#SPEC METHOD MAP READING FULL#
In addition to the Quantitative Analysis, measuring the full UV/Vis absorption spectra allows substance identification. More precisely, the position and, to some extent, the profile of the absorption peaks allow specific compounds to be identified.įigure 2. To calculate the concentration:Ĭ =The sample concentration in mol / L or g / mL, D = Cuvette path length in cm Ε = (epsilon) sample specific constant (describing how much the sample absorbs at a given wavelength) Qualitative Analysis The calculation of concentration is governed by the Lambert-Beer Law. The advantage of this representation is obvious the height of the absorption peaks is directly proportional to the concentration of the species. In general, a UV/VIS spectrum is graphically represented as absorbance as a function of wavelength. An important derived (calculated) variable also reported by the instrument is the Absorbance which is defined as A = −log(Transmittance).įigure 1.
This instrument measures Transmittance which is the ratio of the transmitted intensity I to the original intensity of light. The main components of a UV/VIS spectrophotometer are a light source, a sample holder, a dispersive device to separate the different wavelengths of the light and a suitable detector. This article more specifically explores techniques when using a spectrophotometer to determine concentration of an analyte.Ī UV/VIS spectrophotometer measures the intensity of light passing through a sample solution in a cuvette, and compares it to the intensity of the light before it passes through the sample. Moreover, the amount of absorbed light is related to the amount of sample, and thus, quantitative analysis is possible by optical spectroscopy. Depending on the amount of light and its wavelength absorbed by the sample, valuable information can be obtained, such as the purity of the sample. UV/VIS spectroscopy is based on the absorption of light by a sample. Ultraviolet and visible light range (UV/VIS) is widely applied in research, production and quality control for the classification and study of substances.