With the help of an internal H2S converter , the Serinus 51 H2S/SO2 instruments can integrate seamlessly into continuous monitoring networks. They can sequentially measure H2S and then SO2. This sequencing can be turned off and continuous measurement of the two units becomes available. Serinus 51 LR involves two cycles. H2S is measured by passing the sample through an internal SO2 scrubber removing the SO2; the H2S is then converted to SO2 by using internal converter and measure with the fluoresence technique. The SO2 concentration is then measured using the flourescence technique by bypassing the SO2 scrubber and converter. This range of analysers has been designed using Ecotech's knowledge and experience of producing large air quality monitoring networks.