Description: RuBPS (Ruthenium(tris(bathophenanthrolinedisulfonate), tetrasodium salt) is a negatively-charged water-soluble luminescent ruthenium complex. The complex can be efficiently excited by either UV light or visible light in the wavelength range from 400 nm to 500 nm with bright red emission centered around 605 nm. Ruthenium complexes such as RuBPS typically have luminescence lifetimes in the micro second range and a Stokes shift over 100 nm. By using time-resolved luminescence measurement, the combination of long luminescent lifetime and large Stokes shift offers the possibility for extremely sensitive detection that could approach the sensitivity of radioactive detection. Among many potential applications, RuBPS could be used as a polar tracer similar to Lucifer Yellow and FluoroGold.