Conduct investigations and/or process data to determine the concentration of coloured species and/or metal ions in aqueous solution


  • Technique in analytical and physical chemistry used to determine the concentration of coloured compounds in solution by measuring its absorbance of light of a specific wavelength and on the principles of Beer-Lambert Law.
  • To measure the concentration, a device called colorimeter is used.
  • Based on a two-step comparison process:
    • An initial reading with only the sample being present in the colorimeter
    • Sample reading after the reaction between sample and reagents

Ultraviolet – visible spectrophotometry

  • Measurement of declination of a beam of light in the visible or adjacent region after it passes through a sample or after reflection from a sample surface.
  • Commonly used technique in analytical chemistry for quantitative determination of transition metal ions, highly conjugated organic compounds and biological macromolecules.
  • One of the best methods to detect impurities in organic substances.

 Atomic absorption spectroscopy

  • Technique of quantitative analysis where atoms in free state absorb optical radiation (light) and emits a measurable signal.
  • It is quite a sensitive technique and can measure up to parts per billion of a gram in a sample.
  • Widely used in soil testing, forensics, environmental studies, quality assurance in food industry etc.