SU1211222A1 - Method of quantitative determination of group composition of petroleum hydrocarbons in sea bottom sediments - Google Patents

Description

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Isgeretenne is not classified as analytical, specifically for methods for quantifying the group composition of petroleum hydrocarbons in marine bottom sediments necessary for the assessment of prospective anticlinal uplifts detected by geophysical methods; research, and searches for the nectilinal type, as well as for assessing the degree of contamination of the sea floors and oceans with oil products in environmental studies.

The aim of the invention is to improve the accuracy of the method by eliminating interfering with the determination of vegetable organics.

The invention is as follows.

Example. Samples of bottom sediments obtained in the process of drilling using vibro-piston tubes are delivered in a wet condition to the ship's laboratory. Samples are dried in the air in the shade, without thermal or ultraviolet exposure, by applying a thin layer of the sample on clean glass plates or thick paper. The dried bottom sediments are ground to a fine powder and sieved through a sieve with 0.25 mm openings. The sample is averaged and a sample of 2 g is taken on an analytical or technical scale of class 1 with an accuracy of hundredths. Sample samples are placed in test tubes with ground-in stoppers 160 mm long and 15 mm in diameter, pour 10 ml of chloroform and vigorously mix on a shaker apparatus for 15–20 minutes with subsequent solution settling above the precipitate. The resulting clear extract in the amount of 5 ml is poured into a test tube 300 mm long, 15 mm in diameter, where a strip of chromatographic paper 32 cm long and 7 mm wide is placed. In this case, use any chromatographic paper of domestic production or imported, for example, FN-15. The cut strips must be preliminarily cleaned from impurities (organic, etc.).

Chloroform evaporates during the analysis and a narrow capillary zone is obtained at the end of the strip, in which the substances present in the studied extract are concentrated. After that, the strip is removed, prosuash222

on the air, with a pencil, mark the znu and cut off 1.5-2.0 cm below the marked area. The color of the luminescence, brightness and width of the luminescent zone on paper reflect the quantitative content and qualitative composition of the extracts obtained. However, the presence of vegetable organics distorts all characteristics. For separation it is used sequential fractionation in solvent systems, i.e. The group composition of the separated extracts (petroleum hydrocarbons) is determined.

The essence of the separation is as follows.

Cut a strip of chromatographic paper with a zone of Hydrocarbons placed in a test tube with ground glass

a stopper with a length of 300 ml and a diameter of 15 mm, at the bottom of which there is 0.3-0.5 ml of solvent. The tube is capped in such a way that the strip of chromatographic paper is in the center, without touching the side walls of the tube in order to avoid edge effects.

As the first solvent, petroleum ether of fraction 40-70, C is used (it separates the zone of oils). When the front of the solvent rises to a height of 29 cm from the start, the strip is removed from the tube and dried in air for 1-2 minutes. The border of the luminescent zone mark

pencil in the ultraviolet region under a fluorescent fluorescent type VIO-1.

As the second solvent, a petroleum system is used.

ether - acetone in the ratio of 9: 1, with the help of which the rise of neutral resins occurs, delaying the organic matter at the start. At the same time, the front of the solvent is raised by

10 mm below the lower edge of the previous zone.

The subsequent components are implemented in the same way.

As a third solvent

using acetone, which from the start entrains organic matter in one zone, located under the zone of neutral (low molecular weight) resins.

To obtain a zone of acidic (high molecular weight oxidized) resins, a solvent system consisting of petroleum ether and chlorine is used.

reform in the ratio of 1: 3. The front of the solvent is raised by 10 mm lower boundaries of vegetable organics. The last zone of asphaltenes remains at the start.

Thus, a chromatogram is obtained, consisting of 5 zones, representing the group composition of petroleum hydrocarbons with the separation of vegetable organic matter, which distorts the quantitative determination of other analysis options.

The quantitative content of each component is determined by comparison with a series of reference collections prepared on the basis of artificial mixtures (oils and vegetable organics obtained from the extraction of algae and other materials).

Artificial mixtures are prepared from pure components — oils, neutral and acidic resins, and asphaltenes obtained by liquid adsorption chromatography in batch columns with a coated sorbent — ASA silica gel and alumina in a 1: 1 ratio.

A 50 g sample of oil was dissolved in a small volume of benzene (3-5 ml) and applied to a column with a sorbent. The lower and upper ends of the columns are covered with taps and stoppers of the upper tank. Within 1 hour, the sample is distributed over the entire length of the sorbent into the column and then eluted with various solvents. Oil washed with petroleum ether to a certain volume. (100 ml with control

lem in terms of the refractive index n not higher than 1.47).

Benzene (neutral) resins are also washed out with petroleum ether with the control of the same parameters, similar to the pre-modifying fraction (1.49-1.50), as well as by the color of the resulting solution from the columns. The appearance of a yellow tinge in the luminescence of the solution allows switching to benzene for leaching of acidic resins. The selection of the fraction is controlled by the nature of the luminescence of the solution in the ultraviolet region (until the yellowish luminescence of the solution disappears) and by the refractive index characteristic of high molecular weight oxidized resins (, 50-1.56). Ac

the B1; 1 faltenes are washed with chloroform until the yellow color of the solution flowing from the column disappears into shale and in the refractive index (, 56– 1.60 and higher).

The results of liquid-adsorption separation of artificial mixtures (various types of oil) are given in Table 2 as an example. one.

In the separation of an artificial mixture prepared from petroleum and vegetable organics, the leaching of plant organics is carried out with acetone after selection of the oil fraction.

The preparation of standards is made on the basis of artificial mixtures, as well as on the basis of extraction of a large amount (volume) of the sample of bottom sediments of the studied objects for different. regions.

To prepare the standards, it is necessary to have a 40 MP solution of each component, from which 20 ml are transferred into constant weight cups or cups. The bottles are placed in a vacuum desiccator and brought to constant weight at 50-55 ° C, or evaporated at room temperature. Based on the weight of each component and the amount of solution taken for evaporation, the concentration of the solution can be calculated. From the second half, by further diluting with 20 ml of the solution, a collection of reference solutions is prepared.

For example, the volume of solution taken for evaporation is 20 ml; the weight of the fraction obtained after evaporation is 0.0122 g; fraction concentration (0.0122 g: 20 ml) 0.00061 g / ml.

From tab. 2 find that the nearest lower figure will be a concentration of 10 references (0.00031 g / ml). Since the concentration is equal to 0.00061 g / ml, in order to obtain a concentration of 10 standard, dissolve in o X chloroform, i.e. i

1 ml - 0.00031 g

 5 5o55T-

X ml - 0.00061 g

To obtain a solution equal to a concentration of 10 standards, for each ml of the solution it is necessary to add 0.9 ml of pure chloroform (1.9 ml - 1.0 ml).

Thus, for a 20 ml component solution, add 18 ml.

 lUfToi o chloroform (20 ml x 0.9) and prepare a reference collection, starting with 10 reference. Then, using the dilution dilution method, the subsequent standards of 5 mp each into the tube are prepared. Next, a strip of chromatographic paper is dipped into each tube until the solution is completely evaporated, and the luminescent zone is measured in the ultraviolet region. Reference collections prepared in this way are used for comparison with the test solutions to determine the contents of each component.

The first three standards (1-3) presented in table. 2, practically lie beyond reproducibility; therefore, in practice, standards are used, beginning with the third, considering it first, and so on. up to the 12th (i.e., the 10th), and operate in the range of these concentrations.

If high concentrations of hydrocarbons are found in natural objects, dilution of the extracts to values corresponding to the specified ranges is used.

The process of separation of extracts of organic matter into fractions with the separation of plant organic matter is carried out sequentially by the above-mentioned methods using different ratios of petroleum ether and acetone: (10-9): 1 and (5-4): 1 (Table 3, 2 - system) .

A comparative analysis of the group composition of petroleum hydrocarbons according to the known and proposed methods is presented in Table. 3

Objects

Group composition of hydrocarbons (artificial mixtures)

Sea of Azov (oil)

KacnralcKoe Sea (oil)

Caspian Sea (oil + vegetative organ.)

The results of separation using ratios of 10: 1 and 4: 1 showed incomplete separation of the resins from the vegetable organic matter, due to the presence of which the contents of the former are distorted. Therefore, the use of other ratios that lie outside the interval (10-4): 1 does not make sense. The optimal ratio, at which the resinous components are completely separated and the results of the analysis are reproduced within the limits of permissible deviations, is 9: 1.

The data presented in Table 3 show that when using the system according to the Il'ina method it is impossible to obtain a quantitative estimate of the group composition of liquid hydrocarbons, besides the contents of asphaltenes. It is possible to estimate the presence of oil fractions only qualitatively by the presence of the stretched zone along with the organic matter. according to the Botneva method, only a fraction of the oil fraction is quantifiable (not accurate). Neutral resins cannot be assessed due to the overlapping of their zone with vegetable organic matter, acidic resins and asphaltenes are quantitatively assessed, but with an underestimation of the former for similar reasons.

The use of the proposed method allows to obtain with reliable accuracy data on the group composition of the hydrocarbon extracts in bottom sediments with the determination of their nature (oil, technogenic, syngenetic, etc.).

Table 1

8.31

3.16

6.05

3.02

6.05

3.04

24.24

Table 2

T system by a known method

my

46 2.92

183.68 10.46

283.68 10.46

385.92 8.06, 38 1.52

1211222

8: Continuation of table 2

T a 6 l and c a 3

0.50

0.50 0.50

0.70 0.63 0.63 0.64 0.37

i system not quantified by a known method

 - Neutral pitches are somewhat understated due to the presence of vegetable organics.

33.33

O watches- 0.08 s overlay

PO zones

on HC

0.50 33.33 l with; n -gl-l

Claims (1)

METHOD FOR QUANTITATIVE DETERMINATION OF THE GROUP COMPOSITION OF OIL HYDROCARBONS IN SEA BOTTOM SEDIMENT- KAH using paper chromatography of a chloroform extract of an analyzed sample in a solvent system including acetone, and luminescent analysis, which consists in that, in order to increase the accuracy of the method, filter paper is sequentially placed first in the chloroform extract of the analyzed sample, then in a mixture of petroleum ether and acetone taken in a volume ratio of 10-4: 1, acetone, a mixture of petroleum ether and chloroform taken in a volume ratio of 5-4: 1 followed by lumine. non -centric analysis of the obtained chro- matogram. ’Io Bf bf