Different analytical methods were applied to analyse the leachates obtained from leach tests on S/S industrial waste containing arsenic and the treated percolate water from a landfill. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine total As and other elements, hydride generation-ICP-MS for the determination of As(III) and capillary zone electrophoresis (CZE) for As(III) and As(V). Interferences and matrix effects were studied in detail and corrected for. For the leachates, no corrections were required, for treated percolate water with lower As concentrations, in the case of ICP-MS important corrections were necessary. Results for different types of leach tests (extraction, static and semi-dynamic) and for treated percolate waters are presented. (C) 2000 Elsevier Science Ltd. All rights reserved.