This chapter describes the principle of ambient analyte immunoassay, which has unique characteristics, with potential benefits for future immunoassays. This format senses the analyte concentration and does not require accurate dispensing of the sample.

Professor Roger Ekins recently retired from his position as Head of University College London Molecular Endocrinology, and in 2012 received the UK Department of Health’s Lifetime Achievement Award, presented at UCL. Professor Ekins, a physicist, is internationally recognized for conceptualizing radioimmunoassay and related ligand assay methods in the 1950s, and for his insight into immunoassay physicochemistry. His first publication in this field was in 1960, relating to the assay of serum thyroid hormones. Subsequently he innovated in the field of free hormone assay in the 1970s and in the 1980s he invented the ambient analyte immunoassay concept. He has received many awards for his work in this area, including the prestigious Edwin F. Ullman award in 1998. His theoretical understanding and innovation permeates many of the chapters in The Immunoassay Handbook. David Wild’s first exposure to immunoassay was at one of Professor Ekins’ lectures at the University of London.

Ambient analyte immunoassay, microspot assay, compact disk assay, microarray, free hormone immunoassay.