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Neutral surfaces are designed to coat the exposed silanol groups on the fused silica and serve two major functions: 1) to reduce electroosmotic flow, and 2) to prevent wall interaction with the sample. However, not all neutral surfaces are the same and it is important to understand what the surface is composed of to ensure that other interactions (i.e., hydrophobic) do not replace the ionic interactions you are trying to reduce. For example, when using a neutral capillary with a surface consisting of a hydrophobic bonded phase, it is essential to include hydrophilic polymers in the buffer to prevent hydrophobic interactions. The following is a list of neutral surfaces that are available from Beckman Coulter. All of these surfaces are bi-layers, consisting first of a bonded phase to shield the silanol groups followed by a hydrophilic polymer to prevent hydrophobic interaction.
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eCAP™ Neutral Capillary
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The neutral capillary utilizes a secondary layer of polyacrylamide to generate a hydrophilic surface. This is a general-purpose capillary, which Beckman Coulter recommends as a starting point for handling complex samples such as proteins or basic molecules. Polyacrylamide surfaces are recommended for use with both UV and LIF detection systems but may show some reduction in capillary life with diode-array detection systems.
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| Part No. |
Description |
| 477441
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eCAP Neutral Capillary
50 µm I.D., 67 cm total length, 12 cm from window to outlet (quantity 1)
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eCAP N-CHO Capillary
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The N-CHO capillary utilizes a secondary layer composed of polyvinyl alcohol (PVA). This surface is ideal for the separation of complex samples such as proteins or basic pharmaceuticals in cases where minimal EOF is desired. PVA is a very rugged surface, which is stable with UV, LIF and diode array detection systems. However, due to the chemical nature of PVA, it is not recommended for use with borate buffer systems, as the borate ion will complex with the surface. This capillary has been featured in the N-Linked Oligosaccharide Profiling Kit (P/N 477600).
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| Part No. |
Description |
| 477601
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eCAP N-CHO Capillary
50 µm I.D., 65 cm total length, 12 cm from window to outlet (quantity 1)
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Neutral Surfaces
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1st and 240th runs of basic proteins on a neutral capillary. %RSD for migration time: Lysozyme--0.47%, Cytochrome C--0.51%, and Ribonuclease A--0.96%.
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eCAP Neutral Capillary (SDS-MW)
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This capillary has been optimized for use with the eCAP SDS 14-200 kit (separation of proteins by molecular weight). The capillary utilizes a 100 µm I.D., which allows increased sample loads, ideal for isolation of an analyte by fraction collection.
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| Part No. |
Description |
| 241521
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eCAP Neutral Capillary (SDS-MW)
100 µm I.D., 65 cm total length, 12 cm from window to outlet (quantity 1)
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eCAP Neutral Capillary (DNA)
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This capillary has been optimized for use with Beckman Coulter DNA chemistries. The capillary utilizes a 100 µm I.D., which allows increased sample loads, ideal for isolation of an analyte by fraction collection.
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| Part No. |
Description |
| 477477
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eCAP Neutral Capillary (DNA)
100 µm I.D., 65 cm total length, 12 cm from window to outlet (quantity 1)
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