VDS optilab Columns

Basic Silica Gels: VDSpher® Classic & VDSpher® PUR

All VDSpher phases are based on two different basic silica gels: VDSpher Classic & PUR, which differ from each other essentially in their purity. The physical specifications of both basic silica gels are summarized in Table 1. The purity of the basic silica gel influences noticeably a chromatographic separation, because the metal content changes the properties of the silica gel and the surface (cf. Figure 1).

VDSpher® Normal Phases

Enable a fast equilibration, reproducable analyses despite fluctuating water content in the mobile phase and a problem-free application of the gradient run.

Depending on the type of modification, different mechanisms can be used for separation:

Physical specifications of VDSpher® Classic & PUR normal phases

VDSpher® Reversed Phases

Reversed phase (RP) chromatography is the unique method of HPLC used most frequently. Therefore, the number of available reversed phases is increasing steadily, so that as far as possible, a matching stationary phase is available for each separation problem. Below, C18 phases are used to show how the individual modifications and variants of endcapping differ from one another.

Hydrophobicity of the VDSpher® C18 modifications

Physical specifications of VDSpher® Classic & PUR reversed phases

Normally, the standard phase VDSpher PUR 100 C18-E is a very good starting point for many separation problems. It is of medium hydrophobicity and shows a low silanophilic activity.The phase VDSpher C18-SE, which does not show any silanophilic activity is slightly more hydrophobic. Hydrophobic substances are therefore retarded more by this phase. Besides, due to the complete endcapping and the resulting inertness, the analysis of alkaline substances is implemented better and an increased stability is achieved in strong acidic and slightly alkaline media. On the other side, the not endcapped phase VDSpher PUR 100 C18-NE is available, if importance is given to silanophilic activity during separation. The free silanol groups also increase the water mobility as compared to the endcapped phases. For working with 100% water as mobile phase, we recommend the very hydrophilic phase VDSpher PUR 100 C18-H. The polar spacer ensures that the C18 chains do not collapse despite the high water content. VDSpher PUR 100 C18-H is therefore ideal for the analysis of polar analytes and smaller water-soluble biomolecules.

VDSpher PUR Phenyl-B is a special phase, which enables aliphatic as well as aromatic interactions and therefore represents an interesting alternative to many phenyl-hexyl phases on the market. The product portfolio is rounded off with the VDSpher reversed phases by the alkyl nitrilemodified separation phases VDSpher CN-RP and CN-SE-RP, which are e.g., ideal for the separation of alkaline molecules. The available particle sizes can be obtained from our current price list.

Guideline selection

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VDSpher® PUR HILIC Phases

HILIC (Hydrophilic Interaction Liquid Chromatography) is a special variant of HPLC in which hydrophilic normal phase modifications are handled with mobile phases normally used in reversed phase chromatography. The separation of very polar substances is promoted this way, which is otherwise extremely difficult to analyse by the proven HPLC methods.

The ability to retard polar substances is one of the special strengths of HILIC. Thus for example, Uracil, which is used frequently as dead time marker in HPLC, retards strongly in the HILIC mode.

The available VDSpher PUR 100 HILIC phases are shown in Table below, and normally have a pore size of 100 Å and a medium particle diameter of 5 µm. The optimum phase for each HILIC application can be selected via the different available modifications. Thus VDSpher PUR 100 HILIC-AM and especially VDSpher PUR 100 HILIC-SAC are ideal for sugar separations, while the analysis of nucleobases can be performed ideally with VDSpher PUR 100 HILIC-Z.

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VDSpher® OptiAqua

VDSpher® OptiAqua – your column brand for 100% aqueous reversed phase chromatography

"VDSpher® OptiAqua > 99.95% Si, VDSpher® OptiAqua PUR > 99.995% Si"

VDSpher® OptiAqua phases have been specially developed for highly hydrophilic applications. Special polar endcapping makes it possible to use 100% water as a solvent while still maintaining RP properties. A total of five VDSpher® OptiAqua phases with various pore and particle sizes are available, suitable for a broad range of applications. 

VDSpher® OptiAqua phases can also be used to separate polar substances. Examples of typical analytes include:

• Antibiotics
• Nucleobases
• Pesticides
• Xanthines
• Biomolecules
• Organic acids
• Sulfonamides
• Drugs
• Parabens
• Water-soluble vitamins

All VDSpher® OptiAqua phases are stable from pH 2 to 7.5 and can be used up to temperatures of 60 °C without problem. as specification below;

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VDSpher® OptiBio

VDSpher® OptiBio – your column brand for excellent biochemical separations

VDSpher® OptiBio phases have been specially developed for biochemical analysis such as protein and peptide separation, various VDSpher® OptiBio reversed phases with C18, C8 and C4 bonding have been created that deliver high plate numbers and sharp peaks.

VDSpher® OptiBio phases

Recommended analyte sizes for VDSpher® OptiBio phases

Specifications for VDSpher® OptiBio phases

Hydrophobicity of VDSpher® OptiBio (300 Å) C8 modifications

The example of the C8 phases. The C8-V-E and C8-V modifications are highly hydrophobic, while C8-SE and C8-E have medium hydrophobicity and C8-PSE is hydrophilic.

Guideline selection

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Under the name Optigel, VDS optilab offers various ion-exchange separation phases on a polymer basis. The matrix used as basic material is a polystyrene-divinylbenzene network modified in accordance with the desired function. This allows working over a very wide pH range and – in contrast to silica gel phases – without destroying the phase itself. However, when using polymer phases, it has to be ensured that these materials are not exposed to a pressure higher than 100 bar and a flow rate of 1.0 mL/min.

Optigel CarbEx II cation exchange phases are modified with sulfonic acid groups at polystyrene-divinylbenzene matrix. As counterions, H+ and Ca2+ are available by default. For special separations, Optigel CarbEx II with Pb2+ as counterion can also be produced on request.

Optigel CarbEx II phases can be used for the following separation problems:

The standard dimensions of Optigel CarbEx II columns are 300 x 8.0 mm and 250 x 8.0 mm. For rapid analysis of organic acids we recommend Optigel CarbEx II H+ in 150 x 8.0 mm using 1% phosphoric acid.

The modification Optigel CarbEx II Ca2+ in 150 x 8.0 mm allows a fast separation of carbohydrates or sugar alcohols.

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