A FLOW-ANALYSIS SYSTEM WITH AN AMPEROMETRIC DETECTOR FOR THE DETERMINATION OF HYDROGEN-SULFIDE IN WATERS

A flow analysis system with an amperometric H2S detector and a gas ext raction unit as well as an integrated coulometric calibration unit is described, which allows an on-line determination of hydrogen sulphide in aquatic samples. By variation of different parameters (e.g. flow ra te, gas injection volume, pH of solution) a wide dynamic working range of concentrations from 1 mu mol/l H2S to 750 mu mol/l is accessible. The sampling rate is about 36 samples h(-1) using an average flow rate of 1.78 ml/min and a gas injection volume of 28 mu l. The measuring s ystem is designed as a portable device. In combination with the polyet hylene-tube of a PTFE-underwater pump field-measurements on board are possible.