Cogent TYPE-C HPLC Columns utilize proprietary silica hydride technology that provides chromatographers with unique selectivity, exceptional retention-time stability, rapid equilibration, and excellent performance for both reversed-phase and HILIC applications.
This guide provides practical recommendations for column conditioning, HILIC method development, storage, troubleshooting, and routine operation of Cogent TYPE-C stationary phases.
What Makes TYPE-C Columns Different?
Unlike conventional silica columns that contain large numbers of surface silanol groups, TYPE-C Columns use silica hydride technology that fundamentally changes analyte interactions with the stationary phase. Essentially these columns are rugged, stable and predictable.
Benefits include:
- Excellent HILIC performance
- Fast equilibration
- Exceptional retention-time reproducibility
- Unique selectivity for difficult separations
- Excellent LCMS compatibility
- Flexible operation in HILIC and reversed-phase modes
Getting Started with TYPE-C Columns
Before installing a new column:
- Flush all solvent lines of previous mobile phases.
- Purge the injector system.
- Install the column following standard HPLC practices.
- Condition the column using a 50:50 organic solvent/water mixture containing all method additives for approximately 30 minutes.
- Equilibrate under your starting mobile-phase conditions for at least 15 minutes before analysis.
Storage Recommendation
For long-term storage:
- Flush the column with the storage solvent.
- Store in approximately 90:10 organic solvent/water.
- Never disconnect the column while pressure remains in the system.
- View Complete TYPE-C Column Storage Instructions
Understanding HILIC and Reversed-Phase Operation
Most TYPE-C columns can operate effectively in both:
HILIC Mode
Retention generally increases as organic solvent content increases.
HILIC is commonly used for:
- Polar compounds
- Metabolites
- Organic acids
- Amines
- Pharmaceutical impurities
- LCMS applications
Reversed-Phase Mode
Retention generally increases as water content increases.
Reversed-phase methods are commonly used for:
- Hydrophobic compounds
- Pharmaceutical assays
- Stability studies
- General analytical methods
HILIC Method Development Tips
HILIC separations can be highly sensitive to small changes in mobile phase composition, making method optimization important.
Recommended Starting Conditions
Begin method development using:
- 50:50 organic/water mobile phase
Then:
- Increase organic content to increase retention.
- Decrease organic content to reduce retention.
Useful Screening Gradient
A simple gradient can help identify analyte retention behavior:
- Start: High organic
- Progressively increase aqueous content
- Return to initial conditions
This allows rapid identification of retention windows before optimizing an isocratic method.
Important HILIC Considerations
- Small solvent-composition changes can significantly impact retention.
- Temperature changes can alter retention and selectivity.
- Careful control of mobile-phase composition improves reproducibility.
- Column temperature control is strongly recommended.
Best Practices for Robust HILIC Methods
For maximum reproducibility:
- Small composition changes can create noticeable retention shifts.
Use Temperature Control
- In HILIC methods, even small temperature fluctuations may affect selectivity and retention.
Verify Equilibration
- Allow sufficient time for the column to return to initial conditions after gradients.
Match Sample Diluent to Mobile Phase
- Large mismatches between sample solvent and mobile phase often lead to poor peak shape.
Troubleshooting TYPE-C Columns
Most chromatographic problems originate outside the column itself.
Poor Peak Shape
Peak Fronting. Possible causes:
- Sample overload
- Matrix effects
Possible solutions:
- Reduce sample concentration
- Reduce injection volume
- Use a guard column
Peak Broadening, Possible causes:
- Excessive injection volume
- Long retention
- Large detector cell volume
- Excess tubing volume
- Sample diluent mismatch
Peak Splitting, Possible causes:
- Plugged frits
- Solvent incompatibility
- Sample overload
- Injector valve problems
Peak Tailing, Possible causes:
- Secondary interactions
- Inappropriate pH
- Mobile-phase composition
Possible solutions:
- Adjust pH
- Modify gradient conditions
- Evaluate additives such as TFA or EDTA when appropriate
Noisy Baselines
Possible causes:
- Air bubbles
- Degasser issues
- Detector contamination
- Pump problems
- Contaminated solvents
- Sample contamination
Retention-Time Variability
Possible causes:
- Insufficient equilibration
- Pressure fluctuations
- Buffer concentration changes
- Solvent evaporation
- Temperature changes
- Column contamination
Recommended actions:
- Verify pump performance
- Confirm buffer preparation
- Check solvent reservoirs
- Improve temperature control
- Re-equilibrate after gradient runs
Verify Column Performnce Before Method Development
Each Cogent TYPE-C Column is tested before shipment and supplied with a test chromatogram.
Before placing a new column into service:
- Run the supplied test mixture.
- Compare results to the provided chromatogram.
- Document performance for future troubleshooting and column history.
This provides a useful performance baseline if issues arise later.
Phase-Specific Startup Guides
- View Cogent Amide Startup Guide
- View Cogent Bidentate C8 Startup Guide
- View Cogent Bidentate C18 Startup Guide
- View Cogent Diamond Hydride Startup Guide
- View Cogent Diol Startup Guide
- View Cogent Phenyl Hydride Startup Guide
- View Cogent Silica-C Startup Guide
- View Cogent UDA Startup Guide
- View Cogent UDC-Cholesterol Startup Guide