Mono-(8-carboxy-5-methyloctyl) Phthalate-d4 is labelled Mono-(8-carboxy-5-methyloctyl) Phthalate (M525610) which is an isomer of Monocarboxyisodecyl Phthalate (M525575), a metabolite of Dibutyl phthalate (DBP) (D429495) which is widely used in consumer products.