Ruthenium (Ru) is the fourth element in Group VIII in the periodic table. It has an atomic number of 44, an atomic weight of 101.07, and valences of 1 through 7, the most common being 2, 3, and 4. The average abundance of Ru in the earth’s crust is probably <0.01 ppm, and in groundwaters it is <0.1 mg/L. It occurs in its native state in platinum-bearing river sands. It is used in jewelry with platinum, in electrical contacts, and as a catalyst.
The aqueous chemistry in natural waters is relatively unknown. Ruthenium has no known toxic effects.
For analysis see flame atomic absorption method (Section 3111 B). The inductively coupled plasma mass spectrometric method (Section 3125) also may be applied successfully in most cases (with lower detection levels), even though ruthenium is not specifically listed as an analyte in the method.