RU2485109C1 - Method of extracting 3,4-benz(a)pyrene from soil, bottom deposits and waste water sludge - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of extracting 3,4-benz(a)pyrene, having high toxicity and carcinogenic properties, from soil, bottom deposits and waste water sludge. The method involves mixing the analysed sample in powder form with a liquid extractant in a given volume ratio, heating the obtained mixture with thermal ageing which allows the transfer of 3,4-benz(a)pyrene into the solution, filtering the solution by decantation, adding an extractant of corresponding polarity to the analysed compound, followed by evaporation of the solution to a dry substrate and determining the amount of 3,4-benz(a)pyrene by liquid chromatography. The liquid extractant used is distilled water. Heating and thermal ageing of the obtained mixture are carried out in a sealed reactor and once the 3,4-benz(a)pyrene is transferred into the solution, the reactor is cooled to room temperature.

EFFECT: using a simple technology, the method enables to cut the duration and number of steps of extraction and increases the output of the extracted 3,4-benz(a)pyrene.

5 cl, 5 ex, 2 tbl, 3 dwg

Description

The invention relates to physicochemical processes occurring in tubular reactors in the presence of liquid and solid particles, and can be used in environmental monitoring of soil conditions, bottom sediments and sewage sludge contaminated with 3,4-benz (a) pyrene to determine the extent pollution and taking measures to eliminate them.

Among ecotoxicant substances, polyaromatic compounds (PAHs) take first place in terms of damage to the environment [1]. The main sources of the emission of technogenic PAHs into the environment are the enterprises of the energy sector, automobile transport, the chemical and oil refining industries. Almost all technogenic sources of PAHs are based on thermal processes associated with the burning and processing of organic raw materials: petroleum products, coal, wood, garbage, food, tobacco, etc. The first place in terms of negative impact on the environment and human health is 3.4- benzo (a) pyrene due to its high toxicity and carcinogenic properties.

3,4-benz (a) pyrene has the general structural chemical formula

and is a representative of the class of polycyclic aromatic hydrocarbons (PAHs) - organic compounds, which are characterized by the presence in the chemical structure of three or more condensed benzene rings. The melting and boiling points of 3,4-benz (a) pyrene are 177 ° С and 456 ° С, respectively [1]. This compound has toxic, carcinogenic and mutagenic properties. Its content is about 80% of the total amount of PAHs in contaminated soils. It was established that 3,4-benz (a) pyrene is an indicator of the presence of the entire list of PAHs [2], therefore, its presence is the main indicator of the level of environmental pollution of PAHs. Sources of 3,4-benz (a) pyrene can be caused by natural biochemical and metabolic processes in soils, while its amount does not exceed the maximum permissible concentration (MPC), which is subject to mandatory control and amounts to 20 ng / g for soil [3 ].

Methods for the extraction of PAHs, in particular, 3,4-benz (a) pyrene from soils, are based on the use of organic solvents, re-concentration and heat treatment of the samples under study.

Studies of the extraction of PAHs from soils by various organic solvents (methylene, acetone, mixtures of acetone with hexane) showed that the extraction of PAHs with acetone for 20 min at a temperature of 120 ° C is most effective [4]. For the same purposes, one can use methylene chloride [5], 2-methoxyethanol [6], or a mixture of hexane, methylene chloride and methanol [7]. In the first case [5], the dichloromethanol extract of hardly volatile organic compounds was separated on a silica gel column into a fraction of polar substances and a fraction containing nitroarenes, hydrocarbons, and carbazoles. PAHs were eluted with benzene.

In another known method, alcohol was used as an extractant for PAHs [8], while 25 ml of 2-methoxyethanol was added to 25 mg of soil, the mixture was placed on a rotary shaker and stirred for 15 minutes. After filtration, the obtained extract was separated on a separatory funnel with silica gel and eluted with pentane for subsequent determination by high performance liquid chromatography (HPLC).

Known methods for the extraction of PAHs from the soil using acetone in the Soxhlet apparatus [9]. The share of extraction of the substance under these conditions is insignificant and is equal to 40% of the total PAH content in the soil obtained by hexane extract. In another similar method [10], PAHs are extracted with acetone and purified on a stainless steel column with a chromosphere. The analyzed compounds are eluted from the column for 2 min with a 40:60 mixture of methanol and water with a solvent flow rate of 0.5 ml / min, and then the obtained extract is chromatographed by HPLC.

The methods described above are characterized by a low degree of PAH extraction, laboriousness and require the use of organic solvents in a volume of about 200-400 ml per sample.

A more efficient method is the extraction of polycyclic aromatic hydrocarbons from solid samples (RU 2018110 IPC ⁹ G01N 21/25; 1994-08-15) [11], according to which the crushed sample is poured with benzene to form a mirror, insisted in a dark place for 18 hours, sonication with an oscillation frequency of 18.1 kHz three times for 15 min, the extract is drained and the sample is again filled with benzene, sonicated for 15 minutes, the extraction with benzene and sonication are repeated as for the second time and the combined extracts are evaporated to a volume of 1.0 -1.5 ml in a darkened fume hood at room temperature. From the description of the patent it follows that the completeness of the extraction of PAHs is 100%, which is practically unattainable, since 3,4-benz (a) pyrene quickly degrades within two days of processing. The benzene consumption in this case is up to 200 ml of benzene per 1 sample. The process is time consuming and expensive, since the purchase and disposal of toxic solvent is required.

To extract 3,4-benz (a) pyrene from soils, bottom sediments, and sewage sludge, the most commonly used saponification method is hydrolysis of organic compounds using an ultrasonic bath, hexane extraction, purification by solid-phase extraction and HPLC analysis taken as a prototype of the present invention [4]. The yield percentage of 3,4-benz (a) pyrene is maximum and amounts to 68 ± 2.5% of the total content of 3,4-benz (a) pyrene in the soil with a reduction in extraction time to 11 hours instead of 18-48 hours in other analogues .

The prototype method includes the following five operations:

- mixing the test soil sample in the form of a powder with a liquid extractant in a predetermined volume ratio;

- heating the resulting mixture with temperature exposure, ensuring the transition of 3,4-benz (a) pyrene into the solution;

- filtering the solution by decantation;

- adding the appropriate polarity extractant to the test compound, followed by evaporation of the solution to a dry substrate;

- determination of the amount of 3,4-benz (a) pyrene by liquid chromatography.

To a sample of soil 2.5-40 g are added, as an extractant, corresponding in polarity to 3,4-benz (a) pyrene, 40-60 ml of a solution of KOH in a mixture of sodium hydroxide and water in a ratio of 10: 1 and a solution of internal state standard 3,4-benz (a) pyrene (GSO). The mixture is heated for 1 hour in an ultrasonic bath at a temperature of 65 ° C, this ensures the transfer of 3,4-benz (a) pyrene into the solution, left overnight, extracted again 3,4-benz (a) pyrene from the solution, what is added 25 ml of a 2 molar solution of potassium hydroxide, incubated for another 1 hour in an ultrasonic bath, centrifuged at a speed of 3000 rpm, the liquid is separated over the precipitate, the residue is extracted again with 20-40 ml of methanol. Then all the previous extracts are poured into one flask and shaken for 10 minutes on a rotator with hexane in a volume of 50 ml for 3 hours.

Then, in the fifth stage, the hexane extract is dried over anhydrous sodium sulfate, 100 μl of toluene is added and the extract is concentrated to a volume of 200-300 μl and the content of 3,4-benz (a) pyrene is determined by HPLC.

The disadvantages of the prototype method are as follows:

1. The use of organic solvents in an amount up to 200 ml per sample worsens the ecological state of the environment during disposal.

2. The multi-stage process, representing at least five stages of processing.

3. The processing time is 11-48 hours.

4. The solvents used - hexane, toluene, sodium hydroxide are toxic in direct contact with humans.

5. After extraction of 3,4-benz (a) pyrene partially decomposes in less than a day (rapid destruction), which reduces the accuracy of its determination by HPLC.

6. Insufficiently high yield of 3,4-benz (a) pyrene, constituting 68 ± 2.5% of its total content in the test sample.

The technical result of the claimed invention is to simplify the technology by eliminating the use of organic solvents and alkalis at the stage of extraction of 3,4-benz (a) pyrene from the test sample, reducing the extraction time to 30-40 minutes instead of 11-48 hours, and reducing the number of stages extraction to one stage instead of five, increasing the yield of 3,4-benz (a) pyrene to 96% of the total content.

The specified technical result is achieved by the fact that in the known method for extracting 3,4-benz (a) pyrene from soils, bottom sediments and sewage sludge, comprising mixing the test soil sample in the form of a powder with a liquid extractant in a given volume ratio, heating the resulting mixture with temperature exposure, which ensures the transfer of 3,4-benz (a) pyrene into the solution, filtering the solution by decantation, adding the appropriate polarity extractant to the test compound, followed by evaporation of the solution to dry th substrate and determining the amount of 3,4-benzo (a) pyrene by liquid chromatography.

According to the present invention, distilled water is used as a liquid extractant, heating and temperature exposure of the resulting mixture are carried out in a sealed reactor, and upon completion of the transition of 3,4-benz (a) pyrene to solution, the reactor is cooled to room temperature.

In the particular case of the method:

- the volume ratio of the amount of the test sample and distilled water is 1: 8;

- heating the mixture of the test sample with distilled water is carried out in a temperature range of 240-250 ° C and maintained at this temperature for 30-40 minutes;

- the volume of the sealed reactor is 10 cm ³ ;

- heating the sealed reactor is carried out in an oven.

When the mixture of the test sample with distilled water is heated in a ratio of 1: 8 at a temperature of 230-270 ° C and a holding time of 30-40 minutes in a sealed reactor with a volume of 10 cm ³ , the lipid fraction of the soil, bottom sediments or sewage sludge are oxidized and the maximum transition 3 , 4-benz (a) pyrene in an aqueous solution. This is due to the fact that with an increase in the temperature of distilled water to Т _cr . = 374 ° С and pressure Р = 218 atm, according to the discovery made by academician V.V. Lunin [13], water becomes a unique solvent. In addition, under these conditions, water has a permittivity ε = 34.50 at 200 ° C [14], comparable with ε = 32.63 for methanol at 25 ° C, which leads to almost complete dissolution in water of 3.4 -benz (a) of pyrene from the test sample at specified temperature and time conditions. Given the fame from the prior art of the indicated properties of water, the possibility of its use as a solvent of 3,4-benz (a) pyrene, which is part of the test sample, should not be a priori. It is not obvious that when the mixture of the test sample with distilled water is heated above the boiling point of 3,4-benz (a) pyrene, according to the authors of the present invention, the process of splitting the complex components of the studied soil samples, bottom sediments and sewage sludge intensifies , which leads to an increase in the yield of 3,4-benz (a) pyrene.

The operation of the method is illustrated by the figures of the drawings.

Figure 1 shows a schematic drawing of a device (cross section) used to implement the method.

Figure 2. presents a histogram of the yield of 3,4-benz (a) pyrene,%, from the temperature of extraction, T ° C, for examples 1-5.

Figure 3 shows comparative chromatograms of 3,4-benz (a) pyrene in the soil, obtained by a - saponification method; b - the claimed method.

Table 1 shows the dependence of the yield of 3,4-benz (a) pyrene on the total content in the soil sample, in%, on the extraction temperature, T, ° С with an exposure time of 30, 35, 40 min.

Table 2 shows the comparative technical characteristics of the proposed method, the prototype method (Yaroshchuk A.V., Maksimenko E.V., Borisenko N.I. Development of a method for extracting benz (a) pyrene from soils // News of Universities. North Caucasian region Natural sciences. Appendix. - 2003. - No. 9 - C.44-47) [4] and its analogue (RU No. 2018110 Method for the extraction of polycyclic aromatic hydrocarbons from solid samples) [11].

The method of extraction of 3,4-benz (a) pyrene from soils, bottom sediments and sewage sludge is carried out using the device (Fig. 1), which contains a heating cabinet 1, inside which a sealed reactor 2 is placed, made in the form of a specially made hollow cylindrical stainless steel chambers with a volume of 10 cm ³ , at the ends of which an inlet 3 and an outlet 4 openings are provided, provided with threaded connections 5, 6 through sealed gaskets 7, 8 of the upper 9 and lower 10 caps. Prepared by the standard method (GOST 17.4.4.02-84 Methods of sampling and sample preparation for chemical, bacteriological, helminthological analysis; Introduced 12.19.84.- 9 C.- Group 019) [14]. A sample of soil, bottom sediment or sewage sludge 11 in the form of a powder with a particle diameter of not more than 1 mm is loaded into the sealed reactor 2 through the inlet 3 and distilled water 12 is poured in a ratio of 1: 8. Close the inlet 3 with the top cap 9 and place in a heating cabinet 1, preheated to a temperature of 240-250 ° C, and maintained at this temperature for 30-40 minutes. At this temperature, water goes into a physical state in which it acquires properties similar to an organic solvent and reacts with the particles of the test sample, which causes oxidation of the lipid fraction of the soil, bottom sediments or sewage sludge and a maximum transition of 3,4-benz (a) pyrene in an aqueous solution. The sealed reactor 2 is then removed from the heating cabinet 1 and cooled to room temperature. Unscrew the bottom cap 10 and the resulting solution is transferred by decantation to the filter in the flask. To prepare for liquid chromatography, 3,4-benz (a) pyrene was extracted from the resulting aqueous solution with hexane three times 5 ml each and evaporated to a dry substrate, to which 1 ml of acetonitrile was added and stirred. The amount of 3,4-benz (a) pyrene was determined on a Thermo Separation Product liquid chromatograph, 2000A, US. The content of benzo (a) pyrene in the analyzed samples is calculated by the external standard method (absolute calibration) using standard solutions of various concentrations [15].

The content of benz (a) pyrene in the soil sample is calculated by the formula:

a = k S _I * C _st * 1000 / S _st * m

where, a is the content of benz (a) pyrene, ng / g or μg / kg

S _article S _I - peak areas of benz (a) pyrene standard solution and sample

With _st - the concentration of benz (a) pyrene standard solution, ng / ml

k is the coefficient of extraction of benzo (a) pyrene from the sample

m is the mass of the sample, g

The following are examples of extracts of 3,4-benz (a) pyrene from soils.

Example 1

At the first stage of the method, a sealed reactor 2 containing 1 g of the investigated soil sample with a particle size of 1 mm and 8 ml of distilled water was placed in a heating cabinet at a temperature of 230 ° C and kept at this temperature for 30-40 minutes. In this case, 3,4-benz (a) pyrene is extracted from the soil into the solution. To prepare the solution for liquid chromatography, 5 ml of hexane is added to the resulting aqueous extract to transfer 3,4-benz (a) pyrene from the aqueous solution to hexane and placed on a mechanical shaker for 15 minutes at a speed of 135 shakes per minute. Separation of the layers is carried out in a 50 ml separatory funnel. Since 3,4-benz (a) pyrene is insoluble in water at room temperature, 3,4-benz (a) pyrene is transferred from an aqueous solution to hexane by adding 3 ml of hexane three times in succession. The resulting hexane extracts are combined and passed through a funnel filled with calcined sodium sulfate into a clean dry rotary flask, evaporated on a rotary evaporator with a water-jet pump at a temperature of a water bath of 40 ° C to a dry residue. 1 ml of acetonitrile was added to the obtained dry residue, held for 30 minutes and analyzed by liquid chromatography. The yield of 3,4-benz (a) pyrene with an exposure of 30 minutes was 26.04 ng / g, with an exposure of 35 minutes it was 23.62 ng / g, and with an exposure of 40 minutes it was 22.75 ng / g (example No. 1 table, figure 2).

The identification of 3,4-benz (a) pyrene is carried out by the relative retention times of the standard sample while simultaneously being detected on two detectors (ultraviolet - UV-1000 and fluorescent - FL-3000) with high sensitivity to 3,4-benz (a) pyrene, that allows you to identify the peak of benz (a) pyrene with an error of ± 0.2% (figure 3).

Example 2

A sealed reactor 2 containing 1 g of a test soil sample with a particle size of 1 mm and 8 ml of distilled water was placed in a heating cabinet 1 at a temperature of 240 ° C and kept at this temperature for 30-40 minutes. The yield of 3,4-benz (a) pyrene with an exposure of 30 minutes was 34.02 ng / g, with an exposure of 35 minutes it was 23.62 ng / g, with an exposure of 40 minutes it was 22.75 ng / g (example No. 2 tables, figure 2)

Example 3

A sealed reactor 2 containing 1 g of a test soil sample with a particle size of 1 mm and 8 ml of distilled water was placed in a heating cabinet 1 at a temperature of 240 ° C and kept at this temperature for 30-40 minutes. The yield of 3,4-benz (a) pyrene with an exposure of 30 minutes was 42.00 ng / g, with an exposure of 35 minutes it was 38.50 ng / g, with an exposure of 40 minutes it was 35, 44 ng / g (example No. 3 tables, figure 2).

Example 4

A sealed reactor 2 containing 1 g of a test soil sample with a particle size of 1 mm and 8 ml of distilled water was placed in a heating cabinet 1 at a temperature of 240 ° C and kept at this temperature for 30-40 minutes. The yield of 3,4-benz (a) pyrene with an exposure of 30 minutes was 31.52 ng / g, with an exposure of 35 minutes it was 27.56 ng / g, and with an exposure of 40 minutes it was 23.63 ng / g (example No. 4 tables, figure 2).

Example 5

A sealed reactor 2 containing 1 g of a test soil sample with a particle size of 1 mm and 8 ml of distilled water was placed in a heating cabinet 1 at a temperature of 240 ° C and kept at this temperature for 30-40 minutes. The yield of 3,4-benz (a) pyrene with an exposure of 30 minutes was 21.01 ng / g, with an exposure of 35 minutes it was 19.69 ng / g, with an exposure of 40 minutes it was 15.75 ng / g (example No. 5 tables, figure 2).

As follows from the table, the maximum amount of extracted 3,4-benz (a) pyrene was obtained at an extraction temperature of 250 ° C for 30 minutes. When lowering the water temperature to 230 ° C, the degree of extraction of 3,4-benz (a) pyrene decreases by 38% (example No. 1 of the table). This may be due to a change in the dielectric constant of water, which determines its behavior under these conditions as an organic solvent. As the temperature rises to 260 ° -270 ° C, the degree of extraction of 3,4-benz (a) pyrene decreases and amounts to 50%, which in turn may be associated with the partial decomposition of 3,4-benz (a) pyrene.

As can be seen from the histogram (figure 2), at a temperature of 250 ° C, 96% of 3,4-benz (a) pyrene from its total content in the test sample was extracted from the soil by the claimed method, which, compared with the prototype, represents an increase in yield by 28% .

Table 2 shows the comparative specifications of the proposed method, the prototype method (Yaroshchuk A.V., Maksimenko E.V., Borisenko N.I. Development of a method for extracting benz (a) pyrene from soils // News of Universities. North Caucasus Region Natural sciences. Appendix. - 2003. - No. 9 - C.44-47) [4] and its analogue (RU No. 2018110 Method for the extraction of polycyclic aromatic hydrocarbons from solid samples IPC ⁹ G01N 21/25 from 1994-08-15) [ eleven].

As follows from figure 3, the presence of a peak of 3,4-benz (a) pyrene in the chromatogram "b" indicates the purity of the obtained compound, and accurately characterizes the leaving substance by the exit time t = 20.321 min. Chromatogram “b” is represented by a sharper curve compared to chromatogram “a” and is practically not overloaded with peaks of organic solvents.

Chromatogram “a” is less informative due to overload with trace amounts of solvent, while the release time of 3.4 benz (a) pyrene is shifted to t = 23.138 min. Perhaps that is why the peak of 3,4-benz (a) pyrene is observed 2 minutes earlier than in the corresponding chromatogram "a". Thus, the extraction of 3,4-benz (a) pyrene by the claimed method provides more accurate data for the identification of 3,4-benz (a) pyrene by HPLC than the saponification method.

As follows from table 2:

- extraction of 3,4-benz (a) pyrene by the claimed method is carried out without using an organic solvent at the stage of extracting 3,4-benz (a) pyrene from the soil, and using 15 ml of hexane at the stage of preparing the extract for liquid chromatography. The amount of solvent used at all stages of extraction is reduced by more than 10 times compared with the known analogues and prototype, which significantly reduces the cost of environmental monitoring and the harmful effects on the environment;

- the number of stages of sample processing by the claimed method is reduced to two instead of five stages according to the prototype method and instead of seven in comparison with the analogue;

- the duration of the extraction process by the claimed method was reduced to 0.5 hours instead of 11-48 hours by the prototype method and instead of 18-48 hours in comparison with the analogue;

- the yield of 3,4-benz (a) pyrene by the claimed method is 96%, which is 28% higher compared to the prototype method.

The method of extraction of 3,4-benz (a) pyrene from soils, bottom sediments and sewage sludge can be used in scientific and monitoring studies: when assessing the environmental impact; when assessing degradation changes in the soil; when monitoring the state of soils, as well as natural and man-made ecosystems in general; with environmental regulation of soil pollution and other degradation processes; when creating environmental maps (zoning, factual and forecasting); in predicting the environmental consequences of economic activity in a given territory; in assessing the risk of disasters; in assessing the feasibility and effectiveness of reclamation of soils contaminated with oil and oil products, during environmental impact assessment, certification, certification of the territory or economic facility, etc.

Information sources

1. Gennadiev A.N. Geochemistry of polycyclic aromatic hydrocarbons in rocks and soils / A.N. Gennadiev [et al.] - M.: Moscow State University Publishing House, 1996. - P.196.

2. Ilnitsky A.P. Carcinogenic hydrocarbons in soil, water and vegetation / A.P. Ilnitsky // Carcinogens in the environment. - M .: Gidrometeoizdat, 1975.- P.53-71.

3. GN.2.1.7.2041-06 Maximum allowable concentration (MPC) of chemicals in the soil // Hygienic standards. M .: Federal Center for Hygiene and Epidemiology of Rospotrebnadzor. - 2006. - P.11.

4. Yaroshchuk A.V., Maksimenko E.V., Borisenko N.I. Development of a method for extracting benz (a) pyrene from soils // News of Universities. North Caucasus region. Natural Sciences. Application. - 2003. - No. 9 - S.44-47. - prototype.

5. Barnabas I.J.a. Extraction of polycyclic aromatic hydrocarbons from highly contaminated soils using microwave energy // Analyst, 1995.- v. 120. - No. 7. - P.1897-1904.

6. Warzecha L. The analysis of PAHs nitrogen derivatives in the sewage sludges of upper Silesia, Poland // Chem. Anal. 1993. - No. 3. - v. 38. - P.303-313, 571-573.

7. Aner V, et.al. Innovations in chemical reaction processes using supercritical water: an environmental application to the PAH extraction // Anal Chim. Acta, 1990 .-- v. 237. - No. 2. - P.451-457.

8. Lancar L.T. e.a. Extraction PAH from soils - J. Chim. Phys. Et phys.-chim. Boil, 1999, v. 96, No. 3, p. 352-363.

9. Maseda C.e.a. Alkylation Reactions in Near-Critical Water in the Absence of Acid Catalysts // J. Chromatogr, 1989 .-- v. 490. - No. 2 - P.313-327.

10. Andraves E.F. Organic chemical reactions in supercritical water // J. Chromatogr, 1984. - v. 284. - No. 2. - P. 487-490.

11. RU №2018110 Method for the extraction of polycyclic aromatic hydrocarbons from solid samples IPC ⁹ G01N 21/25 date publ. 1994-08-15.

12. Hartmann R. Subcritical Water Extractor for Mars Analog Soil Analysis Astrobiology // Inst. J. Environment. Anal. Chem., 1996 .-- v. 62. - No. 2. - P.161-173.

13. A.A. Galkin, V.V. Lunin. Water in sub- and supercritical states - a universal medium for the implementation of chemical reactions // Successes in chemistry. - 2005. - T.74. - No. 1. - S.24-40.

14. GOST 17.4.4.02-84 Methods of sampling and sample preparation for chemical, bacteriological, helminthological analysis; Introduced on 12.19.84. - 9 S. - Group 019.

15. Bartulevich, Y., Yagov G.V. Analytical methods for determining PAHs in environmental objects / Ya. Bartulevich, GV Yagov // Drinking water. - 2001. - No. 6. - S.11-14.

Table 1 Dependence of the yield of 3,4-benz (a) pyrene on the total content in the soil sample, in%, on temperature
extraction, T, ° С at an exposure of 30, 35, 40 min Example No. The temperature of extraction, T, ° C Exposure 30 min Exposure 35 min Exposure 40 min The amount of 3,4-benz (a) pyrene, ng / g The yield of 3,4-benz (a) pyrene of the total content,% The amount of 3,4-benz (a) pyrene, ng / g The yield of 3,4-benz (a) pyrene of the total content,% The amount of 3,4-benz (a) pyrene, ng / g The yield of 3,4-benz (a) pyrene of the total content,% one 230 26.04 60 23.62 54 22.75 52 2 240 34.02 78 31.52 72 30.19 69 3 250 42.00 96 38.50 88 35.44 81 four 260 31.52 72 27.56 63 23.63 54 5 270 21.01 48 19.69 45 15.75 36

Comparative technical characteristics of the proposed method, the prototype method (Yaroshchuk A.V., Maksimenko E.V., Borisenko N.I. Development of a method for extracting benz (a) pyrene from soils // News of Universities. North Caucasus Region. Natural Sciences. Appendix. - 2003. - No. 9 - P.44-47) [4] and its analogue (RU No. 2018110) [11].

table 2 No. Technical characteristics of the method The inventive method (subcritical extraction) Prototype (saponification method) [4] Analogue [11] (use of a solvent in combination with ultrasonic extraction) one The amount of organic solvent per test sample, ml fifteen 200 200 2 The number of stages of sample processing, units 2 5 7 3 The duration of the extraction process, per hour 0.5 11-48 18-48 four The yield of 3,4-benz (a) pyrene, in% 96% 68 ± 2.5% one hundred%

Claims (5)

1. The method of extraction of 3,4-benz (a) pyrene from soils, bottom sediments and sewage sludge, comprising mixing the test sample in the form of a powder with liquid extractant in a predetermined volume ratio, heating the resulting mixture with a temperature exposure that ensures a transition of 3.4 -benz (a) pyrene to the solution, filtration of the solution by decantation, addition of an appropriate polarity extractant to the test compound, followed by evaporation of the solution to a dry substrate and determination of the amount of 3,4-benz (a) pyrene by liquid oh chromatography, characterized in that the liquid extractant is distilled water, heating and temperature maintaining the resulting mixture is carried out in a sealed reactor and at the end of the transition 3,4-benzo (a) pyrene in solution the reactor was cooled to room temperature. 2. The method according to claim 1, characterized in that the volume ratio of the amount of the test sample and distilled water is 1: 8. 3. The method according to claim 1, characterized in that the heating of the mixture of the test sample with distilled water is carried out in the temperature range of 240-250 ° C and maintained at this temperature for 30-40 minutes 4. The method according to claim 1, characterized in that the volume of the sealed reactor is 10 cm ³ . 5. The method according to claim 1, characterized in that the heating of the sealed reactor is carried out in an oven.

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