LC Simulator: Selecting HILIC equations for modeling

Description

Hydrophilic Interaction Liquid Chromatography (HILIC) is used for polar and ionized compounds that are poorly retained in reversed-phase LC. LC Simulator provides several equation types for modeling HILIC retention behaviour, but selecting the most appropriate one depends on the compound properties and the mobile phase conditions.

Solution

1. Select the appropriate HILIC equation in LC Simulator

For HILIC modeling, LC Simulator supports two primary equation types:

          Type A (Linear): ln k' = a + b × X

• Use for simple linear relationships between retention and mobile phase composition (e.g., % water).

• Requires a minimum of 2 experiments; 3+ are recommended for robustness .

  Type B (Logarithmic): ln k' = a + b × ln X

• Use when retention behavior is logarithmic (e.g., retention decreases sharply at low % water).
• Requires a minimum of 2 experiments; 3+ are recommended .

Important: These equation types (Type A/Type B) are unrelated to the "A" and "B" columns or mobile phases in LC methods.  Type A/Type B equations describe mathematical models for retention prediction.

2. Validate the model

• Run at least 3–4 experiments covering the range of mobile phase compositions (e.g., 5–30% water in acetonitrile).
• Compare predicted vs. experimental retention times:
• If residuals are large or trends are inconsistent, switch between Type A/Type B equations or add experiments to improve fit.
• If the model overfits, reduce complexity (e.g., switch from quadratic to linear).
• Check peak shapes and resolution for critical pairs to confirm the model reflects experimental behavior.

3. Refine if needed

• If retention behavior is poorly described, consider:
• Adding experiments to improve model robustness.
• Testing alternative equations (e.g., switching between Type A/Type B).
• Adjusting mobile phase conditions (e.g., pH, buffer type) to better align with the selected equation.