Introduction

Since about one hundred year mankind develops particles surfaces and constructs not only to separate, , to extract, to purify, to synthesise, to catalyse and as unique surface construct for bioassays.

Post war period until about mid seventies the focus of research is to create new chemistries, after that research changed towards hybrids, copolymer, and application (Happy clients) focussed developments, from mid eighties the need for better reproducibility, new particle functions  (Merrifield, hydrometalurgy, scavenging, adsorption, immunosensors, bio-catalysis, solid phase chiral synthesis, liposomes, drug delivery, oil muds  etc) did emerge. With the emergence of “Nanotechnology” we observe a divergence in R & D.

1. 1 Industry is now in possession of sophisticated  analytical technology (TOF-SIMS, Electron Microscopy,  XPS. Solid State NMR etc) to analyse ones own and the competitors products. The focus is on uniqueness, efficiency, effectiveness, reproducibility and product cost reduction
2. Universities and Public research organisation are moving town the Nanotechnology track developing many new processes to produce various forms (metallic, metal oxide, hybrids and polymeric nano, particles, buckey balls and tubes). Industry was quick to take up some nano particle processes from universities (Plasma sputtering, production of nano-silber to enhance their current products. In recent years concern is being raised that “Nano based pollution” could negatively influence our health and ecology.

The proprietors of Chromatographyshop participate in particle research for very many years and actively seek new particle technologies for commercialisation. (Please contact us if you have some interesting new particle technology!) However, to succeed in any application the new technology has to be reproducibly, scalable and necessary capital invest low. Furthermore, for life and food science application the process has to be validateable  and certifyable. (The process chemistry, microbiology, kinetics has to be well analysed and rationally debated) 

Separation / Purification materials for modern chromatography (so called stationery phases)

To separate molecules effectively and efficiently molecules requires a wide range of stationary phases which differ in terms of

1. Base materials,
2. Particle shape,
3. Porosity and
4. Surface chemistry

Base Material

SILICA is the most popular base material. It has a high physical strength and a surface which is easily chemically modified to give phases suitable for use in a broad range of HPLC modes. However silicas dissolve in water at pH ≥6.5 whilst bonded silicas are unstable at pH ≤2.5. Newer bonded silicas may have an extended pH range of 2 - 10

POLYMERIC materials have minimal pH restrictions but are less physically stable and exhibit lower separation efficiencies than silica for small molecules. For large molecules such as proteins or synthetic polymers their performance is comparable to that of silica based materials.

TITANIA (TiO2) is stable over a wide pH range and at  elevated temperatures. In contrast to silica, the surface of  titania is alkaline, which can be beneficial in the analysis of  basic drugs, but separation efficiencies are generally lower.

ALUMINA has greater pH stability than silica but cannot be easily chemically modified.

GRAPHITISED CARBON has high strength and excellent  pH stability but cannot be modified. It is expensive and best  used in unique selectivity applications.

ZIRCONIA (ZrO2) has the advantage of unique selectivity combined with extreme chemical and thermal stability (up to 200°C).

Particle shape, diameter  and porosity

The earlier materials were irregular shaped particles and still used today in flash chromatography to purity compounds. For high resolution separation spherical particles are required. The trend is towards  manufacture of high strength, monodisperse and smaller diameter particles.  To separate large molecules particles with large pore diameters are required. Pore diameter however is affecting the physical strength of the particles. Pore diameters range from 60A to 5000A. More detail you find with the individual product specifications

Surface chemistries

To improve specific selectivity and of interaction with the target molecules with the particles many different groups of chemistries have been developed.

Learn more about specific stationery phases

1. Reverse-Phase Chromatography (RPC) materials
2. High Aqueous Reversed-Phase Materials
3. Wide Pore Reversed-Phase Materials
4. Phenyl-Bonded Phases
5. Polar-Bonded Phases
6. Hydrophilic Interaction Chromatography Phases
7. Silica Phases
8. Ion-Exchange Phases
9. Ion Chromatography Phases
10. Size Exclusion Chromatography Phases
11. Affinity Chromatography Phases
12. Chiral Phases