Determination of Cr(VI) using an ion selective electrode with SLMs containing Aliquat336.

An ion selective electrode (ISE) for the measurement of Cr(VI), using supported liquid membranes (SLMs), containing tricaprylmethyl ammonium chloride (Aliquat336), was investigated in this study. Aliquat336, as a carrier, had a high selectivity for Cr(VI) in the presence of interfering ions, in the order SO4(2-) > CO3(2-) > Cl(-) > NO2(-) > NO3(-) > I(-) > SCN(-). The composition of the SLM for the detection of Cr(VI) was optimized at 0.169 mL Aliquat336 mL(-1) NPOE (o-nitrophenyl octyl ether) 0.5 g Poly (vinyl chloride), for the preparation of a 19.6 cm2 sheet. The Cr(VI) concentrations were measured, using the SLM prepared in the study, in the range 2.023 x 10(-5) to 0.1 M (1.052 to 5200 ppm). It seemed that the Cr(VI) was transported as a negatively charged monovalent ion, as indicated by the slope of the electromotive force (emt) response. The selectivity coefficients and detection limits for the Cr(VI). against the interfering ions, were determined experimentally using the fixed interference (FIM) and the separate solution methods (SSM).