IDENTIFICATION AND QUANTIFICATION OF AN UNKNOWN PEAK IN RESIDUAL SOLVENT ANALYSIS BY GC USING RELATIVE RESPONSE FACTOR

摘要

Organic solvents are integral part of chemical synthesis in pharmaceutical industry. These are commonly used as reaction media, in separation, purification of synthetic products and also for cleaning of equipment. Some of the solvents degrade to other solvents or unknown impurity either during synthesis or in analytical conditions. In this study, we have investigated formation of a trace level impurity, its identification and quantitation by successfully applying the concept of relative response factor (RRF) in GC-HS. The trace level impurity was identified as dimethyl ether (DME), formed due to interaction of strong acid and methanol. Unavailability of its commercial standard made the quantitation in drug substance challenging using gas chromatography. In this work, we have extended the concept of RRF for determination of DME in drug substances. The RRF of DME was established against other process solvents used in method of analysis. Application of RRF in quantitation of DME eliminates the requirement of its external standards during routine analysis at quality control laboratories