A Typical Schematic Diagram Of Uv 4h236k

A typical schematic diagram of uv-vis instrument will have 5 important components which consist of; light source, monochromator, sample and reference cuvette, detector, and signal processor and readout (UV-Visible Absorption Spectroscopy, 2017). The straightforward instrument started from where the ultraviolet (uv) and visible radiation act as light sources which provides a combination of tungsten and hydrogen-deuterium lamps, covering the range from 200 to about 800 nm. From the RSC (2009) notes, a beam of light from the light source will be separated based on its component’s colour of wavelengths by monochromator.

As shown in figure above, monochromator is composed of prisms, slits and diffraction grating. Diffraction grafting plays the same role as the prism, but more efficient. The separated beam reflected from the grafting will be selected by the slit and further divided by the half-mirrored prism into two beam. As for the sample, it will be held in an optical flat, transparent container called cell or cuvette. One of the beam will es through the sample solution, and the other one will es through the

reference solution. The intensities of the beam through both cuvette will be measured by the electronic detectors and compared. The intensity of the reference beam is defined as I0, while for the sample beam is known as I. if I is found less than I0, it means that the sample has absorbed some of the light. The absorbance of the sample shows how it obeys the Beer’s Law, which state that the absorbance is proportional to the concentration of the substance in the solution as a result of uv-vis spectroscopy. It can be expressed by: 𝐴𝑏𝑠𝑜𝑟𝑏𝑎𝑛𝑐𝑒, 𝐴 = log10

𝐼0 𝐼

Based on the equation from a series of sample absorbance, a graph of absorbance versus concentration plotted should linear if it obeys the law. Also, the absorbance can be measured in range from 0 to 1. At 0 absorbance, no light of the wavelength has been absorbed, hence the ratio is 1 and the absorbance, A will be 0. This can happened vice versa when the absorbance of is 90%. (Jim C., 2007)

UV-Visible Absorption Spectroscopy. (2017). Www2.chemistry.msu.edu. Retrieved 1 October 2017, from https://www2.chemistry.msu.edu/faculty/reusch/virttxtjml/spectrpy/uv-vis/uvspec.htm

Ultraviolet-Visible Spectroscopy (UV). (2009). Royal Society of Chemistry. Retrieved from https://edisciplinas.usp.br/pluginfile.php/1695367/mod_resource/content/1/UVVis_Student%20resource%20pack_ENGLISH.pdf

Jim, C. (2007). Double beam UV-visible absorption spectrometer. Chemguide.co.uk. Retrieved 1 October 2017, from http://www.chemguide.co.uk/analysis/uvvisible/spectrometer.html#top