Indicating composition for molybdenum ( vi ) detection in aqueous solutions

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

 

The invention relates to analytical chemistry (test compounds), and can be used for the determination of molybdenum (VI) in aqueous solutions, in particular in natural and waste waters.

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

The lack of technical solutions is the low specificity of definition due to the interfering influence of the number of ions, therefore, requires prior separation of molybdenum extraction of various organic reagents, which increases the duration of analysis and requires compliance with special safety regulations for work with toxic organic solvents.

To increase the sensitivity and selectivity of the definitions used indicator compounds, including various sorbents. Describes the determination of molybdenum (VI) with Tyrone in phase sorbent Sephadex QAE-25 method of solid-phase spectrophotometry [Yoshimura K., Matsuoka S, Waki H. / Anal. Chem. Acta, 1989, V.225, No.2. R].

The drawback of this technique is a narrow linear range of the defined concentrations of molybdenum (0.15 to 6 µg/l), and the complexity of storage of the sorbent due to its susceptibility to bacterial action.

Most near them the technical nature of the claimed composition is an indicator composition to identify 50-2500 mg/l molybdenum (VI) in aqueous solutions by the method of diffuse reflection spectroscopy, containing the resin, the reagent - pyrocatechin purple, acid and water in the following ratio of reacting components, wt.%:

Anionite AV-17-10P 0,4

Pyrocatechin purple 0,002

Hydrochloric acid 0,007-0,02

Water the Rest

The disadvantage of this indicator is relatively narrow linear range of the defined contents of molybdenum [Chaykovskaya SUPERVISION, Kachin S.V. Kononova O., Kolmogorov A.G. Patent RF № 2162221 from 20.01.2001].

The technical result of the invention is the extension of the linear range of the designated contents of molybdenum (VI) in aqueous solutions, as well as increasing expressnet analysis and reducing the complexity.

The technical result is achieved by the fact that in the indicator composition to identify ions of Mo (VI) in aqueous solutions containing sorbent - anionite AV-17-10P, hydrochloric acid and water, it is new that contains the anionite AV-17-10P, modified organic reagent - Tyrone, in the following ratio, wt.%:

Anionite AV-17-10P, modified Tyrone 0,4

Hydrochloric acid 0,0011-0,0015

Water the Rest

Anionite AV-17-10P is copolymerizations strong monofunctional anion exchange resin with Quaternary benzyltrimethylammonium groups (with macroporous structure), the floor is aemy by chlorotoluene copolymer of styrene and 8% divinylbenzene, followed by aminating the trimethylamine (A. Ashirov Ion exchange wastewater treatment, solutions and gases. - L.: Chemistry, 1983, p.85-86).

Modification of the sorbent - anionite AV-17-10P is as follows. The sorbent in the chloride form pre-swollen in a solution of Hcl at pH~3, add 0.2 M solution of Tyrone, 50 μg 0.2 g of the resin. Mix thoroughly and leave for the day. Then, the desiccant is filtered off and dried in air, then keep it in bottles with ground stoppers. Modified Tyrone sorbent can save up to 1.5 years.

For the determination of molybdenum (VI) of the analyzed solution with a pH of 3 is placed in a graduated test tube with a glass stopper with a capacity of 50 ml, injected with 0.2 g of pre-swollen modified anionite AV-17-10P, add to 50 ml of 0.001 M Hcl and shaken for 15 minutes and Then the adsorbent is filtered off and measure the diffuse reflectance at a wavelength of 430 nm in a colorimeter pulsar relative to the reference sample representing the above-described modified anionite AV-17-10P.

The content of molybdenum (VI) in the sample solution is calculated by the calibration curve. To build in a graduated test tubes with ground stoppers with a capacity of 50 ml injected aliquots of a standard solution of molybdenum (VI) with the latest content from 2.5 to 500 mcg, add 0.2 g of modified that the Ron of anionite AV-17-10P, bring to 50 ml of 0.001 M Hcl solution and then proceed as described above.

The diffuse reflectance count in the function of the Gurevich-Kubelka-Munk equation:

Δ F(R)=[(1-R)2/2R]-[(1-R0)2/2R0],

whereR and r0- diffuse reflection coefficients of the reacted sample and reference sample, respectively.

Build dependency coordinates Δ F(R)Mo(VI), mg/l,

where CMo(VI)the concentration of molybdenum (VI) in solution.

Introduction in the indicator composition of the anionite AV-17-10P modified Tyrone, allows you to extend the linear range of the designated contents of molybdenum (VI), to halve the volume of the sample Mo(VI) and increase expressnet analysis (table. 1-3). In addition, the modified Tyrone sorbent is stable when stored for 1.5 years.

Table 1
Comparative characteristics of the designed test composition for the determination of molybdenum (VI) and of known composition (method on Sephadex QAE a-25)
The composition of the AV-17-10PKnown composition
The range of the defined concentrations, ug/l50-10000 0,15-6
The detection limit, µg/l50,15
The analysis duration, min1530
Volume of sample, ml50100
The stability of the sorbent during storageUp to 1.5 yearsNo 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
Put Mo(VI), mg/lFound Mo(VI), Ccf±ΔC, mg/lThe standard deviation SThe relative error of QRel, %
0,50,52± 0,030,00224,0
5,05,06± 0,090,0731,2
9,59,29± 0,10of 0.081-2,2

Table is 3
Sorption-spectroscopic determination of molybdenum (VI) in the presence of other components. The initial concentration of Mo(VI) - 5 mg/l; n=5; P=0,95
Macro-component (MC)The ratio of MC to molybdenum (concentration)Found Mo(VI), mg/lQRel, %
Cu(II)1:20005,612
Fe(II)1:350of 5.48
Fe(III)1:5005,24
HF1:3005,36
H2C2O41:3505,24
H2SiO31:15005,510
H3RHO41:3005,612
EDTA1:20005,510
Ascorbic acid1:20005,612

Thus, the operation of concentration allows to increase the sensitivity of the determination of molybdenum (VI), and getting painted concentrate in the phase of the ion exchanger extends the linear range of the defined compounds. In addition, the pre-modification and the organic ion exchanger reagent increases expressnet definition and cost effective methods.

The indicator composition for the determination of molybdenum (VI) in aqueous solutions containing sorbent-anionite AV-17-10P, hydrochloric acid and water, characterized in that it contains a sorbent-anionite AV-17-10P, modified organic reagent - Tyrone, in the following ratio, wt.%:

Anionite AV-17-10P, modified Tyrone 0,4

Hydrochloric acid 0,0011-0,0015

Water the Rest



 

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