Ternary complexes of vanadium(IV) with 4-(2-pyridylazo)-resorcinol (PAR) and ditetrazolium chlorides (DTC)

Phenylmethoxybis(tetrazolium) ion-association complexes with an anionic indium(III) — 4-(2-pyridylazo)resorcinol chelate

Complex formation and liquid-liquid extraction were studied in systems containing indium(III), 4-(2-pyridylazo)resorcinol (PAR), phenylmethoxybis(tetrazolium) salt (MBT), water and chloroform. The following MBTs, which differ only by the number of -NO2 groups in their cationic parts, were used: 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis(2,5-diphenyl-2H-tetrazolium chloride) (Blue Tetrazolium chloride, BT), 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis[2-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride] (Nitro Blue Tetrazolium chloride, NBT) and 3,3′-(3,3′-dimetoxy-4,4′-biphenylene)bis[2,5-di(4-nitrophenyl)-2H-tetrazolium chloride] (Tetranitro Blue Tetrazolium chloride, TNBT). The composition of the formed ternary complexes was determined, In:PAR:MBT=1:2:2, and the optimum conditions for their extraction found: pH, shaking time, concentration of the reagents and the sequence of their addition. Some key constants were estimated: constants of extraction (Kex), constants of association (β) and constants of distribution (KD). BT appears to be the best MBT for extraction of the In(III)-PAR species, [In3+(OH)3(PAR)2]4−, (Log Kex=10.9, Log β=9.8, Log KD=1.12, R%=92.7%). Several additional characteristics concerning its application as extraction-spectrophotometric reagent were calculated: limit of detection (LOD = 0.12 µg cm−3), limit of quantification (LOD = 0.40 µg cm−3) and Sandell’s sensitivity (SS =1.58 ng cm−2); Beer’s law is obeyed for In(III) concentrations up to 3.2 µg mL−1 with a molar absorptivity coefficient of 7.3×104 L mol−1 cm−1 at λmax=515 nm.

Extraction-spectrophotometric investigations on two ternary ion-association complexes of gallium(III)

Complex formation and liquid-liquid extraction were studied in systems containing Ga(III), azoderivative of resorcinol {4-(2-pyridylazo)resorcinol (PAR) or 4-(2-thiazolylazo)resorcinol (TAR)}, 2,3,5-triphenyltetrazolium chloride (TTC), water and chloroform. The optimum conditions w.r.t. pH, extraction time, concentration of ADR and concentration of TTC for the extraction of Ga(III) as an ion-associate complex were found.. The composition of the extracted complexes, (TT+)[Ga(PAR)2] (I), (TT+)[Ga(TAR)2] (II) or (TT+)2[Ga(OH)(TAR)2] (III), and the constants of association (β) between 2,3,5-triphenyltetrazolium cation (TT+) with corresponding anionic chelates were established by several methods. The constants of distribution (KD) and extraction (Kex) of the principal species I and III were determined as well. The apparent molar absorptivities of the chloroform extract at the optimum extraction-spectrophotometric conditions were ɛ′510=9.5×104 L mol−1 cm−1 (I) and ɛ′530=4.6×104 L mol−1 cm−1 (III). The validity of Beer’s law was checked and analytical characteristics that were calculated are reported herein.

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

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 (Kex), constants of association (β), constants of distribution (KD) and recovery factors (R%) were determined. The apparent molar absorptivities in chloroform were calculated to be ɛ′520=6.6×104 L mol−1 cm−1 and ɛ′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−1I and LOD=0.12 µg mL−1II), limits of quantification (LOQ=0.24 µg mL−1I and LOQ=0.41 µg mL−1II) and Sandell’s sensitivities (SS) were estimated as well.