This is because it is now recognised that the toxicity of many elements depends not on the total amount of metal present but rather on the specific toxic species present. Different species of the same element may have different oxidation states and exhibit different behaviour or potential for toxicity within environmental and biological systems [1]. In the case of chromium (Cr), the two most environmentally important oxidation states are Cr(III) and Cr(VI), where Cr(VI) has a greater water solubility and potential for toxicity [2]. Environmental contamination by chromium chiefly results from industrial processes such as electroplating, paint production, leather tanneries and metallurgy [2–4]. Since chromium toxicity is species-specific, determining the total chromium concentration in environmental samples is insufficient for a toxicity assessment of chromium.