to remove the salts to protect both the column and the HPLC equipment by first flushing the column with the same mobile phase without the buffer (e.g., when using 90/10 ACN/buffer, flush the column with 90/10 ACN/H2O) to eliminate any concern about salt precipitation or corrosion from the salts then flush the column with 100% acetonitrile for storage.Before storing the column, the end-fittings should be tightly sealed with the endplugs that came with the column to prevent the packing from drying.
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Can I use Ascentis Express on any type of HPLC system?
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Ascentis Express HPLC columns are capable of use on standard HPLC systems as well as UHPLC systems. Columns are packed in high pressure hardware capable of withstanding the pressures used in UHPLC systems.
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How can I measure my instrument bandwidth (IBW) and determine what Ascentis® Express HPLC Columns can be used with minimal efficiency loss created by too much internal instrument volume?
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The Guide to Dispersion Measurement has simple instructions on how to measure IBW and can be found at sigma-aldrich.com/express.
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What column do you recommend for an anionic compound?
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If the acids are hydrophilic or you can adjust the pH to make them hydrophilic enough, any of the phases that exhibit HILIC partitioning are possible (bare silica, OH5, diol, Zwitterionic, amide). We typically go with the OH5 first to try and avoid any negative impacts on the like charge.
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Can Ascentis® Express HPLC Columns be used for LC-MS?
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Express Fused-Core™ particles were designed with LC-MS in mind. Even extremely short column lengths exhibit sufficient plate counts to show high resolving power. The flat van Deemter plots permit resolution to be maintained at very high flow rates to maximize sample throughput. All Ascentis stationary phases have been evaluated for MS compatibility during their development, and the Express phases are no exception. You can expect extremely low column bleed and background while maintaining longest possible column lifetime. A bonus of Ascentis Express columns for high throughput UHPLC and LC-MS is that they are extremely rugged and highly resistant to plugging, a very common failure mode for competitor columns.
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Is there anything special I need to do to my HPLC system to use Ascentis Express?
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Nothing special is required to use Ascentis Express HPLC columns. To obtain the full benefits of Ascentis Express, one should minimize dispersion or instrument bandwidth in the HPLC system (tubing, detector flow cell) as well as confirm the detector response system is set at a fast level. For more information, request Guidelines for Optimizing Systems for Ascentis Express Columns (T407102)
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