Generation of Ultrahigh Peak Capacity LC Separations via Elevated Temperatures and High Linear Mobile-Phase Velocities

The use of a combination of ultraperformance liquid chromatography at ∼11 000 psi on sub 2-μm particles combined with reversed-phase gradient chromatography at a temperature of 90 °C is described as applied to the analysis of endogenous and drug metabolites in human and animal urine. By using elevated temperatures, back pressures can be reduced while maintaining high flow rates and chromatographic efficiency, with peaks 1−3 s wide at the base. Application to urine samples provided a peak capacity of ∼700 for a 10-min analysis and greater than ∼1000 in 1 h. Despite the narrow nature of the peaks, good quality mass spectra were also obtained, allowing the identification of typical drug and endogenous metabolites. These ultra-high-resolution chromatograms should be ideal for the analysis of complex samples in, for example, metabolite identification, impurity identification, and metabonomic/metabolomic studies. Applications in natural product analysis and proteomics can also be envisaged.