Absorption measurements were collected on a СФ 46 “LOMO” spectrophotometer or КФК-3 photoelectrocolourymeter using 1 cm cells. The pH-meter EV-74 is used for pH measurements.

Stock solution of 1.52 × 10⁻² M manganese (II) was prepared from MnCl₂∙4H₂O salt with qualification “p.f.a.” (pure for analysis) and quantity of manganese standardized gravimetrically with o-phenantroline and SCN− [6] . Working solution of 4.5 × 10⁻⁴ M manganese (II) was prepared by dilution of stock solution with deionized water. Solution of AlR with 5 × 10⁻³ M concentration was prepared by dissolving the required amount in water, while pH of this water was arrived to 12, preliminarily. Because, pK₁ = 2.65 and pK₂ = 11.78 for AlR [7] . Solution of BPhen with 6.0 × 10⁻³ M concentration was prepared by dissolving the required amount of preparate which was productioned in the University of Lvovby order of “Soyuzreaktiv” in ethanol: water (50:50, by volume). Universal or borate buffer solutions (H₃BO₃ + HCl, H₃BO₃ + NaOH) or 0.1 M CH3COOH and 1NNaOH solutions were used for obtaining appropriate pH.

Suitable amount of solutions of BPhen and AlR have been added to the definite amount of solution of manganese (II) in test-tube with stoppers or in separatory funnel. Then all out of volume have been diluted to 10 ml by adding of various (pH 5.0 - 11.0) buffer solution. The mixture has been trembled for a minute with adding of 5 ml solvent (chloroform). Then colored extract has been transferred to the cells, when the phases separated and absorbance has been measured relative to the water. The same experiment has been carried out without manganese and absorbance of the extract of reagent has been measured also relative to the water.

The absorption spectra of AlR and complex of manganese with BPhen and AlR obtained in the pH range 5.5 - 11.0 of the aqueous phase showed that manganese (II) with BPhen and AlR forms a complex one composition. The absorption spectra of solutions of reagent and the complex show that the maximum absorbance takes place at pH 8.3 (Figure 1) and wavelengths of 390 and 370 nm, respectively in extract and reagent have been selected for the present work (Figure 2).

The influence of the concentration of BPhen and AlR was studied. The optimal concentration of BPhen and AlR for formation of the complex was found to be 9.0 × 10⁻⁵ M and 4.5 × 10⁻⁴ M, respectively. Extra quantity of reagents doesn’t affect the formation and extraction of the complex. As, the carboxyl group of the chromogenic organic reagent in the condition of complexing is ionized and charged form is preferably in the aqueous phase. The heteroligand complex of manganese (II) with BPhen and AlR was extracted with chloroform and 1,2-dichloroethane. Optimal volume of aqueous and organic phase was found to be 25 - 50 and 5 ml, respectively. Mn-BPhen-AlR complex is formed immediately after adding the reagents and extraction equilibrium is achieved by trembling 1 minute. The sequence of reagents to be added does not influence the complex formation and extraction. The intensity of color of the complex does not change depending on time and stable during the day.

The stoichiometric coefficients of the complexing were established. The molar ratio Mn:BPhen:AlR was proved by the method of shear equilibrium and crossing the lines [8] . The results for the light absorption of the extracts at 390 nm showed that the complex was formed at a ratio Mn:BPhen:AlR = 1:2:2. By the method of V. A. Nazarenko [9] was established that the complexing form of manganese are the ions Mn²⁺. The same amount of complex two times was extracted consistently and extraction percentage was found: 99.00%.

Extraction percentage was established by two ways. In once the same amount of complex consistently two times was extracted with chloroform, respectively for each time 5 ml. And in the second way again the same experiment carried out, but 5 and 7 ml chloroform was used, respectively for first and second extraction process. Both of measurements carried out under the optimum condition. Results were calculated with equations below, accordingly for first and second way.

E % = ( Δ A 1 − Δ A 2 ) ⋅ 100 % Δ A 1 E % = V 1 ( Δ A 1 − Δ A 2 ) ⋅ 100 % Δ A 2 ( V 2 − V 1 )

Here, E%-extraction percentage, DA₁ and DA₂―extracts absorption, V₁ and V₂―extracts volume.

Extraction constant was found as K_ext =8.32 × 10¹⁴ [10] , stability constant was found as lgβ_K = 7.2 ± 0.1 by the method of intersection of curves [8] . For this purpose was used equation below, which latest was used for building of graphical dependency lgb_k = f(n).

lg β k = C k ( C M n − C k ) ( C R − n C k ) n

Here, C_Mn, C_k, C_R―the concentration of manganese, complex and chromogenic reagent, respectively. n = 1, 2, 3.

By the method of Komar [8] was found molar absorptivity is ε = (2.27 ± 0.08) × 10⁴ l∙g⁻¹∙cm⁻¹. By repeating the experiment with different amounts of manganese, a calibration curve is prepared. Beer’s law is obeyed in the range of 0.5 - 23.0 µkg manganese (II). Equation of the calibration curve was based to be A = 0.042C + 0.06. Calibration curve are presented in Figure 3.

The relative standard deviation for 5 determinations with 0.5 - 1.0 - 5.0 - 10.0 - 20.0 µkg of manganese (II) of the method is ±(1.50 - 1.98)%. The detection limit of manganese was found as 0.0020 µkg∙ml⁻¹. Statistical results are presented in Table 1 [11] .

In order to assess the usefulness of the proposed method the influence of strange ions on the extraction-photometric determination of manganese was studied. The tolerance of the method of foreign ions was investigated with

solutions containing 10 µkg Mn (II) per 25 ml and various amounts of foreign ions. Mn (II) was determined as Mn(BPhen)₂(AlR)₂ under the optimum conditions as described in the experimental procedure. The determination of manganese was possible in the presence of K (I), Li (I), Na (I), Sr (II), Ca (II), Ba (II), Cd (II), Hg (II), Al (III), Ti (IV), Zn (II), V (V), Mo (VI), Cr (III), Ni (II), Pb (II), As (V), Mg (II), Bi (III), In (III), Ge(IV). But Co (II), Zn (II), Cu (II), Fe (III), Ag (I) ions were influenced on the extraction-photometric determination of manganese (II).

2 g dried crushed eggplant mass was transferred to the flask with distilled water. For the oxidation of organic part was added concentrated sulfuric and nitric acid. Then was heated a little. The solution was heated in the 450˚C - 500˚C temperature during the 10 minute after the completely oxidation of the organic part. Chilled solution was transferred to a 50 ml flask by filtering, then was diluted with the distilled water to the mark. 2 ml aliquot part was transferred to the separatory funnel or test-tube. BPhen and AlR with optimal concentrations was added. Then was diluted by the buffer solution to 10 ml and was extracted with 5 ml chloroform for 1 minute. Absorbance was measured in СФ 46 in the cuvette of 1 cm when the phases separated. Amount of manganese was determined from the calibration graph. The results were compared with the results of the determination method of manganese with atom-absorption. Amount of manganese have been determined in eggplant by the proposed method: 173.0 ± 4.22 µg/kg. The proposed system yielded results that compare very well with standart methods. Comparison of methods of manganese is presented in Table 2.