Method chromatographic determination of phenols in wastewater

 

Use: in analytical chemistry of organic compounds, namely in the determination of organic compounds in their joint presence using gas-liquid column chromatography. Can be used for the separate determination of phenols in liquid environments, mainly in industrial effluents, as well as the analysis of natural waters. Essence: the analyzed sample is acidified to pH 1-2 and distilled volatile fraction of phenols together with water vapor. Phenols are extracted and perform gas chromatography detection, using as internal standard creosol. As stationary phase for gas chromatographic detection using silicone oil applied to the polychrome I, and as the mobile phase using nitrogen. Extraction of phenols carried out in diethyl ether or by adsorption-desorption, passing the sample through a column Packed with polystyrene MN-200. The technical result of the invention is to improve detection accuracy while expanding the number of defined phenols. 6 C.p. f-crystals, 2 ill., 3 table.

The invention relates to the field of analytical chemistry organic jidkostey column chromatography, and can be used for the separate determination of phenols in liquid environments, mainly in industrial effluents, as well as the analysis of natural waters.

There is a method of determining monochlorophenols in aqueous media (RU, patent 2142627, G 01 N 30/00, 1999). According to a known method conduct the bromination of monochlorophenols by introducing bromine in the sample, produce brominated flame monochlorophenol extraction concentration with subsequent gas chromatographic detection of the extract.

The disadvantage of this method should recognize the limited scope, as well as its low accuracy.

There is also known a method for determining phenol in the presence of guaiacol in the aquatic environment (RU, patent 2155957, G 01 N 30/00, 2000). According to a known method pass the sample through a chromatographic column filled with a polymer sorbent, pre-treated with a liquid mixture containing tri-n-butylphosphate and dinonylphenol followed by desorption of phenol, and set it decorate physico-chemical methods.

The disadvantage of this method should recognize the limited scope, as well as its low accuracy.

The closest analogue is possible to recognize (RU, patent 2183832, G 01 N 30/00, 2002). the mass of the sample with subsequent extraction preconcentration and gas chromatographic detection, moreover, for the identification of phenols using rate constants of the oxidation reaction of bromo derivatives of phenols.

The disadvantage of this method should recognize the limited scope, as well as its low accuracy.

The technical problem to be solved by the proposed method is to develop a method for determining various phenols in their joint presence in aquatic environments.

The technical result obtained by the implementation of the proposed method is to improve detection accuracy while expanding the number of defined phenols and metal columns.

To achieve the technical result it is proposed to use the method chromatographic determination of phenols in wastewater, the essence of which is provided below. According to the proposed method performed the sampling of waste water, acidifying the sample to pH 1-2, distilled with water vapor fraction volatile with steam phenols extracted fraction of phenols in the extract obtained is injected internal standard, pass the extract through a chromatographic column in which the stationary phase used slightly polar silicone oil with a density of from 0.9 to 2D/chr/176.gif">(In particular, silicone oil PFS-4 or GS - 200), applied to the polychrome I, at the same time as the mobile phase using nitrogen, and as an internal standard cresol (2-methoxy-4-METHYLPHENOL). Extraction of phenols from the sample operate with diethyl ether. The preferred volumetric ratio of phases in the analyzed sample: extractant is from 10:1 to 20:1. Mainly from the extract is distilled off excess diethyl ether. Extraction of phenols from the sample can spend, passing the sample through the column with sorbent followed by desorption fraction of phenols by the carrier gas. In this case, preferably as a sorbent to use nonpolar escaparate sorbents carbon-based or polystyrene, in particular, polystyrene MN-200, Sbeats=1000 m2/g, a pore diameter of 1 nm, and as desorbent - carrier gas, which before the chromatographic column is passed through predalone with the sorbent. Typically, the content by weight of silicone oil is from 2 to 40% by weight of polychrome I. Usually the internal standard injected in the form of a solution of cresol in benzene to a concentration of 5 g/l (benzene used as a solvent for creosol as benzene low volatile compound is diethyl ether).

To validate the proposed method was carried out by chromatography was carried out using a metal column with a length of 3 m and an inner diameter of 3 mm model mixture of phenols, filled with polychrome I as the stationary liquid phase used 5% silicone oil (DC-200) (maximum operating temperature is 240C) on the polychrome I, and as an internal standard creosol, as the connection is resistant to thermal decomposition in the chromatographic column and having the time a lot more than the studied phenols.

In Fig.1 shows the chromatogram of a model mixture of phenolic components with internal standard Kreosotum. The experiment was conducted in the following conditions - volume of sample 3 µl; temperature metal column 150C; the temperature of the flame ionization detector 200C; the temperature of the evaporator 250C; carrier gas - nitrogen 0,14 MPa designation peaks: 1 - phenol; 2 - o-cresol; 3 - n, m-cresol; 4 - guaiacol; 5 - creosol. Table 1 shows the chromatographic separation characteristics (the selectivity coefficient, RS- resolution ratio, t1Rthe time table.1

To determine the correctness of the calculation method for the quantitative content of components according to the area of the corresponding peak in the chromatogram obtained according to the peak areas (S) of the respective components in the chromatogram from the quantitative content in the sample (µg) injected into the chromatograph. The range of changes in the quantitative content model components are introduced into the chromatograph was 0.1-10 μg. Experimental results (table. 2) were processed by the least squares method.

The functional dependence of the form S=a+bC is given in tab.2.

The results show that for all the investigated substances in the used concentration range remains linear relationship between the mass of a substance and the peak area on the chromatogram with a high value of the coefficient of linear correlation. The angular values of the coefficients of this function are comparable in magnitude, however, has been decreasing digital values of this parameter with increasing time of output of a component, which obeys the following equation: S=-15,73 tR+697,7 (r=0,899).

For practical assay developed gathermate pulp and paper mill, the last stage of biological treatment. The resulting aqueous fraction of phenols after acidification to a pH of 1.6 was subjected to three times of extraction with diethyl ether (10 min), the ether extracts were collected, has introduced an internal standard, the excess ether drove in a water bath with the aim of concentrating the sample and chromatographically in the same conditions. In Fig.2 presents typical chromatogram of the investigated wastewater (just analyzed more than 40 samples), the designation of peaks: 7 - phenol; 9 - o-cresol; 10 - n-cresol; 11 - guaiacol; 14 - cresol; peaks marked as 6, 8, 12, 13, 15, 16 - on the chromatogram are not identified.

Calculate the concentration of individual components was performed using the computer program "Z-LAB".

In the quantitative calculations of the content of components in the sample analyzed water was considered that the peak area of internal standard (creosol) on the chromatogram S corresponds to 100 µg substances, and taking into account the volume of sample taken for distillation (i.e., in terms of concentration)where V is the volume of the water samples taken for distillation fraction of volatile phenols.

The obtained data on the composition of samples Arkhangelsk pulp and paper mill wastewater showed that along with the main is by the following values of tR(min) 3,49; 5,12; 10,50; 11,54; 19,24 and 25,59. This fact can be associated: first, using in the process of pulp production stage bleaching with chlorine compounds. These compounds easily form various chlorine substituted derivatives of phenol, which are present in the wastewater, distills water vapor and pass into the ether extraction.

If additional verification of the proposed method was carried out to identify most of the components of the above at times hold using a validated set of mixtures of solutions of chlorinated phenols. The composition and quantity of their content in the wastewater sample are presented in table. 3.

As is well known in the chemical processing of vegetable raw materials components fraction of volatile phenols can undergo redox transformations, the result is often the formation of dimeric structures. These compounds are also capable of Athanasia with water vapor and proceed with the extraction in diethyl ether, for example a component corresponding to a peak of 12.

The qualitative composition and quantitative content of components in the sample wastewater are given in table.3.

Claims

1. Method chromatographic determination of phenols in wastewater, including sampling, extraction of phenols and gas chromatographic detection using an internal standard, wherein the acidifying the sample to pH 1-2, distilled with steam from the acidified sample fraction volatile with steam phenols, from which is extracted phenols as the stationary phase for gas chromatographic detection use silicone oil with a density of 0.9 - 1.1 kg/DM3, the viscosity of 8.5 to 10.2 MPawith and resistant to temperatures up to 240With printed on polychrome I, as a mobile phase using nitrogen, and as an internal standard creosol.

2. The method according to p. 1, characterized in that the extraction of phenols from tests carried out in diethyl ether.

3. The method according to p. 1 or 2, characterized in that the volume ratio of the phases analysed the excess diethyl ether.

5. The method according to p. 1, characterized in that the extraction of phenols from the sample is carried out, passing the sample through the column with sorbent followed by desorption fraction of phenols.

6. The method according to p. 5, characterized in that the sorbent is used polystyrene MN-200, and as desorbent - nitrogen.

7. The method according to any of paragraphs.1-6, characterized in that the injected cresol dissolved in benzene.

 

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FIELD: chemical technology.

SUBSTANCE: invention relates to a method for synthesis of ester perfluorinated derivative by using a chemical reaction. This reaction represents the fluorination reaction of the parent compound as a raw, the reaction of chemical conversion of fragment of ester perfluorinated derivative to yield another ester perfluorinated derivative or the interaction reaction of carboxylic acid with alcohol under condition that at least one or reagent, i. e. carboxylic acid or alcohol, represents a perfluorinated compound wherein indicated perfluorinated derivative of ester represents a compound comprising a fragment of the formula (1):

with a boiling point 400°C, not above. The reaction time for carrying out abovementioned chemical reaction is sufficient to provide the required yield of ester perfluorinated derivative and wherein this yield of ester perfluorinated compound is determined by the gas chromatography method by using a nonpolar column. Also, invention relates to a method for pyrolysis of ester perfluorinated derivative with a boiling point 400°C, not above, to yield the dissociation product wherein this product represents a derivative of acyl fluoride or ketone and wherein pyrolysis time is sufficient to provide the required degree of conversion of ester perfluorinated derivative and wherein the indicated conversion degree of ester perfluorinated derivative is determined by gas chromatography method by using a nonpolar column. Also, invention relates to a method for analysis of ester perfluorinated derivative with a boiling point 400°C, not above, that involves analysis of ester perfluorinated derivative in a sample containing ester perfluorinated derivative by gas chromatography method by using a nonpolar column wherein ester perfluorinated derivative represents compound comprising a fragment of above given formula (1).

EFFECT: improved method of synthesis.

8 cl, 1 dwg, 2 ex

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