The Japan Society for Analytical Chemistry carried out a seventh proficiency testing for the determination of dioxins (polychlorodibenzo-p-dioxins, polychlorodibenzofurans and dioxin-like polychlorobiphenyls) in marine sediment. This proficiency testing of analytical laboratories was based on ISO/IEC Guide 43-1, "Proficiency testing by interlaboratory comparisons" The testing was carried out from September '05 to January '06, with the participation of 96 laboratories. As a result, 83 laboratories (86.4%) were estimated as "satisfactory", 9 laboratories (9.4%) as "questionable" and 4 laboratories (4.2%) as "unsatisfactory".
