1.8 µm Particle Size - Increase in HPLC Separation Efficiency
10 May 2007Product news
MACHEREY-NAGEL, the manufacturer of NUCLEOSIL® and NUCLEODUR®, one of the leading companies for chromatography products, introduces the new NUCLEODUR® 1.8 µm particles!
Miniaturization in HPLC has a long history. With the introduction of the new 1.8 µm NUCLEODUR® particles now researchers have turned over a new leaf in HPLC column technology.
Features of 1.8 µm NUCLEODUR® silica particles:
- Increase of separation efficiency by higher number of theoretical plates (N):
Increase of the plate number by app. 67% offers the possibility of using shorter columns with equal plate numbers resulting in a decrease of analysis time. - Significant improvement in resolution
Use of 1.8 µm instead of 3 µm particles leads to an increase of resolution by a factor 1.29 (29%). - Column back pressure
Due to the smaller particle size the back pressure will increase. Because of the high sphericity of the NUCLEODUR® particles and the very narrow particle size distribution we were able to keep the back pressure on a moderate level. - Higher flow rates and shorter run times
optimal flow rate for 1.8 µm particles is higher than for 3 and 5 µm particles and through this, the analysis time can be reduced.
Currently all NUCLEODUR® premium phases (C18 Gravity, C8 Gravity, C18 Isis, C18 Pyramid, Sphinx RP) are available in 1.8 µm.
Further information can be found on the article webpage.
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NUCLEODUR® C18 ISIS
MACHEREY-NAGEL GmbH & Co. KGA unique C18 phase with high steric selectivity • C18 phase with special polymeric surface modification • particle sizes 1.8 µm, 3 µm and 5 µm • exceptional steric selectivity • outstanding surface deactivation • pH stability 1 – 10 • broad range of applications: steroids, (o,p,m-) substituted aromatics, fat-soluble vitamins, positional isomers Surface modification By use of specific C18 silanes and appropriate polymeric bonding technologies a dense shield of alkyl chains protects the subjacent silica matrix. Elemental analysis of NUCLEODUR® C18 Isis shows a carbon load of 20%. The target crosslinking of the C18 chains on the surface enables the separation of compounds with similar molecular structure but different stereochemical properties. The separation of o-terphenyl and triphenylene is a concrete example to evaluate the selectivity potential of a reversed phase column in terms of the different shape of two molecules. The phenyl rings of o-terphenyl are twisted out of plane while triphenylene has a planar geometry. Surface deactivation The chromatography of basic analytes requires a high density of surface-bonded C18 silanes combined with a thorough endcapping procedure to keep silanol activity at a minimum. This ensures tailing-free elution of even strongly basic amino-containing compounds. Stability The applied special surface bonding technology also provides improved stability features for the NUCLEODUR® C18 Isis phase. The proof for this was given in a long-term test in which the decrease of plate counts for caffeine at pH 10 and 50 °C has been observed over a period of 200 hours and 2000 sample injections respectively.