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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Karakth on July 26, 2005, 06:41:07 AM

Title: The presence of Nitrogen or Sulphur in an organic compound.
Post by: Karakth on July 26, 2005, 06:41:07 AM: Hi all,

I wasn't quite sure if I was to post this in the Organic Chemistry section or here, but I finally decided it was analytical in nature.

My question(s) are:

1. How do you identify chemically the presence of Nitrogen in an organic compound?
2, How do you identify chemically the presence of Sulphur in an organic compound?

Any help would be appreciated, I've got a feeling it involves methods that have long become obsolete thanks to Mass Spectrometry.
Title: Re:The presence of Nitrogen or Sulphur in an organic compound.
Post by: Borek on July 26, 2005, 08:06:50 AM: Quote from: Karakth on July 26, 2005, 06:41:07 AM
1. How do you identify chemically the presence of Nitrogen in an organic compound?
2, How do you identify chemically the presence of Sulphur in an organic compound?

Classic procedure will be to melt sample with sodium and throw hot testglass into water. Filtrate is then tested for CN^- (addition of Fe²⁺ gives Prussian blue) and sulfides (PbS precipitation). In both cases you must maintain correct pH. Procedures are described in Vogel's Textbook of Practical Organic Chemistry.
Title: Re:The presence of Nitrogen or Sulphur in an organic compound.
Post by: Karakth on July 26, 2005, 10:06:42 AM: Ah yes, the Carius method.

Thank you for your help.
Title: Re:The presence of Nitrogen or Sulphur in an organic compound.
Post by: Dude on July 26, 2005, 10:35:26 AM: From an industrial perspective, sulfur and nitrogen are usually detected via chemiluminescence (0.2 ppm DL). The organic sample is combusted- converting nitrogen and sulfur compounds to their oxides-which are then spectroscopically measured for sulfur dioxide and nitrogen dioxide content (N actually takes two steps). Antek is one of the more well-known manufacturers of the sulfur and nitrogen detectors.
Title: Re:The presence of Nitrogen or Sulphur in an organic compound.
Post by: sdekivit on July 26, 2005, 12:32:50 PM: when u combust a nitrogencontaining molecule, you get nitrous gases which are yellow/brown, so that's a good indication for nitrogen :)
Title: Re:The presence of Nitrogen or Sulphur in an organic compound.
Post by: oldddog on August 12, 2005, 04:27:01 AM: I seem to remember using FTIR to determine the various components/chemical bonds in an organic compound - of course it helps if its to be pure.