Nanjing Chemical Material Corp.

Methyl iodide has been highlighted as a potential genotoxic impurity (PGI). A sensitive HS-GC method with ECD was developed and validated for the determination of methyl iodide impurity in Tedizolid phosphate, an active pharmaceutical ingredient. HS-GC method on DB-624,column 60m × 0.53mm, film thickness 3μm, with electron capture detector (ECD) was used. The proposed method was specific, linear, accurate, rugged and precise. The calibration curves showed good linearity over the concentration range of 0.78 μg/g to 11.7 μg/g and the correlation coefficient was 0.997. Method had very low limit of detection (LOD) and limits of quantification (LOQ) are 0.23 μg/g and 0.78 μg/g, respectively, with respect to test concentration. Accuracy was observed within the range 96.0% to 103.2%. This method is a further extended good quality control tool for low level quantitation of methyl iodide impurity in another API, alogliptin benzoate. Methyl iodide is such a special electrophile, however, that

254 g of potassium iodide dissolved in 125 ml of water are mixed with 100 g of ammonium sulfate dissolved in 125 ml of boiling water. After cooling, 40 ml of alcohol are added and the mixture is kept 12 hours. The obtained precipitate of potassium sulfate is filtered and the filtrate is evaporated occasionally adding ammonia water containing some alcohol, until crystallization begins. The crystals of potassium sulfate are additionally washed with dilute alcohol (20%), and after combining the filtrates and evaporation the ammonium iodide is obtained. Ammonium iodide crystallizes in cubes and deliquesces in the air. It should be preserved in a dark place, as light decomposes the salt, causing it to turn brown. This coloration may be removed by dissolving in distilled water, treating the solution with ammonium sulfide, filtering, and evaporating the filtrate on the steam bath, to crystallize. It is readily soluble in alcohol. The aqueous solution becomes yellow on standing, owing to

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