ULDC – Effects of extra column volume and extra column dispersion

Significance of Topic

Ultra Low Dispersion Chromatography is important in high performance liquid chromatography workflows for improving peak shape resolution and signal to noise by minimizing components outside the column.

Objectives and Study Overview

This study compares standard HPLC configuration with a ULDC system by evaluating the impact of extra column volume on separation performance using a mixed standard of eight compounds.

Methodology and Instrumentation

System used AZURA 862 ULDC HPG with DAD measuring cell and low volume capillaries, Supelco Titan C18 50 x 2.1 mm 1.9 microm phase and Chromeleon control. Sample preparation involved a stock solution of eight analytes diluted in acetonitrile water mixtures. Extra column volume was measured by injecting caffeine under isocratic conditions. Both isocratic and gradient runs were conducted at 0.5 to 0.7 milliliter per minute flow rates with column temperature controlled at 25 to 30 degrees.

Main Results and Discussion

Extra column volume decreased from 24 to 8.5 microliter corresponding to a 65 percent reduction. Peak height increased by 35 percent. Signal to noise ratio improved between 56 and 156 percent across compounds. Peak width at half height was reduced by 0.72 seconds and theoretical plate count rose substantially. Critical peak pairs gained baseline separation. System backpressure increased to around 510 bar but remained within instrument limits.

Benefits and Practical Application

Reducing extra column volume yields sharper peaks, higher sensitivity, and faster run times. It enables robust quantitation without the need for dedicated ultrahigh pressure equipment. This approach suits high throughput QA QC and industrial analysis environments.

Future Trends and Potential Applications

Further miniaturization of flow pathways, integration with microfluidic devices, and development of higher pressure tolerant components will extend ULDC benefits. Coupling with automated sample handling and advanced detectors can broaden use in pharmaceutical, food, and environmental analysis.

Conclusion

The investigation demonstrates that ULDC driven reduction of extra column volume significantly enhances chromatographic performance while operating within standard system pressure capabilities. This strategy offers improved sensitivity, resolution, and throughput in a single platform.

Reference

[1] J P Grinias B Bunner M Gilar J W Jorgenson Measurement and Modeling of Extra Column Effects Chromatography 2015
[2] A Schultze Jena M A Boon P J Th Bussmann A E M Janssen A van der Padt Journal of Chromatography A 2017
[3] P Hong P R McConvill Waters White paper 2018
[4] Chromeleon 7 2 manual