Bentonite-based functional material as preconcentration system for determination of chromium species in water by flow injection analysis technique

Chromium species have different level of toxicities. For example, Cr(VI) is 100 times more toxic than Cr(III). This characteristic makes speciation analysis of chromium become important. This research will discuss about a development of a Flow Injection Analysis-Atomic Absorption Spectrometry (FIA-AAS) technique that utilizes bentonite based functional material as a retention column. The separation, preconcentration and trace analysis of the Cr species in the water has been successfully performed using a Bt-MCCs mini-column in the FIA-AAS system. Analytical performance of the developed method is described as repeatability, linearity, and detection limit. Analytical performance for Cr(III) are 1.78 %, correlation coefficient 0.9975 for the concentration range of 50-600 mu g.L-1, and 2.76 mu g.L-1, respectively. Whereas, analytical performance for Cr(VI) are 0.60 %, correlation coefficient 0.9926 for concentration range of 50-600 mu g.L-1, and 2.42 mu g.L-1, respectively. This limit detection is better than the other selective method that has been reported using AAS as detector and the concentration range can be widened with this limit detection. Evaluation of FIA performance for both of Cr(III) and Cr(VI)is that it has an enrichment factor of 10 times higher, it has a concentration efficiency of 12 h(-1) and it has a consumptive index of 12 mL. The analysis that was obtained in Cidurian River, West Java, Indonesia are 38.28 g.L-1 for Cr(III) and 26.73 g.L-1 for Cr(VI), while the accuracy are 98.84 % for Cr(III), and 100.73 % for Cr(VI).