UV-Vis Spectrophotometer

The Uv-Vis spectrophotometer is used to analyze phosphate in sediments through the interaction between light/rays at specific wavelengths and material in the form of molecules or atoms.

Light/rays can be visible (visible), ultraviolet (not visible) and infrared light, while matter can be molecules or atoms with valence electrons.

Light emitted from a source is also called electromagnetic radiation. The interaction between light or electromagnetic radiation and matter can occur through emission, absorption and scattering, so it is commonly known as emission spectroscopy, absence spectroscopy and scattering spectroscopy. The UV-Vis spectrophotometer uses absorption interactions.

Simply put, a UV-Vis spectrophotometer consists of:
1. Light source, in the form of polychromatic light from a Tungsten/Wolfram lamp in the Visible region (400-800 nm) and a Deuterium lamp in the Ultraviolet region (0-400 nm) (3).

2. Monochromator to select to select the wavelength.

3. Cuvette / sample cell as sample holder. It has a rectangular shape 1 cm wide, has a straight and parallel optical surface, is transparent, does not react to chemicals, is not easy to be brittle, and has a simple but solid shape.

4. A detector to capture light passing through the sample.

5. Readout, which is a system that picks up electrical signals coming from the detector and outputs them in the form of transmission or absorption numbers that are displayed on the device’s display.

UV-Vis spectroscopy is an analytical technique used to measure the absorption or emission of ultraviolet (UV) and visible light (Vis) by a sample. This method is very useful in several fields, including chemistry, biology, and materials science, for determining the amount of substances in solutions, studying reaction kinetics, and identification of compounds.

Basic Principles

UV-Vis spectrophotometry works on the principle that molecules can absorb light at certain wavelengths, which causes the transition of electrons from the ground state to the excited state. The wavelength of light absorbed depends on the structure of the molecule and its chemical environment.