HPLC instrumentation ultra-high-pressure liquid

In order to obtain better and faster separation, instruments using higher pressures than common HPLC have been developed. These are often referred to as ultra-high-pressure liquid chromatographs (UPHPLC), or some similar abbreviation. They are used in a manner similar to HPLC and can be connected to mass spectrometers. 

The penalty for using fine particles is resistance to solvent flow. Until recently, HPLC operated at pressures of 70-4(X) bar to attain flow rates of 0.5-5 mL/min. In 2004, equipment became available to employ 1.5- to 2-p.m-diameter particles at pressures up to 1 000 bar. These instruments provide increased resolution or decreased run time. Chromatography with 1.5- to 2-p,m-diameter particles at high pressure is commonly called UPLC (Ultra-Performance Liquid Chromatography). 

Also, new-generation HPLC instrument which can exceed the pressure limitation of conventional equipment has been developed. This technique is ultra performance liquid chromatography (UPLC), where small particle size columns with 1.7 pm particle size in combination with high flow rates offers increased speed, resolution, and sensitivity [15]. Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has shown to be well suited for support of PK studies [16-19], Often, there is a need to improve the sensitivity of the assay for the determination of PK parameters, especially for very potent compounds, since lower amount is administrated, and also for compounds with low bioavailability. UPLC-MS/MS has shown decreased ion suppression and superior sensitivity, and has been successfully applied to PK studies for compounds with low bioavailability [20-22]. 

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