Chromium usually occurs in the (III) or (VI) oxidation state. Cr(III) is essential for mammalian systems to influence maintain several metabolic pathways. In contrast. Cr(YI) exerts toxic influence on biological systems and is strongly canccrogcnic. Cr(Vl) compounds arc usually highly soluble, mobile and bioavailable compared to sparingly soluble trivalent chromium compounds. Chromium is most often analysed using instrumental methods such as AAS or ICP. These methods are precise and sensitive but make determination of only total chromium. Possible content of Cr(VI) is estimated from the difference of total chromium content and Cr(III), which is analysed using photometric methods. This so-called "difference method" makes the calculated concentration of Cr(VI) is inaccurate. This paper describes sensitive and selective determination of Cr(VI) in various waters at ug/dnr' levels using a simple ion chromatography system with UV detector.

Disinfection of drinking water is usually carried out by chlorination process. This is a well known, effective technology, which has many advantages. however during this process dangerous for health byproducts, such as trihalornethanes as well as chlorate, chlorite and bromale arc formed. Another disinfection process. which has emerged as the most promising alternative to chlorination technique, is ozonation. In spite of undeniable advantages. there are certain undefined hazards resulting from this method of water treatment. It is especially due to formation of carcinogen bromale anions in bromide containing waters. Determination of bromale as well as other inorganic oxyhalides is usually carried out by ion chromatography with conductivity detection. The detection sensitivity can be improved by using alternative hyphenated techniques such as IC-ICPMS or IS-MS-MS. These techniques are very sensitive, but are highly sophisticated and the instrumentation is very expensive. "Post-column reactions". i.e. derivative techniques coupled with ion chromatography are a relatively cheap and good alternative. This paper is a review or the newest achievements in analytical techniques used for determination of inorganic oxyhalides by-products formed during various drinking water disinfection processes.