GC–MS method for the quantification of potential genotoxic thionyl chloride impurity in Teneligliptin drug substance

The compounds with poor volatility and thermal stability, and injector interaction can end up with non-reproducible peaks and shapes. Using the GC–MS technique, this research succeeded with the conversion of potentially genotoxic thionyl chloride into diethyl sulfite by treating it with ethanol. The derivatization procedure was optimized with excellent accuracy and precision on the silica column (coated with 6% cyanopropylphenyl and 94% polydimethylsiloxane ZB-624, 60 m × 0.25 mm × 1.4 μm) through selective ion monitoring (SIM) mode. The detection and quantification limits of thionyl chloride (as diethyl sulfite) were 0.50 and 1.50 ppm, respectively. The method was linear (1.5 to 56 ppm) with a correlation coefficient of 0.998 and the average drug substance recovery was 108 %. The established method was verified as linear, precise, and specific, and applicable for the low-level detection and quantification of thionyl chloride in Teneligliptin and other gliptins.