title: Peak distortions arising from large-volume injections in supercritical fluid chromatography.
abstract: Preparative separations in supercritical fluid chromatography (SFC) involve the injection of large volumes of the solute. In SFC, the mobile phase is typically high pressure CO2+modifier and the solute to be injected is usually dissolved in the modifier. Two-types of injection methods, modifier-stream and mixed-stream, are common in commercial preparative SFC systems. In modifier-stream injection, the injection is made in the modifier stream which is later mixed with the CO2 stream, while in the mixed-stream injection, the injection is made in a mixed CO2+modifier stream. In this work a systematic experimental and modelling study of the two techniques is reported using single-enantiomers of flurbiprofen on Chiralpak AD-H with CO2+methanol as the mobile phase. While modifier-stream injection shows non-distorted peaks, mixed-stream injection results in severe peak-distortion. By comparing the modelling and experimental results, it is shown that the modifier "plug" introduced in the mixed-stream injection is the primary cause of the peak distortions. The experimental results also point to the possible existence of viscous fingering which contributes to further peak distortion.
authors: School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore.
authors: Yun
authors: Y
authors: Dai
authors: School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore.
authors: Geng
authors: G
authors: Li
authors: School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore; Department of Chemical and Materials Engineering, University of Alberta, 9107-116 Street, Edmonton, Alberta, Canada T6G2V4. Electronic address: arvind.rajendran@ualberta.ca.
authors: Arvind
authors: A
authors: Rajendran
mesh_terms: D000688:Amylose / Q000031:analogs & derivatives; D002245:Carbon Dioxide; D025924:Chromatography, Supercritical Fluid / Q000379:methods*; D005480:Flurbiprofen / Q000032:analysis; D000432:Methanol; D048448:Phenylcarbamates; D011312:Pressure; D013237:Stereoisomerism
chemical_list: D048448:Phenylcarbamates; C080033:Chiralpak AD; D002245:Carbon Dioxide; D005480:Flurbiprofen; D000688:Amylose; D000432:Methanol
keywords: Carbon dioxide; Injection; Modeling; Supercritical fluid chromatography; Viscous fingering