Methylphenidate is a medication used to combat attention-deficit/hyperactivity disorder by speeding up brain activity. Methylphenidate has two chiral centers; however, d-threo-methylphenidate is responsible for its effects. Few studies have analyzed methylphenidate and its metabolites, ritalinic acid and ethylphenidate, in blood. Stability studies are crucial in a forensic setting to provide insight on ideal storage conditions and analysis time. In this study, d,l-methylphenidate,…