spektrofotomeetrit

Spectrofotometri, or spectrophotometry in English, is a measurement technique that quantifies the intensity of light absorbed by a sample as a function of wavelength. A light source emits a beam that passes through the sample, and the transmitted light is detected by a photodetector. By comparing the transmitted intensity with that of a reference (usually a blank that contains the same medium but no absorbing species), the amount of light absorbed can be ascertained. The fundamental relation that links absorption to concentration is the Beer–Lambert law, A = εlc, where A is absorbance, ε is the molar absorptivity, l is the optical path length, and c is the concentration of the absorbing species.

Spectrophotometers operate across a wide spectral range. Ultraviolet–visible (UV–Vis) instruments cover wavelengths from about 200 to 800 nm and are commonly used to analyze biomolecules, transition metal complexes, and organic dyes. Infrared (IR) spectrophotometers probe vibrational transitions in the 4000 to 400 cm⁻¹ region and are essential for identifying functional groups in organic and inorganic compounds. More specialized instruments, such as near-infrared (NIR) or Fourier-transform spectrophotometers, extend the analytical capabilities to complex mixtures and solid-state samples.

The technique emerged in the late nineteenth century with the invention of the ultraviolet spectroscope and gained widespread adoption in the mid‑twentieth century when electronic photomultipliers and diode arrays improved sensitivity and speed. Today, spectrophotometry is integral to many scientific fields: chemistry, biochemistry, pharmaceuticals, environmental monitoring, and material science. It enables rapid determination of concentrations, assessment of reaction kinetics, monitoring of cellular metabolites, and detection of pollutants or contaminants in water and air. Because the measurements are non‑destructive and require minimal sample preparation, they remain a staple in both research laboratories and quality control facilities worldwide.