The method of determining the total hydrocarbon content in the analyzed mixture

 

Usage: the invention relates to chromatography, is intended to determine the total content of hydrocarbons in the air or in water and can be used to measure the concentration of hydrocarbons in the ambient air, in particular, in the working area sources of industrial emissions, as well as in natural and waste waters as part of environmental monitoring and other studies of environmental objects. Essence: the sample is chromatographically separated detektywa hydrocarbons in the form of the undivided peak flame ionization detector. The selection of the hydrocarbons is carried out in a chromatographic column sorbent, representing hydrated perchlorate magnesium deposited on a chromatographic hard-shelled asiansurvey media. However, the selection of the hydrocarbons is carried out at a temperature of 80-170With and hydrated perchlorate magnesium deposited on the chromatographic media in the maximum withholding their number. For analysis of a liquid sample pre transferred into the gaseous state in the evaporator chromatograph. The technical result of the invention is to provide opportunities for operational and h is, Il., table 2.

The invention relates to chromatography, is intended to determine the total content of hydrocarbons in the air or in water and can be used to measure the concentration of hydrocarbons in the ambient air, in particular, in the working area sources of industrial emissions, as well as in natural and waste waters as part of environmental monitoring and other studies of environmental objects.

In the quantitative assessment of the total content of hydrocarbons used the following methods: gravimetric, infrared spectrophotometry, ultraviolet luminescence, gas chromatography.

Method for determination of hydrocarbons in water by the method of infrared spectrophotometry (1) consists in extracting emulsified and dissolved oil from water by carbon tetrachloride, separating oil from an associated organic compounds of other classes in a chromatographic column filled with alumina and measurement of the mass concentration of oil products by means of IR spectroscopy.

The disadvantage of this method is the use of a specialized expensive abolene total hydrocarbon content in the analyzed test - due to the need for sample preparation errors can occur both in the direction of understating the results of the analysis with the initial use speakers with aluminum oxide and inflated in the prolonged use of a chromatographic column - it can be washed out polar substances. In addition, this method is designed to determine hydrocarbon content only in a liquid medium, and does not apply to gases.

Known chromatographic method for determination of hydrocarbon impurities in the water (2) as the stationary liquid phase supported on a carrier of a chromatographic column, use “doxil”.

However, this method does not allow to determine the presence in the analyzed test light hydrocarbons up to C8and a hydrocarbon, C8+inare defined component-wise, and to determine their total value requires additional processing, which increases the duration of the analysis. In addition, this method also does not allow to handle gaseous samples.

Known application of chromatographic equipment to determine any part of hydrocarbon contamination (for example, aromatic) or the contents of one of the hydrocarbon from traditional sorbents.

The drawback of this method is the length and complexity of the determination of the total content of hydrocarbons due to the determination of hydrocarbon contamination in parts in several stages, the need to prepare appropriate filter media for trapping undetectable in one of the hydrocarbon pollution and the need for further processing of the received data to obtain the total value of all hydrocarbon impurities in the sample gas. The use of such a method is difficult for environmental studies, which often require operational definition it is the total content of hydrocarbon impurities. In addition, this method cannot be applied for analysis of water, because water vapor interfere with the analysis and distort the measurements, due to the malfunction detector.

Closest to the claimed solution is a way of measuring the mass concentration of hydrocarbons in ambient air (4), which includes the introduction of samples were collected in a gas pipette atmospheric air with a stream of pre-purified from hydrocarbons air as a carrier gas in an empty chromatography columns the detector.

Common features of known technical solutions and the proposed method of determining the total hydrocarbon content in the analyzed mixture is the introduction of the sample in gaseous form with the flow of carrier gas into the chromatographic column followed by the detection of hydrocarbons in the form of the undivided peak in a flame ionization detector.

Consider the method of determination of hydrocarbon content has several disadvantages. Due to the use of empty chromatographic column is difficult to maintain stable flow of carrier gas that is necessary to ensure the accuracy and reproducibility of the analysis. In addition, if the analyzed air, in addition to hydrocarbons, organic compounds of other classes (for example, ketones or alcohols) the measurement result is distorted, because the response of the detector are formed, and one peak overlook the responses of all organic substances. When this air is used as carrier gas, requires pre-drying because water vapor when it enters the detector violate his work. Consider the method of determination of hydrocarbon content in the analyzed mixture does not allow to analyze the liquid sample due to nereshennosti rapid and reliable determination of total content of hydrocarbons in the gaseous, and in liquid media.

The technical problem is achieved by a method for determination of total hydrocarbon content in the analyzed mixture, including the introduction of the sample in gaseous form with the flow of carrier gas into the chromatographic column followed by the detection of hydrocarbons in the form of the undivided peak flame ionization detector, the emission of hydrocarbons is carried out in a chromatographic column sorbent, representing hydrated perchlorate magnesium deposited on a chromatographic hard-shelled asiansurvey media.

In addition, the emission of hydrocarbons is carried out at a temperature of 80-170C.

Also for analyzing a liquid sample pre transferred into the gaseous state in the evaporator chromatograph.

In addition, hydrated perchlorate magnesium deposited on the chromatographic media in the maximum withholding their number.

Use in chromatographic column sorbent, representing hydrated perchlorate magnesium deposited on a chromatographic hard-shelled asiansurvey media that allows to stabilize the amount of water vapor that enters the detector it is possible through the evaporator chromatograph to measure out the water, "razmazalas" column, gradually enters the detector without disturbing its operation. Thus, the use of hydrated perchlorate magnesium avoids the need preparation (drying) of a gaseous sample, which provides a high speed of analysis, and analysis of water samples (after moving their gaseous state). Also hydrated perchlorate magnesium reduces the operable surface of the carrier, making it more hydrophilic, so that even heavy hydrocarbons practically do not stay in the column and reach the detector, while polar substances are well trapped on the sorbent due to the formation of adducts or dissolving in it. In addition, as a strong oxidant, hydrated perchlorate magnesium at the temperature of the process in column deep oxidize a variety of organic substances, non-hydrocarbons (e.g., phenols), and they do not interfere with the analysis, even with significant content in the analyzed sample, which increases the reliability and validity of the definition of the total hydrocarbon content in the analyzed sample.

Application of hydrated perchlorate of magnesium on khromatograficheskaya capacity of the column.

The selection of the hydrocarbons at a temperature of 80-170With helps to ensure detection of as the lung, the heavy hydrocarbons in the stability properties of the sorbent.

A preliminary translation of the sample liquid mixture in the gaseous state in the evaporator chromatograph allows to determine the total content of hydrocarbons in liquid environments, namely, in the water.

Hydrated perchlorate magnesium deposited on the chromatographic media in the most held by them amount to give the sorbent maximum hydrophilicity.

The drawing shows a diagram of an apparatus for the chromatographic analysis of the mixture.

Preparation of air for use as the carrier gas is carried out as follows. The air from the diaphragm compressor is served in the gas treatment unit 1 through adsorption cartridge 2 from stainless steel, which is filled with hard-shelled chromatographic media with 10% of Nickel nitrate and placed in a tube furnace 3, which provides the temperature of 600-650C. Nitrate Nickel, degradable under such conditions to oxide, provides deep cleaning of air from organic substances. In the preparation unit 1 woitke or sampler through the inlet 5. Next, analyze the air with the flow of carrier gas passes through the evaporator 6 (for the analysis of gaseous samples evaporator is switched off when the analysis of liquid samples, the evaporator is heated to 200-350C, where the liquid evaporates and enters the chromatographic column 7 length of 1-2 m, located in thermostat 8 at 80-120C. Column 7 filled chromatographic carrier with a specific surface area of 2-5 m2/g coated from water or methanol-hydrated perchlorate magnesium. As the carrier can be used symalit, chromo-sorbitol - W, chromo-sorbitol - G celite - 554, chromatin-N, spirogram - 1, program etc. On each carrier depending on the brand is applied from 5 to 30% stationary liquid phase in the maximum withholding their number. Check hydrocarbons is a flame ionization detector 9.

To determine the total content of hydrocarbons in a gaseous environment took State standard (GSO) with a known concentration of methane in nitrogen (air) and perform the analysis on the chromatograph Shimadzu GC-4C PTF. At the same time as the carrier gas used air, catalytically purified in the reactor at a temperature of 610S; the speed of the carrier gas is 80 cm3/min, the Sample was injected into the chromatograph through a tap-dispenser in the amount of 1 cm3. Peak hydrocarbon recorded a flame ionization detector and recorded on a chart recorder, the calculation of the square was performed automatically on the integrator Shimadzu Chromatopac - 4V.

The chromatography was carried out tests were performed 3 times and calculated the average value of a given square. The calculation result performed by the method of absolute calibration.

Also analyzed data from GSO by the method (4).

Comparative results of the content of hydrocarbons is presented in table 1.

As can be seen from the above results, the values of hydrocarbons in gaseous media in the analysis of the proposed method gives more accurate data, as well as the proposed method has a higher detection limit compared to the prototype. However, the duration of analysis as the proposed method and by well-known methods (4) was of the order of 5-10 minutes.

To determine the total content of hydrocarbons in the aquatic environment took Goudarzi on the chromatograph Shimadzu GC - 4C PTF as well as for gaseous media, with some modifications: the temperature of thermostat was increased to 110With, and joined the staff of the evaporator 6 chromatograph, the evaporator temperature was set to 200C.

The sample without prior preparation in quantities of 1 µl was injected into the chromatograph evaporator by microprism.

Also analyzed data from GSO method X (1).

Comparative results of oil (hydrocarbon oil) are presented in table 2.

As can be seen from the above results, the values of the content of petroleum hydrocarbons in aquatic environments, obtained using the proposed method are close to the true values, although the analysis method X gives a somewhat more accurate data. However, the proposed method for determination of total hydrocarbon content does not require lengthy sample preparation. Duration analysis of one sample is about 10 minutes, while the analysis time per sample, method X is 3.5 hours. The accuracy and reliability of determination of total hydrocarbon content of the proposed method meets the metrological requirements, prednosti rapid and reliable determination of total content of hydrocarbons in the gaseous, and in liquid media.

Bibliography

1. “Method for determination of mass concentration of oil products in natural and waste waters by the method of X”, PND f 14.1:2.5.11-95, M, Gascom of the Russian Federation on environmental protection, 1995

2. Drugov Y. C. “Environmental analytical chemistry”, - M., 2000, S. 95-98.

3. “Methods of measurement of mass concentration of saturated hydrocarbon, C1-C10(total), unsaturated hydrocarbons With2-C5(total) and aromatic hydrocarbons (benzene, toluene, ethylbenzene, xylenes, styrene) at their joint presence in the ambient air, the air of the working zone and the industrial emissions by gas chromatography”, LIM f 13.1:2:3.25-99, M, Gascom of the Russian Federation on environmental protection, 1999

4. “Methods of measurement of mass concentration of hydrocarbons in the atmospheric air, the air of the working zone and the industrial emissions by chromatography”, LIM f 13.1:2:3.11-97, Gascom of the Russian Federation on environmental protection, M., 1997

Claims

1. The method of determining the total hydrocarbon content in the analyzed mixture, including the introduction of the sample in gaseous form with the flow of carrier gas in chromatography the second detector, characterized in that the separation of the hydrocarbons is carried out in a chromatographic column sorbent, representing hydrated perchlorate magnesium deposited on a chromatographic hard-shelled asiansurvey media.

2. The method according to p. 1, characterized in that the separation of the hydrocarbons is carried out at a temperature of 80-170C.

3. The method according to p. 1, characterized in that for the analysis of a liquid sample pre transferred into the gaseous state in the evaporator chromatograph.

4. The method according to p. 1, characterized in that the hydrated perchlorate magnesium deposited on the chromatographic media in the maximum withholding their number.

 

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FIELD: analytical instrumentation engineering; chromatographic analysis of composition of substances.

SUBSTANCE: proposed method includes delivery of carrier gas to evaporation chamber through gas supply line, introduction of sample into evaporation chamber, delivery of part of gas flow from evaporation chamber to chromatographic column and discharge of remaining of gas flow to atmosphere. Delivery of carrier gas to evaporation chamber is effected in direction opposite to motion of evaporated sample to chromatographic column. Device proposed for introducing the sample into chromatograph has sample introducing line, evaporation chamber, chromatographic column, carrier gas supply and carrier gas discharge line which are connected with evaporation chamber. Carrier gas discharge line is connected with evaporation chamber in area of introduction of sample and carrier gas supply line is connected with opposite end of evaporation chamber.

EFFECT: enhanced accuracy of dosing the sample; improved quality of separation of components; enhanced reliability; simplified construction.

11 cl, 3 dwg

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