SPS
Semi-Permeable Surface (SPS)
In an effort to extend the applicability of the RAM Direct Injection columns, Regis, in conjunction with Dr. Fred Regnier and Dr. Carla Desilets at Purdue University, developed the Semi-Permeable Surface (SPS). Their initial work involved the adsorption of oxythylene detergents onto reversed phase silica to act as shielding agents, protecting the inner chromatographic surface. The material worked effectively, but the detergent layer slowly leached from the silica. Regis Technologies improved the design by covalently bonding a polyoxyethylene polymer to the silica, creating a more stable outer phase. The result was a new, longer-lasting SPS material.
SPS Structure
Like the ISRP phase, the SPS phases consist of both hydrophilic outer and hydrophobic inner surfaces. The distinct difference is that the inner and outer surfaces of the SPS are bonded separately, allowing each to be varied independently. The SPS structure includes a hydrophobic inner phase such as ODS, and a hydrophilic outer phase of polyethylene glycol (Figure 4.). The outer phase provides size exclusion and hydrophilic shielding, which repels large biomolecules. The various inner phases allow for separation of small analytes.
SPS Column Advantages
The SPS offers the following advantages:
- Increased durability
- Increased selectivity
- Allows use of buffered, normal-phase, and reversed-phase systems
SPS Selectivity
The primary advantage of SPS over ISRP GFF is that the inner surface of SPS may be varied independently of the outer, resulting in a wider scope of analysis opportunities. Available inner phases include:
- Octyl (C8)
- ODS (C18)
- Phenyl
The retention mechanism of these SPS phases involves hydrogen bonding by the outer phase and hydrophobic interaction by the inner phase. Polar solutes interact primarily with the outer phase and show little discrimination among the various inner phases. Conversely, the enonpolar solutes interact primarily with the inner phase.
The SPS phases allow use of buffered, normal-phase, and reversed-phase eluents. The actual composition is limited only by the pH and organic modifier parameters dictated by the proteins contained within the sample.
| Product | Particle Size | Column Dimensions | Regis
Product # | U.S. Price |
| |
| Octyl | 5 µm, 100 Å | 15 cm x 4.6 mm i.d. | 785108 | $606.63 |  |
| Octyl | 5 µm, 100 Å | 25 cm x 4.6 mm i.d. | 785208 | $912.58 | |
| Octyl | 5 µm, 100 Å | 5 cm x 2.1 mm i.d. | 785308 | $400.90 | |
| Octyl | 5 µm, 100 Å | 5 cm x 4.6 mm i.d. | 785008 | $474.75 | |
| ODS | 5 µm, 100 Å | 15 cm x 4.6 mm i.d. | 785118 | $606.63 | |
| ODS | 5 µm, 100 Å | 25 cm x 4.6 mm i.d. | 785218 | $912.58 | |
| ODS | 5 µm, 100 Å | 5 cm x 2.1 mm i.d. | 785318 | $400.90 | |
| ODS | 5 µm, 100 Å | 5 cm x 4.6 mm i.d. | 785018 | $474.75 | |
| Phenyl | 5 µm, 100 Å | 15 cm x 4.6 mm i.d. | 785107 | $606.63 | |
| Phenyl | 5 µm, 100 Å | 25 cm x 4.6 mm i.d. | 785207 | $912.58 | |
Octyl Guard
Cartridges** | 5 µm, 100 Å | 1 cm x 3.0 mm i.d. | 785508 | $205.73 | |
| Octyl Guard Kit* | 5 µm, 100 Å | 1 cm x 3.0 mm i.d. | 785408 | $305.95 | |
ODS Guard
Cartridges** | 5 µm, 100 Å | 1 cm x 3.0 mm i.d. | 785518 | $205.73 | |
| ODS Guard Kit* | 5 µm, 100 Å | 1 cm x 3.0 mm i.d. | 785418 | $305.95 | |
Phenyl Guard
Cartridges** | 5 µm, 100 Å | 1 cm x 3.0 mm i.d. | 785507 | $205.73 | |
| Phenyl Guard Kit* | 5 µm, 100 Å | 1 cm x 3.0 mm i.d | 785407 | $305.95 | |
* Includes 1 holder and 2 guard cartridges
** Includes 3 guard cartridges |