Editing Thiol (section)

==Characterization==
Volatile thiols are easily and almost unerringly detected by their distinctive odor. Sulfur-specific analyzers for [[gas chromatograph]]s are useful. Spectroscopic indicators are the [[Heavy water|D<sub>2</sub>O]]-exchangeable S'''H''' signal in the [[Proton NMR|<sup>1</sup>H NMR spectrum]] ([[sulfur-33|<sup>33</sup>S]] is [[NMR]]-active but signals for divalent sulfur are very broad and of little utility<ref>{{cite web|url=http://www.pascal-man.com/periodic-table/sulfur.shtml|title=Sulfur-33 NMR references|first=Pascal P.|last=Man|website=www.pascal-man.com|access-date=3 May 2018|url-status=live|archive-url=https://web.archive.org/web/20170823184753/http://www.pascal-man.com/periodic-table/sulfur.shtml|archive-date=23 August 2017}}</ref>). The ''ν''<sub>SH</sub> band appears near 2400&nbsp;cm<sup>−1</sup> in the [[IR spectrum]].<ref name=Patai/> In the [[nitroprusside reaction]], free thiol groups react with [[sodium nitroprusside]] and [[ammonium hydroxide]] to give a red colour.