Rapid and Automated Analytical Methods for Redox Species Based on Potentiometric Flow Injection Analysis Using Potential Buffers

Figure 5

Schematic diagram for the simultaneous determination of Cr(VI) and Cr(III) and flow injection peaks of Cr(VI) ((A), (B)) for different reagent solutions and of Cr(III) (C). C.S: carrier stream (water); R.S.₁: reagent solution 1 (0.05 M H₂SO₄); R.S.₂: reagent solution 2 (2×10⁻⁴ M Ce(IV), 0.05 M H₂SO₄); R.S.₃: potential buffer solution (1×10⁻² M Fe(III)-Fe(II) 0.6 M NaBr, 3.6 M H₂SO₄); R.C.₁: reaction coil 1 (230 cm); R.C.₂: reaction coil 2 (75 cm); B: switching six-way valve.