ABSTRACT
Cobalt is considered an essential element in trace amounts for humans and other mammals as it is an integral component of the vitamin B12 complex (Smith and Carson, 1981). Cobalt in this form is obtained from microorganisms or from animal sources (USEPA, 2005). It is a naturally occurring element, widely distributed in rocks, soils, vegetation, and water (Gál et al., 2008). This element usually is found in association with nickel and appears in two oxidation states (Co2+ and Co3+), Co3+ being, except in certain complexes, thermodynamically unstable under typical oxidation-reduction and pH conditions (Palit et al., 1994; Nagpal, 2004).
