Flow injection apparatus for carrying out chemical analyses

摘要

In a flow injection analysis apparatus, the flow of reagent to a measuring apparatus is generated by means of a peristaltic pump. A sample liquid which is contained in a loop of tubing is introduced into the flow of reagent by a change-over valve with the loop being connected in a conduit of a carrier liquid. The measuring apparatus measures the reaction between sample liquid and reagent. The peristaltic pumps are driven by stepper motors. The stepper motors are controlled by control electronics such that nonuniformities of the delivery of the peristaltic pumps caused by geometry are compensated by inverse nonuniformities of the angular rates. For that purpose the frequencies of the switching pulses are varied depending on position sensors.