CN103163007A - Solid phase and liquid phase compound dynamic gas preparation device and gas preparation method - Google Patents

Abstract

The invention provides a dynamic gas distribution device and gas distribution method for solid-phase and liquid-phase compounds. The gas distribution system used includes a dilution gas supply part, a dilution gas preheating part, a sample standard liquid trace control sampler, and a gas mixing part. and gas analyzers. The gas distribution method is to use the above gas distribution device, the dilution gas enters the liquid evaporation device through the dilution gas preheating device at a certain flow rate, and at the same time, the sample standard liquid enters the liquid evaporation device at a certain flow rate to mix with the dilution gas. Finally, the mixed gas is mixed through the gas mixing part, and part of it enters the gas analysis device for analysis, and the rest is discharged as tail gas. Changing the flow rate of the micro-control injector and the flow rate of the diluent gas can effectively control the flow ratio of the sample gas to the diluent gas, and obtain mixed gas with different concentrations without preparing sample standard solutions at all concentration points, which improves the solid phase and liquid phase. Compound standard gas preparation efficiency and accuracy.

Description

A dynamic gas distribution device and gas distribution method for solid-phase and liquid-phase compounds

technical field

The invention relates to a dynamic gas distribution device and gas distribution method for solid-phase and liquid-phase compounds. Specifically, the gas distribution device is used to inject a sample standard liquid into a constant-volume liquid evaporation device at a required flow rate to be vaporized and mixed with the required gas distribution device. The flow rate is mixed with the diluent gas with a stable temperature, and the standard gas at different concentration points can be obtained by simply adjusting the flow rate of the micro-syringe pump or the flow rate of the diluent gas, so as to realize continuous online preparation and supply of a certain concentration of sample standard gas.

Background technique

Standard gases for solid and liquid compounds are in great demand in the fields of environmental monitoring, product inspection and experimental research. In environmental monitoring, industrial production and residential life emit a wide variety of toxic and harmful gases into the atmosphere with low concentrations. The degradation, distribution and pollution characteristics of these harmful gases are often characterized by changes in concentration; in the inspection of analytical instruments In calibration, it is often necessary to calibrate the instrument with a gas that can provide a stable concentration of gas, otherwise the accuracy of the calibration result will be affected; in product inspection, the standard curve of the substance to be tested is also required to obtain the concentration of the substance to be tested in the product. The standard curve of the substance to be tested requires a gas distribution device that can prepare a series of standard gases in a range of concentrations. In short, it is very important to develop a standard gas distribution system and method for solid-liquid organic matter with the advantages of simple operation, low cost, wide gas distribution range, and good gas distribution stability.

At present, the main gas distribution methods are exponential dilution method, static gas distribution method and dynamic gas distribution method.

The exponential dilution method can quickly prepare a standard gas with a certain component content by changing the operating parameters such as the flow rate of the dilution gas, the initial content of the component gas, and the dilution time. Its equipment is simple, the environmental conditions are not strict, and the operation is easy. Usually, the static headspace method is used to obtain pure component gases, which takes a long time, and the sampling amount of volatile sources is limited, and it is not suitable for the preparation of standard gases of semi-volatile and difficult-volatile organic compounds with high boiling points. Static gas distribution method is mostly used as static volume method, which is to add a certain amount of raw material gas into a known volume of normal pressure or pressurized container, and then fill it with diluent gas and mix it evenly. If necessary, use a stirrer, etc. The stirring device helps the mixed gas to fully mix. This method is simple in equipment and easy to operate, but like the sampling method of the exponential dilution method, the static headspace method is often used, so it is not suitable for semi-volatile and refractory organic compounds with high boiling points. In addition, the adsorption problem of the gas distribution chamber often causes the preparation concentration and There is a certain deviation in the calculated concentration, especially when the low-concentration gas is prepared, the error is relatively large, so that the range of the prepared gas concentration is also limited to a certain extent. In addition, this method is not suitable for the situation where the amount of target gas is large or the ventilation time is required to be long.

Dynamic gas distribution methods mainly include flow ratio mixing method, infiltration method, diffusion method and constant volume method. This method is to mix the raw material gas and diluent gas with known concentration into the mixer according to a certain ratio, and calculate the concentration of the target gas according to the dilution ratio. A dynamic preparation device and application of standard gas for solid-phase or liquid-phase compounds (CN 101713712A) provides a standard gas preparation device for compounds with low saturated vapor pressure at normal temperature, which is simple in structure and easy to operate, especially for the standard of solid compounds The problem of gas preparation provides an effective solution, but there is a lack of standard gas for organic compounds that is prepared and tested in conjunction with gas analysis devices. Permeation tube rapid dynamic gas distribution device (CN 2421650Y) provides a device and method for rapid gas distribution using permeation tubes. The permeation tube, constant temperature chamber, and gas path are combined into an integral structure, and the replacement of the permeation tube is realized through a quick plug-in joint. The structure is simple and compact, and it is easy to use. However, it is still necessary to replace the permeation tube when preparing different gases. High-precision mixed gas and gas supply device (CN 2555922Y) discloses a high-precision mixed gas and gas supply device, which uses parallel gas paths to achieve the purpose of mixing different mixed gases in a single set of gas distribution devices through multi-position switching valves. It has the advantage of uniform and stable gas supply for the mixed gas supply system with a large flow rate, but the device is not suitable for the preparation of high boiling point mixed gas with low volatile (normal temperature liquid or solid) components.

To sum up, in order to solve the problems of complex gas path, cumbersome operation, small concentration range of gas that can be prepared, limited types of gas that can be prepared, and poor stability caused by mass transfer and adsorption in the above-mentioned gas distribution method, the dynamic The gas distribution device and gas distribution method only need to prepare a sample standard solution of one concentration, and the standard gas at other concentration points can be obtained by adjusting the flow rate of the sample standard liquid micro-syringe pump, and standard solutions of various components can be prepared, greatly The operation is simplified; the liquid evaporation device heated by the heating rod is suitable for semi-volatile or refractory organic compounds with a high boiling point, and the types of gases that can be distributed are expanded; at the same time, interlaced partitions are set in the inner cavity of the liquid evaporation device. Following the helical heated stainless steel tube, the mass transfer of dilution gas and sample gas is accelerated to avoid problems such as uneven mixing and adsorption. In addition, the gas circuit of the device is simple, the cost is low, and the operation is convenient.

Contents of the invention

The object of the present invention is to provide a dynamic gas distribution device and gas distribution method for solid-phase and liquid-phase compounds.

To achieve the above object, the technical scheme of the present invention is as follows:

A dynamic gas distribution device for solid-phase and liquid-phase compounds, including a diluent gas supply part, a diluent gas preheating part, a sample standard liquid micro-sampler, a liquid evaporation device, a gas mixing part and a gas analysis device;

Wherein, the dilution gas supply part includes a carrier gas cylinder and a mass flow controller and a two-way valve on its outlet pipeline;

The preheating part of the diluted gas includes a stainless steel tube and a heating belt and a thermal resistance temperature sensing element arranged on the tube wall; one end of the stainless steel tube is connected with the outlet pipeline of the carrier gas cylinder;

The liquid evaporating device is a hollow airtight cavity, the side wall of the cavity is provided with a heating rod connected to the external power supply, the side wall of the cavity is provided with a dilution gas inlet, and the dilution gas inlet is connected to the stainless steel tube. One end is connected, and the sample standard liquid inlet is provided on the side wall of the cavity near the dilution gas inlet. The sample standard liquid inlet is connected with the sample standard liquid micro-sampler through a stainless steel needle, away from the dilution gas sample injection. A mixed gas outlet is provided on the side wall of the cavity on the side of the port, and a gas baffle is provided in the cavity between the dilution gas inlet and the mixed gas outlet;

The gas mixing part includes a helical stainless steel tube and a heating belt and a temperature sensing element arranged on the tube wall; one end of the helical stainless steel tube is connected with the mixed gas outlet, and the other end is connected with the sample inlet of the gas analysis device.

The gas analysis device is an analysis device for direct gas sampling, which can be a gas chromatograph or a mass spectrometer for gas sampling, intercepting a part of the mixed gas for analysis, and discharging the rest as tail gas.

The gas baffles are interlaced partitions. There is a gap between one end of the partition and the inner wall of the cavity to form an open end. The other end faces of the partitions are connected to the inner wall of the cavity. Staggered settings to lengthen the transmission route and turbulence degree of diluent gas and sample gas, and the spacing of the partitions is adjusted according to the actual size of the cavity and the number of partitions.

The dilution gas is mainly non-oxidizing gas, which is transmitted through a polytetrafluoroethylene tube, and the two-way valve is connected to the preheating part of the dilution gas through a stainless steel tube;

The sample standard liquid micro-sampler includes a syringe pump and a syringe that can precisely adjust the flow rate. The sample standard liquid enters the liquid evaporation device through a stainless steel needle, and the stainless steel needle is inserted into the liquid evaporation chamber for a certain distance to the sample inlet of the diluent gas.

The liquid evaporating device is provided with a dilution gas inlet and a sample liquid inlet, and the two are perpendicular to each other, and the dilution gas vertically sweeps the incoming sample liquid and takes it away from the needle in time.

A method for dynamic gas distribution of solid-phase and liquid-phase compounds, comprising the steps of:

Preparation of sample standard solution: according to the flow rate of the diluent gas and the temperature of the liquid evaporation device, weigh or measure the sample, dissolve it in an organic solvent, and use a volumetric flask to accurately prepare a sample standard solution with a certain concentration of the substance;

Simultaneously heat the liquid evaporation device, the dilution gas preheating part and the gas mixing part to the required temperature and stabilize it;

Open the dilution gas supply cylinder, and the dilution gas enters the liquid evaporation device after being heated by the dilution gas preheating part through the PTFE tube;

Use a micro-sample injector to inject the sample standard solution from the stainless steel needle into the liquid evaporation device to vaporize and initially mix it with the dilution gas, and then fully mix it through the gas mixing part, and then part of it enters the gas analysis device, and the rest is discharged as waste gas;

Use the gas analysis device to sample a standard gas of one concentration, and then adjust the flow rate of the micro-syringe pump or the flow rate of the diluent gas to obtain the standard gas at the next concentration point, and use the gas analysis device to sample the standard gas of the next concentration.

It only needs to prepare one or two concentrations of sample standard solution, and can obtain a series of concentration points of standard gas by adjusting the flow rate of the micro-syringe pump or the flow rate of diluent gas, without the need to prepare sample standard solutions corresponding to all concentration points.

The sample is a multi-component sample, and the mixed standard liquid of the multi-component sample is prepared to obtain their standard gas at the same time.

The sample is a solid phase or liquid phase compound. The standard gas of the solid phase compound is prepared by dissolving the solid phase compound in an organic solvent to prepare its standard liquid, and then the standard gas is prepared by using a dynamic gas distribution system.

The length of the spiral stainless steel tube in the gas mixing part is 0.5-1.5m, which can be heated to 500°C; the dilution gas preheating part can be heated to 500°C;

The liquid evaporating device can be heated up to 500°C, which is suitable for preparing the standard gas of semi-volatile or non-volatile organic compounds, and can adjust the stable temperature of the liquid evaporating device according to their boiling points.

The basic principle of this gas distribution method is:

Suppose the concentration of the mixed gas to be configured is γ (volume ratio), the flow rate of the diluent gas is V _carrier L/min, the flow rate of the micro-injection pump is vμl/min, and the substance concentration of the sample standard solution is C _A mol/L , the gas molar volume at the cavity temperature is V _m L/mol, and the volume of the analyte vaporized in the liquid evaporation device (5) is V _A L.

In unit time (within 1min):

V _A (L)=C _A (mol/L)·v(μl)·10 ^-6 ·V _m (L/mol) (1)

The concentration of the mixed gas can be expressed as:

$\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}}{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; carrier</span>}}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; mol</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&mu;l</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; mol</span>}<span\; class="notranslate">\; )</span>}{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; carrier</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; 10</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

From the above formula, the concentration of the substance in the sample standard solution can be obtained as:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; A</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; mol</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; 10</span>}}^{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; carrier</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&mu;l</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; mol</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The relationship between temperature and molar volume of gas is as follows:

but:

After determining the concentration γ (volume ratio) of the mixed gas to be prepared, the flow rate V _carrier (L/min) of the diluent gas, the flow rate v (μl/min) of the micro-injection pump and the cavity temperature T _cavity , it can be obtained from the above formula The amount concentration of a substance in a sample standard solution. If the concentration range of the gas to be prepared is 1ppbV-1ppmV, you can prepare a sample standard solution corresponding to a gas concentration of 50ppbV, and then adjust the flow rate of the micro syringe pump to obtain concentration points less than and greater than 50ppbV. The number of sample standard solutions to be prepared can be determined according to the concentration range of the gas to be prepared. If the concentration range is large, such as spanning 4 orders of magnitude, two concentrations of sample standard solutions can be prepared to avoid one concentration of sample standard solutions. When adjusting the flow rate of the micro-injection pump, the error is large because the concentration range is too large.

The advantages of the gas distribution device and gas distribution method:

1. Fix the flow rate of the diluent gas, and obtain different concentrations of standard gas by changing the flow rate of the micro-injection pump, without the need to prepare solutions at all concentration points, which simplifies the operation, and with the increase of the concentration, the time for the signal intensity to stabilize gradually Shorter, compared with the traditional standard solution serial dilution method, the analysis time is greatly shortened;

2. The liquid evaporating device is equipped with a heating rod for heating. The temperature can be set according to the boiling point of the analyte. The maximum temperature can be raised to about 500°C, which is better than the general circulating water heating system. It expands the types of gas that can be equipped and is suitable for high boiling points. Preparation of liquid and solid organic standard gases.

3. Interlaced baffles are set in the inner cavity of the liquid evaporation device, and there are heated spiral stainless steel tubes for further mixing, which speeds up the mass transfer of dilution gas and sample gas and avoids problems such as uneven mixing and adsorption. , which enhances the stability of the gas distribution of the device.

4. The dilution concentration range is wide, the measured dynamic range is from 1000 to 25000, and the linear correlation is good. The standard gas concentration can reach ppbV level, and it can be adjusted continuously.

5. Save gas consumption. The maximum air consumption of diluent gas is 0.5L/min. When the time-of-flight mass spectrometer using capillary sampling is used as a gas analysis device, it only takes 30s for a concentration point, and the waste of gas is less.

6. The sample standard solution of multiple components can be prepared to realize the simultaneous preparation of multi-component standard gas, which simplifies the operation steps.

7. After the prepared solution is injected into the cavity through the syringe pump and the diluent gas is turned on, online sampling can be performed continuously, and it can be paused at any time to flexibly respond to unexpected changes.

8. There are many types of compounds applicable, such as polycyclic aromatic hydrocarbons, ethers, ketones, esters, etc., and good results can be obtained.

Description of drawings

Figure 1 is a schematic diagram of a dynamic gas distribution device for solid and liquid compounds; 1-carrier gas cylinder; 2-mass flow controller; 3-two-way valve; 4-diluent gas preheating part; 5-liquid evaporation device; 6- Heating rod; 7-sample standard solution micro-injector; 8-stainless steel needle; 9-gas mixing part; 10-gas analysis device.

Fig. 2 is the overall schematic diagram of the time-of-flight mass spectrometer of capillary injection; 11-molecular pump, 12-acceleration zone, 13-field-free flight zone, 14-MCP ion detector, 15-pulse repeller plate, 16 -Ion extraction electrode, 17-mechanical pump, 18-lamp electrode, 19-metal grid, 20-sampling capillary, 21-VUV lamp;

Fig. 3 is with methanol as solvent, the linear response curve of the standard gas that benzene standard solution is made;

Fig. 4 is with pure water as solvent, the linear response curve of the standard gas that 2-butanone standard solution is prepared;

Fig. 5 is with pure water as solvent, the linear response curve of the standard gas that methyl tert-butyl ether standard solution prepares;

Fig. 6 is the linear response curve of the standard gas prepared with ethanol as solvent, naphthalene and methyl salicylate standard solution.

Detailed ways

First, Figure 1 is a dynamic gas distribution device for solid and liquid compounds, which is characterized in that it includes a diluent gas supply part, a diluent gas preheating part 4, a sample standard liquid micro sampler 7, a liquid evaporation device 5, a gas mixing Part 9 and gas analysis device 10;

Wherein, the dilution gas supply part includes a carrier gas cylinder 1 and a mass flow controller 2 and a two-way valve 3 on its outlet pipeline;

The dilution gas preheating part 4 includes a stainless steel tube and a heating belt and a thermal resistance temperature sensing element arranged on the tube wall; one end of the stainless steel tube is connected to the outlet pipeline of the carrier gas cylinder 1;

The liquid evaporating device 5 is a hollow airtight cavity, the side wall of the cavity is provided with a heating rod 6 connected to an external power supply, the side wall of the cavity is provided with a dilution gas inlet, and the dilution gas inlet is connected with the stainless steel One end of the tube is connected, and an inlet for sample standard solution is provided on the side wall of the cavity near the dilution gas inlet, and the inlet for sample standard solution is connected to the sample standard solution micro-sampler 7 through a stainless steel needle 8, away from A mixed gas outlet is provided on the side wall of the cavity on one side of the dilution gas inlet, and a gas baffle is arranged in the cavity between the dilution gas inlet and the mixed gas outlet;

The gas mixing part 9 includes a spiral stainless steel tube and a heating belt and a temperature sensing element arranged on the tube wall;

The gas analysis device 10 is an analysis device for direct gas sampling, which may be a gas chromatograph or a mass spectrometer for gas sampling, which intercepts a part of the mixed gas for analysis, and discharges the rest as tail gas.

The gas baffles are interlaced partitions. There is a gap between one end of the partition and the inner wall of the cavity to form an open end. The other end faces of the partitions are connected to the inner wall of the cavity. Staggered settings to lengthen the transmission route and turbulence degree of diluent gas and sample gas, and the spacing of the partitions is adjusted according to the actual size of the cavity and the number of partitions.

The dilution gas is mainly a non-oxidizing gas, which is transmitted through a polytetrafluoroethylene tube, and the two-way valve 3 is connected to the dilution gas preheating part 4 through a stainless steel tube;

The sample standard liquid micro-sampler 7 includes a syringe pump and a syringe that can precisely adjust the flow rate. The sample standard liquid enters the liquid evaporation device 5 through the stainless steel needle 8, and the stainless steel needle 8 is inserted into the liquid evaporation chamber for a certain distance and is facing the sample inlet of the diluent gas. .

The liquid evaporating device is provided with a dilution gas inlet and a sample liquid inlet, and the two are perpendicular to each other, and the dilution gas vertically sweeps the incoming sample liquid and takes it away from the needle in time.

A method for dynamic gas distribution of solid and liquid compounds, comprising the steps of:

Preparation of sample standard solution: according to the flow rate of the diluent gas and the temperature of the liquid evaporation device, weigh or measure the sample, dissolve it in an organic solvent, and use a volumetric flask to accurately prepare a sample standard solution with a certain concentration of the substance;

Simultaneously heat the liquid evaporation device 5, the dilution gas preheating part 4 and the gas mixing part 9 to the required temperature and stabilize;

Open the dilution gas supply cylinder, the dilution gas enters the liquid evaporation device 5 after being heated by the dilution gas preheating part 4 through the polytetrafluoroethylene tube;

Use a micro-sample injector to inject the sample standard solution from the stainless steel needle 8 into the liquid evaporation device 5 to be vaporized and initially mixed with the diluent gas, and then fully mixed evenly through the gas mixing part 9, and then part of it enters the gas analysis device 10, and the rest is discharged as waste gas;

Using the gas analysis device 10 to sample a standard gas of one concentration, the standard gas of the next concentration point can be obtained by adjusting the flow rate of the micro-injection pump or the flow rate of the diluent gas, and the gas analysis device 10 is used to sample the standard gas of the next concentration.

It only needs to prepare one or two concentrations of sample standard solution, and can obtain a series of concentration points of standard gas by adjusting the flow rate of the micro-syringe pump or the flow rate of diluent gas, without the need to prepare sample standard solutions corresponding to all concentration points.

The sample is a multi-component sample, and the mixed standard liquid of the multi-component sample is prepared to obtain their standard gas at the same time.

The sample is a solid phase or liquid phase compound. The standard gas of the solid phase compound is prepared by dissolving the solid phase compound in an organic solvent to prepare its standard liquid, and then the standard gas is prepared by using a dynamic gas distribution system.

The length of the spiral stainless steel tube of the gas mixing part 9 is 0.5-1.5m, which can be heated to 500°C; the dilution gas preheating part 4 can be heated to 500°C;

The liquid evaporating device 5 can be heated up to 500° C., which is suitable for preparing standard gases of semi-volatile or non-volatile organic compounds, and can adjust the stable temperature of the liquid evaporating device according to their boiling points.

Among them, three heating rods each with a power of 50W, a length of 60mm, and a diameter of 6mm are used, and are distributed around the cavity of the liquid evaporation device. In order to simplify the operation and reduce the error, only one concentration of standard solution was prepared in the test, and then the standard gas of other concentrations was obtained by changing the flow rate of the micro-injection pump. In addition, this device is used in conjunction with the time-of-flight mass spectrometer shown in Figure 2. It adopts an orthogonal acceleration design and is detected by an MCP detector. Part of the mixed gas enters the mass spectrometer through a capillary for analysis, and the rest is discharged as exhaust gas. The air pressure in the ionization region can be adjusted by changing the inner diameter and length of the capillary. The inner diameter of the capillary used in the experiment is 250μm, the length is about 1m, and the air pressure in the ionization zone is maintained at about 20-30Pa.

Example 1

Aiming at the examination of the performance of a dynamic gas distribution system and gas distribution method for a solid-phase and liquid-phase compound described in the present invention, methanol was used as a solvent in the experiment, and four kinds of concentrations of 5.6×10 ^-4 mol/L, 5.6× 10 ^-3 mol/L, 5.6×10 ^-2 mol/L, 5.6×10 ^-1 mol/L benzene solution. Set the flow rate of the diluent gas to 4L/min, and the chamber temperature to 75°C. For the sample standard solution with a concentration of 5.6×10 ^-4 mol/L, the flow rates of the microsyringe pumps are 2.5 μl/min, 5 μl/min, At 12.5μl/min, the corresponding standard gas concentrations are 10ppbv, 20ppbv and 50ppbv. By analogy, when the flow rates of the micro-injection pumps are 2.5μl/min, 5μl/min, and 12.5μl/min, the concentrations are 5.6×10 ^-3 mol/L, 5.6×10 ^-2 mol/L, 5.6× The concentration of the standard gas corresponding to the sample standard solution of 10 ^-1 mol/L is easy to obtain. In the experiment, the switching voltage of the ionization source is 30V, and the ionization method adopts the ionization method of vacuum ultraviolet single photon ionization (VUV-SPI), and the pressure in the ionization area is maintained at about 30Pa. First, the purge air enters the mass spectrometer for sampling and analysis. The sampling time is 15 s, and 10 parallel samples are taken. The time interval between two adjacent samples is 15 s. The collected signal is used as the background signal. Afterwards, the sample standard solution is injected into the liquid evaporation chamber by the micro-injection pump in the order of concentration from low to high, and the flow rate of the micro-injection pump is adjusted according to the order from low to high. Fig. 3 is a linear fitting diagram of benzene after subtracting the background signal of air. It was found that the linear range of benzene is 20ppbv-100ppmv, the dynamic range can reach 5000, and the linear correlation coefficient of the linear fitting graph can reach 0.9993, showing a good concentration linearity relationship.

Example 2

Aiming at the examination of the performance of a dynamic gas distribution system and gas distribution method for a solid-phase and liquid-phase compound described in the present invention, pure water was used as a solvent in the experiment, and four kinds of concentrations of 6.54×10 ^-5 mol/L, 6.54 ×10 ^-4 mol/L , 6.54×10 ^-3 mol/L , 6.54×10 ^-2 mol/L, 6.54×10 ^-1 mol/L solutions of methyl tert-butyl ether and 2-butanone. Set the flow rate of the diluent gas to 0.5L/min, the temperature of the chamber to 120°C, and the temperature of the gas mixing part to 120°C. For the sample standard solution with a concentration of 6.54×10 ^-5 mol/L, when the flow rate of the micro syringe pump is 2.5μl/min, 5μl/min, and 12.5μl/min, the corresponding standard gas concentrations are 10ppbv, 20ppbv, and 50ppbv . By analogy, when the flow rates of the micro-injection pumps are 2.5μl/min, 5μl/min, and 12.5μl/min, the concentrations are 5.6×10 ^-3 mol/L, 5.6×10 ^-2 mol/L, 5.6× The concentration of the standard gas corresponding to the sample standard solution of 10 ^-1 mol/L is easy to obtain. In the experiment, the switching voltage of the ionization source is 30V, and the ionization method adopts the ionization method of vacuum ultraviolet single photon ionization (VUV-SPI), and the pressure in the ionization area is maintained at about 30Pa. First, the purge air enters the mass spectrometer for sampling and analysis. The sampling time is 15 s, and 10 parallel samples are taken. The time interval between two adjacent samples is 15 s. The collected signal is used as the background signal. Afterwards, the sample standard solution is injected into the liquid evaporation chamber by the micro-injection pump in the order of concentration from low to high, and the flow rate of the micro-injection pump is adjusted according to the order from low to high. Figure 4 and Figure 5 are linear fitting diagrams of the main ion peak intensities of 2-butanone and methyl tert-butyl ether after deducting the background signal of air respectively. It was found that the linear range of 2-butanone is 20ppbv-500ppmv, the dynamic range can reach 25000, and the linear correlation coefficient of the linear fitting graph can reach 0.9989, showing a good concentration linearity relationship. MTBE The linear range is 100ppbv-100ppmv, the dynamic range can reach 1000, and the linear correlation coefficient of the linear fitting graph can reach 0.9992, showing a good concentration linearity relationship.

Example 3

Aiming at the examination of the performance of a dynamic gas distribution system and gas distribution method of a solid-phase and liquid-phase compound described in the present invention, four kinds of concentrations of 6.54×10 ^-5 mol/L, 6.54× 10 ^-4 mol/L, 6.54×10 ^-3 mol/L, 6.54×10 ^-2 mol/L solutions of naphthalene and methyl salicylate. Set the flow rate of the diluent gas to 0.5L/min, the temperature of the cavity to 120°C, and the temperature of the gas mixing part to 120°C. For the sample standard solution with a concentration of 6.54×10 ^-5 mol/L, when the flow rate of the micro syringe pump is 2.5 μl/min, 4 μl/min, 5 μl/min, 8 μl/min, 10 μl/min and 12.5 μl/min, The corresponding standard gas concentrations are 10ppbv, 16ppbv, 20ppbv, 32ppbv, 40ppbv and 50ppbv. By analogy, when the flow rates of the microinjection pumps are 2.5μl/min, 5μl/min, and 12.5μl/min, the concentrations are 5.6×10 ^-3 mol/L, 5.6×10 ^-2 mol/L, 5.6 ×10 ^-1 mol/L sample standard liquid corresponding to the standard gas concentration is easy to obtain. In the experiment, the switching voltage of the ionization source is 30V, and the ionization method adopts the ionization method of vacuum ultraviolet single photon ionization (VUV-SPI), and the pressure in the ionization area is maintained at about 30Pa. First, the purge air enters the mass spectrometer for sampling and analysis. The sampling time is 15 s, and 10 parallel samples are taken. The time interval between two adjacent samples is 15 s. The collected signal is used as the background signal. Afterwards, the sample standard solution is injected into the liquid evaporation chamber by the micro-injection pump in the order of concentration from low to high, and the flow rate of the micro-injection pump is adjusted according to the order from low to high. Figure 6 is the linear fitting graph of the main ion peak intensities of naphthalene and methyl salicylate after subtracting the background signal of air respectively. It is found that the linear range of naphthalene is 32ppbv-100ppmv, the dynamic range can reach 3125, and the linear correlation coefficient of the linear fitting graph can reach 0.9962, showing a good concentration linearity relationship. The linear range of methyl salicylate is 20ppbv-100ppmv, the dynamic range can reach 5000, and the linear correlation coefficient of the linear fitting graph can reach 0.9991, showing a good concentration linearity relationship.

Claims (10)

1. a solid phase and liquid phase compound dynamic air-distributing device, is characterized in that: comprise carrier gas air feed part, carrier gas preliminary heating section (4), sample standard liquid microsyringe (7), liquid vaporising unit (5), gas mixing portion (9) and gas analyzing apparatus (10);

Wherein, described carrier gas gas supply part divides the mass flow controller (2) and two-way valve (3) that comprises on carrier gas steel cylinder (1) and its export pipeline;

Described carrier gas preliminary heating section (4) comprises heating tape and the thermal resistance temperature-sensing element that arranges on stainless-steel tube and tube wall; One end of stainless-steel tube is connected with the export pipeline of carrier gas steel cylinder (1);

described liquid vaporising unit (5) is the airtight cavity of hollow, cavity wall is provided with the heating rod (6) that is connected with extraneous power supply, the sidewall of cavity is provided with the carrier gas injection port, the carrier gas injection port is connected with an end of stainless-steel tube, be provided with the injection port of sample standard liquid near the cavity wall of carrier gas injection port, the injection port of sample standard liquid is connected by stainless steel syringe needle (8) with sample standard liquid microsyringe (7), cavity wall away from carrier gas injection port one side is provided with mixed gas outlet, be provided with gas baffle plate in cavity between carrier gas injection port and mixed gas outlet,

Described gas mixing portion (9) comprises heating tape and the temperature-sensing element that arranges on spiral fashion stainless-steel tube and tube wall; Spiral fashion stainless-steel tube one end is connected with mixed gas outlet, and the other end is connected with the injection port of gas analyzing apparatus (10).

2. device according to claim 1 is characterized in that:

Described gas analyzing apparatus (10) is the analytical equipment of direct gas sampling, can be the mass spectrometer of gas chromatograph or gas sampling, and the part of intercepting combination gas is analyzed, and all the other are discharged as tail gas.

3. device according to claim 1 is characterized in that:

Described gas baffle plate is the dividing plate of interlaced setting, leave the gap between one end of dividing plate and cavity inner wall, form openend, other end face of dividing plate is connected with cavity inner wall, the interlaced setting of the openend of adjacent separator, to lengthen landline and the turbulent extent of carrier gas and sample gas, clapboard spacing is regulated according to cavity actual size and dividing plate number.

4. device according to claim 1 is characterized in that:

Carrier gas is mainly non-oxidizing gas, transmits by polyfluortetraethylene pipe, and two-way valve (3) is connected with carrier gas preliminary heating section (4) by stainless-steel tube;

Sample standard liquid microsyringe (7) but comprise syringe pump and the syringe of accurate flow adjustment, sample standard liquid enters liquid vaporising unit (5) by stainless steel syringe needle (8), and stainless steel syringe needle (8) inserts liquid evaporation cavity one segment distance over against the injection port of carrier gas.

5. device according to claim 1 is characterized in that:

Described liquid vaporising unit is provided with carrier gas injection port and sample liquid injection port, and both are perpendicular, and carrier gas is vertical to be purged the sample liquid that enters and it is in time taken away syringe needle.

6. a solid phase and liquid phase compound dynamic air-distributing method is characterized in that:

In employing claim 1-5, arbitrary described device operates, and comprises the steps:

A. prepare sample standard liquid: press the temperature of flow and the liquid vaporising unit of carrier gas, take or measure sample, be dissolved in organic solvent, use volumetric flask accurately to make the sample standard liquid of certain amount of substance concentration;

B. heating liquid vaporising device (5), carrier gas preliminary heating section (4) and gas mixing portion (9) arrive temperature required and stable simultaneously;

C. open carrier gas for gas cylinder, carrier gas enters liquid vaporising unit (5) by polyfluortetraethylene pipe after carrier gas preliminary heating section (4) heating;

D. use the micro-example injector that sample standard liquid is vaporized and tentatively mixed with carrier gas by stainless steel syringe needle (8) filling liquid vaporising device (5), fully mix rear portion through gas mixing portion (9) again and enter gas analyzing apparatus (10), all the other are discharged as waste gas;

E. pass through to regulate the flow velocity of micro-injection pump or the flow of carrier gas after utilizing the Standard Gases sampling of gas analyzing apparatus (10) to a concentration, can obtain the Standard Gases of next concentration point, utilize gas analyzing apparatus (10) to the Standard Gases sampling of next concentration.

7. method according to claim 6 is characterized in that:

Only need the sample standard liquid of one or two concentration of preparation to obtain the Standard Gases of a series of concentration point and not need to prepare sample standard liquid corresponding to all concentration point by the flow velocity of adjusting micro-injection pump or the flow of carrier gas.

8. method according to claim 6 is characterized in that:

Described sample is multicomponent sample, by the hybrid standard liquid of preparation multicomponent sample, obtains simultaneously their Standard Gases.

9. according to claim 6 or 8 described methods is characterized in that:

Described sample is solid phase or liquid phase compound, by the Standard Gases of preparation solid-phase compound, is about to solid-phase compound and is dissolved in organic solvent, and preparation obtains its titer, adopts afterwards dynamic gas mixer preparation Standard Gases.

10. method according to claim 6 is characterized in that:

The spiral stainless-steel tube length of gas mixing portion (9) is 0.5-1.5m, can be heated to 500 ℃; Carrier gas preliminary heating section (4) can be heated to 500 ℃;

Liquid vaporising unit (5) is the highest is heated to 500 ℃, is suitable for preparing the Standard Gases of half volatilization or difficult volatile organic compounds, and the equilibrium temperature that can regulate liquid vaporising unit according to their boiling point.

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