SU1718073A1 - Method of determination of copper - Google Patents

Abstract

The invention relates to analytical chemistry, in particular to methods for determining copper using the electron paramagnetic resonance method, and can be used in determining impurity amounts of copper in zinc, cadmium, mercury and in their compounds. The aim of the invention is to increase the sensitivity of the determination of copper in zinc, cadmium, mercury and in their compounds. Before transferring to the diethyldithiocarbamate complex, a copper isotope label is introduced into the sample to be analyzed. The high-field components of copper-63 and copper-65 are recorded, the isotopic composition is determined by their amplitudes, and the copper content is calculated from the change in the isotopic composition of the label. 1 tab.

Description

This invention relates to analytical chemistry, and specifically to methods for determining copper using electron paramagnetic resonance (EPR). and can be used in determining the impurity amounts of copper in zinc, cadmium, mercury and in their compounds.

The aim of the invention is to increase the sensitivity of the determination of copper in zinc, cadmium, mercury and in their compounds.

A small, precisely known amount of one of the copper isotopes (copper-63 or copper-65) of a high degree of isotopic enrichment is fed into the analyzed sample. The sample is then analyzed by treatment with an aqueous solution of sodium diethyldithiocarbamate is converted into a diethyldithiorcarbamate complex, its EPR spectrum is recorded, and the copper isotopic composition is calculated from the amplitudes of the high-field components of the spectrum. Since the isotopic composition of the isotope used

the labels are known in advance, comparing the values of the initial isotopic composition and experimentally measured in the analyzed sample. It is not difficult to calculate the amount of copper present in the analyzed sample (with the natural isotopic composition: copper-63 {69.17 at.%) and copper-65 (30.83 at. %). resulting in observed change in isotopic composition.

The copper isotope tag is introduced into the solution of the analyzed sample containing zinc, cadmium and mercury (Me) in the ratio of Cu: Me 1: 5000.

The increase in sensitivity is due to the fact that the isotope of copper, which is present in the isotopic label as an impurity, is very sensitive to small amounts of natural copper.

Example 1. A weighed portion (300 mg) of zinc sulfate heptahydrate is taken and dissolved in 50 cm of distilled water. Then take the sample (4.2 mg) dihydrate chloride media With

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63 (copper isotopic purity - 63 - 99.3 g at.%), Dissolved in 100 cm of water and 0.75 cm of the obtained solution of copper salt is fed to a solution of zinc salt. Prepare a solution of 500 mg of sodium diethyldithiocarbamate in 50 cm3 of water. Next, the solutions of sodium zinc salt and diethyldithiocarbamate are drained, as a result of which the metal cations precipitate into the diethyldithiocarbamate complex. The precipitate is washed and dried. 50 mg of the complex are poured into the ampoule, placed into the resonator of the radio spectrometer, and the EPR spectrum is recorded 6 times. From the amplitudes of the high-field components of the peak of additional absorption caused by copper-63 and copper-65 isotopes, the isotopic composition of copper in the analyzed sample is calculated. It turned out that the content of copper-65 increased from 0.7 to 4.92 at.%. Then the copper content corresponding to the observed isotopic shift in the analyzed sample is calculated. Example 2. A weighed portion of metallic mercury (184.65 mg) was taken and dissolved in 3 cm of nitric acid. Next, a weighed portion (4.2 mg) of copper-63 chloride dihydrate (copper is-63 is 99.3 at.%) Is dissolved in 100 cm3 of distilled water and 0.5 cm3 of the copper salt solution is fed into the mercury salt solution. Prepare a solution of 500 mg of sodium diethyldithiocarbamate) in 50 cm3 of water. Then the solutions of mercury salt and sodium diethyldithiocarbatemate are drained. The precipitate is washed, filtered and dried. Next, 65 mg of the complex is poured into the ampoule and the EPR spectrum is recorded 6 times. In the amplitudes of the high-field components of the peak of the additional absorption due to

copper isotopes, calculate the isotopic composition of copper in the analyzed sample. It is established that the content of copper-65 increased from 0.7 to 3.55 at.%. Then calculate the copper content (with natural isotopic composition) in the analyzed sample, corresponding to the observed isotopic shift.

The table shows the results of statistical processing of the obtained data.

Thus, the invention allows for the simple, accurate and rapid determination of impurity amounts of copper in zinc, cadmium, mercury and their compounds. Compared with the known method, the sensitivity of the determination of copper in zinc, cadmium, mercury and their compounds is improved.

Claims (1)

The formula invented is the Method of copper determination, including the dissolution of the sample being analyzed, the addition of sodium diethyldithiocarbamate, the precipitation, the drying of the dithiocarbamate complex of copper, the registration of its EPR spectrum, so that it is possible to increase the sensitivity of the determination of copper in zinc, cadmium, mercury (Me) and in their compounds, a copper isotope tag is preliminarily added to the solution of the sample to be analyzed in a Cu: Me ratio of 1: 5000, the amplitudes of the high-field components of copper-63 and copper-65 are determined in SpectrRPR, the isotopic composition, and the copper content is determined by the change in the isotopic composition of the label.