CN111239234B

CN111239234B - Non-radioactive method for on-line monitoring of ammonia gas

Info

Publication number: CN111239234B
Application number: CN201811443928.1A
Authority: CN
Inventors: 李海洋; 厉梅; 黄卫; 陈红; 蒋丹丹
Original assignee: Dalian Institute of Chemical Physics of CAS
Current assignee: Dalian Institute of Chemical Physics of CAS
Priority date: 2018-11-29
Filing date: 2018-11-29
Publication date: 2023-04-07
Anticipated expiration: 2038-11-29
Also published as: CN111239234A

Abstract

The invention discloses a non-radioactive device and a non-radioactive method for quickly, accurately and continuously monitoring ammonia gas. The invention utilizes the nonradioactive ion mobility spectrometry of the photo-ionization assisted by the reagent molecules, selects butanone as the reagent molecules in the positive ion mode, and realizes the rapid, accurate and high-sensitivity online measurement of ammonia gas. The detection device comprises: floating gas, carrier gas, a reagent molecule generating device, an ion mobility spectrometry system, a pump and the like.

Description

Non-radioactive method for on-line monitoring of ammonia gas

Technical Field

The invention belongs to the technical field of ion mobility spectrometry. The method utilizes the non-radioactive vacuum ultraviolet lamp ion mobility spectrometry, adopts air-breathing sampling in a positive ion mode, and initiates a chemical reaction by optimizing and screening reagent molecules and paraxylene, thereby improving the sensitivity and selectivity of ammonia detection and realizing the rapid and accurate online monitoring of ammonia.

Technical Field

Ammonia gas is a colorless, strongly pungent inorganic gas, is very soluble in water, is a Lewis base, and exists in both human bodies and the environment.

In the human body, ammonia gas has an important role and is considered to be an important exhaled breath biomarker. The main sources of ammonia in the human body include: deamination of amino acids, the majority of amino acids in the kidney are transaminated with α -ketoglutarate by glutaminase to form glutamate. In addition, ammonia can also be produced by purine and pyrimidine compounds metabolism; ammonia gas is also produced by the decomposition of amino acids in food by intestinal bacteria and by monoamine oxidase. Ammonia is absorbed at the porta hepatis and is separately converted to urea in the liver by urea circulation. Part of the ammonia gas is also discharged out of the body in the form of exhaled breath. In fact, ammonia is a harmful gas, which is transformed into harmless substances in the liver and kidney, and causes functional disorders in these organs when ammonia in blood is not normally filtered out. Ammonia also can damage the nervous system, causing hepatic encephalopathy. As the ammonia content of the blood increases, it can diffuse into the lungs and be expelled in the form of exhaled breath. It has been found that the ammonia gas in exhaled breath is associated with many diseases, such as renal failure, asthma, infection with helicobacter pylori, halitosis, etc.

In the environment, ammonia is the only high-concentration alkaline gas in the atmospheric environment, can react with sulfur dioxide, nitrogen oxide and volatile organic compounds VOCs and generate aerosol particles, thereby influencing the global radiation balance, being an important reason for the formation of secondary particles in the aerosol haze pollution process, and being capable of causing the eutrophication of rivers and lakes.

Therefore, the detection of ammonia gas has important significance in human disease diagnosis, atmospheric quality detection and the like.

The main instruments and methods currently used for detecting ammonia gas are Mass Spectrometry (MS), gas chromatography-mass spectrometry (GC-MS), spectroscopy, such as cavity ring-down spectroscopy (CRDS), acousto-optic spectroscopy (PAS), chemical sensors, and the like. The detection limit of mass spectrometry and GC-MS can reach ppb to ppt magnitude, but the mass spectrometry and GC-MS are large in size, expensive and need to be operated by professional personnel. The detection limit of spectroscopy can be up to ppb level, but there is a large background interference. Chemical sensors are portable, simple, have low detection limits but generally have poor stability and short service life.

Ion mobility spectrometry is an instrument that uses differences in ion mobility at atmospheric pressure to achieve ion separation. The ion mobility spectrometry monitoring system is simple in structure, low in cost, easy to miniaturize, short in response time and very suitable for on-line monitoring, and the sensitivity of the ion mobility spectrometry is high. However, the currently used ionization sources are all radioactive ⁶³ Ni, which limits its wide use.

Disclosure of Invention

The invention aims to provide a non-radioactive device and a non-radioactive method for rapid online monitoring of ammonia gas.

A non-radioactive device and a method for on-line monitoring of ammonia gas comprise: sample gas, carrier gas, a reagent molecule generating device, a pump, tail gas, a radio frequency vacuum ultraviolet lamp, a migration tube system and floating gas.

The adopted device comprises a migration spectrum taking a radio frequency vacuum ultraviolet lamp as an ionization source, a migration tube of the migration spectrum comprises a reaction zone, an ion gate and an ion migration zone, and a floating gas inlet is arranged on one side of the ion migration zone far away from the reaction zone; a gas main outlet is arranged on one side of the reaction zone far away from the ion migration zone, and a pump is arranged at the gas main outlet; a sample gas and carrier gas inlet is arranged on one side of the reaction area close to the ion gate, the sample gas and carrier gas inlet is connected with a sample gas source through a pipeline, the sample gas and carrier gas inlet is connected with a gas outlet of the reagent molecule generating device through a pipeline, and a gas inlet of the reagent molecule generating device is connected with the carrier gas source; the reagent molecule generating device is a closed container, an open container for containing reagent molecules is arranged in the closed container, and the upper part of the closed container is provided with a gas outlet and a gas inlet; the reagent molecule is butanone.

The material of the conduit adopted by the gas circuit is polytetrafluoroethylene so as to reduce ammonia adsorption.

The reagent molecule adopted by the ion mobility spectrometry is 2-butanone. The reagent molecule generating device comprises a constant temperature system, the temperature range is 30-60 ℃, and the temperature of the reagent molecule generating device is kept in a specific temperature range.

The carrier gas flow rate range is 50-100ml/min, the floating gas flow rate range is 500-600ml/min, and the tail gas flow rate range is 600-750ml/min;

the temperature range of the migration tube is 100-150 ℃, and the electric field intensity range of the migration area is 450-500V/cm.

The invention has the advantages that:

the instrument and the method developed by the invention are based on an ion mobility spectrometry technology with a simple structure, a vacuum ultraviolet lamp non-radioactive ionization source is adopted, butanone is taken as a reagent molecule, the ammonia gas can be rapidly and accurately monitored on line, the selectivity of ammonia gas detection is improved, and the instrument and the method are convenient for large-scale application.

Drawings

FIG. 1 is a schematic structural diagram of rapid online ammonia gas monitoring. Wherein: the device comprises a radio frequency vacuum ultraviolet lamp 1, a reaction zone 2, an ion gate 3, a migration zone 4, a migration tube system 5, a floating gas 6, a carrier gas 7, a reagent molecule generating device 8, a sample gas 9, a pump 10 and a tail gas 11.

FIG. 2 is the ion migration spectrum of ammonia gas when 2-butanone is used as reagent molecule

FIG. 3 working curves for ammonia gas

FIG. 4 is an outdoor atmosphere chart of continuously monitoring for one day

Detailed Description

The following examples illustrate the use of the invention without limiting the scope of application described.

The adopted device comprises a migration spectrum taking a radio frequency vacuum ultraviolet lamp as an ionization source, a migration tube of the migration spectrum comprises a reaction zone and an ion migration zone, and a floating gas inlet is arranged on one side of the ion migration zone far away from the reaction zone; a gas main outlet is arranged on one side of the reaction zone far away from the ion migration zone, and a vacuum pump is arranged at the gas main outlet; a sample gas and carrier gas inlet is arranged on one side of the reaction area close to the ion migration area, the sample gas and carrier gas inlet is connected with a sample gas source through a pipeline, the sample gas and carrier gas inlet is connected with a gas outlet of the reagent molecule generating device through a pipeline, and the gas inlet of the reagent molecule generating device is connected with the carrier gas source; the reagent molecule generating device is a closed container, an open container for containing reagent molecules is arranged in the closed container, and a gas outlet and a gas inlet are arranged at the upper part of the closed container; the reagent molecule is butanone.

Example 1

Detecting ammonia gas by using a reagent molecule assisted photoionization positive ion mobility spectrometry, wherein the reagent molecule is butanone, the carrier gas flow rate range is 50-100ml/min, the drift gas flow rate range is 500-600ml/min, and the tail gas flow rate range is 600-750ml/min; the temperature range of the migration tube is 100-150 ℃, and the electric field intensity range of the migration area is 450-500V/cm. The ion mobility spectrum of ammonia gas is shown in fig. 2, the product ion is a compound of butanone and ammonia gas, the reduced mobility of the compound is 1.87, the reduced mobility of the reagent ion is 1.66, and the two ions can be completely separated.

Example 2

Air and/or nitrogen containing a series of ammonia gases with known gradient concentrations are taken as standard gases, the standard gases enter a migration spectrum through a sample gas and a carrier gas inlet of the migration spectrum for detection, and a series of migration spectrograms of the standard gases with the gradient concentrations are obtained; plotting the signal intensity of a series of standard gases with gradient concentrations against the concentration to obtain a working curve of the ammonia gas, as shown in figure 3; the linear range is 25-455ppb, with a lower detection limit of 6ppb.

Example 3

And introducing the sample gas to be detected into the mobility spectrum for detection, and substituting the signal intensity of the mobility spectrum of the sample gas to be detected into the working curve equation to obtain the concentration of ammonia gas in the sample gas. Fig. 3 is a graph showing the change in the concentration of ammonia in the outdoor atmosphere during the day.

Claims

1. A non-radioactive method capable of continuously monitoring ammonia gas on line is characterized in that:

the adopted device comprises an ion mobility spectrometry taking a radio frequency vacuum ultraviolet lamp as an ionization source, a migration tube of the mobility spectrometry comprises a reaction zone, an ion gate and an ion migration zone, and a floating gas inlet is arranged on one side of the ion migration zone far away from the reaction zone; a gas main outlet is arranged on one side of the reaction zone far away from the ion gate, and a pump is arranged at the gas main outlet; a sample gas and carrier gas inlet is arranged on one side of the reaction area close to the ion gate, the sample gas and carrier gas inlet is connected with a sample gas source through a pipeline, the sample gas and carrier gas inlet is connected with a gas outlet of the reagent molecule generating device through a pipeline, and a gas inlet of the reagent molecule generating device is connected with the carrier gas source; the reagent molecule generating device is a closed container, an open container for containing reagent molecules is arranged in the closed container, and a gas outlet and a gas inlet are arranged at the upper part of the closed container;

the molecule of the reagent is butanone, and the reagent is methyl ethyl ketone,

air and/or nitrogen containing a series of ammonia gases with known gradient concentrations are used as standard gases, and the standard gases enter a mobility spectrometry through a sample gas and a carrier gas inlet of the mobility spectrometry to be detected, so that a series of mobility spectrograms of the standard gases with the gradient concentrations are obtained; plotting the signal intensity of a series of standard gases with gradient concentration against the concentration to obtain a working curve of the ammonia gas;

introducing the sample gas to be detected into a migration spectrum for detection, and substituting the migration spectrum signal intensity of the sample gas to be detected into a working curve equation to obtain the concentration of ammonia in the sample gas;

wherein the flow rate range of the carrier gas is 50-100ml/min, the flow rate range of the floating gas is 500-600ml/min, and the flow rate range of the tail gas is 600-750ml/min;

the temperature range of the migration tube is 100-150 ℃, and the electric field intensity range of a migration area is 450-500V/cm;

the temperature range of the reagent molecule generating device is 30-60 ℃.

2. The method of claim 1, wherein:

the floating gas inlet is connected with a floating gas source; the air floating source is clean compressed air.

3. The method of claim 1, wherein:

and tail gas in the mobility spectrometry is discharged through a gas main outlet through a pump.

4. The method of claim 1, wherein: the gas inlet of the reagent molecule generating device is connected with a carrier gas source.

5. The method of claim 1, wherein: the guide pipe used by the gas pipeline is made of polytetrafluoroethylene.

6. The method of claim 1, wherein: the inner wall surface of the closed container of the reagent molecule generating device is provided with an electric heating device, namely, the wall surface of the closed container of the reagent molecule generating device is provided with an electric heating belt and/or an electric heating wire, the inner side wall of the reagent molecule generating device is provided with a thermocouple temperature measuring element, the thermocouple is in signal connection with a temperature controller through a lead, and the electric heating device is connected with an external circuit through the temperature controller.

7. The method of claim 1, wherein:

the ion mobility spectrometer comprises 4 working gas paths, namely a drift gas, a carrier gas, a sample gas and a tail gas, wherein the sample gas enters a sample gas inlet of a migration tube, the carrier gas enters a reagent molecule generating device at a certain flow velocity to generate a reagent molecule gas, and then the reagent molecule gas is connected with the sample gas and the carrier gas inlet;

the floating gas is clean air and enters the mobility spectrometer at a certain flow rate after passing through the mass flow meter; the tail gas is discharged from the pump through a tail gas port; and the difference value of the tail gas flow velocity, the floating gas flow velocity and the carrier gas flow velocity is the sample introduction amount of the sample.