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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Ascentis® Express 90 Å HILIC (2.7 μm) HPLC Columns
L × I.D. 3 cm × 4.6 mm, HPLC Column
About This Item
Empfohlene Produkte
Produktbezeichnung
Ascentis® Express HILIC HPLC Column, 2.7 μm particle size, L × I.D. 3 cm × 4.6 mm
Materialien
stainless steel column
Qualitätsniveau
Agentur
suitable for USP L3
Produktlinie
Ascentis®
Leistungsmerkmale
endcapped: no
Hersteller/Markenname
Ascentis®
Verpackung
1 ea of
Parameter
≤100 °C temp. range
600 bar max. pressure (9000 psi)
Methode(n)
HPLC: suitable
LC/MS: suitable
UHPLC-MS: suitable
UHPLC: suitable
L × ID
3 cm × 4.6 mm
Oberflächenbereich
135 m2/g
Verunreinigungen
<5 ppm metals
Matrix
Fused-Core particle platform
superficially porous particle
Aktive Matrixgruppe
silica phase
Partikelgröße
2.7 μm
Porengröße
90 Å
Betriebs-pH-Wert
1-8
Anwendung(en)
food and beverages
Trenntechnik
hydrophilic interaction (HILIC)
normal phase
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Verwandte Kategorien
Allgemeine Beschreibung
Visit the Ascentis Express home page for more information on this new column technology.
Rechtliche Hinweise
Erforderlich, aber nicht bereitgestellt
Vorsäulenkartusche
Ähnliches Produkt
Lagerklassenschlüssel
11 - Combustible Solids
WGK
WGK 3
Flammpunkt (°F)
Not applicable
Flammpunkt (°C)
Not applicable
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Artikel
For separation of polar compounds including polar neutrals, polar acids, and polar and non-polar basic amines use our Ascentis® Express HILIC column.
Protokolle
We offer the tools for the analysis of the metabolites; including certified reference standards, enzymes, substrates, and chromatographic products.
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Would you advise addition of a buffer when using diol or amide stationary phase?
1 answer-
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Why is it recommended to run isocratically for HILIC methods?
1 answer-
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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Can peptide or protein samples be analyzed using HILIC columns?
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Polar peptides are quite amenable to HILIC separations; however, our experience with larger peptides has been only minimally successful - mainly due to solubility issues. Proteins are even more difficult due to the same issue. An additional problem with proteins is that they are often multiply charged. When IEX is performed on multiply charged analytes, you often get what is referred to as a rolling effect where the analyte interacts with ionic sites on the surface in many different ways as it 'rolls' down the column; this produces broad and misshapen peaks.
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Is there anything special I need to do to my HPLC system to use Ascentis Express?
1 answer-
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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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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Do I need special fittings and tubing to connect Ascentis® Express HPLC Columns?
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While operating pressures may not exceed the 400 bar (6,000 psi) capability of your traditional instruments, sustained pressures of about 200 bar (3,000 psi) will exceed the recommended pressure for conventional PEEK tubing and fittings at the column inlet. We recommend changing to stainless steel fittings in all high pressure locations and have designed special High Performance HPLC Fittings/Interconnects that will stay tight at pressures of 1,000 bar (15,000 psi) or greater, even when elevated column temperatures are employed.
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When you recommend only changing one parameter at a time, does this also refer to the total ionic strength?
1 answer-
If you change organic, try to keep the overall buffer concentration (and all other parameters, for that matter) constant. There are times when you will want to change both and perhaps pH/temp/etc. simultaneously, but that drastically complicates the system and thus should be avoided, if possible.
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What is the Department of Transportation shipping information for this product?
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Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product.
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What flow rate should I use with Ascentis® Express HPLC Columns?
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Based on the minimum in the van Deemter curves, higher flows than 5um particle columns are required in order to maximize Ascentis Express column efficiency. The suggested starting point for flow rate for Ascentis Express columns: 1.6 mL/min for 4.6 mm ID; 0.8 mL/min for 3.0 mm ID; and 0.4mL/min for 2.1 mm ID.
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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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