Formaldehyde-containing gas storage method and application thereof

Abstract

The invention belongs to the technical field of gas storage, and discloses a formaldehyde-containing gas storage method and application thereof. The storage method comprises the following steps that formaldehyde and balance gas are added into a container made of polytetrafluoroethylene to be mixed, gas is obtained, the content of the formaldehyde is the ppb level, and the balance gas comprises nitrogen and does not comprise argon or helium. The container made of polytetrafluoroethylene is used for storing the gas containing trace formaldehyde, and nitrogen is used as balance gas in the gas, so that the formaldehyde content in the gas is stable, and an accurate detection result can be obtained during subsequent formaldehyde content detection.

Description

Technical Field

[0001] The invention belongs to the technical field of gas storage, and in particular relates to a storage method for formaldehyde-containing gas and application thereof. Background Art

[0002] Lung cancer is one of the most common cancers with the highest morbidity and mortality worldwide. Due to the mild symptoms of patients in the early stage and the limitations of detection conditions, most lung cancer patients often miss the best time for treatment. In recent decades, early screening of lung cancer patients through the detection of breath markers has gradually become a new research hotspot. Early studies have identified some breath markers of lung cancer through gas chromatography-mass spectrometry (GC-MS), including small molecules such as formaldehyde, valeraldehyde, and hexanal.

[0003] When testing people for lung cancer breath markers, it is generally necessary to first collect people's breath and store it in a container or bag. During the storage process, the more stable the breath is, the more accurate the test results will be. However, the existing methods for storing breath are not very stable, which causes fluctuations in breath components, further making the test results less accurate.

[0004] Therefore, there is an urgent need to provide a new storage method for formaldehyde-containing gas, so that the exhaled breath components have good stability and are not prone to fluctuations, which further helps to obtain accurate test results. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a storage method for formaldehyde-containing gas and its application. The storage method of the present invention can stably store gas containing trace formaldehyde (for example, formaldehyde with a content of 40-60 ppb), so that the formaldehyde content in the gas is stable, which is conducive to obtaining accurate detection results when performing subsequent formaldehyde content detection.

[0006] The present invention adopts a container made of polytetrafluoroethylene to store gas containing trace formaldehyde, and nitrogen is used as a balancing gas in the gas, so that the formaldehyde content in the gas is stable, which is conducive to obtaining accurate detection results when performing subsequent formaldehyde content detection.

[0007] A first aspect of the present invention provides a method for storing a gas containing formaldehyde.

[0008] Specifically, a method for storing formaldehyde-containing gas comprises the following steps:

[0009] Formaldehyde and balance gas are added into a container made of polytetrafluoroethylene and mixed to obtain a gas, wherein the formaldehyde content is at ppb level, and the balance gas includes nitrogen but does not include argon or helium.

[0010] Preferably, the formaldehyde content in the gas is 40-60 ppb, more preferably 50-55 ppb.

[0011] Preferably, the formaldehyde is produced within 1 year, and more preferably, the formaldehyde is produced within 2 months.

[0012] Preferably, the gas needs to be stored at 25° C. and normal pressure away from light.

[0013] Preferably, the container comprises an air bag.

[0014] The second aspect of the present invention provides application of the above-mentioned method for storing formaldehyde-containing gas.

[0015] Specifically, an application of a method for storing formaldehyde-containing gas comprises the following steps:

[0016] The gas in the storage method is injected into a gas chromatography-mass spectrometer (GC-MS) to analyze the gas composition and content; or an electrochemical analysis method is used to analyze the electrochemical impedance spectroscopy of formaldehyde in the gas, or an AHMT solution is used to detect the formaldehyde content in the gas, wherein the structural formula of the AHMT is

[0017] Preferably, the application of a method for storing formaldehyde-containing gas comprises the following steps:

[0018] Step (1): Mix the reagent a and the reagent b to obtain a first mixture, then take the gas in the storage method as the gas to be tested and add it to the first mixture, seal it, and let it stand to obtain a second mixture; the reagent a includes an acid solution of AHMT, and the structural formula of AHMT is The reagent b is a potassium hydroxide solution;

[0019] Step (2): adding the reagent C to the second mixture, shaking, sealing, and standing to obtain a third mixture, and measuring the UV-visible absorbance data of the third mixture; the reagent C includes an alkaline solution of KIO4;

[0020] Step (3): replacing the gas to be tested in step (1) with a mixed gas of formaldehyde and nitrogen with known standard series concentrations, and obtaining a linear equation of UV-visible light absorbance and formaldehyde concentration according to the processes of steps (1) and (2);

[0021] Step (4): Substitute the ultraviolet-visible light absorbance data of the third mixture corresponding to the gas to be tested into the linear equation of step (3) to calculate the formaldehyde concentration in the gas to be tested.

[0022] Preferably, the application of a method for storing formaldehyde-containing gas comprises the following steps:

[0023] Step (1): Mix the reagent a and the reagent b to obtain a first mixture, then take the gas in the storage method as the gas to be tested and add it to the first mixture, seal it, and let it stand to obtain a second mixture; the reagent a includes an acid solution of AHMT, and the structural formula of AHMT is In the AHMT acid solution, the mass concentration of AHMT is 0.5-3%, the acid in the AHMT acid solution is HCl, and the concentration of HCl is 0.2-0.5 mol / L; the reagent b is a potassium hydroxide solution, and the mass ratio of potassium hydroxide to water in the potassium hydroxide solution is 28-100:100;

[0024] Step (2): adding the reagent C to the second mixture, shaking, sealing, and standing to obtain a third mixture, and measuring the UV-visible absorbance data of the third mixture; the reagent C comprises an alkaline solution of KIO4, and the mass concentration of KIO4 in the alkaline solution of KIO4 is 1-3%;

[0025] Step (3): replacing the gas to be tested in step (1) with a mixed gas of formaldehyde and nitrogen with known standard series concentrations, and obtaining a linear equation of UV-visible light absorbance and formaldehyde concentration according to the processes of steps (1) and (2);

[0026] Step (4): Substitute the ultraviolet-visible light absorbance data of the third mixture corresponding to the gas to be tested into the linear equation of step (3) to calculate the formaldehyde concentration in the gas to be tested.

[0027] Preferably, in step (1), a syringe pump is used to uniformly inject the gas into the first mixture, and the injection time is controlled within 10-15 minutes.

[0028] Preferably, in step (1), the reagent a and the reagent b are mixed in a centrifuge tube.

[0029] Preferably, in step (1), the volume ratio of reagent a to reagent b is 1:(0.9-1.1), more preferably 1:(1.0-1.05).

[0030] Preferably, in step (1), the volume of the gas to be measured is 150-400 mL, more preferably 200-400 mL.

[0031] Preferably, in step (1), the gas obtained by the storage method can be replaced by human exhaled gas. Using human exhaled gas as the test gas can detect the formaldehyde content in human exhaled gas.

[0032] Preferably, in step (1), the standing time is 20-40 minutes, more preferably 30-40 minutes.

[0033] Preferably, in step (2), the amount of reagent c is 0.5-1.5 mL, more preferably 0.5-1 mL.

[0034] Preferably, in step (2), the standing time is 20-40 minutes, more preferably 20-35 minutes.

[0035] Preferably, in step (2), the UV-visible spectrum data of the third mixture is measured, the absorbance data at 500-600 nm is collected, and the absorbance data at 550 nm is further collected.

[0036] Preferably, in step (3), the linear equation is: y=0.00358x+0.00182, and the correlation coefficient is 0.99572, wherein x is the formaldehyde concentration and y is the absorbance.

[0037] Preferably, in step (3), the concentration of formaldehyde in the mixed gas of formaldehyde and nitrogen of known standard series concentrations is 10-180 ppb, more preferably 10-170 ppb.

[0038] The reaction process of AHMT and formaldehyde is:

[0039] AHMT has a higher specificity for formaldehyde.

[0040] The formaldehyde in the test gas condenses with AHMT under alkaline conditions and then is oxidized by potassium periodate to form a purple-red compound of 6-mercapto-5-triazine[4,3-b]-S-tetraazine. The color depth is proportional to the formaldehyde content and has a maximum absorption peak at 550nm.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] The present invention adopts a container made of polytetrafluoroethylene to store gas containing trace formaldehyde, and nitrogen is used as a balancing gas in the gas, so that the formaldehyde content in the gas is stable, which is conducive to obtaining accurate detection results when performing subsequent formaldehyde content detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The linear equation curve of UV-visible light absorbance and formaldehyde concentration obtained in Example 1. DETAILED DESCRIPTION

[0044] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0045] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0046] The 10 ppm formaldehyde standard gas used in the following examples and comparative examples comes from Dalian Date Gas Co., Ltd. The formaldehyde standard gas has a production time of 2 months, 1 year, and 2 years.

[0047] Example 1

[0048] The linear equation curve of UV-visible absorbance and formaldehyde concentration was obtained by the following method:

[0049] Weigh 0.25 g AHMT and dissolve it in hydrochloric acid with a concentration of 0.5 mol / L. Add water to dilute to 50 mL to obtain reagent a.

[0050] Dissolve 28 g of KOH in 100 g of water to obtain reagent b;

[0051] Take 0.75g KIO4 and dissolve it in 50g 0.2mol / L KOH solution, heat it on a water bath to dissolve, and obtain reagent c;

[0052] Step (1): 1.5 mL of reagent a and 1.5 mL of reagent b are mixed in a centrifuge tube (the centrifuge tube is fixed on an iron stand) to obtain a first mixture, and then 200 mL of a mixed gas of formaldehyde and nitrogen with a known standard concentration is injected into the first mixture. The injection operation is completed within 10 minutes, and the centrifuge tube is sealed and allowed to stand for 30 minutes to obtain a second mixture;

[0053] Step (2): adding 1 mL of reagent c to the second mixture, shaking, sealing, and standing for 25 minutes to obtain a third mixture, and measuring the absorbance data of ultraviolet-visible light at 550 nm of the third mixture;

[0054] The formaldehyde concentration in the mixed gas in step (1) is changed, and the absorbance data are tested according to the process of step (1) and step (2) to obtain a linear equation of the ultraviolet-visible light absorbance at 550 nm and the formaldehyde concentration. The linear equation is: y=0.00358x+0.00182, and the correlation coefficient is 0.99572, wherein x is the formaldehyde concentration and y is the absorbance.

[0055] Figure 1 is the linear equation curve of UV-visible light absorbance and formaldehyde concentration obtained in Example 1; Figure 1( Figure 1 In the figure, “Absorbance” means absorbance. It can be seen that there is a good linear correlation between UV-visible light absorbance and formaldehyde concentration.

[0056] Example 2

[0057] A method for storing formaldehyde-containing gas comprises the following steps:

[0058] A formaldehyde standard gas with a concentration of 10 ppm (2 months from the production time) and high-purity nitrogen (volume fraction of 99.999%) were added into a polytetrafluoroethylene air bag at a volume ratio of 1:199 and mixed to obtain a gas with a formaldehyde content of 50 ppb.

[0059] An application of a method for storing formaldehyde-containing gas comprises the following steps:

[0060] According to the method of Example 1, the gas with a formaldehyde content of 50 ppb in Example 2 is used to replace the mixed gas in step (1) of Example 1 to measure the absorbance data of ultraviolet-visible light at 550 nm, and then substitute it into y=0.00358x+0.00182 to calculate the formaldehyde content in the gas of Example 2.

[0061] Example 3

[0062] A method for storing formaldehyde-containing gas comprises the following steps:

[0063] Add 10ppm formaldehyde standard gas and high-purity nitrogen (99.999% by volume) into a polytetrafluoroethylene bag at a volume ratio of 1:199 to obtain a gas with a formaldehyde content of 50ppb.

[0064] An application of a method for storing formaldehyde-containing gas comprises the following steps:

[0065] A gas chromatograph-mass spectrometer (GC-MS) was used to analyze the composition and content of the gas sample with a formaldehyde content of 50 ppb in Example 3. The solid phase microextraction technique was used to enrich the gas, and the fiber extraction needle was inserted into the gas sampling bag to expose the fiber extraction needle to the gas. The extraction time was 1.5 hours. The fiber extraction needle was pulled out and then moved to the preheated GC-MS. The GC-MS injection port temperature was 250°C, the column front pressure was adjusted to 75 kPa, the ion source temperature was 200°C, and the purge flow rate was adjusted to 1.5 mL / min. The formaldehyde content was measured to be 49.8 ppb, and the accuracy was 49.8 / 50*100%=99.6%.

[0066] Example 4

[0067] A method for storing formaldehyde-containing gas comprises the following steps:

[0068] Add 10ppm formaldehyde standard gas and high-purity nitrogen (99.999% by volume) into a polytetrafluoroethylene bag at a volume ratio of 1:199 to obtain a gas with a formaldehyde content of 50ppb.

[0069] An application of a method for storing formaldehyde-containing gas comprises the following steps:

[0070] The gas with a formaldehyde content of 50 ppb in Example 4 was tested using an electrochemical sensing method. UIO-67-NH2 was in situ grown on an Ag-Pd interpolation electrode sheet through a one-step self-assembly hydrothermal method. The electrode sheet was fixed in a vacuum-sealed plexiglass box with a box volume of 20 L. 300 mL of the gas with a formaldehyde content of 50 ppb in Example 4 was introduced into the box to obtain an impedance spectrum of the electrode sheet after the gas was introduced. The formaldehyde content in the gas was calculated to be 49.7 ppb, and the accuracy was 49.7 / 50*100%=99.4%.

[0071] Example 5

[0072] Compared with Example 2, the only difference in Example 5 is that the formaldehyde standard gas with a concentration of 10 ppm and a time of 1 year from the production time is used to replace the formaldehyde standard gas with a concentration of 10 ppm and a time of 2 months from the production time in Example 2, and the rest of the process is the same as Example 2.

[0073] Comparative Example 1

[0074] Compared with Example 2, the difference of Comparative Example 1 is that an air bag made of aluminum foil is used instead of the air bag made of polytetrafluoroethylene in Example 2, and the rest of the process is the same as Example 2.

[0075] Comparative Example 2

[0076] Compared with Example 2, the difference of Comparative Example 2 is that the air bag made of rubber material is used instead of the air bag made of polytetrafluoroethylene in Example 2, and the rest of the process is the same as that of Example 2.

[0077] Comparative Example 3

[0078] Compared with Example 2, the difference of Comparative Example 3 is that high-purity helium (volume fraction is 99.999%) is used to replace the high-purity nitrogen in Example 2, and the rest of the process is the same as Example 2.

[0079] Comparative Example 4

[0080] Compared with Example 2, the difference of Comparative Example 4 is that high-purity argon gas (volume fraction is 99.999%) is used to replace the high-purity nitrogen in Example 2, and the rest of the process is the same as Example 2.

[0081] Comparative Example 5

[0082] Compared with Example 2, the only difference in Example 5 is that the formaldehyde standard gas with a concentration of 10 ppm produced 2 years ago is used to replace the formaldehyde standard gas with a concentration of 10 ppm produced 2 months ago in Example 2, and the rest of the process is the same as Example 2.

[0083] Product effect testing

[0084] The concentration and accuracy of formaldehyde in the gas measured in the above-mentioned Example 2, Example 5, and Comparative Examples 1-5 (accuracy = formaldehyde concentration obtained by test / 50*100%, the closer the accuracy is to 100%, the more accurate the result) are shown in Table 1 below.

[0085] Table 1

[0086]

[0087] It can be seen from the data in Table 1 above that when the material of the air bag is changed, or the type of the balancing gas is changed, the accuracy of the formaldehyde content in the gas corresponding to the comparative example is greatly reduced.

[0088] The relative molecular mass of formaldehyde is 30.03, and the relative molecular mass of nitrogen is 28.02. The two are close, so formaldehyde can be mixed evenly with nitrogen, and the formaldehyde concentration in the gas taken out from the air bag valve is basically 10ppm; the relative molecular mass of helium is 4.0026, which is much lower than formaldehyde. After the two are mixed, formaldehyde is located in the lower layer and helium is located in the upper layer, so the main component of the gas taken out from the air bag valve is helium, and the concentration of formaldehyde is significantly lower than 10ppm; similarly, the relative molecular mass of argon is 39.948, which is higher than formaldehyde. After the two are mixed, formaldehyde is located in the upper layer and argon is located in the lower layer, so the formaldehyde concentration in the gas taken out from the air bag valve is significantly higher than 10ppm.

[0089] Application Examples

[0090] Compared with Example 2, this application example collects the breath of volunteers, and the collected gas replaces the gas with a formaldehyde content of 50 ppb in Example 2, and then the formaldehyde content in the breath of volunteers is tested according to the method of Example 2.

[0091] During the process of collecting the breath of volunteers, they are required to abstain from food, alcohol, and strenuous activities within 8 hours before the collection. They are not required to brush their teeth on the day of the collection, but only rinse their mouths with water. Before the collection, the quiet room where the volunteers are located is required to be ventilated, dry, clean and odor-free.

[0092] The patient goes to the gas collection room to prepare, takes 5 deep breaths, then takes a deep breath, and then slowly exhales the gas. The first part of the gas is exhaled directly into the air without being collected. Then unscrew the valve of the polytetrafluoroethylene gas collection bag, blow the second part of the gas into the gas collection bag, and close the valve of the gas collection bag in time after the second part of the gas is blown out, and then repeat the above operation. Close the valve immediately after the gas collection bag is full and save it.

[0093] The application method of the present invention is an auxiliary method in the diagnosis process of lung cancer. The results of the application method of the present invention cannot directly determine whether the patient has lung cancer. Whether the patient has lung cancer needs to be further determined in combination with computed tomography (CT) scanning, pathology and other methods.

Claims

1. A method for storing formaldehyde-containing gas, characterized in that: The following steps are involved: Formaldehyde and balance gas are added into a container made of polytetrafluoroethylene and mixed to obtain a gas, wherein the formaldehyde content is at ppb level, and the balance gas includes nitrogen but does not include argon or helium.

2. The storage method according to claim 1, characterized in that: The content of formaldehyde in the gas is 40-60 ppb.

3. The storage method according to claim 1, characterized in that: The formaldehyde is formaldehyde produced within 1 year.

4. Application of the storage method according to any one of claims 1 to 3, characterized in that: The following steps are involved: The gas in the storage method is injected into a gas chromatograph-mass spectrometer to analyze the gas composition and content, an electrochemical analysis method is used to analyze the electrochemical impedance spectrum of formaldehyde in the gas, or an AHMT solution is used to detect the formaldehyde content in the gas. The structural formula of the AHMT is 5. The use according to claim 4, characterized in that: The following steps are involved: Step (1): Mix the reagent a and the reagent b to obtain a first mixture, then take the gas in the storage method as the gas to be tested and add it to the first mixture, seal it, and let it stand to obtain a second mixture; the reagent a includes an acid solution of AHMT, and the structural formula of AHMT is The reagent b is a potassium hydroxide solution; Step (2): adding the reagent C to the second mixture, shaking, sealing, and standing to obtain a third mixture, and measuring the UV-visible absorbance data of the third mixture; the reagent C includes an alkaline solution of KIO4; Step (3): replacing the gas to be tested in step (1) with a mixed gas of formaldehyde and nitrogen with known standard series concentrations, and obtaining a linear equation of UV-visible light absorbance and formaldehyde concentration according to the processes of steps (1) and (2); Step (4): Substitute the ultraviolet-visible light absorbance data of the third mixture corresponding to the gas to be tested into the linear equation of step (3) to calculate the formaldehyde concentration in the gas to be tested.

6. The use according to claim 5, characterized in that: The following steps are involved: Step (1): Mix the reagent a and the reagent b to obtain a first mixture, then take the gas in the storage method as the gas to be tested and add it to the first mixture, seal it, and let it stand to obtain a second mixture; the reagent a includes an acid solution of AHMT, and the structural formula of AHMT is In the AHMT acid solution, the mass concentration of AHMT is 0.5-3%, the acid in the AHMT acid solution is HCl, and the concentration of HCl is 0.2-0.5 mol / L; the reagent b is a potassium hydroxide solution, and the mass ratio of potassium hydroxide to water in the potassium hydroxide solution is 28-100:100; Step (2): adding the reagent C to the second mixture, shaking, sealing, and standing to obtain a third mixture, and measuring the UV-visible absorbance data of the third mixture; the reagent C comprises an alkaline solution of KIO4, and the mass concentration of KIO4 in the alkaline solution of KIO4 is 1-3%; Step (3): replacing the gas to be tested in step (1) with a mixed gas of formaldehyde and nitrogen with known standard series concentrations, and obtaining a linear equation of UV-visible light absorbance and formaldehyde concentration according to the processes of steps (1) and (2); Step (4): Substitute the ultraviolet-visible light absorbance data of the third mixture corresponding to the gas to be tested into the linear equation of step (3) to calculate the formaldehyde concentration in the gas to be tested.

7. The use according to claim 6, characterized in that: The following steps are involved: In step (1), the volume ratio of reagent a to reagent b is 1:(0.9-1.1).

8. The use according to claim 6, characterized in that: In step (1), the volume of the gas to be tested is 150-400 mL.

9. The use according to claim 6, characterized in that: In step (1), the gas obtained by the storage method can be replaced by human exhaled gas.

10. The use according to claim 6, characterized in that: In step (3), the linear equation is: y=0.00358x+0.00182, and the correlation coefficient is 0.99572, wherein x is the formaldehyde concentration and y is the absorbance.

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