Visible UV Spectrophotometer and Its Use at the Indonesian Colorimeter Laboratory

UV Visible Spectrophotometer is an instrument used to measure the intensity of light before and after passing a sample - the ratio of one to another is called transmittance and is expressed as a percentage. From transmittance, absorbance can be calculated.

While spectrophotometers are most commonly used in the UV spectrum region and are visible, there are also instruments operating in the near-infrared region.

The bottom of the spectrophotometer is a light source, sample holder, diffraction grating or monochromator (used to separate light from wavelengths) and detectors. The radiation source is usually a deuterium lamp, which provides continuous light over the ultraviolet region. Recently, light-emitting diodes (LEDs) and Xenon lamps have begun to be used for visible wavelengths. The detector is usually in the form of a photodiode or CCD. Photodiodes are used with visible UV calorimeter indonesia spectrophotometers that use monochromators, while diffraction gratings are used with CCDs, which collect light from different wavelengths on different pixels.

UV Visible spectrophotometers are routinely used in quantitative determination of transition metal ion solutions and high conjugated organic compounds. Because electrons in metal atoms can be attracted from one electronic state to another, this solution can be colored; color is affected by the presence of certain anions or ligands. The color of the aqueous solution of copper sulfate, for example is light blue. Adding ammonia intensifies the color and changes the wavelength of the maximum absorption of the solution.

Organic compounds also absorb light in the UV and visible areas of the electromagnetic spectrum. The solvent for this determination by visible UV spectrophotometer is water for water-soluble compounds or ethanol for organic soluble compounds. Organic solvents may have significant UV absorption, but this does not mean that these solvents are universally suitable for use in any application involving UV light spectrophotometer, especially because ethanol absorbs very badly at most wavelengths.

Solvent polarity and pH can also affect the absorption spectrum of organic compounds. The Beer-Lambert Law states that the absorbance of a solution is directly proportional to the concentration of species that absorb in solution and the length of the path. As a result, for a fixed path length, visible UV spectrophotometers can be used to determine absorber concentrations in a solution. It is important to know how quickly absorbance changes with concentration. This can be ascertained from the molar extinction coefficient reference table or from the calibration curve.

UV light spectrophotometers can be used as detectors for high performance liquid chromatography (HPLC). The presence of analytes gives a response that can be assumed to be proportional to concentration. Regional spectrophotometry is seen widely used in colorimeter science. Ink manufacturers, printing companies, textile suppliers and many other companies need data provided by UV light spectrophotometers. This data can be used to test a collection of new dyes to determine whether they meet specifications such as ISO printing standards.

Traditional Visible UV Spectrophotometer cannot detect whether the dye or base material has fluorescence. In terms of ink, this can make it difficult to manage color problems if one of the printing inks becomes fluorescent - if the given dye is fluorescent, a bi-spectral fluorescent spectrophotometer can be used instead.