Method of determining composition of equilibrium solid phases in multi-component water-salt systems

FIELD: physical and chemical analysis.

SUBSTANCE: carried out by determining compositions of nonvariant solutions saturated with n-2 and n-1 salts, and calculating the component ratio using a straight-line equation, the coordinates of borders of nonvariant areas of isohydric sections in (n-1)- and apexes in n-component systems are determined experimentally without separating the equilibrium phases, and compositions of equilibrium solid phases are determined by identifying the intersection point of two limit nodes predetermined by the compositions of the corresponding nonvariant solutions and borders or apexes of novariant areas.

EFFECT: decrease in labour consumption and increase in determination reliability.

3 ex, 12 tbl, 6 dwg

 

The technical field

The invention relates to the field of chemistry, namely the use of the method of physico-chemical analysis to determine the composition of the equilibrium solid phases in the study of solubility in multicomponent water-salt systems.

The level of technology

Well-known classical methods of determining the composition of the equilibrium solid phases in the study of solubility in ternary systems, such as the remnants of Schreinemakers [Anosov VA) S.A. the Basic principles of physical and chemical analysis. M; Leningrad: Izd-vo an SSSR, 1947.; Anosov VA, Ozerov M.I., Violet Y.A. Basis of physico-chemical analysis. M.: Nauka, 1976.], method of sections Marcelina [Nikolashin NI, Merlin RV Method of sections, its application to the study of the state of multicomponent multiphase systems. Saratov: Publishing house of Kuratowski. University, 1969]; the material balance Method [Fedotov P.P. Collection of research papers. L: lecture notes-HISTORY, 1936] and prognostic method [Mazunin S.A. fundamentals of physico-chemical analysis: Educational. manual course / VT. UN-so - Perm, 2000. - Part 2. Multi-component water-salt system.] allow to calculate the ratio of the initial components in benthic phase equilibrium compositions of the liquid phase and the initial mixture of components (hereinafter-the CLAIM), using a mathematical equation.

The essence of the method of residues of Schreinemakers state is t in determining the composition of the saturated solution and solid phase, soaked in mother liquor - residue methods of chemical analysis. Analyzing several paired solutions and residues, building and defining the intersection of the connecting lines (rays crystallization) with the axes of the composition concentration figures graphically find the equilibrium composition of the solid phase (crystalline, chemical compounds or formed solid solutions).

The disadvantages of this method are applicable to four or more component systems, the inability to determine the CLAIM on the phase boundaries of the areas (i.e., it is not structurally-sensitive), and does not give the exact composition of the equilibrium solid phases in ternary systems due to the inevitable changes in the balance when they are isolated for chemical analysis.

The essence of the method of sections is to measure some physical properties of the liquid phase formed in the equilibrium conditions of the SUIT system, located in well-defined cross-sections of figures in the composition. The experimental data build graph "composition-property", a system of intersecting lines, the number of which equals the number of fields, dissected the studied section. The point of crossing functional lines in several sections define the boundaries of fields with different phase state, including the marginal nodes. Continue limit the level nod to the intersection with branches solubility on the one hand and the borders of the triangle composition - on the other graphically find the equilibrium compositions of liquid and solid phases. The method of sections is graphic and structural-sensitive.

This method is elaborated only for three-component systems. Using equations analytic geometry allows to apply it to more vysokokonkurentnym systems, but the method is extremely time-consuming.

To control the composition of the bottom phase in the study of Quaternary reciprocal salt-water system underlying the ammonia method of production of soda, Fedotov applied the method of material balance. Based on the data of chemical analysis of the equilibrium liquid phase direct proportions were calculated amount of dissolved salt components were compared with those taken for the preparation of the CLAIM and determined the excess salts that are in the bottom phase. This procedure was applied to solutions saturated one, two and three salts.

However, this procedure does not allow to determine the presence of a new solid phase, if it is a mixture of two or more components or solid solution. In addition, the method does not allow the calculation of the optimal ACTION for the research interest of phase equilibria determination of coordinates of points on the phase boundaries of the regions and equilibrium compositions, liquid and solid phases without R is selenia in four or more component systems.

The closest to the technical nature of the proposed method is a control method of the composition of the bottom phase in the research of water-salt systems [Mazunin S.A. fundamentals of physico-chemical analysis: Educational. manual course / VT. UN-so - Perm, 2000. - Part 2. Multi-component water-salt system].

This method indirectly determines the equilibrium bottom phase, when using the data of chemical analysis of the equilibrium liquid phase and the composition of the CLAIM, by calculating the ratio of the components is the equation of a straight line. Solving a system of equations that determine the optimal ACTION for the research interest of phase equilibria.

The disadvantages of this method-prototype is the inability to determine the coordinates of points on the phase boundaries of the regions and the composition of the equilibrium solid phases without their separation from the liquid in four or more component systems.

Disclosure of inventions

The objective of the invention is to develop a universal way to determine with sufficient accuracy the composition of the equilibrium solid phases in water-salt systems with any number and complexity of interaction between the components without isolation of the phases and disturbances.

The problem is solved by the characteristics specified in the claims, in common with the prototype, such as a method of study of solubility in n-components is ntih water-salt systems by determining the compositions nonvariant solutions saturated n-2 and n-1 salts, and calculate the ratio of components in the equation of a straight line, and distinctive essential features, such as experimental determination of the coordinates of the boundaries nonvariant areas etherically incisions (n-1)vertices in n-component systems, without resorting to the separation of equilibrium phases, establishing the composition of the equilibrium solid phases by finding the point of intersection of the two extreme nodes specified by the compositions of the respective nonvariant solutions and borders or vertices nonvariant areas (n is the number of components in the system).

The technical result is a significant reduction in the complexity of the research and possible to reliably determine the composition of the equilibrium solid phases without their separation from the liquid.

The proposed combined method uses the best side of the considered methods and allows the experimental data to determine the composition of the equilibrium solid phases without isolating them from the liquid phase. The compositions of the solid phases are the coordinates of liquid phase boundaries in contouring systems and vertices nonvariant areas in etherically sections of the system, determined experimentally, as the intersection of the respective marginal nod.

Examples of embodiment of the invention.

Example 1. Determination of the composition of the equilibrium solid phases in ternary water-salt is the system with the crystallization time, incongruently soluble chemical compound.

System NaHCO3-Na2CO3-H2O at 25°With the ternary water-salt system with crystallization time, incongruently soluble chemical compounds [Mazunin S.A.].

To determine the composition of the equilibrium solid phases it is necessary to experimentally find the compositions nonvariant saturated solutions one and two salts (table 1), as well as the borders nonvariant areas (table 2) in etherically sections of the ternary system, without resorting to the separation of equilibrium phases, to establish the point of intersection of the marginal nod, given these compositions.

Table 1

The compositions nonvariant solutions system NaHCO3-Na2CO3-N2O at 25°
PointThe composition of the saturated solution, wt.%Solid phase
NaHCO3Na2CO3H2O
R20.0022.7077.30Na2CO3·10H2O
E1.5022.6075.90NaHCO3·Na2CO3·2H2O+Na2CO3·10H2O
P4.0517.9078.05 NaHCO3+NaHCO3·Na2CO3·2H2O
R19.300.0090.70NaHCO3

The results of determination of the composition of the equilibrium solid phases, are given in table 3 and depicted in figure 1, confirm the crystallization in the system of anhydrous sodium hydrogen carbonate, chemical compound and desativado sodium carbonate.

Figure 1 white circles shows the experimental compositions of the saturated solutions, borders etherically nonvariant areas and the true equilibrium solid phases, black mugs - set of the proposed procedure, the point of intersection of the marginal nod. The thick solid lines depict the "master part" ultimate nod, dashed lines - they continue to the point of mutual intersection.

b
Table 2

Border nonvariant areas etherically sections
PointThe composition of the saturated solution, wt.%Note

The point on the node:
NaHCO3Na2CO3H2O
and34.000.0066.00R1- NaHCO3
18.8615.1466.00R - NaHCO3
10.4723.5366.00p - NaHCO3·Na2CO3·2H2O
f3.8224.1872.00e - NaHCO3·Na2CO3·2H2O
g1.0526.9572.00e - Na2CO3·10H2O
h0.0028.0072.00R2- Na2CO3·10H2O

Table 3

Installed the compositions of the solid phases
№ p/pThe solid phase composition, wt.%/The mole fraction of the componentNote

The intersection of nod:
NaHCO3Na2CO3H2O
1100.10/1.000.00/0.00-0.10/-0.00R1-a and p-b;
236.90/1.0046.71/0.9816.38/2.07R-C and e-f;
30.00/0.0037.10/1.0062.90/10.17R2-h and e-g.

The data show that the error in the determination of molar ratio of the components in the composition of the equilibrium solid phases is satisfactory and does not exceed 0.17.

Example 2. Determination of the composition of the equilibrium solid phases in the Quaternary water-salt system simple avtoritetnogo type with the crystallization of anhydrous individual initial salt components.

System of NH4H2PO4-(NH4)2NRA4-NH4Cl-H2O at 20°With a simple four-water-salt system avtoritetnogo type [Mazunin S.A.].

To find the equilibrium compositions of the solid phases in the Quaternary system is also necessary to determine experimentally the compositions nonvariant saturated solutions two and three salts (table 4), all boundaries nonvariant etherically areas in which contour triple systems and the vertices of these areas (see table 5 and 6 respectively), without resorting to the separation of equilibrium phases, to establish the point of intersection of the marginal nod, given these compositions.

The results of determination of the composition of the equilibrium solid phases, are presented in table 7 and depicted in figure 2, confirm the crystallization in the system anhydrous source of salt components.

Figure 2 white circles shows the experimental compositions of the saturated solutions, borders etherically nonwar is based areas black circles - set of the proposed procedure, the point of intersection of the marginal nod. The thick solid lines depict the "master part" ultimate nod, dashed lines - they continue to the point of mutual intersection.

Table 4

The compositions nonvariant solutions of the system of NH4H2PO4-(NH4)2HPO4-NH4Cl-H2O at 20°
PointThe composition of the saturated solution, wt.%Hard

phase
NH4H2PO4(NH4)2HPO4NH4ClH2O
E1225.032.7-42.3NH4H2PO4+(NH4)2HPO4
E135.2-25.469.4NH4H2PO4+NH4Cl
E23-12.922.464.7(NH4)2HPO4+NH4Cl
E16.023.211.549.3(NH4)2HPO4+NH4Cl+H 4H2PO4

Table 5

Border nonvariant areas etherically sections triple counting systems
PointComposition, wt.%Note

The point on the node:
NH4H2PO4(NH4)2HPO4NH4ClH2O
and36.227.80.036.0E12- NH4H2PO4
b21.342.70.036.0E12- (NH4)2HPO4
19.40.021.659.0E13- NH4H2PO4
d4.40.036.659.0E13- NH4Cl
f0.026.019.055.0E23- (NH4)2HPO4
g0.011.034.055.0E23- NH4Cl

Table 6

Tops nonvariant region in isolationsim the context of the quadruple system of NH4H2PO4-(NH4)2HPO4-NH4Cl-H2O at 20°
PointComposition, wt.%Note

The point on the node:
NH4H2PO4(NH4)2HPO4NH4ClH2O
N31.818.89.440.0E - NH4H2PO4
To13.037.79.340.0E - (NH4)2HPO4
M13.018.828.240.0E - NH4Cl

The data show that errors in the determination of the composition of the equilibrium solid phases are satisfactory and does not exceed 0.58 wt.%.

Figure 3 shows the definition of the crystallizable compositions of all phases. Phosphate of ammonia in the system crystallizes in the form of an anhydrous source of salt, the composition of which is mutual intersection of three marginal gcd (E13-b; F23-f; F-k), the values of the contents of the components are summarized in table 8. Chloride Ammon is I in the system also crystallizes in the form of an anhydrous source of salt, the composition of which is determined by the mutual intersection of three marginal gcd (E13d; E23-g; E-m), the values of the contents of the components are summarized in table.

Figure 2 and 3 white circles marked experimental data, black - established. The thick solid lines depict the "master part" ultimate nod, dashed lines - they continue to the point of mutual intersection.

Table 7

Found the composition of the solid phase NH4H2PO4
№ p/pThe solid phase composition, wt.%Note

The intersection of nod:
NH4H2PO4(NH4)2HPO4NH4ClH2O
1100.110.000.00-0.11E12a and E13-C;
299.300.350.000.35E12-a and E-H;
3100.580.00-0.26-0.32E13-c and E-H.
Cf.100.000.12-0.09-0.03The average composition

Table 8

Found the composition of the solid phase (NH4)2HPO4
№ p/pThe solid phase composition, wt.%Note

The intersection of nod:
(NH4)2HPO4NH4H2PO4NH4ClH2O
199.140.340.110.42E12-b and E-K;
2100.780.00-0.14-0.64E23-f E-K;
3100.050.000.00-0.05E12-b and E23-f.
Cf.99.990.11-0.01-0.09The average composition

Table 9

Found the composition of the solid phase NH4Cl
№ p/pThe solid phase composition, wt.%Note

The intersection of nod:
NH4Cl(NH4)2HPO4NH4H2PO4H2O
1100.43 0.000.05-0.48E13-d and E-M;
299.990.110.13-0.24E23-g & E-Th;
3100.690.00-0.14-0.55E23-g and E13-d.
Cf.100.370.040.01-0.42The average composition

Example 3. Determination of the composition of the equilibrium solid phases in quintuple water-salt system simple avtoritetnogo type with the crystallization of anhydrous individual initial salt components.

System of NH4H2PO4-(NH4)2HPO4-NH4Cl-(C2H5)3NHCl-H2O at 20° - quintuple water-salt system avtoritetnogo type [Mazunin S.A.].

To determine the composition of the equilibrium solid phases it is necessary to experimentally determine the composition menicucci saturated solutions three and four salts (table 10), and the coordinates of the vertices etherically nonvariant areas in which contour quadruple and quintuple systems (table), without resorting to the separation of equilibrium phases, to establish the point of intersection of the marginal nod, given these compositions.

The results of determination of the composition of the equilibrium solid phases, carried away is in table and depicted in Fig.4-6, confirm the crystallization in the system anhydrous source of salt components.

Table 10

The compositions nonvariant solutions of the system of NH4H2PO4-(NH4)2HPO4-NH4Cl-(C2H5)3NHCl-H2O at 20°
The composition of the saturated solution, wt.%Solid phase
PointNH4H2PO4(NH4)2HPO4NH4Cl(C2H5)3NHClH2O
E1241.20.2-56.042.6(NH4)2HPO4+NH4H2PO4+(C2H5)3NHCl
E1340.4-7.050.542.1NH4H2PO4+NH4Cl+(C2H5)3NHCl
E234-0.16.951.541.5(NH4)2HPO4+NH4Cl+(C2H5)3NHCl
E12316.023.211.5-49.3 (NH4)2HPO4+NH4Cl+NH4H2PO4
E0.40.16.751.141.7(NH4)2HPO4+NH4H2PO4+NH4Cl+(C2H5)3NHCl

Table 11

Tops nonvariant areas in etherically sections fivefold system of NH4H2PO4-(NH4)2HPO4-NH4Cl-(C2H5)3NHCl-H2O at 20°
PointComposition, wt.%Note.

The point on the node:
NH4H2PO4(NH4)2HPO4NH4ClEt3NHClH2O
N33.5518.359.100.0039.00E123- NH4H2PO4
To12.6639.249.100.0039.00El23- (NH4)2HPO4
M12.6618.3529.990.0039.00E123- NH4Cl
p21.150.160.0044.6934.00E124- NH4H2PO4
q0.9620.350.0044.6934.00E124- (NH4)2HPO4
o0.960.160.0064.8834.00E124- Et3NHCl
x21.930.005.4939.5833.00E134- NH4H2PO4
0.310.0027.1139.5833.00E134- NH4Cl
z0.310.005.4961.2033.00E134- Et3NHCl
r0.0020.565.49At 40.9533.00E234- (NH4)2HPO4
s0.000.08At 25.97At 40.9533.00E234- NH4Cl
t0.000.085.4961.4333.00E234- Et3 NHCl
and21.180.085.3040.4433.00E - NH4H2PO4
b0.3220.945.3040.4433.00E - (NH4)2HPO4
0.320.0826.1640.4433.00E - NH4Cl
d0.320.085.30At 61.3033.00E - Et3NHCl

Figs.4-6 white circles shows the experimental compositions of the saturated solutions, borders etherically nonvariant areas, black mugs - set of the proposed procedure, the point of intersection of the marginal nod. The thick solid lines depict the "master part" ultimate nod, dashed lines - they continue to the point of mutual intersection.

Figure 4 shows using saline projection quintuple system definition of the compounds one of the crystallizing phases, namely ammonium dihydrophosphate, which was found by the mutual intersection of three marginal gcd (E123is h; E124-p and E134-x) child node with E-a found value of the contents of the components are summarized in table.

IG shows using saline projection quintuple system determination of compositions of all of the crystallizing phases, the values of components which are summarized in tabl. The initial crystallization of anhydrous ammonium chloride proven formulations of mutual intersection of three marginal gcd (E123-m; E234-s and E134- ) child node E.-C. Crystallization source of anhydrous hydrogen phosphate ammonium defined by the sets of mutual intersection of three marginal gcd (E123-k; E234-r and E124-q) with the child node E.-b. Crystallization of the original anhydrous chloride of triethylamine proven formulations of mutual intersection of three marginal gcd (E124-o; E134z and E234-t with child node E-d.

6 allows to consider on an enlarged scale angle saline projection quintuple system that meets the chloride of triethylamine, and determination of the composition of this salt is found by the intersection of three marginal gcd (E124-o; E134z and E234-t) with the child node E-d.

The data show that errors in the determination of the composition of the equilibrium solid phases depend on the size of the intersection angle limit nod, are satisfactory and do not exceed 2.39 wt.%.

The proposed method of determining the composition of the equilibrium solid phases in water-salt systems is universal, applicable to systems with any number and complexity of interaction between components.

The method for determining the composition of the equilibrium solid phase is in the study of the solubility in n-component water-salt systems by determining the compositions nonvariant solutions saturated n-2 and n-1 salts, and calculate the ratio of components in the equation of a straight line, characterized in that the experimentally determined coordinates for the boundaries of nonvariant areas etherically cuts in the (n-1)vertices in n-component systems, without resorting to the separation of equilibrium phases, and establish the composition of the equilibrium solid phases, finding the point of intersection of the two extreme nodes specified by the compositions of the respective nonvariant solutions and borders or vertices nonvariant areas.



 

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3 ex

FIELD: chemistry, various oxygen-containing substances and compounds, possible use in good technology, perfume industry, biology, pharmacology, medicine.

SUBSTANCE: in the kinetic method for testing anti-oxidants by saturating a sample of ethers of high non-saturated fatty acids and anti-oxidants with oxygen with stirring thereof at 60,0±0,2°C and creation of chains of their oxidized radicals, determining of amount of absorbed oxygen in time with construction of dV/dt graph in time, the sample of ethers of non-saturated fatty acids is mixed with water solutions of cetyltrimethylammonium of bromide and copper salt, a batch or solution of anti-oxidant is added, resulting sample is finished with water up to 4 ml, saturated with oxygen, the volume of oxygen absorbed over time is determined volumetrically, dV/dt graph is built in time on basis of differentiation of resulting kinetic curves, approximated across three sections: first and third ones - by straight lines, second one - by a parabola, on basis of which the time, corresponding to first bend, is used to determine efficiency of participation of anti-oxidant in tearing of chains, the tangent of angle of inclination of tangent line of second section is used to determine participation of antioxidant in branching on chains, and time of second bend is used to determine full flow of antioxidant, where the dV/dt value of the fourth section defines the total speed of the process.

EFFECT: increased efficiency of testing.

4 ex, 1 tbl, 5 dwg

FIELD: analytical chemistry and ecology, in particular, method for determining micro-concentrations of antimony in water.

SUBSTANCE: method includes preparation of analyzed sample by concentrating analyzed solution, which contains antimony, to the state of solid residual, dissolution of dry residual in 3,5-4,0 M hydrochloric acid, placement of prepared sample in a solution which contains 30-40% of potassium iodide, 10-15% solution of ascorbic acid, aging of resulting mixture over 15-25 minutes and addition of metallic zinc, distillation of resulting product by letting it through absorbing solution of partially oxidized diphenyl carbazide until the color of absorbing solution stops changing, photometry of absorbing solution.

EFFECT: increased selectivity and sensitivity of analysis.

3 ex, 3 tbl, 1 dwg

FIELD: analytical chemistry, possible use for determining concentrations of ethyl spirits in steam-gas mixtures using an array of piezo-electric quartz resonators with films.

SUBSTANCE: method for determining micro-concentrations of ethyl spirits in steam-gas mixtures includes extracting 3-5 cm3 of analyzed steam-gas mixture, injecting the sample into closed detection cell, on the lid of which 3 piezo-electric quartz resonators are mounted with base frequency of 40 Mhz, onto electrodes of which on two sides solutions are applied, respectively, polyethylene glycol of sebacate, polyethylene glycol of succinate and Triton X-100 in such a way, that after removing free solvents the mass of films amounts to 7-10 micrograms, responses of piezo-electric quartz resonators with films are simultaneously recorded over 1-2 minutes and formed into kinetic "visual imprint", on basis of area of which using a calibrating graph the concentration of ethyl spirits is determined.

EFFECT: correctness, precision, selectivity, speed and convenience of analysis.

1 ex, 3 dwg

FIELD: analytical methods.

SUBSTANCE: invention relates to analysis of non-biological materials with chemical methods via hydrolysis followed by titration in presence of chemical indicators. Method consists in analysis of aqueous solutions of these materials wherein 0.10-0.12 g sample is treated with 4 mL of concentrated 47.6% hydrobromic acid solution, reaction mixture is evaporated to residual volume 0.3-0.5 mL of test solution, neutralized with 1 N sodium hydroxide solution in presence of methyl red indicator until weakly rose coloration appears, after which it is titrated with 0.1 N sodium hydroxide solution until weakly red coloration is transformed into stramineous. Finally, thymolphtalein is added and solution is post-titrated until stable blue-green color. Mass portion of major substance is calculated in terms of following equation: M = [(V1-V2)*T*K/m]*100, where V1 is volume of 0.1 N sodium hydroxide solution utilized for titration of the sample of alkylphosphonic acid dialkyl ester in presence of thymolphtalein, mL; V2 is volume of 0.1 N sodium hydroxide solution utilized for titration of blank sample in presence of thymolphtalein, mL; T is titer of alkylphosphonic acid dialkyl ester equivalent to 1 mL of 0.1 N sodium hydroxide, g/mL; K is correction factor for concentration of sodium hydroxide solution (K=1 when standard titer is used); m is mass of the sample of alkylphosphonic acid dialkyl ester used for measurements, g.

EFFECT: simplified analytical procedure and increased accuracy of measurement.

4 tbl

FIELD: analytical methods.

SUBSTANCE: invention relates to analysis of non-biological materials with chemical methods and can find use when solving tasks concerning environmental control on chemical weapon destruction objects. Method of determining mass portion of major substance of beta-chlorovinylarsonic acid in aqueous solutions comprises dissolving sample of beta-chlorovinylarsonic acid having mass 0.1-0.3 g in 50 mL water, to which two drops of 0.1% water-alcohol solution of phenolphthalein is added as indicator. Solution is titrated with 0.1 N sodium hydroxide solution to rose coloration and mass portion of major substance is calculated in terms of following equation: % (mass portion of major substance) = [(V1-V2)*K*0.00932135*100]/q, where V1 is volume of 0.1 N sodium hydroxide solution utilized for titration of weighed sample of beta-chlorovinylarsonic acid, cm3; V2 is volume of working solution utilized for titration of blank sample and decomposition of indicator, cm3; K is correction factor for titer of sodium hydroxide solution (K=1 when standard titer is used); 0.00932135 is quantity of beta-chlorovinylarsonic acid equivalent to 1 cm3 of 0.1 N sodium hydroxide solution, g/cm3, and q is mass of beta-chlorovinylarsonic acid sample. As measurement result, arithmetic mean of two parallel measurements is taken, wherein permissible deviation between the two measurements has not to exceed ±1%.

EFFECT: increased accuracy and simplified analytical procedure.

1 tbl

FIELD: analytical methods.

SUBSTANCE: invention relates to analytical chemistry of inorganic compounds and comprises providing chemisorbent, filling test device therewith, exposing it to ammonia vapors, registering analytical signal with a time range 10-15 sec, and finding ammonia concentration from calibrated graph. Test device represents quartz piezoelectric resonator with its electrodes modified by sulfosalicylic acid solution so that mass of the film formed after drying-mediated removal of solvent in drying oven at 40-50°C for 15-20 min at horizontal arrangement of resonator is 10-15 μg.

EFFECT: increased sensitivity, accuracy, rapidity, and selectivity of analysis.

2 dwg, 1 tbl

FIELD: analytical methods.

SUBSTANCE: invention is directed to provide a method for determining gold(III) in secondary raw materials and scraps, in natural materials, and in process solutions. When performing analysis, gold(III) is sorbed from hydrochloric acid solutions with ion-exchanger AB-17, on which rhodanine is preliminarily fixed via chemisorption, after which gold(III) is determined in solid phase.

EFFECT: increased reproducibility and accuracy in individual determination in the form of express-analyses due to fuller extraction gold from solutions thanks to increased sorption capacity.

1 tbl

FIELD: analytical methods in food industry.

SUBSTANCE: invention relates to analytical chemistry of organic compounds and is intended for use in development of processes of production of biologically active supplements, polyvitamins, and protein mixtures. Method comprises preparation of aqueous solution of aspartic acid and quantitative determination of acid. More specifically, to aqueous solution of acid, crystalline lithium sulfate is added as desalting agent and then mixture of hydrophilic solvent is added to water-salt solution of acid, said mixture of hydrophilic solvent being prepared from butyl alcohol, acetone, and ethyl acetate. Thereafter, extract is separated and amount of aspartic acid is determined therein with the aid of potentiometric titration technique, which involves plotting differential curve of medium potential vs. volume of titrant and calculating degree of recovery of aspartic acid using suitable formula.

EFFECT: accelerated analytical procedure using safety reagents.

2 tbl, 7 ex

FIELD: analytical methods.

SUBSTANCE: invention concerns analytical determination of acids, acid salts, and other substances having acid reaction and reacting with alkalis, in particular titration method for use both in educational process and in industry. Method comprises weighing and dissolving in water sample of a substance, or taking measured volume of a substance followed by titration thereof using alkali titrants and pH-meter-mediated determination of equivalence point, said titrants being electrochemically activated alkaline water with pH 11.9-12.1 thereto 0.1% NaCl was added before activation.

EFFECT: reduced expenses on preparation of alkali solutions.

7 dwg, 12 ex

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