HPTLC offers a unique advantage of evaluating colored zones in daylight without any special equipment. Substances with absorption at 254 nm can be visualized on plates with fluorescence indicator F254 by exposure to short-wave UV light (254 nm). The fluorescence of some substances can be excited by long-wave UV light (350 nm, broadband). Substances with or without chromophore can be derivatized for improved detectability.
With a suitable device (e.g., documentation system, digital camera, smartphone), electronic images can be captured of the chromatogram in different detection modes. With suitable software, these images comply with cGMP and can be evaluated against the descriptions provided (e.g., by pharmacopoeias or other standards). Furthermore, electronic images are the basis for “Comprehensive HPTLC Fingerprinting”.
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