1. Brooks Rand Instruments, Seattle, WA, USA
2. Brooks Applied Labs, Bothell, WA, USA
3. P S Analytical Ltd., Orpington, UK
4. U.S. Geological Survey, Middleton, WI, USA
5. Jožef Stefan Institute, Ljubljana, Slovenia
6. Southeast Laboratory, San Francisco PUC, San Francisco, CA, USA
7. Chemistry Section, Environment Canada PYLET, North Vancouver, BC, Canada
8. Department of Biology, University of North Carolina at Greensboro, Greensboro, NC, USA
9. Norwegian Institute for Water Research (NIVA), Oslo, Norway