Actual problems of modern science, education and training

Determination of the ratio of constituent moles of a complex compound.

In the determination of the ratio of moles of the components of a complex compound by the isomolar series method, selected solutions of the organic reagent AB with lead
(II) ion immobilized are used.
Determination method: starting from 0.2000 g of PPD-1 chlorinated fibers selected for each reagent in separate cups, variable volumes of lead (II) ion solution (from 1.0 ml to 10, 0 ml and variable amounts of AB solution (from 1.0 ml to 10.0 ml) in 5 ml of universal buffer solution (pH=3.0-6.0) were added and sorbed for 4-5 min. Before and after immobilization the optical densities measured against the reference solution are presented in Table 1 and Figures 5.
Table 1

Determination of the ratio of moles of complex compounds by the method

of isomolar series

^PPD-1, САB^=1·10-5^М, λмах^=490, l=1, t=10^min
VR, ml	1,0	2,0	3,0	4,0	5,0	6,0	7,0	8,0	9,0
Vml Pb2+	9,0	8,0	7,0	6,0	5,0	4,0	3,0	2,0	1,0
^APb2+	0,002	0,025	0,12	0,33	0,5	0,35	0,25	0,15	0,015

Figure 5. IMR:Me2+ ratio according to the isomolar series method. (for

PPD-1 fiber)
The ratio between organic reagent and metal ions was proved to be 1:1 when immobilized amido black organic reagent was tested with lead(II) ion by isomolar series method.

FT/IB-UATR spectroscopy

Analysis of the FT/IR-UATR spectra of the ligand and the complex (Figure 6) highlights the following aspects: Amido black reagent: the absorption region at 3414 cm^-1 is characteristic of the -OH group in the aromatic ring, the main amino group - NH₂ is in the absorption region at 3058 cm^-1 will appear. The -N=N- group in the free ligand creates an absorption frequency in the region of 1487 cm^-1. The frequencies in
the 1455 cm^-1, 755-859 cm^-1 absorption areas of the aromatic group held by the - OH group were evident. Absorption in 1606 cm^-1, 935-912 cm^-1 regions was observed in the main ligand -C=C- in 2 or 3 substituted compounds in the ligand sample. -SO₂- O-R groups with 2 sulfonatium in the aromatic ring have absorption areas at 1283-1170 cm^-1 and -O-Na bonds at 538 cm^-1. The main changes were observed in the absorption areas of 1455 - 1330 сm^-1, 859- 755 сm^-1, 643 сm^-1, 538 сm^-1.
Fiber: In the PPD-1 fiber IR-spectra, the absorption line of -СH acrylic groups in the absorption region of 2242 cm^-1 is visible, the absorption lines in the region of 3345 cm^-1 correspond to the valence and deformation vibrations of the -N-H group. Area changes at 3000-3400 cm^-1, i.e. expansion, indicate the presence of hydrated water molecules in the polymer, absorption lines at 1560 cm^-1 belong to deformational vibrations of the NH group, and absorption lines at 1662 cm^-1 belong to valence vibrations of C=N- bonds. The R-NH₂⁺-R group in the fiber produced an absorption line in the region of 2927 cm^-1.
During the immobilization of the organic reagent AB on PPD fiber, a change in the R-NH₂⁺-R group absorption area from 2927 cm^-1 to 2946 cm^-1 area was observed, and an increase in the >C=N-H group from 1662 cm^-1 area to 1678 cm^-1 area was observed. The immobilized organic reagent AB showed changes in the absorption areas of the aromatic group 2 sulfonatrium -SO₂-O-R groups at 1283 - 1170 cm^-1 and -O-Na bonds at 538 cm^-1 (Fig. 5).


%T
4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0
cm-1
Figure 6. IR spectra of Amido black 10B (1), reagent immobilized on fiber (2), synthetic fiber (3).
The IR spectrum of the complex formed by the lead (II) ion with the organic reagent AB immobilized on the PPD fiber shows a broadening of the 3471 cm^-1 area and a change in the absorption area of the -N=N- group at 1487 cm^-1 due to the -OH group of the organic reagent and -N=N- indicates that the lead (II) ion forms a complex with groups. -O-Pb metal oxygen bond was observed in the absorption region of 415 cm^-1 (Figure 6) [20].

Figure 7. Reagent immobilized on fiber (1) and its complex with lead (2), IR

spectra.
The difference between the color intensity of the immobilized reagent and the complex was higher at 600-830 nm, increasing the stability and saturation through complexation. Based on these analyses, the method of sorption-spectroscopic determination of lead (II) ion in artificial mixtures using the amido black reagent immobilized on synthetic fiber was tested (Table 2).
Table 2 Results of determination of lead (II) ion in artificial mixtures using IMAB
organic reagent
[λ=490 nm, pH=4-6, P=0,95; n=5]

Composition of the analyzed mixture, µg	Found Pb^2+, mkg ^̅Х ± ∆^̅Х	S	^Sr
Pb(10)+Cd(2,0)	9,95 ± 0,18	0,160	0,016
Pb(20)+Co(5,0)+Ni(5,0)	19,89 ± 0,22	0,188	0,009
Pb(20)+Fe(10,0)+Ni(10,0)	19,87 ± 0,23	0,199	0,010
Pb(20)+Cd(20,0)+Mn(5,0)+Cu(10,0)	19,82 ± 0,36	0,316	0,016
Pb(25)+Cu(20,0)+Mn(10,0)+Fe(15,0)	24,91 ± 0,25	0,217	0,009
Pb(40)+Cr(50,0)+Hg(1,0)+Cd(30,0)	39,83 ± 0,24	0,205	0,005
Pb(50)+Ni(30,0)+Cu(1,5)+Zn(10,0)+Cd(5,0)	49,84 ± 0,19	0,163	0,003

As can be seen from Table 2, the developed sorption-spectroscopic detection method was used to detect lead (II) ion in binary, ternary and complex model mixtures, the relative standard deviation (Sr) does not exceed 0.016, which indicates the accuracy and reproducibility of the developed method.