Abstract: Achemiluminescenee method for in-line monitor of Cr(Ⅵ) and Cr(Ⅲ) in environmental water is proposed.The method is based on Cr(Ⅲ)-H₂O₂-luminoIchemiluminescence system.To determine Cr(Ⅲ) in sample, an anion-exchange column is used.Cr(Ⅲ) that passes through the column can be determined selectively by Cr(Ⅲ)-H₂O₂-luminol system.Cr(Ⅵ) can not be determined directly by this system because it can not react with H₂O₂ and luminol in alkaline medium.In order to determine Cr (Ⅵ), an cation-exchange column is used to separate Cr (Ⅵ) from Cr (Ⅲ) in sample.Cr (Ⅵ) that passes through the column is reduced into Cr(Ⅲ) by acidic H₂O₂ in the flow and determined subsequently with Cr(Ⅲ)-H₂O₂-luminol system in alkaline medium.By rotating the selecting-valve, Cr(Ⅲ) and Cr(Ⅵ) in sample can be determined alternatively.The method offers potential advantages of simplicity, selectivity and applicability to the determination of Cr(Ⅲ) and Cr(Ⅵ) in environmental water.The detection limit of the method is 4×10^-11 g/mL Cr.The linear range is 10^-5-10^-10g/mL Cr.

Key words: Chromium(Ⅵ), Chromium(Ⅲ), Chemiluminescence analysis, Monitor in time