The hydrogen peroxide (H2O2) monitor AL2021 has an extraordinary high sensitivity and a unique low detection limit of <100ppt (parts per trillion) for gaseous samples and <100 ng/liter (eq. 3×10-9 molar) for liquid samples, respectively. The complete chemical processing, including gas stripping, is integrated into the instrument. The measurement process is fully automated, all necessary reagents are provided by a digitally controlled high precision peristaltic pump. The standard dual-channel instrument AL2021 provides absolute concentrations for H2O2 and relative concentrations for all other peroxides. There is a special single-channel version (AL2021SC) for decontamination control and drinking water quality monitoring.