RU2799664C1 - Luminescent method for the determination of samarium with guanidine methacrylate - Google Patents

Abstract

FIELD: analytical chemistry.

SUBSTANCE: methods for the luminescent determination of samarium Samarium is converted into a luminescent complex compound with an organic reagent (R) - guanidine methacrylate. The ratio Sm:R=1:1 at pH=6.2±0.1. The proposed method is characterized by high selectivity, accuracy and reproducibility. The maximum luminescence of the Sm complex with MAG is observed in the wavelength range of 500–700 nm with a maximum at λ=642 nm.

EFFECT: reduced detection limit, increased stability, sensitivity and selectivity of the luminescent method for the determination of samarium, where the lower detection limit of Sm with guanidine methacrylate is 5.8×^10–9 g/ml Sm.

1 cl, 2 dwg

Description

The invention relates to analytical chemistry, in particular to methods for the luminescent determination of samarium, and can be used to determine trace amounts of samarium in the analysis of high-purity lanthanides.

Known methods for the luminescent determination of samarium in combination with organic reagents: with β-dicarbonyl compounds - acetylacetone, benzoylacetone, fluorinated and cyclic β-diketones, with carboxylic acids [N.S. Poluektov, L.I. Kononenko, N.P. Efryushina, S.V. Beltyukov. Spectrophotometric and luminescent methods for the determination of lanthanides. Kyiv, Naukova Dumka, 1989. S. 100-106].

RF patent No. 2186029 C1 "Luminescent method for the determination of samarium". The invention relates to the field of analytical chemistry - to methods for the luminescent determination of samarium, and can be used to determine trace amounts of samarium in the analysis of high-quality lanthanides and in natural waters. An organic reagent (R) - methyl ester of S-(4-bromoanilide) sulfosalicylic acid (MEBASK) is used as a complexing agent, and a surfactant (surfactant) - decylpyridinium chloride (HDCP) is poured into a solution of a luminescent complex compound of samarium with MEBASK, in ratios Sm:R:surfactant=1:15:13 and weak ammonia solutions create pH=6.7±0.05.

RF patent No. 2514190 C2 "Luminescent method for the determination of samarium". The invention relates to analytical chemistry, in particular to methods for the luminescent determination of samarium. The method includes converting it into a luminescent compound with an organic reagent. Diphenyl ether of sulfosalicylic acid (DESC) is used as an organic reagent and a cationic surfactant (surfactant) cetylpyridinium bromide (CPB) is added in the following ratio of components: Sm:DESC:surfactant=1:2:14 at pH=6.4.

The disadvantages of the proposed methods are insufficient sensitivity, selectivity and stability in standing time and irradiation, as well as the high complexity of obtaining a complex compound and the duration of the analysis.

The problem solved by the invention is to find a new reagent that will reduce the detection limit, increase stability, sensitivity, selectivity and reduce the duration of the analysis.

The technical result is achieved by the fact that samarium is converted into a luminescent complex compound with an organic reagent (R) - guanidine methacrylate (MAG), the ratio Sm:R=1:1, at pH=6.2±0.1.

Example 1

To obtain solutions of lanthanide chlorides, their oxides were preliminarily calcined for one hour in a muffle furnace at a temperature of 650–700°C and cooled in a desiccator. A portion of lanthanide oxides according to their 10 ^-2 M concentrations is treated with hydrochloric acid and H ₂ O ₂ , and then the solution is evaporated. The dry residue of rare earth elements (REE) is dissolved in distilled water. Solutions with a lower concentration of the reagent were prepared by appropriate dilution. The concentration of the standard solution of terbium chloride is controlled by the complexometric method. Titration is carried out in the presence of urotropin, arsenazo I is used as an indicator. A MAG solution with a concentration of 10 ^-2 M is prepared by dissolving its sample of 1.45 g in distilled water, the solution is filtered and transferred into a 50 ml volumetric flask.

The acidity of the environment is created by adding an aqueous solution of ammonia to pH=6.2±0.1. The pH of solutions was measured using an EV-74 universal ion meter with glass electrodes calibrated with standard buffer solutions. To determine the content of samarium in REE oxides, the addition method was used.

When a MAG solution is added to the samarium solution, pH = 6.2 ± 0.1 is set and irradiated with UV light, a red glow is observed, which is characteristic of samarium ions, which proves the formation of the Sm-MAG complex.

Example 2

To obtain solutions of lanthanide chlorides, their oxides were preliminarily calcined for one hour in a muffle furnace at a temperature of 650-700°C and cooled in a desiccator. A portion of lanthanide oxides according to their 10 ^-3 M concentrations is treated with hydrochloric acid and H ₂ O ₂ , and then the solution is evaporated. The dry residue of rare earth elements (REE) is dissolved in distilled water. Solutions with a lower concentration of the reagent were prepared by appropriate dilution. The concentration of the standard solution of samarium chloride was controlled by the complexometric method. Titration was carried out in the presence of urotropin, arsenazo I was used as an indicator.

Solutions of guanidine methacrylate (MAG) 10 ^-2 M were prepared from an accurate sample of 0.145 g, dissolved in distilled water, the solution was filtered and transferred into a 50 ml volumetric flask.

In the course of the search work, a photometric reaction of samarium (Sm) with guanidine methacrylate (MAG) was discovered.

The luminescence spectra were recorded on a Fluorat-02-Panorama luminescent setup with the Frog prefix. The content of samarium in the analyzed sample was calculated from the magnitude of the luminescence peaks of the sample solutions and the sample with additives.

The maximum glow of the complex Sm with MAG is observed in the wavelength range of 500-700 nm with a maximum at λ=642 nm.

The ratio of components in the complex of Sm with MAG was determined by the methods of isomolar series and molar ratios.

For this, solutions of Sm and MAG of the same molar concentration of 1⋅10 ^-5 M were prepared, they were mixed in antibatic ratios from 0.0:1.0 to 1.0:0.0 with a constant system volume of 10 ml. The measurements were carried out at pH=6.2±0.1 and λ=642 nm.

Example 3

To obtain solutions of lanthanide chlorides, their oxides were preliminarily calcined for one hour in a muffle furnace at a temperature of 650-700°C and cooled in a desiccator. A portion of lanthanide oxides according to their 10 ^-3 M concentrations is treated with hydrochloric acid and H ₂ O ₂ , and then the solution is evaporated. The dry residue of rare earth elements (REE) is dissolved in distilled water. Solutions with a lower concentration of the reagent were prepared by appropriate dilution. The concentration of the standard solution of samarium chloride was controlled by the complexometric method. Titration was carried out in the presence of urotropin, arsenazo I was used as an indicator.

Solutions of guanidine methacrylate (MAG) 10 ^-5 M were prepared from an accurate sample of 0.00145 g, dissolved in distilled water, the solution was filtered and transferred into a 50 ml volumetric flask.

In the course of the search work, a photometric reaction of samarium (Sm) with guanidine methacrylate (MAG) was discovered.

The luminescence spectra were recorded on a Fluorat-02-Panorama luminescent setup with the Frog prefix. The content of samarium in the analyzed sample was calculated from the magnitude of the luminescence peaks of the sample solutions and the sample with additives.

The maximum glow of the complex Sm with MAG is observed in the wavelength range of 500-700 nm with a maximum at λ=642 nm.

The ratio of components in the complex of Sm with MAG was determined by the methods of isomolar series and molar ratios.

For this, solutions of Sm and MAG of the same molar concentration of 1⋅10 ^-5 M were prepared, they were mixed in antibatic ratios from 0.0: 1.0 to 1.0: 0.0 with a constant system volume of 10 ml. The measurements were carried out at pH=6.2±0.1 and λ=642 nm.

The data obtained is shown in Fig. 1 and 2, where the ratio of components in the complex is Sm:MAG=1:1.

In FIG. 1 shows the study of the composition of the complex of samarium with MAG by the method of isomolar series, C _Sm = C _MAG =1⋅10 ^-3 M; λ=642.0 nm; pH=6.2; V = 10 ml.

The dependence of the intensity of the luminescence of a solution of the Sm complex on the MAG concentration has been studied. To do this, take 0.5 ml of 1⋅10 ^-3 M samarium solution and various concentrations of 1⋅10 ^-3 M MAG solution, create a medium with pH=6.2±0.1 and remove the relative intensity of luminescence.

The data obtained is shown in Fig. 2., where it can be seen that the luminescence intensity increases to a reagent content of 1.0 ml 1⋅10 ^-3 M in a volume of 10 ml of MAG solution, and then remains practically constant.

Fig. Fig. 2. Dependence of I _lum on the concentration of the reagent (MAH) in the complex Sm - MAG, C _Sm = C _MAG =1⋅10 ^-3 M; λ=642 nm; pH=6.2; V = 10 ml.

With a change in the concentration of the solution, no change in the nature of the luminescence spectrum of samarium is observed, which indicates the formation of a single complex compound in the solution.

The technical result achieved by the invention: lowering the detection limit, increasing the stability, sensitivity and selectivity of the luminescent method for the determination of samarium, where the lower detection limit of Sm with guanidine methacrylate is 5.8×10 ^-9 g/ml Sm.

Claims (1)

Luminescent method for the determination of samarium, including its conversion into a luminescent complex compound with an organic reagent (R), characterized in that guanidine methacrylate (MAG) is used as an organic reagent in the ratios Sm:R=1:1 at pH=6.2±0 ,1 and wavelength λ=642 nm, with the lower detection limit of samarium with guanidine methacrylate is 5.8 × 10 ^-9 g/ml Sm, and to obtain solutions of lanthanide chlorides, their oxides are preliminarily calcined for one hour in a muffle furnace at a temperature of 650 -700°C and cooled in a desiccator, a sample of lanthanide oxides is treated with hydrochloric acid and H ₂ O ₂ according to the calculation of their concentrations, and then the solution is evaporated, then the dry residue of rare earth elements is dissolved in distilled water, then titration is carried out in the presence of urotropine, as an indicator arsenazo I is used, where solutions of Sm and MAG are prepared with the same molar concentration, and mixing them in antibatic ratios from 0.0:1.0 to 1.0:0.0 with a constant system volume of 10 ml, then when irradiated with UV light, red glow, characteristic of samarium ions.

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