阅读说明：本技术 一种气相色谱法检测气体中乙烯的方法 (Method for detecting ethylene in gas by gas chromatography ) 是由 桑运普 牛军舰 孙斌 丛明日 高丽 于 2019-12-05 设计创作，主要内容包括：本发明公开了一种气相色谱法检测气体中乙烯的方法,属于环境中气体检测技术领域,本发明气相色谱法检测气体中乙烯的方法包括样品采集、标准曲线的绘制、气相色谱分析等步骤,本发明的气相色谱检测乙烯的方法操作简单,灵敏度高,采用本发明方法检测乙烯的精密度为0.24％,准确度为104％,检出限为0.07ppm,定量限为0.21ppm。(The invention discloses a method for detecting ethylene in gas by gas chromatography, which belongs to the technical field of gas detection in the environment, and comprises the steps of sample collection, standard curve drawing, gas chromatography analysis and the like.)

1. A method for detecting ethylene in gas by gas chromatography is characterized in that: the method comprises the following steps:

(1) collecting gas to be detected at a sampling site by using a glass injector, cleaning the glass injector for at least 3 times by using sample gas in advance, immediately sealing the injector by using an inert bee head after sampling is finished, and storing the injector in a sample storage box until the sample is analyzed;

(2) the sampling container injected with the high-purity nitrogen is taken to a sampling site, and is sent back to a laboratory for analysis together with sample instruments collected in the same batch so as to verify whether the transportation process is polluted or not;

(3) using a 100mL glass syringe as a container, and performing the following steps of 1: 1, diluting ethylene standard gas by high-purity nitrogen step by step to prepare at least 4 calibration series of concentration gradients;

(4) sequentially injecting 1mL of standard series concentration points into a gas chromatograph from low concentration to high concentration, measuring the response value of each standard series concentration point, and drawing a calibration curve by taking the concentration of each series concentration point as a horizontal coordinate and the peak area of each concentration point as a vertical coordinate;

(5) analyzing 1mL of sample to be detected according to the operation steps and conditions which are the same as those for drawing the calibration curve, and determining the peak area of ethylene in the sample; and substituting the peak area corresponding to the sample into a calibration curve, and calculating the content of ethylene in the sample.

2. The method of claim 1 for detecting ethylene in a gas by gas chromatography, wherein: the gas chromatographic analysis conditions are as follows: sample inlet temperature: 180 ℃; column temperature: 90 ℃; detector temperature: 180 ℃; carrier gas: high-purity nitrogen; combustion gas: high-purity hydrogen; combustion-supporting gas: high purity air; sample introduction amount: 1.0 mL.

3. A method for detecting ethylene in a gas by gas chromatography as claimed in claim 1 or 2, characterized in that: the chromatographic column in the gas chromatograph is a packed column made of stainless steel or hard glass, 2m multiplied by 4mm, polyethylene glycol 20000: dibutyl phthalate: GDX support 1:5: 36.

4. A method for detecting ethylene in a gas by gas chromatography as claimed in claim 3, wherein: the GDX carrier is GDX-502 or GDX-104, and the particle size is 60-80 meshes.

5. Use of the method of any one of claims 1 to 4 for the detection of ethylene in a gas by gas chromatography in the measurement of ethylene content in stationary pollutant-derived organic waste gas, ambient air, indoor air, public places.

Technical Field

The invention belongs to the technical field of gas detection in the environment, and particularly relates to a method for detecting ethylene in gas by using a gas chromatography.

Background

Ethylene (ethylene) the simplest olefin, formula C₂H₄. Is a metabolite of plant and is present in small amount in plant bodyThe growth is slowed down, and the leaf fall and the fruit ripening are promoted. A colorless flammable gas. Melting point-169 ℃ and boiling point-103.7 ℃. Hardly soluble in water, hardly soluble in ethanol, and easily soluble in diethyl ether and acetone.

Ethylene belongs to one of volatile organic pollutants (VOCs) and is the most main factor causing air pollution and harming human health in indoor environment; ethylene belongs to a low-toxicity substance, has simple asphyxia and strong anesthetic action, and can cause dizziness, hypodynamia, general discomfort and inattention after being contacted for a long time. In addition, the ethylene content in the closed environment reaches a certain degree, and the closed environment has the danger of combustion and explosion when being heated or exposed to fire. At present, the method for detecting ethylene in air is mainly a gas chromatography detection method, and the existing method for detecting ethylene by gas chromatography has the problems of high detection limit, complex operation, unstable result and the like.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a method for detecting ethylene in gas by using gas chromatography, which has the advantages of simple operation, accurate result and low detection limit.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a method for detecting ethylene in gas by gas chromatography comprises the following steps:

(1) collecting gas to be detected at a sampling site by using a glass injector, cleaning the glass injector for at least 3 times by using sample gas in advance, immediately sealing the injector by using an inert bee head after sampling is finished, and storing the injector in a sample storage box until the sample is analyzed;

(2) the sampling container injected with the high-purity nitrogen is taken to a sampling site, and is sent back to a laboratory for analysis together with sample instruments collected in the same batch so as to verify whether the transportation process is polluted or not;

(3) using a 100mL glass syringe as a container, and performing the following steps of 1: 1, diluting ethylene standard gas by high-purity nitrogen step by step to prepare at least 4 calibration series of concentration gradients;

(4) sequentially injecting 1mL of standard series concentration points into a gas chromatograph from low concentration to high concentration, measuring the response value of each standard series concentration point, and drawing a calibration curve by taking the concentration of each series concentration point as a horizontal coordinate and the peak area of each concentration point as a vertical coordinate;

(5) analyzing 1mL of sample to be detected according to the operation steps and conditions which are the same as those for drawing the calibration curve, and determining the peak area of ethylene in the sample; and substituting the peak area corresponding to the sample into a calibration curve, and calculating the content of ethylene in the sample.

On the basis of the scheme, the gas chromatographic analysis conditions are as follows: sample inlet temperature: 180 ℃; column temperature: 90 ℃; detector temperature: 180 ℃; carrier gas: high-purity nitrogen; combustion gas: high-purity hydrogen; combustion-supporting gas: high purity air; sample introduction amount: 1.0 mL.

On the basis of the scheme, a chromatographic column in the gas chromatograph is a packed column, is made of stainless steel or hard glass, and is 2m multiplied by 4mm, and the polyethylene glycol 20000: dibutyl phthalate: GDX support 1:5: 36.

On the basis of the scheme, the GDX carrier is GDX-502 or GDX-104, and the particle size is 60-80 meshes.

The method for detecting ethylene in gas by gas chromatography is applied to the measurement of ethylene content in fixed pollution source organic waste gas, ambient air, indoor air and public places.

The technical scheme of the invention has the advantages that:

the method for detecting the ethylene by the gas chromatography is simple to operate and high in sensitivity, and the precision of the ethylene detected by the method is 0.24%, the accuracy is 104%, the detection limit is 0.07ppm, and the quantification limit is 0.21 ppm.

The chromatographic column of the invention adopts polyethylene glycol 20000, dibutyl phthalate and GDX carrier, and the combination of the polyethylene glycol 20000, dibutyl phthalate and GDX carrier can reduce the influence of other low molecular weight olefins or alkanes in the air on the ethylene detection of the invention, improve the detection sensitivity and reduce the detection limit.

Drawings

FIG. 1 blank sample chromatogram;

FIG. 29.86 ppm ethylene chromatogram;

FIG. 312.3 ppm ethylene chromatogram;

FIG. 419.7 ppm ethylene chromatogram;

FIG. 522.2 ppm ethylene chromatogram;

FIG. 649.3 ppm ethylene chromatogram;

FIG. 7 ethylene calibration curve.

Detailed Description

Terms used in the present invention have generally meanings as commonly understood by one of ordinary skill in the art, unless otherwise specified.

The invention adopts the following steps:

high-purity nitrogen gas: the purity is more than or equal to 99.99 percent, and no ethylene peak and other miscellaneous peaks are detected on a gas chromatograph.

Ethylene standard gas: ethylene standard gas with a certificate is purchased as required, and the concentration of the standard gas used in the test is 49.3 ppm.

Hydrogen gas: the purity is more than or equal to 99.99 percent.

The present invention will be described in further detail with reference to the following data in conjunction with specific examples. The following examples are intended to illustrate the invention and are not intended to limit the scope of the invention in any way.