Hydrophilic interaction liquid chromatography, or HILIC, is a powerful method for separating polar analytes using polar stationary phases and high organic mobile phase conditions. Proper column conditioning is essential for achieving stable performance and reliable results.
Column Conditioning: Why It Matters
When setting up a new column or switching from reversed phase columns to HILIC, proper column conditioning ensures the stationary phase forms the characteristic water-rich layer needed for retention. Without adequate conditioning, you may experience shifting retention times, unstable baseline, and poor peak shape. Always follow the manufacturer’s guidelines for initial conditioning protocols.
Mobile Phase Preparation and System Flushing
HILIC uses highly organic mobile phase conditions. Before starting analysis, flush your system with the mobile phase to remove any aqueous solvents from previous reversed phase work. This prevents solvent incompatibility and ensures the mobile phase properly equilibrates the stationary phase.
Stationary Phase Equilibration
The stationary phase requires sufficient time and volume to establish equilibrium with the high-organic mobile phase. Flush the column with at least 50 column volumes at the recommended flow rate, then perform 10 blank injections.
This column conditioning process ensures the stationary phase develops the water layer essential for HILIC retention mechanisms. When working with buffer concentration in your mobile phase, ensure buffers remain soluble in high organic conditions to prevent precipitation at the column inlet.
Sample Preparation and Injection Best Practices
Proper sample preparation protects the column inlet from particulates and extends column lifetime. Filter samples for injection to prevent blockages, especially when using a low flow rate during equilibration. Between analyses, storing the column in an appropriate organic solvent helps maintain the stationary phase and preserve column performance.
Consistent HILIC Performance Starts with Proper Conditioning
Reliable HILIC performance depends on conditioning both the LC system and the column so the stationary phase can reach a stable equilibrium under high-organic mobile phase conditions. In this context, HPLC column conditioning involves flushing with the intended mobile phase, allowing adequate equilibration time, and confirming stable retention before routine analysis.
Good sample injection practices and appropriate column storage also help preserve performance between runs by minimizing contamination, protecting the inlet, and supporting consistent retention characteristics over time.
Additional Resources
- How to Avoid Common Problems with HILIC Methods
- Simplify the Switch to HILIC with Raptor HILIC-Si Columns
Restek Recommended Tools & Parts
Transcript
So, now you get a new HILIC column and are very eager to develop or run a HILIC analysis. What should you do at the very beginning?
As we discussed previously, for HILIC-based LC separation, the initial condition is under highly organic mobile phase to generate a water-rich layer on the surface of the polar stationary phase. Therefore it is necessary to condition and then equilibrate the column between runs to fully reestablish the water layer on the particle surface. When you start using a new HILIC column or change the mobile phase composition, we recommend to flush the column with at least 50 column volumes of the mobile phase. In addition, at least 10 blank injections running the full-time elution program should be performed when you start a new batch run. As for the equilibration time between injections, this could be very analyte dependent, so make sure to observe the retention time reproducibility to determine the time needed for re-equilibration.
Now, other than the column itself, we want to remind you that your LC systems has to be conditioned for HILIC analysis as well. We know most commonly LC instruments are used for reversed-phase LC analysis. So before switching to the HILIC analysis, make sure to flush the system with high organic phase for a period of 30 to 60 minutes. Now that you’ve conditioned your column and your system for HILIC analysis, you’re ready to go.
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Frequently Asked Questions
How should a HILIC column be conditioned before first use?
Before first use, a HILIC column should be equilibrated with the intended high-organic mobile phase so the stationary phase can establish the water-rich surface layer needed for retention.
This HPLC column conditioning process typically involves flushing with at least 50 column volumes, running blank injections to confirm baseline stability, and allowing enough equilibration time to achieve reproducible retention and peak shape.
Proper conditioning is essential whether starting with a new column or returning one to service after storage.
Why does switching from reversed phase columns to HILIC require extra attention?
A system that has been used with reversed phase columns often contains aqueous solvent residues that are not ideal for starting HILIC work. Before using a HILIC column, the system should be flushed thoroughly with a suitable organic-rich mobile phase so the new conditions are fully established. If that transition is incomplete, retention may drift, and equilibration may take longer.
What is the best way to approach column storage for HILIC?
For HILIC methods, column storage should follow the manufacturer’s recommendations for the specific stationary phase. Using the correct storage solvent and following proper storage procedures help maintain column performance and reduce changes in retention characteristics after periods of inactivity. Before returning the column to service, it should be re-equilibrated under method conditions.
What are the most common HILIC method problems?
Common problems include irreproducible retention times caused by insufficient conditioning or re-equilibration, poor peak shape from injection solvent mismatch, and retention or instrument issues related to mobile phase pH and buffer concentration.
