Instrument, autosampler resolution

In modern instrument configurations, derivatization can take place in a conventional autosampler the resultant derivatives are separated on the analytical column. Detection limits at the femtomole level are achieved, and the resolution of polar amino acids is greatly enhanced. 

Shimadzu has produced the Prominence HPLC, Agilent has developed the 1200 Rapid Resolution HPLC (Figure 3.22), Thermo Scientific has the Accela LC system and Waters has brought out the Acuity UPLC. Jasco s X-LC system allows two systems to fit in the footprint previously occupied by one traditional system. It is also a modular system of detectors and autosamplers, which allows it to be customised. LC Packings has launched the UltiMate 3000, which is a nanoflow LC system for use with columns of 50 im and larger. Modular systems are common now, e.g. Cecil Instruments produces both HPLC and ion chromatography systems and various detectors can be accommodated including UV-Vis, refractive index, conductivity and fluorescence. 

System volume is one of the parameters that instrument manufacturers have striven to reduce when the engineering of UHPLC systems began. Some reductions were simple. In others, for instance, in autosamplers, the volume reduction was more complicated. For this reason, total system volumes are not uniform across all available instrumentation. Some manufacturers strictly define their system volume, and the qualification of the instruments for use in regulated environments hinges on this volume being fixed. Other manufacturers offer more flexible options. Virtually all UHPLC systems are modular and can have different components (column switcher vs. single column, binary pump vs. quaternary pump, multiple detectors), and for some manufacturers, two systems may have the same components but be plumbed differently. All of these configurations have an effect on the system volume. Because some of the benefits of UHPLC are the speed of analysis, sharpness of the peaks, and retention of resolution, extra dead volume is undesirable, as it reduces these benefits. To ease method transfer problems, one must account for these types of differences. 

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