What is Residue on Ignition (ROI)?
Residue on Ignition (ROI) is a widely used analytical method to determine the amount of inorganic impurities in a material. It is commonly applied in pharmaceutical, chemical, and food-related industries where material purity is critical. In simple terms, ROI measures the non-combustible residue remaining after a sample is subjected to high-temperature ignition. Why ROI Matters Residue on Ignition is widely used for: Pharmaceutical quality control (e.g., USP <281>) Raw material purity evaluation Contamination monitoring Process consistency verification It provides a reliable indicator of total inorganic residue, even though it does not identify specific components. The Principle: Loss on Ignition ROI is based on gravimetric analysis , also known as loss-on-ignition . When a sample is heated in a muffle furnace (typically 500°C–800°C ): Organic substances decompose and volatilize Carbon-based materials are burned off Inorganic residues remain as ash The remaining residue re...