The complexation of gallium with 2-hydroxy-5-T-butylphenol-4'-methoxyazobenzene (HR) has been studied by atomic absorption and spectrophotometric methods. The optimal conditions for the formation and extraction of the complex were found. The maximum light absorption of the complex in n-butanol is in the range of 450-470 nm. The molar absorption coefficient is (3.3-4.2)⋅10 4. The stability constant of the gallium coordination compound in n-butanol is β l = 4.2⋅10 10. The developed technique allows to determine the gallium content within n × 10 −1-n × 10 −4 %. The selective and sensitive technique for the extraction-atomic absorption determination of gallium in soils has been developed.

This study deals spectrophotometric analysis of the multi-ligand complex of zirconium (IV) with stilbazole and cetylpyridinium chloride. Dichloroethane was selected as the extragent and acetonitrile as the dispersant solution. Optimal conditions for the complex formation were identified. The results of the extraction process and complex formation were calculated statistically withPlackett Burman design and central composite design (via the Minitab 19 program). The values obtained showed that experimental results can be expressed as statistical results. Most important factors influencing absorption during complex formation were pH and ligand content. To obtain the maximum absorption, pH should be 4.5 and the ligand content should be 300 µL. The stoichiometric composition of the components in the complex was determined by various methods. The interval of subordination to Baer's law was 2-7.6 μg mL-1 , the molar light absorption coefficient was 2.6 × 104 L Mol-1 cm -1 , λmax = 590nm. A highly selective methodology was developed to determine the zirconium (IV) micronutrients in water samples.

The coordination compound of gallium (III) with stillbazo-stillbene-4,4'-bis [(1-azo)3,4-dihydroxybenzene]-2,2'-disulfonic acid has been investigated by spectrophotometric method in the presence of cetyl pyridinium chloride (CPC) as surface active compound. It has been determined that the mixed ligand complexes were formed with the ratio of 1:2:4 in CPC-mediated phase. The molar coefficient and the stability constant of the complex compound β к = 6.8 × 10 9 , ε к = 66,834 have been studied by various spectrophotometric methods. The effect of pH, time, temperature, concentration of the reagents and CPC on formation of the unmixed and mixed ligand coordination compounds has been also studied. It has been determined that the Beer's law is respected within 0.008-10 µg of Ga(III) in 25 mL solution. The technique of the photometric determination of gallium in natural compositive objects and industrial objects has been developed.

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