Patent ID: 6969613

Claim:
A method for quantitatively determining hydrogen sulfide or sulfide ions which comprises (a) adding to a sample containing hydrogen sulfide or sulfide ions, (i) metal ions or a compound which liberates said metal ions and (ii) a metal indicator which reacts with the metal ions and resultantly undergoes a color development, the color development being accelerated or inhibited by the hydrogen sulfide or sulfide ions, wherein complexes are formed by the reaction of the metal ions and the metal indicator, and (b) measuring the degree of color development of the metal indicator by determining the amount of the formed complexes and subtracting from said amount the amount of formed complexes when the metal ions are reacted with the metal indicator when no hydrogen sulfide or sulfide ions are present, whereby a decreased amount of the formed complexes indicates an inhibition of color development and corresponds to the amount of the hydrogen sulfide or sulfide ions present in the sample, or an increased amount of formed complexes indicates an acceleration of color development and corresponds to the amount of the hydrogen sulfide or sulfide ions present in the sample.