Aalborg Universitet Quality improvement in determination of chemical oxygen demand in samples considered difficult to analyze, through participation in proficiency-testing schemes Raposo, Francisco; Fernández-Cegrí, V.; De la Rubia, M.A.; Beltrán, J.; Cavinato, C.; Clinckspoor, M.; Demirer, G.; Diamadopoulos, E.; Frigon, J.C.; Koubova, J.; Launay, M.; Méndez, R.; Menin, G.; Noguerol, J.; Uellendahl, Hinrich; West, S. Published in: Trends in Analytical Chemistry Publication date: 2010 Document Version Early version, also known as pre-print Link to publication from Aalborg University Citation for published version (APA): Raposo, F., Fernández-Cegrí, V., De la Rubia, M. A., Beltrán, J., Cavinato, C., Clinckspoor, M., Demirer, G., Diamadopoulos, E., Frigon, J. C., Koubova, J., Launay, M., Méndez, R., Menin, G., Noguerol, J., Uellendahl, H., & West, S. (2010). Quality improvement in determination of chemical oxygen demand in samples considered difficult to analyze, through participation in proficiency-testing schemes. Trends in Analytical Chemistry, 29(9), 1082-1091. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. ? Users may download and print one copy of any publication from the public portal for the purpose of private study or research. ? You may not further distribute the material or use it for any profit-making activity or commercial gain ? You may freely distribute the URL identifying the publication in the public portal ?