spektrifotometrit

Spektrifotometrit, or spectrophotometers, are analytical instruments that measure the intensity of light as a function of wavelength after it passes through a sample. They quantify how much light is absorbed or transmitted, enabling determination of sample concentration and optical properties. The measurements underpin many laboratory methods, from chemical analysis to environmental monitoring.

Most spectrophotometers use a broadband light source, a monochromator to select a precise wavelength, a sample holder, and a photodetector. The instrument can report absorbance (A) or transmittance (T) and can generate spectra across a wavelength range. Modern devices may feature a diode-array detector or a CCD to record many wavelengths simultaneously.

Two common configurations are single-beam and double-beam designs. In a double-beam instrument, light is alternately directed to a reference path and the sample, allowing compensation for source fluctuations. Scanning instruments move the monochromator across wavelengths, while diode-array or microplate readers produce rapid, parallel measurements.

Applications span chemistry, biology, medicine, and environmental science. They include determining concentrations via Beer-Lambert law, monitoring reaction kinetics, and assessing quality and purity. Calibration and performance criteria include wavelength accuracy, photometric accuracy, baseline correction, path length, and linearity.

Safety and maintenance are straightforward but essential: periodic calibration with known standards, regular cleaning of cuvettes, and instrument validation avoid drift. Innovations continue in miniaturization, integration with microplates, and handheld devices for field use.