General scheme of an air-segmented analyser

Automatic air-segmented analysers are characterized by the use of one or several liquid streams (diluents, washing solutions, reagents) where the sequentially aspirated samples are introduced and spaced by means of air bubbles aimed at avoiding the undesirable carry-over [10-12]. 

Sampling system, which consists of a sample turntable and moving articulated aspiration probe, and differs very little from the generic designs described in Chapter 3. 

Propelling unit(s), aimed to move the analyser. They are generally peristaltic pumps, although their function can also be served by piston pumps and the pressure exerted by a gas or gravitational force. In short, they are meant to set and keep several streams In motion. The flow-rate of such streams should be regulatable and maintained as constant as possible, which is normally accomplished by using flexible tubes that withstand the mechanical pressure to which they are subjected. 

Heating system, usually consisting of thermostated baths or electrical wires wrapping the colls to favour the development of the analytical reaction. 

Continuous separation systems, optional elements such as dialysers, liquid-liquid extractors, sorption or ion-exchange columns, filters, etc. that can be placed before the reaction coils to remove potentially interfering species. 

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