piperazine diethanesulfonic acid

pi·per·a·zine di·eth·ane·sul·fon·ic ac·id (PIPES),

(pī-per'ă-zēn dī-eth'ān-sŭl-fon'ik as'id), One of several aminosulfonic acids (for example, HEPES) used in biologic buffers; active range, 6.0-8.5.