The Cu2FeTi3S8 and Cu2FeZr3S8 compounds: Crystal structure and electroanalytical application

The Cu2FeTi3S8 and Cu2FeZr3S8 compounds were produced by solid-state synthesis. The crystal structure of the quaternary phases was investigated by X-ray powder method. The compounds are described in the thiospinel structure (space group Fd 3 ¯ m) with the unit cell parameters a = 1.00099(1) nm (Cu2FeTi3S8) and a = 1.03837(2) nm (Cu2FeZr3S8). The atomic parameters were calculated in the isotropic approximation (RI = 0.0496 and RI = 0.0422 for Cu2FeTi3S8 and Cu2FeZr3S8, respectively). Iron(III)-selective electrodes were prepared using the chalcogenide compounds Cu2FeTi3S8 and Cu2FeZr3S8. The electrode function slopes are 52.7 mV/pC for Cu2FeTi3S8 and 66.2 mV/pC for Cu2FeZr3S8, the detection limits are 1 × 10−5 M and 2 × 10−5 M respectively. The prepared electrochemical sensors are not sensitive to Cd2+, Zn2+, Mn2+, Ni2+, Co2+, Mg2+, Cr3+, and Fe2+ ions, and were tested in the potentiometric titration of Fe(III) with EDTA solution.