RU2129454C1 - EXTRACTANT COMPOSITION FOR EXTRACTION OF β-CHLOROVINYLARSINE OXIDE FROM SOIL SAMPLES - Google Patents

Abstract

FIELD: analytical methods. SUBSTANCE: composition contains carbon dioxide in supercritical state (92-96 vol %) and methanol. Method can by applied in environmental monitoring. EFFECT: increased yield of extraction and reduced extraction time. 2 tbl, 9 ex

Description

 The invention relates to the field of research and analysis of materials by separation into components and can be used in analytical chemistry to isolate β-chlorovinylarsine oxide from soil samples, as well as in environmental and environmental monitoring.

 Russia, having signed the Convention on the Prohibition of Chemical Weapons in 1993, has undertaken to completely eliminate its stockpiles of toxic substances. One of the main toxic substances of the skin-boiling effect, which is subject to destruction, is β-chlorovinyl dichlorarsin (lewisite). It is known that lewisite almost instantly reacts with water, forming a poorly soluble and toxic compound - chlorovinylarsine oxide (Savin Yu.N., Vishenkova E.M., Pasynkova E.M. Zh. Ros. Chemical island named after D.I. Mendeleev, 1995, v. 39, No. 4, pp. 121-125; Karlsson E., Ruin P., Winter S. Ibid., Pp. 79-88; Alexandrov V.N., Emelyanov V.I. Poisoning substances M.: Military Publishing, 1990, 272 p.).

 Ecological and analytical aspects of the problem of destruction of toxic substances of skin-boiling effect, and in particular lewisite, imply comprehensive monitoring of the activities of chemical weapons destruction facilities, daily assessment of the state of various environmental objects in the storage and destruction of chemical weapons.

 To extract chlorovinylarsonic acid from water, a sample (5 ml) was added to a 10 ml glass tube equipped with a teflon seal screw stopper, 0.5 ml of a 0.01% (vol.) Solution of 1,3-propanedithiol in hexane was added. The solution was continuously shaken for 1 h, then the hexane layer was separated and subjected to chromatographic analysis. The degree of extraction of chlorovinylarsonic acid is not more than 60% (Elbro T., Durst D., Simak R. Zh. Ros, chemical island named after D.I. Mendeleev, 1995, v. 39, No. 4, p. 125 -128).

To extract lewisite from the soil, if necessary, the sample was ground, thoroughly mixed with a glass spatula, 10-20 g of the test material were taken, transferred to a conical flask and 15-20 ml of solvent was added (petroleum ether, ethyl alcohol, water). The flask was closed with a stopper, the contents were thoroughly mixed, placed in a water bath with a temperature of 35-40 ^o C and kept for 10 minutes with periodic stirring. The resulting extract was filtered through a paper filter previously moistened with the solvent used. If the extract was obtained less than 15 ml, an additional half amount of solvent was added to the same part of the sample, and the extraction operation was repeated. The obtained extracts were combined and used for analysis. In some cases, when extracting lewisite from soil samples, the extracts were colored. To bleach the colored extracts, powdered birch activated carbon (BAU) was used. To do this, 8-10 ml of the extract was poured into a test tube, 0.5 cm ^{3 of} coal was added with a measuring device, and after stirring, it was heated in a water bath until the solution boiled. The hot solution was quickly filtered through a paper filter and analyzed in accordance with the "Guide ..." designed to analyze infected samples of water, air, soil, vegetation, food, fodder, nuclear explosion products or taken from various shells (shells, bombs), containing toxic substances (Manual for work in the automotive radiometric and chemical laboratories AL-4M. M: Military Publishing House, 1980).

 To extract β-chlorovinylarsine oxide, 5 g of soil was introduced into a 10 ml glass tube equipped with a screw plug with teflon seal, 5 ml of water (electrical resistance 18 Ohm) was added and the mixture was adjusted to pH 2.0 by dropwise addition of hydrochloric acid. The tube with the contents was continuously shaken for 1 h, after which it was kept for 1 min in a centrifuge until a distinctly visible liquid layer formed above the soil. Using a calibration pipette, 3 ml of the aqueous layer was transferred to another glass tube equipped with a stopper, then 0.5 ml of a 0.01% (vol.) Solution of 1,3-propanedithiol in hexane was added. The solution was continuously shaken for 1 h, then the hexane layer was separated and subjected to chromatographic analysis. The degree of extraction of β-chlorovinylarsine oxide was not more than 60% (Elbro T., Durst D., Simak R. Zh. Ros. Chemical island named after D.I. Mendeleev, 1995, v. 39, No. 4, p. 125).

 This composition of the extractant for the extraction of β-chlorovinylarsine oxide from soil samples is the closest to the claimed and is considered by us as a prototype.

 With all the undoubted advantages (the ability to extract β-chlorovinylarsine oxide), the prototype has, however, a number of disadvantages, the main of which should be considered the duration of the extraction process and the insufficient completeness of extraction.

 The objective of the invention is to increase the degree of extraction and decrease the time of extraction of β-chlorovinylarsine oxide from soil samples.

The objective is achieved by the use of an extractant consisting of supercritical carbon dioxide and methanol in the following ratio of ingredients, vol.%:
Supercritical Carbon Dioxide - 92-96
Methanol - Else
To confirm the possibility of carrying out the invention, 1 g of soil was infected with 0.2 ml of a solution of β-chlorovinylarsine oxide with a concentration of 5 mg / ml. The extraction of β-chlorovinylarsine oxide from the soil was carried out by the claimed extractant (10 ml) using a Suprex SFE supercritical fluid extractor under the following conditions:
Pressure in the system, atm. - 350
Thermostat temperature, ^o C - 65
Trap temperature, ^o C - 0
Desorption temperature, ^o C - 40
Back pressure device temperature, ^o C - 80
The time of the static stage, min - 20
The flow rate of carbon dioxide, ml / min - 1
The final volume of methanol extract, ml - 1
The analysis was carried out on an HP 1090 liquid chromatograph (series 2), using an HP ODS hypersil stainless steel column (5 μm; 100 • 2.1 mm). The degree of extraction was 82%.

Example 1. To extract β-chlorovinylarsine oxide, a soil sample (1 g) contaminated with a substance was placed in an extraction vessel of a supercritical extractor and extracted with 10 ml of a mixture, vol.%:
Supercritical Carbon Dioxide - 94
Methanol - Else
Under the above analysis conditions, the degree of extraction under these extraction conditions was 82%.

Example 2. The conditions for the extraction are the same, while the extractant has the following composition, vol.%:
Supercritical Carbon Dioxide - 92
Methanol - Else
The degree of extraction was 82%.

Example 3. The conditions for the extraction are the same, while the extractant has the following composition, vol.%:
Supercritical Carbon Dioxide - 96
Methanol - Else
The degree of extraction was 82%.

 Examples 4 to 9. The conditions for the extraction are similar to example 1, but the extraction of chlorovinylarsine oxide from soil samples is carried out by varying the composition of the extractant. Data on the time of extraction and the degree of extraction of β-chlorovinylarsine oxide from soil samples are presented in table. 1.

 An analysis of the results shows that the greatest degree of extraction of β-chlorovinylarsine oxide from soil samples is achieved by using an extractant of the following composition (vol%): carbon dioxide in a supercritical state - 92-96; methanol - the rest. Deviation from the above ratios of carbon dioxide and methanol leads to a decrease in the degree of extraction of β-chlorovinylarsine oxide (examples 4-9).

 Comparative characteristics of the claimed composition of the extractant and prototype are presented in table. 2.

 The data table. 2 indicate a clear advantage of the claimed composition of the extractant for the extraction of β-chlorovinylarsine oxide from soil samples consisting of supercritical carbon dioxide and methanol in the following ratio of ingredients, vol.%, 92-96: the rest, before the prototype.

 Using the proposed composition of the extractant allows to increase the degree of extraction of β-chlorovinylarsine oxide to 82% and to reduce the extraction time by 2 times compared with the prototype, and also helps to achieve greater productivity with a possible mass analysis of environmental pollution (16 samples in 1 working day).

Claims (1)

The composition of the extractant for the extraction of β-chlorovinylarsine oxide from soil samples, characterized in that they use a mixture consisting of supercritical carbon dioxide and methanol in the following ratio of ingredients, vol.%:
Supercritical carbon dioxide - 92 - 96
Methanol - Else

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