Fast ultrahigh-pressure liquid chromatography: On-column UV and time-of-flight mass spectrometric detection

Abstract

An ultrahigh-pressure liquid chromatography (UHPLC) system capable of generating 52,000 psi (3,600 bar) was constructed. Fused-silica capillaries with inner diameters of 29 μm and lengths up to 70 cm were packed with nonporous 1.5-μm isohexylsilane-modified (C6) silica particles using a carbon dioxide enhanced slurry packing method. The system performance was evaluated by monitoring the UV absorbance of small organic compounds on-column. At optimum linear velocity, efficiencies as high as 570,000 plates m−1 (k=0.5) were obtained. Analysis times could be reduced significantly, both by operating at higher than optimum linear velocities and by shortening the column. Selected benzodiazepines and triazine herbicides were separated in less than 60 s. The UHPLC system was also coupled to a time-of-flight mass spectrometer for the separation and detection of selected benzodiazepines. A loss in efficiency due to the liquid sheath interface was observed. ©1999 John Wiley & Sons, Inc. J Micro Sep 11: 631–643, 1999