Ultraviolet-visible spectrophotometry liquid chromatography detection

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. 

UV—visible spectrophotometry is a convenient detection methodology for liquid chromatography in the clinical laboratory because of the low cost and reliability of the detector and because many small molecules of interest in the clinical laboratory absorb ultraviolet light. Absorbance is one of the least sensitive detection modalities, however, so some low-abimdance drug and hormone analytes can be difficult to detect. 

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