Analyser with bio-sensor for determining on=line specific components of samples in bio-food technology or environmental protection

The analyser with a biosensor has a hose or volume loop (3) which is respectively connected between a pair of corresp. 3/2 way solenoid valves (1,2). These valves are simultaneously controlled electronically together, so that the vol. loop is either connected between the output (E1) and the output (A1), or between the input (E2) and the output (A2). The loop is alternately filled with a liquid using a pump. Their contents after a complete filling is dosed with compressed air into a mixing vessel, by a simultaneous changeover of the two associated 3/2 way valves. One vol. loop is fed with a sample and at least one further loop with the diluting reagent. The vol. ratio of the two loops is so selected, that it allows a stepped dilution line, in which the vol. loops are filled independently from each other and are emptied at different frequencies in a mixing vessel. After the ending of the dosing cycle the sensor is exposed to the sample, with the concn. determined by the dilution achieved in the mixing vessel.