A dishwasher sanitation cycle includes sampling a temperature of rinse water inside a dishwasher, executing a heating cycle to keep water temperature at optimal levels, and executing a heat sum cycle to ensure that dishes are sanitized according to accepted standards. Said high purity trithiodipropionic acid is comprised of polythiodipropionic acids containing at least 80 weight percent trithiodipropionic acid based upon said polythiodipropionic acids. The retention member is radially movable within the lumen of the biological unit removal tool.