Flame ionization detection residual solvent

Fig. 19.6. Gas chromatogram of a residual solvent mixture, detected by flame ionization detection (FID). The peak top labels and retention times identify components.

API-related organic impurities usually involves high performance liquid chromatography (HPLC)-based analytical methods, with relatively non-specific detection techniques such as Ultraviolet/Visible (UV/Vis) Spectrophotometry. Residual solvents analysis usually involves gas chromatography (GC)-based analytical methods, again with relatively non-specific detection techniques such as flame ionization (FID). GC-based methods are most appropriate for volatile analytes such as residual solvents, whereas HPLC-based methods are more appropriate for the relatively non-volatile and polar API-related analytes. 

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