What is the Difference Between C8 and C18 Column?
🆚 Go to Comparative Table 🆚The main difference between C8 and C18 columns lies in the polarity and hydrophobicity of their bonded phases. Both C8 and C18 are reversed-phase columns used for analyzing weakly polar substances. Here are the key differences between the two:
- Bonded Phases: C8 columns have octadecyl (C18) groups bonded to the silica support, with 18 carbon atoms in each group. C8 columns have octyl (C8) groups bonded to the silica support, with 8 carbon atoms in each group.
- Polarity: The polarity of C18 is smaller than that of C8. C8 is on the side with stronger polarity, while C18 is on the side with weaker polarity.
- Hydrophobicity: C8 columns are less hydrophobic than C18 columns. The longer the carbon chain, the more hydrophobic the stationary phase.
- Applications: C18 columns are suitable for acidic, basic, neutral, polar, medium polar, and non-polar sample analysis. C8 columns are suitable for lipids, steroids, analytes with high hydrophobicity, and samples with different hydrophobicity.
In summary, C18 columns have a weaker polarity and are more hydrophobic than C8 columns. They are suitable for a wider range of analytes, while C8 columns are specifically useful for hydrophobic samples and compounds with high hydrophobicity.
Comparative Table: C8 vs C18 Column
The main difference between C8 and C18 columns lies in the stationary phase and the polarity of the alkyl chain. Both C8 and C18 columns are reversed-phase columns used in high-performance liquid chromatography (HPLC) systems. Here is a comparison between the two columns:
Feature | C8 Column | C18 Column |
---|---|---|
Alkyl Chain | Octylsilane | Octadecylsilane |
Carbon Atoms in Alkyl Chain | 8 | 18 |
Polarity | Stronger | Weaker |
Retention of Analytes | Lower | Higher |
Retention Time of Main Components | Shorter | Longer |
Suitability for Hydrophobic Compounds | Less suitable | More suitable |
C8 columns have Octylsilane as the stationary phase, with 8 carbon atoms in the alkyl chain, while C18 columns have Octadecylsilane as the stationary phase, with 18 carbon atoms in the alkyl chain. The C18 column has a smaller polarity than the C8 column. This difference in polarity leads to C18 columns having a stronger analyte retention performance than C8 columns. Additionally, the higher carbon content in the C18 column results in a longer retention time for the main components. In general, C18 columns are more suitable for separating compounds with stronger hydrophobic interactions.
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