title: Sample enrichment by using monolithic precolumns in microcolumn liquid chromatography.
abstract: An on-line sample enrichment system was designed using monolithic precolumns in microcolumn LC. The monolithic ODS capillary columns were prepared via in situ sol-gel processes. The enrichment efficiency of the monolithic columns was tested by using phthalates as the analytes. The relative standard deviations (n = 6) for the retention time, peak area and peak height were between 0.4 and 1.2%, 0.9 and 5.5% and 0.4 and 3.9%, respectively. The system was linear (R2 > 0.99) within the working sample concentration and sample volume ranges. Comparing to 0.2 microl injection with a typical sample injector, the theoretical plate number of a same separation column was increased by 3-6-fold when the precolumn unit was used for sample injection. The recoveries of the analytes were between 88 and 120%, and the sample volume that could be injected into the system was increased up to 5000-fold. The limits of detection were improved by more than 2000-fold and were between 0.21 and 0.87 ng ml(-1) even with a UV absorbance detector. This system was applied to the determination of phthalates contained in laboratory distilled water and tap water samples.
authors.affiliation: Department of Chemistry, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
authors.forename: Lee Wah
authors.initials: LW
authors.lastname: Lim
authors.forename: Katsuaki
authors.initials: K
authors.lastname: Hirose
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tatsumi
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Uzu
authors.forename: Megumi
authors.initials: M
authors.lastname: Mizukami
authors.forename: Toyohide
authors.initials: T
authors.lastname: Takeuchi
mesh_terms: D002853:Chromatography, Liquid / Q000295:instrumentation* / Q000379:methods; D008855:Microscopy, Electron, Scanning; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet