Phar Organic Lab: Spectrophotometry

What is a Spectrophotometer?

• A spectrophotometer measures the amount of light absorbed by a sample.
• It is used to measure the concentration of solutes in solution by measuring the amount of light absorbed by the solution in a cuvette.

Spectrophotometry

• Spectrophotometry is a method to measure how much a chemical substance absorbs light by measuring the intensity of light as a beam of light passes through a sample solution.
• Each compound absorbs or transmits light over a certain range of wavelength.
• This measurement can also be used to measure the amount of a known chemical substance.

Spectrometer

• A spectrometer produces a desired range of wavelength of light.
• It consists of:
  • A collimator (lens) that transmits a straight beam of light (photons).
  • A monochromator (prism) that splits the light into several component wavelengths (spectrum).
  • A wavelength selector (slit) that transmits only the desired wavelengths.

Applications of Spectrophotometers

• Spectrophotometry is one of the most useful methods of quantitative analysis in various fields, including:
  • Chemistry
  • Physics
  • Biochemistry
  • Material and chemical engineering
  • Clinical applications

Types of Spectrophotometers

• Visible spectrophotometers
• UV/Visible spectrophotometers
• NIR (Near-Infrared) spectrophotometers
• NMR (Nuclear Magnetic Resonance) spectrophotometers
• Atomic Absorption Spectrophotometers

Using a Spectrophotometer in Lab

• A spectrophotometer is used in lab to measure the concentration of solutes in solution.
• A standard curve is plotted to determine the unknown concentration of a sample.
• A standard curve is a plot of absorbance vs. concentration of a known substance.