... sulfides react with N, N-diethyl-p-phenylenediamine to form a blue complex.The range of the determination: 0.02~0 ... tube, compare the shown color with colorimetric chart, come out a result.Note: SO32-, S2O32-, NO3-, SCN-, I-, Pd2+, Hg2+, Cu2 ... water) and domestic sewage usually contain sulfides, some of which are produced by decomposition of sulfur-containing organic compounds or sulfate reducing due ...