Methodologies to determine b-term coefficients revisited.

Area of Science:

• Analytical Chemistry
• Chromatography

Background:

• Accurate determination of the longitudinal diffusion term (b-term) is crucial for understanding mass transfer in High-Performance Liquid Chromatography (HPLC).
• Several methods exist for b-term determination, each with potential limitations.

Purpose of the Study:

• To compare the accuracy, reproducibility, and efficiency of three common methods for determining the b-term constant in HPLC.
• To identify the most reliable method for accurate b-term measurement.

Main Methods:

• Investigation of three methodologies: peak parking, fitting of an experimental van Deemter curve, and the dynamic method.
• Comparison based on mutual agreement, intra- and inter-day variation, and measurement time.
• Utilized h.ν versus ν plots for enhanced visualization of the b-term region.

Main Results:

• The dynamic method exhibited impractically long waiting times and baseline variations, compromising accuracy.
• Peak parking and van Deemter curve fitting methods produced highly similar b-values.
• Both reliable methods demonstrated inter-day variation within 1% relative standard deviation (RSD).

Conclusions:

• Peak parking and van Deemter curve fitting are reliable and accurate methods for determining the b-term in HPLC.
• The dynamic method is not recommended due to practical limitations.
• Using h.ν versus ν plots aids in identifying anomalous data and verifying method agreement.