This chapter explains the technology and chemistry behind the AxSYM^® random-access analyzer for the quantitative determination of a broad range of analytes. The system consists of an automated analyzer, reagent packs, disposable test reaction vessels and generic reagents. Samples may be loaded at any time and urgent requests can be run in Stat mode. The immunoassays have a range of chemistries: microparticle capture, radiative energy attenuation, enzyme immunoassay, ion capture immunoassay, homogeneous and heterogeneous formats, and competitive and immunometric assay designs. The analyser can run one- and two-step assay protocols. The features, designs and principles are explained. There are also sections on calibration, antibodies, separation, signal generation and detection, and data processing, including interfacing to laboratory information systems.

This chapter was written for the second edition by Theresa Donahue, previously at Abbott Diagnostics and subsequently Program Director, Growth Technologies, Ethicon Ltd., New Jersey, USA. The chapter was reviewed and revised for the fourth edition by Frank Quinn and David Wild.

AxSYM^®, fluorescence polarization, microparticle capture, enzyme immunoassay, ion capture immunoassay, radiative energy attenuation, random-access, homogeneous, competitive, immunometric, calibration, antibodies, separation, signal generation, signal detection, Stat test.