title: Efficiency of short, small-diameter columns for reversed-phase liquid chromatography under practical operating conditions.
abstract: Prototype small-size (1.0mm I.D., 5cm long) columns for reversed-phase HPLC were evaluated in relation to instrument requirements. The performance of three types of columns, monolithic silica and particulate silica (2μm, totally porous and 2.6μm, core-shell particles) was studied in the presence of considerable or minimal extra-column effects, while the detector contribution to band broadening was minimized by employing a small size UV-detector cell (6- or 90nL). A micro-LC instrument having small system volume (<1μL) provided extra-column band variance of only 0.01-0.02μL(2). The three columns generated about 8500 theoretical plates for solutes with retention factor, k>1-3 (depending on the column), in acetonitrile/water mobile phase (65/35=vol/vol) at 0.05mL/min, with the instrument specified above. The column efficiency was lower by up to 30% than that observed with a 2.1mm I.D. commercial column. The small-size columns also provided 8000-8500 theoretical plates for well retained solutes with a commercial ultrahigh-pressure liquid chromatography (UHPLC) instrument when extra-column contributions were minimized. While a significant extra-column effect was observed for early eluting solutes (k<2-4, depending on column) with methanol/water (20/80=vol/vol) as weak-wash solvent, the use of methanol/water=50/50 as wash solvent affected the column efficiency for most analytes. The results suggest that the band compression effect by the weak-wash solvent associated with partial-loop injection may provide a practical means to reducing the extra-column effect for small-size columns, while the use of an instrument with minimum extra-column effect is highly desirable.
authors: University of California, Davis, 451 Health Sciences Drive, Davis, CA 95616, USA.
authors: Yan
authors: Y
authors: Ma
authors: University of California, Davis, 451 Health Sciences Drive, Davis, CA 95616, USA.
authors: Alexander W
authors: AW
authors: Chassy
authors: GL Sciences Inc., 237-2 Sayamagahara, Iruma, Saitama 358-0032, Japan.
authors: Shota
authors: S
authors: Miyazaki
authors: GL Sciences Inc., 237-2 Sayamagahara, Iruma, Saitama 358-0032, Japan.
authors: Masanori
authors: M
authors: Motokawa
authors: GL Sciences Inc., 237-2 Sayamagahara, Iruma, Saitama 358-0032, Japan; Kyoto University, Department of Chemistry, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan.
authors: Kei
authors: K
authors: Morisato
authors: GL Sciences Inc., 237-2 Sayamagahara, Iruma, Saitama 358-0032, Japan.
authors: Hideyuki
authors: H
authors: Uzu
authors: GL Sciences Inc., 237-2 Sayamagahara, Iruma, Saitama 358-0032, Japan.
authors: Masayoshi
authors: M
authors: Ohira
authors: GL Sciences Inc., 237-2 Sayamagahara, Iruma, Saitama 358-0032, Japan.
authors: Masahiro
authors: M
authors: Furuno
authors: Kyoto University, Department of Chemistry, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan.
authors: Kazuki
authors: K
authors: Nakanishi
authors: Kyoto Monotech Co., 1095 Shuzei-cho, Kamigyo-ku, Kyoto 602-8155, Japan.
authors: Hiroyoshi
authors: H
authors: Minakuchi
authors: AB SCIEX, 1201 Radio Road, Redwood City, CA 94065, USA.
authors: Khaled
authors: K
authors: Mriziq
authors: Phenomenex, Inc., 411 Madrid Avenue, Torrance, CA 90501, USA.
authors: Tivadar
authors: T
authors: Farkas
authors: University of California, Davis, 451 Health Sciences Drive, Davis, CA 95616, USA; University of Jeddah, Biochemistry Department, Saudi Arabia.
authors: Oliver
authors: O
authors: Fiehn
authors: University of California, Davis, 451 Health Sciences Drive, Davis, CA 95616, USA; GL Sciences Inc., 237-2 Sayamagahara, Iruma, Saitama 358-0032, Japan. Electronic address: n-tanaka@gls.co.jp.
authors: Nobuo
authors: N
authors: Tanaka
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation; D056148:Chromatography, Reverse-Phase / Q000295:instrumentation*; D000432:Methanol / Q000737:chemistry; D010316:Particle Size; D010539:Permeability; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D014867:Water; D012822:Silicon Dioxide; D000432:Methanol; C032159:acetonitrile
keywords: 1mm I.D. column; Column efficiency; Core–shell particles; Extra-column effect; Monolithic silica; Weak-wash solvent