Introduction to UV-VIS
UV-VIS spectroscopy is routinely used in analytical chemistry for the quantitative determination of different analytes in solution. In Particle Analytical, concentration determinations by UV-VIS spectroscopy is used for solubility and dissolution/IDR measurements.
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Instrument and measuring principles
UV-VIS is used in analytical chemistry for the quantitative determination of different analytes containing π-electrons or non-bonding electrons (n-electrons), These bonds absorb the energy in the form of ultraviolet or visible light to excite these electrons to higher anti-bonding molecular orbitals.
The Beer-Lambert law states that the absorbance of a solution is directly proportional to the concentration of the absorbing species in the solution and the path length. Thus, for a fixed path length, UV/VIS spectroscopy can be used to determine the concentration of the absorber in a solution. It is necessary to know the absorbance changes with concentration. For well-known samples this can be taken from references (tables of molar extinction coefficients), or more accurately, determined from a calibration curve.
|Measuring range||Absorbance up to 2|
|Concentration range||Depends on the extinction coefficient of the compound. Usually < 0.1 mg/ml|