spectrophotometric

Spectrophotometric refers to spectrophotometry, a quantitative analytical technique that measures how much light a sample absorbs as a function of wavelength. The method is commonly used to determine the concentration of a solute in solution by applying the relationship between absorbance, light path length, and molar absorptivity, often summarized by the Beer-Lambert law.

In a typical spectrophotometer, light from a source passes through a monochromator to select a wavelength, then through a sample held in a cuvette, and finally to a detector. The instrument records the incident light intensity (I0) and the transmitted light intensity (I), from which transmittance (T = I/I0) and absorbance (A = -log10 T) are derived. In the UV–visible range, which spans roughly 200 to 800 nanometers, absorbance spectra provide information about the electronic transitions of molecules and can be used for both identification and quantification. Infrared and other spectrophotometric techniques extend these principles to different energy scales for various applications.

Procedurally, measurements are typically performed with a blank to establish a baseline, followed by standards to construct a calibration curve. Once validated, this curve enables determination of unknown concentrations in samples.

Applications span many fields, including pharmaceutical analysis, clinical chemistry, environmental monitoring, food and beverage quality control, and materials science. Advantages of spectrophotometric methods include speed, simplicity, and cost-effectiveness, while limitations can arise from sample color, turbidity, scattering, and the need for careful calibration and appropriate solvents or cuvettes.