Continuous-flow analysis: the Auto-Analyzer

An increase in the work-load of clinical and analytical chemistry laboratories in the 1940s resulted in a drive towards automation. The repetitive nature of analyses, with the associated tedium, provided further incentive toward developing automated systems. To these ends, Skeggs conceived Continuous-Flow analysis (CFA), introduced commercially by the Technicon Instruments Corporation in 1957 in the form of an automated system under the name 'Auto-Analyzer' [1 and 2]. The term 'continuous flow' refers to the flow of liquid continually pumped through the system while it is being analysed for particular components. Samples, standards, and reagents are injected into this stream at regular intervals and a report is generated only after all injections have been made. In some cases a run may consist of as many as 120 injections. The first CFA systems were modular in design and were used for large-volume tests such as serum glucose and blood-urea-nitrogen levels. A typical system used by the pharmaceutical industry is shown in figure 1. Simpler systems use a peristaltic pump to pass samples and reagents through a temperature-controlled reaction coil and into a colorimetric detector.