UPS, or 3-S-Isothiuronium-propylsulfonate, is a white powder with a molecular weight of 198.26 and an assay of ≥ 99.0% (by HPLC, dried basis). It is highly soluble in water, forming a clear and complete solution at 4% concentration. With a loss on drying (LOD) of ≤ 1.0% at 140°C for 30 minutes, UPS is used in electroless plating applications.

SPS, or Bis-(3-sulfopropyl) disulfide disodium salt, is a white to yellowish powder with a molecular weight of 354.4. It has an assay of ≥ 95.0% (by HPLC, dried basis) and a moisture content of ≤ 1.0%. With a turbidity of ≤ 10 NTU, SPS is used primarily in copper plating applications.