Titanium (Ti) is the first element in Group IVB in the periodic table. It has an atomic number of 22, an atomic weight of 47.88, and valences of 2, 3, and 4. The average abundance of Ti in the earth’s crust is 0.6%; in soils it is 1700 to 6600 ppm; in streams it is 3 μg/L, and in groundwaters it is <0.1 mg/L. The element is commonly associated with iron minerals. Titanium is used in alloys for aircraft, marine, and food-handling equipment. Compounds of the metal are used in pigments and as a reducing agent.
Titanium species are usually insoluble in natural waters, with the Ti4+ species being the most common ion when found. Some compounds are toxic by ingestion and the pure metal is flammable.
Either of the flame atomic absorption spectrometric methods (Section 3111 D or E) may be used. The inductively coupled plasma mass spectrometric method (Section 3125) also may be applied successfully in most cases (with lower detection limits), even though titanium is not specifically listed as an analyte in the method.