Official GC methods for RS determination

Ciurent official GC methods are described in USP XXIII under chapter 467 Organic volatile impurities . Fom methods (I, IV, V, VI) are mentioned. Methods I, V and VI are based on direct injection. They are suitable for water-soluble drugs and V for water insoluble drugs. Method IV describes the static headspace technique and is used for water soluble drugs. Method VI is very general and refers to the individual monograph which describes the chromatographic conditions (injection, colunm, conditions) which should be used. The main characteristics of these four methods are summarized in Table 16.2.2. 

The European Pharmacopoeia used a two-tiered process based on two different columns  

System A. Fused silica capillary or semi capillary coliunn (30 m x 0.32 mm (ID) or 30 m X 0.53 mm (ID)) DB 264 (1.8 pm or 3 pm film thickness of the phase (6 per cent cyanopropylphenyl-94 percent dimethylpolysiloxane)) which is identical to the USP method V. 

USP 467 Method I Direct GC injection Dissolved in water or another appropriate solvent External 30 m X 0.53 aim ID, fused silica, with 5 m crosdinked G27 stationary phase and A 5 m X 0.53 mm ID silica guard column, phenylmethy] siloxane deactivated FID  

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