Three approaches to improving performance of liquid chromatography using contour maps with pressure, time, and number of theoretical plates

• Published in: Journal of Chromatography A Vol. 1637; p. 461778
• Main Authors: Ito, Masahito, Shimizu, Katsutoshi, Nakatani, Kiyoharu
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 25.01.2021
• Subjects: Chromatography, Liquid - methods; Coefficients of pressure-application; Hold-up time; Kinetic performance limit; Models, Theoretical; Number of theoretical plates; Optimal velocity; Pressure; Pressure drop; Time Factors; Number of theoretical plates; Kinetic performance limit; Hold-up time; Optimal velocity; Pressure drop; Coefficients of pressure-application
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2020.461778

•Contour map with three axes, of pressure, time, and number of theoretical plates•Flow rate and column length are varied to improve speed or separation performance•A method to improve separation by increasing the pressure while maintaining time•An alternative approach for increasing speed by pressure while maintaining plates•A delta region defined by the optimal velocity and upper limit of pressure drop Attempts to improve HPLC performance often focus on increasing the speed or separation performance. In this article, both the flow rate and column length are optimized as separation conditions, while observing the number of theoretical plates and hold-up time with isocratic elutions. In addition, the upper pressure limit must be simultaneously considered as the boundary condition. Approaches based on the optimal velocity (Opt.) are often adopted; but the kinetic performance limit (KPL) in Desmet's method can also be utilized for three-dimensional graphing with axes of pressure, time, and number of theoretical plates. Here, two approaches involving pressure increase are introduced, beginning with the condition of optimal linear velocity: one aimed at greater speed and the other at higher resolution. Coefficients of pressure-application are derived to measure the effectiveness of the intermediate conditions between the Opt. and KPL methods. In the third approach, the hold-up time is extended while maintaining a fixed pressure. Coefficients of time-extension are also derived, to determine the effectiveness to improve the separation performance.