Ternary ion-association complexes between the indium(III) - 4-(2-pyridylazo)resorcinol anionic chelate and some tetrazolium cations Research Article

Complex formation and liquid-liquid extraction were studied in systems containing indium(III), 4-(2-pyridylazo)resorcinol (PAR), tetrazolium salt (TZS), water and chloroform. Two different TZS were used: 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT). The optimum conditions for extraction of In(III) as a ternary complex, (TT+)[In(PAR) 2 ] or (MTT+)[In(PAR) 2 ], were found: pH, extraction time, concentration of PAR and concentration of TZS. The constants of extraction (K ex ), constants of association (β), constants of distribution (K D ) and recovery factors (R%) were determined. The apparent molar absorptivities in chloroform were calculated to be e’ 520 =6.6×104 L mol–1 cm–1 and e’ 515 =7.1×104 L mol–1 cm–1 for the systems with TTC (I) and MTT (II), respectively. Beer’s law was obeyed for In(III) concentrations up to 3.4 μg mL-1 in both the cases. The limits of detection (LOD=0.07 μg mL-1 I and LOD=0.12 μg mL-1 II), limits of quantification (LOQ=0.24 μg mL-1 I and LOQ=0.41 μg mL-1 II) and Sandell’s sensitivities (SS) were estimated as well.