This guide provides recommended startup procedures, HILIC method development strategies, operational best practices, storage recommendations, and troubleshooting resources to help achieve reproducible, high-efficiency separations.
Related Resources
- View Cogent Diamond Hydride HPLC Column Ordering Information
- View General Instructions for All Cogent TYPE‑C HPLC Columns
When Should You Use Diamond Hydride?
Primary Application: HILIC Chromatography
- Diamond Hydride is specifically designed for highly polar compounds that exhibit little or no retention on conventional reversed-phase columns.
Typical Applications
- Amino acids
- Polar metabolites
- Organic acids
- Peptides
- Small polar pharmaceuticals
- Low-abundance analytes
- LCMS applications
- Method development for difficult polar compounds
Example Compounds (Structures are shown below).
- Meglutol
- L-Methionine
- L-Glutamic Acid
- Domoic Acid
Reversed-Phase Applications
Because Diamond Hydride contains very little hydrophobic carbon functionality, its usefulness in traditional reversed-phase chromatography is limited.
For hydrophobic compounds, consider:
- Cogent Bidentate C18™
- Cogent Bidentate C8™
- Cogent Phenyl Hydride™
- Cogent UDC-Cholesterol™
- Cogent RP Columns™
Important Precautions Before Use
Avoid Phosphoric Acid
Phosphoric acid should not be used with Diamond Hydride columns.
Use of phosphoric acid may permanently alter stationary phase performance and reduce column lifetime.
General System Preparation
Before installing the column:
- Flush all solvent lines thoroughly.
- Remove previous mobile phases from the instrument.
- Purge the injector.
- Use only freshly prepared mobile phases.
- Degas solvents before use whenever possible.
Startup Instructions
Recommended Initial Conditioning
- Install the column using good laboratory practices.
- Verify all tubing and fittings are properly connected.
- Prepare a 50:50 organic solvent/water solution that includes all planned mobile-phase additives.
- Flush and equilibrate the column for approximately 30 minutes.
- Switch to your initial method conditions and allow stabilization before analysis.
Solvent Requirements
- Use HPLC-grade solvents only.
- Degas all solvents.
- Prepare buffers fresh daily.
- Remove buffers from the system after daily use.
Column Protection
For dirty samples or aggressive mobile phases:
- Use guard columns when appropriate.
- Use inline filters when appropriate.
These accessories may help improve column lifetime and maintain performance.
Related Resource
Diamond Hydride Method Development
HILIC Method Development
Diamond Hydride is primarily developed for HILIC-like separations.
General Rule
To increase retention:
- Increase organic solvent concentration.
- Decrease aqueous content.
Acetonitrile is typically the preferred organic solvent.
Polar Neutral Compounds
Polar neutral analytes are often retained effectively using HILIC conditions.
Recommended starting conditions:
- 50% acetonitrile
- 50% aqueous phase
Optimize by increasing organic content as needed.
Acidic Compounds
To maximize retention:
- Ensure acids are ionized.
Recommended starting buffer:
- 10 mM ammonium formate
- or
- 10 mM ammonium acetate
Recommended starting pH:
- Approximately 6.5
Simple Samples
Begin with:
- 50% aqueous buffer
- 50% acetonitrile
Increase organic content until desired retention is achieved.
Complex Samples
Suggested scouting gradient:
- 90% acetonitrile
- To 20% acetonitrile
- Over approximately 10 minutes
Adjust gradient slope and composition to optimize separation.
Basic Compounds
For polar bases:
Recommended starting conditions:
- 0.1% formic acid
- or
- 0.2% acetic acid
Both isocratic and gradient methods may be effective depending on sample complexity.
Important Note
Methanol generally does not provide sufficient retention for many Diamond Hydride HILIC methods.
For non-UV detection techniques such as:
- Mass spectrometry
- Light scattering
- Electrochemical detection
Acetone may be considered as an alternative organic modifier.
Troubleshooting & Method Optimization
Common causes of poor retention or performance include: Insufficient organic content
- Inadequate equilibration
- Incorrect buffer selection
- Phosphoric acid contamination
- Sample solvent incompatibility
- Inadequate solvent purity
- Column contamination
Storage Instructions
When analysis is complete:
- Flush the column using approximately 90:10 organic solvent/water.
- Remove all system pressure before disconnecting the column.
- Cap the column and store according to TYPE‑C storage procedures.
Important: Never disconnect a column while pressure remains in the system. Pressure shock can damage the column and negatively affect performance.
Related Resource
Best Practices Summary
- Use Diamond Hydride primarily for highly polar compounds.
- Avoid phosphoric acid.
- Use HPLC-grade solvents only.
- Degas mobile phases.
- Prepare buffers fresh daily.
- Increase organic solvent to increase retention.
- Use acetonitrile whenever possible.
- Consider acetone for non-UV detection applications.
- Use guard columns and filters when appropriate.
- Store in approximately 90:10 organic/water solvent.