This chapter explains the technology and chemistry behind the Elecsys^® random-access family of analyzers for the quantitative determination of a broad range of analytes. The system consists of a family of immunoassay analyzers and modules, which may be combined with clinical chemistry tests (such as tests for glucose and sodium) by linking analyzers. Samples may be loaded at any time and urgent requests can be run in Stat mode. The immunoassays are based on a paramagnetic particle solid phase, with unique electrochemiluminescent signal generation and detection chemistry. Assay designs may be competitive or immunometric. The analyzers can run one- and two-step assay protocols. The features of the different members of the analyzer family are listed, and the designs and principles 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 of The Immunoassay Handbook by Mary Beth Myers, who at the time was Director, Immunoassay Systems, Laboratory Systems, Roche Diagnostics Corporation, Indianapolis, USA. Roche Diagnostics was contacted on a number of occasions by the editorial team to request a revised version for the fourth edition but no replies were received. For the fourth edition this chapter has received minor revision by the editors using information available from the Roche website for their immunoassay product ranges, to correct any obsolete information.

Elecsys^®, microparticle, paramagnetic, electrode, chemiluminescence, electrochemiluminescence, biotin, streptavidin, random-access, homogeneous, competitive, immunometric, calibration, antibodies, separation, signal generation, signal detection, Stat test.