1. Department of Chemistry, Umeå University, S-901 87 Umeå, Sweden
2. Department of Biochemistry & Molecular Biology and VILLUM Center for Bioanalytical Sciences, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
3. Faculty of Health and Society, Department of Biomedical Science, Malmö University, S-205 06 Malmö, Sweden