Prochlorperazine (D8 dimaleate) is a deuterated isotopically labeled analog of the antipsychotic and antiemetic drug prochlorperazine. It is primarily used as an internal standard in analytical chemistry, particularly in mass spectrometry (LC-MS/MS) methods for quantifying prochlorperazine in pharmacokinetic, toxicological, or bioanalytical studies. This specialty chemical aids in accurate detection and measurement due to its similar chemical behavior but distinguishable mass. It appears as a white to yellow oil or waxy solid, conforms to structure by infrared spectrum and NMR, and has a purity of 97.5-100%.