Dear Mustapha,

do you want to determine the H2S in the gaseous phase or in the aqueous solution?

In the gaseous phase I prefer an electrochemical detector, which is specially made for wastwater odors. For the examination of the precipitated ferric aducts you destillate the develloped H2S under acidic terms, oxidize it with H2O2 and detect it as sulfate with IC or conventional other methods.

Thank you very much Mr Ingo Schreiber,

I want to determine H2S in aqueous solution ( S2- precipitated by ferric ions ) with a conventional methods. I ask you to send me the procedure to measure the H2S.

Dear Mustapha,

ferric will react with the sulfide to form ferrous and sulfur.You can use ferrous or copper as described by Ralf Cord Ruwisch in A quick method for the determination of dissolved

and precipitated sulfides in cultures of sulfate-reducing

bacteria Jourtial of Microbiological Methock 4 (1985) 33-36

Jan Weijma

here is a paper publised long time ago: An Amperometric Microsensor for the Determination of H2S in Aquatic Environments, Anal. Chem., 1996, 68 (24), pp 4351–4357 DOI: 10.1021/ac960091b

You can determine by passing the gas through Hydrogen peroxide and then titration with standard alkali or absorbing the gas in alkali and titration with standard iodine solution. You can also determine the gas by instrumental methods like GC and FTIR

Iodimetric method is available in standard book to analyze sulfide ions.

If you are looking for residual (unreacted) H2S in solution, just filter the suspension and carryout an iodometric titration. The procedure is available in: Standard Methods for the Examination of Water and Wastewater, 20th Edition, 1998 Pub: American Public Health Association, American Water Works Association and American Environment Federation (Eds L S Clesceri, A E Greenberg and A D Eaton), p4-167.