Speciative determination of Cr (III) and Cr (VI) in dyeing waste water of Dil Creek discharge to Izmit Gulf (Izmit-Kocaeli, Turkey) by ICP-AES. 
Wastewater pollution in industrial areas is one of the most important environmental problems.  Heavy metal pollution, especially chromium pollution in wastewater sources from dyeing and tannery has affected the life on earth.  This pollution can affect all ecosystems and human health directly or by food chain.  Therefore, the determination of chromium in this study is of great importance.  Dil Creek is located in the eastern Marmara region and discharges into the Izmit Gulf.  This water source is used for irrigation in agriculture and as drinking water for animals.  In this study, a rapid, sensitive and selective method for the speciative direct determination of Cr (III) and Cr (VI) in dyeing waste water samples collected from the nearest station to Izmit Gulf of Dil Creek in May 2006 by inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been developed.  An analysis of a given sample is completed in about 15 min for ICP-AES the method.  As the result of the chromium analysis, the limit of quantification (LOQ) for the Cr (III), Cr (VI) and total Cr were founded as 0.0111 +/- 0.0002 mg/l (RSD, 1.80%), 0.0592 +/- 0.0010 mg/l (RSD, 1.70%) and 0.0703 +/- 0.0020 mg/l (RSD, 2.84%) respectively.  In addition, the general mathematical formula has been developed to calculate the concentration of Cr(III), which can be applied to any other metal species.  The result of Cr (VI) analysis indicated that water quality of Creek was IV.  class quality according to the inland water classification.  In order to validate the applied method, recovery studies were performed.