N-[4-(Acetylamino)benzoyl-d4]-β-alanine is the labeled analogue of N-[4-(Acetylamino)benzoyl]-β-alanine (A168130), an impurity of Balsalazide (B116300), an anti-inflammatory drug that is used to treat patients with ulcerative colitis and also as chemoprevention of colon cancer carcinogenesis.