Topic overview

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Molecules absorb UV–Vis radiation when electrons undergo transitions between energy levels. Absorption depends on molecular structure: chromophores absorb, while auxochromes can alter the wavelength or intensity of absorption. For quantitative work, the Beer–Lambert relationship connects absorbance with concentration and path length within a linear range. Reliable measurements also depend on suitable cuvettes, baseline correction, and control of effects such as stray light. The lesson’s structure moves from electronic transitions and solvent effects to instrumentation, including light sources, monochromators, cells, and detectors. It then considers techniques for resolving overlapping signals, pharmaceutical applications, sensitivity, and validation parameters such as linearity, accuracy, precision, specificity, detection limits, and robustness.