New Column Technologies for Better and Faster Separations in UHPLC

Significance of the topic

New column designs based on superficially porous particles support faster and higher efficiency separations in UHPLC, addressing key challenges in pharmaceutical quality control, method transfer, and high-throughput analysis. By reducing band broadening and operating pressures, these technologies improve laboratory productivity and resource utilization.

Objectives and study overview

This study reviews the properties of new column technologies, explores theoretical optimization methods, and demonstrates applications of superficially porous particles for fast, routine, and high-efficiency separations. Practical aspects such as instrument effects and method transfer strategies are also evaluated.

Methodology and instrumentation

• Theoretical models: three-parameter (Knox-Saleem) and two-parameter (Poppe) approaches to optimize particle size, column length, and flow rate.
• Optimization workflow: identify ideal parameters, select closest available column dimensions, and adjust flow rates for target analysis time.
• Column types: sub-2 µm fully porous (Zorbax RRHD), sub-3 µm superficially porous (Poroshell 120 SB-C18), sub-5 µm superficially porous (Poroshell 300 SB-C18).
• Instrumentation: UHPLC systems capable of up to 1100 bar, temperature control (up to 80 °C), UV detection at 214 nm and 278 nm.
• Mobile phases: typical use of aqueous TFA and acetonitrile gradients, elevated temperature to reduce viscosity.

Main results and discussion

• Superficially porous particles exhibit lower A (eddy diffusion) and B (longitudinal diffusion) terms compared to fully porous, with similar C (mass transfer) factors for small molecules, enabling lower minimum HETP and high efficiency.
• Ultrafast LC methods achieved 30 s separations of methyl paraben and ciprofloxacin with superficially porous columns at 550 bar, matching fully porous performance at 1100 bar, and preserving resolution.
• Dissolution testing for ciprofloxacin tablets was completed in 0.5–2 min per sample versus traditional 5–10 min, yielding equivalent release profiles and aligning with automated UV assays.
• Routine and high-efficiency separations demonstrated: screening of 14 polar APIs in 3 min gradients; peptide digest separations reaching >100 000 theoretical plates using columns in series at moderate pressures.
• Extra-column (instrument) broadening significantly affects plate count at short retention times, emphasizing the need for low-dispersion tubing and optimized injection systems.
• Method transfer strategies preserved resolution when shifting from 5 µm fully porous to 2.7 µm superficially porous particles using shorter columns and adjusted flow rates, achieving 4–5-fold speed increases.

Benefits and practical applications

• Increased sample throughput and reduced analysis time in pharmaceutical QC, content uniformity, and cleaning validation.
• Lower solvent consumption and operating pressures compared to sub-2 µm fully porous columns.
• Compatibility with existing UHPLC platforms via proper instrument tuning to minimize extra-column effects.
• Versatility across small molecule and peptide analyses, as well as food, beverage, and environmental screening.

Future trends and opportunities

As stationary phase technologies continue to evolve, integration with mass spectrometry, microflow UHPLC, and automated method development will expand the reach of superficially porous columns. Emerging applications in proteomics, biopharmaceutical analysis, and high-throughput industrial screening will benefit from ongoing improvements in particle design, column hardware, and instrument miniaturization.

Conclusion

Superficially porous particle columns offer a balanced solution for fast, efficient, and robust UHPLC separations. Theoretical models and practical demonstrations confirm their superior performance over fully porous particles at lower pressures. By addressing instrument dispersion and adopting strategic method transfer workflows, laboratories can achieve significant gains in throughput and analytical quality.

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