RU2252415C1 - Indicating composition for molybdenum ( vi ) detection in aqueous solutions - Google Patents

Abstract

FIELD: analytic chemistry (indicating compositions).

SUBSTANCE: claimed composition contains (mass %): sorbent (anionite, modified with organic reagent) 0.4; hydrochloric acid 0.0011-0.0015; and balance: water. Composition of present invention is useful in determination of Mo(VI) content in natural water and wastewater.

EFFECT: improved sensitivity, increased analysis velocity and decreased effort.

3 tbl

Description

The invention relates to analytical chemistry (indicator compositions) and can be used to determine molybdenum (VI) in aqueous solutions, in particular in natural and waste waters.

Known indicator composition for spectrophotometric determination of 0.2-10 μg / ml of molybdenum (VI) with tyrone [Umland F., Jansen A., Tirig D., Wünsch G. Complex compounds in analytical chemistry. M.: Mir, 1975, 532 p.].

The disadvantage of the technical solution is the low specificity of the determination due to the interfering effect of a number of ions, which requires preliminary separation of molybdenum by extraction with various organic reagents, which increases the duration of the analysis and requires the observance of special safety rules due to work with toxic organic solvents.

To increase the sensitivity and selectivity of the determinations, indicator compositions are used, including various sorbents. The determination of molybdenum (VI) with tyrone in the Sephadex QAE-25 sorbent phase by solid-state spectrophotometry [Yoshimura K., Matsuoka S, Waki H. / Anal. Chem. Acta, 1989, V.225, No.2. P.313].

The disadvantage of this technique is the narrow linear range of the determined concentrations of molybdenum (0.15-6 μg / l), as well as the difficulty of storing the sorbent due to its susceptibility to bacterial exposure.

The closest in technical essence to the claimed composition is an indicator composition for determining 50-2500 μg / l of molybdenum (VI) in aqueous solutions by diffuse reflection spectroscopy containing anion exchange resin, reagent - pyrocatechol violet, acid and water in the following ratio of reacting components, wt. %:

Anion exchange resin AB-17-10P 0.4

Catechol violet 0.002

Hydrochloric acid 0.007-0.02

Water Else

The disadvantage of this indicator composition is the relatively narrow linear range of the determined molybdenum contents [Tchaikovskaya A.E., Kachin S.V., Kononova O.N., Kholmogorov A.G. RF patent No. 2162221 from 01.20.2001].

The technical result of the invention is to expand the linear range of the determined contents of molybdenum (VI) in aqueous solutions, as well as increasing the expressness of the analysis and reducing the complexity.

The technical result is achieved by the fact that in the indicator composition for determining Mo (VI) ions in aqueous solutions containing the sorbent - anion exchange resin AB-17-10P, hydrochloric acid and water, the new is that the anion exchange resin AB-17-10P, modified with organic reagent - tyrone, in the following ratio of components, wt.%:

Anion exchange resin AB-17-10P, modified with tyrone 0.4

Hydrochloric acid 0.0011-0.0015

Water Else

Anion exchange resin AB-17-10P is a copolymerization strongly basic monofunctional anion exchange resin with quaternary benzyltrimethylammonium groups (with a macroporous structure) obtained by chloromethylation of a styrene copolymer with 8% divinylbenzene followed by amination with trimethylamine (Ashirov A. Ionic exchange - ion exchange. .: Chemistry, 1983, p. 85-86).

Modification of the sorbent - anion exchange resin AB-17-10P is as follows. To the sorbent in the chloride form, previously swollen in a HCl solution at pH ~ 3, a 0.2 M tiron solution is added at the rate of 50 μg per 0.2 g of ion exchanger. Mix thoroughly and leave for a day. Then the sorbent is filtered off and dried in air, after which it is stored in bottles with ground stoppers. The sorbent modified by tyrone can be stored for up to 1.5 years.

To determine molybdenum (VI), the analyzed solution with pH 3 is placed in a graduated tube with a ground stopper with a capacity of 50 ml, 0.2 g of pre-swollen modified anion exchange resin AB-17-10P are introduced, up to 50 ml of 0.001 M Hcl are added and shaken for 15 minutes . Then the sorbent is filtered off and the diffuse reflection coefficient is measured at a wavelength of 430 nm on a Pulsar colorimeter with respect to the reference sample, which is the modified anion exchange resin AB-17-10P described above.

The content of molybdenum (VI) in the analyzed solution is calculated according to the calibration graph. For its construction, aliquots of a standard solution of molybdenum (VI) with a content of the latter from 2.5 to 500 μg are introduced into graduated tubes with ground stoppers with a capacity of 50 ml, 0.2 g of anion exchanger modified with tyrone AV-17-10P are added, adjusted to 50 ml A 0.001 M HCl solution and further proceed as described above.

The diffuse reflection coefficient is converted into the Gurevich-Kubelka-Munk function according to the equation:

Δ F (R) = [(1-R) ² / 2R] - [(1-R ₀ ) ² / 2R ₀ ],

where R and r ₀ are the diffuse reflection coefficients of the reacted sample and the reference sample, respectively.

Build the dependence in the coordinates Δ F (R) -C _{Mo (VI)} , mg / l,

where C _{Mo (VI)} is the concentration of molybdenum (VI) in solution.

Introduction to the indicator composition of anion exchange resin AB-17-10P modified with tyrone allows us to expand the linear range of the determined contents of molybdenum (VI), halve the volume of the Mo (VI) sample, and increase the expressness of the analysis (Table 1-3). In addition, the sorbent modified by tiron is stable during storage for 1.5 years.

Table 1 Comparative characteristics of the developed indicator composition for the determination of molybdenum (VI) and known composition (methodology on Sephadex QAE-25) Parameter Composition with AB-17-10P Famous Composition The range of determined concentrations, mcg / l 50-10000 0.15-6 Detection limit, mcg / l 5 0.15 The duration of the analysis, min fifteen thirty Sample volume, ml fifty 100 Sorbent stability during storage Up to 1.5 years Not more than 1-2 months. table 2 Sorption-spectroscopic determination of molybdenum (VI) with tyrone in model solutions of molybdate ions n = 5; P = 0.95 Introduced Mo (VI), mg / L Found Mo (VI), С _cp ± Δ C, mg / L S standard deviation Relative error Q _rel ,% 0.5 0.52 ± 0.03 0.0022 4.0 5,0 5.06 ± 0.09 0,073 1,2 9.5 9.29 ± 0.10 0,081 -2.2

Table 3 Sorption-spectroscopic determination of molybdenum (VI) in the presence of related components. The initial concentration of Mo (VI) is 5 mg / l; n is 5; P = 0.95 Macro Component (MK) The ratio of MK to molybdenum (concentration) Found Mo (VI), mg / L Q _rel ,% Cu (II) 1: 2000 5,6 12 Fe (II) 1: 350 5,4 8 Fe (III) 1: 500 5.2 4 Hf 1: 300 5.3 6 H ₂ C ₂ O ₄ 1: 350 5.2 4 H ₂ SiO ₃ 1: 1500 5.5 10 H ₃ RO ₄ 1: 300 5,6 12 EDTA 1: 2000 5.5 10 Vitamin C 1: 2000 5,6 12

Thus, the concentration operation makes it possible to increase the sensitivity of the determination of molybdenum (VI), and the preparation of a colored concentrate in the ionite phase extends the linear range of the compounds to be determined. In addition, the preliminary modification of anion exchange resin with an organic reagent increases the rapidity of determination and the efficiency of the procedure.

Claims (1)

The indicator composition for the determination of molybdenum (VI) in aqueous solutions containing sorbent anion exchange resin AB-17-10P, hydrochloric acid and water, characterized in that it contains sorbent anion exchange resin AB-17-10P, modified with an organic reagent - tyrone, in the following ratio components, wt.%: Anion exchange resin AB-17-10P, modified with tyrone 0.4 Hydrochloric acid 0.0011-0.0015 Water Else