The United States Pharmacopeia (USP) specifies regulations for pharmaceutical manufacturing to ensure safe and effective drug products. USP <643> Total Organic Carbon (TOC) pertains to requirements for testing pharmaceutical-grade water for TOC. TOC is an important quality attribute that contributes to understanding water quality before use in critical applications and is central to process control and patient safety. Therefore, stringent testing requirements for TOC are enforced by regulatory bodies around the world.