n-Pentyl 3-Methyl-2-pentyl Phthalate-d4, is the labeled form of n-Pentyl 3-Methyl-2-pentyl Phthalate (P283625), a phthalate ester, which are ubiquitous environmental contaminants that interact with peroxisome proliferator-activated receptors (PPARs), a family of nuclear receptors. It is used as a plasticizer to impart softness and flexibility to PVC products.