Pseudolinear Gradient Ultrahigh-Pressure Liquid Chromatography Using an Injection Valve Assembly
- 4 January 2006
- journal article
- Published by American Chemical Society (ACS) in Analytical Chemistry
- Vol. 78 (3), 858-864
- https://doi.org/10.1021/ac058024h
Abstract
The use of ultrahigh pressures in liquid chromatography (UHPLC) imposes stringent requirements on hardware such as pumps, valves, injectors, connecting tubing, and columns. One of the most difficult components of the UHPLC system to develop has been the sample injector. Static-split injection, which can be performed at pressures up to 6900 bar (100 000 psi), consumes a large sample volume and is very irreproducible. A pressure-balanced injection valve provided better reproducibility, shorter injection time, reduced sample consumption, and greater ease of use; however, it could only withstand pressures up to ∼1000 bar (15 000 psi). In this study, a new injection valve assembly that can operate at pressures as high as 2070 bar (30 000 psi) was evaluated for UHPLC. This assembly contains six miniature electronically controlled needle valves to provide accurate and precise volumes for introduction into the capillary LC column. It was found that sample volumes as small as several tenths of a nanoliter can be injected, which are comparable to the results obtained from the static-split injector. The reproducibilities of retention time, efficiency, and peak area were investigated, and the results showed that the relative standard deviations of these parameters were small enough for quantitative analyses. Separation experiments using the UHPLC system with this new injection valve assembly showed that this new injector is suitable for both isocratic and gradient operation modes. A newly designed capillary connector was used at a pressure as high as 2070 bar (30 000 psi).Keywords
This publication has 12 references indexed in Scilit:
- In-Depth Characterization of Slurry Packed Capillary Columns with 1.0-μm Nonporous Particles Using Reversed-Phase Isocratic Ultrahigh-Pressure Liquid ChromatographyAnalytical Chemistry, 2004
- Safety concerns in ultrahigh pressure capillary liquid chromatography using air-driven pumpsJournal of Chromatography A, 2003
- Separation of chiral pharmaceuticals using ultrahigh pressure liquid chromatographyChromatographia, 2002
- Very High Pressure Gradient LC/MS/MSAnalytical Chemistry, 2001
- Fast ultrahigh-pressure liquid chromatography: On-column UV and time-of-flight mass spectrometric detectionJournal of Microcolumn Separations, 1999
- Ultrahigh-Pressure Reversed-Phase Capillary Liquid Chromatography: Isocratic and Gradient Elution Using Columns Packed with 1.0-μm ParticlesAnalytical Chemistry, 1999
- Ultrahigh-Pressure Reversed-Phase Liquid Chromatography in Packed Capillary ColumnsAnalytical Chemistry, 1997
- Instrumental Requirements for Nanoscale Liquid ChromatographyAnalytical Chemistry, 1996
- Capillary electrochromatography — Some important considerations in the preparation of packed capillaries and the choice of mobile phase buffersChromatographia, 1995
- Ultimate limits in high-pressure liquid chromatographyJournal of Chromatography A, 1975