An indicator for detecting residual ethylene oxide comprising a substrate impregnated with a solution of 4-(4-nitrobenzyl)pyridine and an envelope of the substrate which is at least partially transparent and has low permeability to gaseous ethylene oxide is provided, the envelope being preferably made...http://www.google.fr/patents/US4678640?utm_source=gb-gplus-shareBrevet US4678640 - Indicator for detecting residual ethylene oxide
