Gold number

Gold number is the term introduced by  Zsigmondy, which is used to  describe the protective power of different lyophilic colloids. It is expressed as the minimum mass (in milligrams) of stabilizing agent (in the form of dry material) which prevents the 10ml red gold sol against coagulation by the addition of 1ml of 10% NaCl solution.
Here, the coagulation is indicated by color change from red to blue/violet gold sol which occur when particle size increases.
  • More is the gold number, the protective power of lyophilic colloid become less.

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