Bis(1-​ethyl-2-methylpropyl) Phthalate-d4, is the labeled analogue of Bis(1-​ethyl-​2-​methylpropyl) Phthalate (B433950), a phthalic acid ester (PAEs), widely used in many consumable products with potential carcinogenic properties. It can also be used for the studies on the reactions of O2-· with alkyl and aryl esters of benzenedicarboxylic acids.