Basic Silica Gels:
VDSpher® Classic & VDSpher® PUR
All VDSpher phases are based on two different basic silica gels: VDSpher Classic & PUR, which are different from each other in terms of purity. The physical data of both silica gels are summarized in the Tables hereinafter.
The basic silica gel purity influences sensibly the chromatographic separation process, because the metal content changes the properties of the silica gel and the surface. Hence, the interactions between the metal portions and the electron-rich analytes cannot be neglected, as illustrated in the Figure below. Due to the higher metal content of the VDSpher Classic 100 C18-E phase, the analytes were retarded much stronger as compared to VDSpher PUR 100 C18-E.
All VDSpher Classic & PUR silica gels are suitable for analytical, semi-preparative and preparative scale. To achieve the best possible column packing, we recommend VDSpher PUR phases for analytical issues and VDSpher Classic phases for preparative purposes.
Physical Properties: VDSpher® Classic
| Pore size [Å] | 75 | 100 | 150 | 200 | 300 | 1000 |
|---|---|---|---|---|---|---|
| Surface [m2/g] | 500 | 320 | 175 | 130 | 90 | 30 |
| Pore volumes [ml/g] | 0.8 |
0.8 | 0.8 |
0.8 | 0.8 | 0.8 |
| Si concentration [%] | 99.97 | 99.97 | 99.97 | 99.97 |
99.97 | 99.97 |
| Metal content [ppm] | <125 | <100 | <100 | <100 | <100 | <100 |
| Density [g/ml] | 0.45 | 0.45 |
0.45 | 0.45 | 0.45 | 0.45 |
Physical Properties: VDSpher® PUR
| Pore size [Å] | 100 | 150 | 200 | 300 |
|---|---|---|---|---|
| Surface [m2/g] | 320 | 175 | 130 | 90 |
| Pore volumes [ml/g] | 0.8 | 0.8 | 0.8 | 0.8 |
| Si concentration [%] | 99.995 | 99.995 | 99.995 | 99.995 |
| Metal content [ppm] | <20 | <20 | <20 | <20 |
| Density [g/ml] | 0.45 |
0.45 |
0.45 | 0.45 |
Starting from the basic silica gels VDSpher Classic & PUR, a large number of different modifications offer a wide range of VDSpher separation phases which are enlarged upon the following sections: