Keyword Definition

Colorimetry using dithiol

The term “dithiol” is most generally applied to any compound having two “thiol” groups.  In geochemical literature, dithiol is also used as a synonym for toluene-3,4-dithiol.

A thiol is an organosulphur compound that contains a carbon-bonded sulfhydryl (–C–SH or R–SH) group (where R represents an alkane, alkene, or other carbon-containing group of atoms). Thiols are the sulphur analogue of alcohols (that is, sulphur takes the place of oxygen in the hydroxyl group of an alcohol).  Thiols are often referred to as mercaptans. The term mercaptan is derived from the Latin mercurium captans (capturing mercury) because the thiolate group bonds so strongly with mercury compounds.

Toluene-3,4-dithiol, CH3C6H3(SH)2, is easily oxidized, and is more conveniently used as its derivative, zinc dithiol, CH3C6H3S2Zn, which is much more stable in the solid state.  The coloured complexes of molybdenum and tungsten are extractable by a variety of organic solvents, giving yellow-green and blue-green solutions, respectively.

Quinoxaline-2,3-dithiol, C8H6N2S2, has also been used as a colorimetric reagent.


  • Wikipedia, <thiol>, May 2014
  • Stanton, R.E. (1966). Rapid methods of trace analysis for geochemical applications.
  • Skoog, D.A., Lai, M.-G., Furst, A. (1958). Quinoxaline-2,3-dithiol as Colorimetric Reagent. Determination of Nickel in Ammoniacal Solutions. Analytical Chemistry, vol 30, issue 3, p365–368


Hierarchical classification

Technique >> Photometry >> Fluorometry >> Dithiol



Category: Analytical techniques

The different kinds of analytical techniques have been classified hierarchically. Examples: “AAS”, “FA-NA”. Taken from the “Analytical_Techniques_SHARED” database table.

Associated Analytical Suites:

IndexSuite IDSuite Name
1  582     GSC colorimetry: Mo, W

Associated Analytical Packages:

IndexPackage IDPackage Name
1  272     GSC spectrography and colorimetry
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