A stationary mains electricity (AC-powered) laboratory instrument intended to be used for the qualitative and/or quantitative in vitro determination of chemical and/or biological markers in a clinical specimen. The instrument detects fluorescent markers that result from an immunological reaction between the reagents and the specimen, and typically includes an autosampler, reagent dispenser, light source, filter or monochromator, a fluorescent detection system (fluorometer or spectrofluorometer), data processing and/or data display software. The device operates with reduced technician involvement and automation of some, but not all, procedural steps.