The determination of the Total Dissolved Sulphide Amount (TDSA) by means of the H2S micro-sensor is one of the most interesting parameters for the water analysis. The increase of the TDSA shows that the sample is oxygen-free which may lead to problems for all oxygen breathing organisms. AMT GmbH has focussed the activities to offer H2S microsensors in combination with pH and temperature sensors in order to determine the TDSA within a pH-range of 0-8.5. The sensors are offered in the following versions: