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| a) Conventional |
b) YMC J'sphere ODS |
| Fig. 1: Schematic comparison of reversed phase materials of different polarity. |
Alkyl chains of various length, such as C18, C8 and C4 for example, are commonly used for bonding during the synthesis of reversed phase materials of different polarity. YMC however, applies another approach for creating divergent polarities and improving the consistency in the synthesis of reversed phase packings. YMC keeps the C18-alkyl chain length constant, but specifically changes content of C18 groups at the silica surface, yielding three different J´sphere ODS packings with graduated hydrophobicity (fig. 1).
Physica-chemical properties
An elaborate endcapping process is applied to react the remaining silanols to effectively suppress the undesired non-specific interactions (fig. 2).
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1:Uracil
2:Pocainamide
3:N-Acetylprocainamide
4:4-Hydroxyacetophenone |
Column: 150 x 4.6 mm
Eluent: acetonitrile/K2HPO4-KH2PO4 (20 mM, pH 6.9) = 8/92
Flow: 1.0 ml/min
Detection: UV at 254 nm
Temperature: 37 ºC |
| Fig. 2: Influence of carbon load on the separation of basic compounds. |
The stepwise decrease of hydrophobicity in J´sphere ODS-H80, M80 and L80 series is accompanied by an opposite increase of the H-bonding capacity. If a sample molecule is susceptible to H-bonding, the resulting interaction represents additional retention and enhances the selectivity in RP-separations.
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| Fig. 3: Hydrophobicity (determined using k' for n-octyl benzene) and H-bonding capacity (determined using
α of caffeine/phenol) of J’sphere ODS columns. |
Selectivity Data
The exclusive use of C18 groups makes the hydrophobic interaction identical for all three types of J´sphere ODS packings; only the degree of hydrohobicity, i.e. the polarity, is varied.
In addition to the hydrophobic interaction, the surface siloxane groups of J’sphere ODS packings
provide a pronounced H-bonding capacity contributing additional selectivity. The ability to interact
strongly via H-bonding creates the opportunity to make use of an additional degree of freedom in
selectivity. The “controlled hydrogen bonding capacity" of YMC J’sphere ODS packings represents
an efficient tool for the chromatographic discrimination of closely related compounds presenting
only minor molecular differences.
Column care
The recommended pH range of using YMC J’sphere ODS-M80 and -L80 columns is pH 2-7.5 and pH 1-9 for J’sphere ODS-H80. Remove acid and buffer salts before storage. Store the column in methanol/water = 50/50. Clogged inlet frits often can be cleaned by changing the flow direction or replacement.
For detailed information please refer to the “Column Care and Use Instructions”, which are shipped with each analytical column.
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