The Lead Acetate paper detects the presence of sulfur. The strip works best when wet (when testing for sulfur gas – the gas absorbs into the wet paper) or dipped into a test solution. The sulfur will form a black precipitate with the lead, lead sulfide. In dilute solutions, the paper may turn grey, and not black. The detection limit in solution is 5 ppm.

When testing gas, there are several keys…

  • The paper must be moist to facilitate absorption of the Sulfide gas and formation of sulfide ions that would then react with the lead on the paper.
  • The paper cannot be “too wet”.  The Lead Acetate impregnated in the paper is not “bound” to the paper and can be washed away if the paper “wetted” with too much water.
  • The intensity of the reaction of the moist lead acetate paper and sulfide gas will depend on how much gas is getting exposed to the paper and how long the moist test paper is exposed to the gas.  The more intense the gas and the longer the exposure, the better the detection.