A method for sampling exhaled breath that eliminates the effects of humidity

Abstract

The application discloses a breath sampling method for eliminating humidity influence, and belongs to the technical field of chemical analysis and detection. The breath sampling method adopts ion mobility spectrometry online dilution sampling purging detection technology, and simultaneously dilutes breath samples through an online dilution sampling device, so that the influence of breath humidity on accurate quantitative detection is reduced, and the quantitative linear range of breath ammonia is further improved. Meanwhile, ion molecular reaction is not interfered by other components in the breath, the breath low-concentration ppbv ammonia has very high sensitivity and specific signal response, the change of the breath ammonia concentration can be monitored in real time, and the qualitative separation sensitivity and quantitative analysis accuracy are greatly improved. The breath ammonia and liver and kidney organ function monitoring are provided with technical support.

Description

Technical Field

[0001] This invention belongs to the field of analytical chemistry instrumentation, specifically relating to an exhaled breath sampling method that eliminates the influence of humidity, and an ion mobility spectrometry flow pattern and analysis method that improves the selectivity and sensitivity of exhaled ammonia detection. Background Technology

[0002] Since the absolute water vapor content in human exhaled breath is as high as 6%, and the relative humidity in exhaled breath can reach 100% RH at a body temperature of 37°C, humidity not only affects important components of analytical instruments, but also makes the analytical detection process more complicated and has a certain impact on the sensitivity of detecting low-concentration components in exhaled breath. How to eliminate the influence of humidity in exhaled breath, or to achieve the separation of water and other components, places high demands on the sensitivity and selectivity of instruments under high humidity conditions.

[0003] Currently, methods for detecting exhaled breath include gas chromatography, photometry, sensors, and other methods. Among them, chromatography and chromatography-mass spectrometry are most widely used in indoor air ammonia detection, but they have disadvantages such as high cost, large size, and the need for specialized technicians to operate. Photometry has simple operation steps, but its stability and reproducibility are poor. Although sensor methods have advantages such as miniaturization and short response time, their quantification is inaccurate.

[0004] To address the various problems existing in the above-mentioned analytical detection methods, this invention employs direct photoionization ion mobility spectrometry to detect ammonia in exhaled breath. Furthermore, by using an online dilution sampling method and adjusting different dilution gas flow ratios, the influence of high humidity in exhaled breath on the detection of various components and the sensitivity response of each component in exhaled breath are further reduced. This method is then applied to the detection of ammonia and other component concentrations in exhaled breath. This invention and analytical method provide a way to achieve real-time monitoring of ammonia concentration in exhaled breath. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to eliminate the influence of humidity in exhaled air. By setting an online dilution gas path in the sampling pipeline, the exhaled air sample can be diluted in real time. This not only eliminates the influence of humidity changes on detection, but also reduces the adsorption of various exhaled air components in the sampling pipeline.

[0006] Specific content includes

[0007] A method for exhaled breath sampling to eliminate the influence of humidity, characterized in that: the device includes a sampling blowing tube with two open ends, a sampling blowing nozzle is provided at one open end of the blowing tube, which is a tube with a truncated cone-shaped hollow through hole, one end of the upper bottom surface of the truncated cone-shaped through hole (the radial cross-sectional area of ​​the lower bottom surface at the other end of the through hole is larger than the radial cross-sectional area of ​​the upper bottom surface) is connected to one open end of the blowing tube; a branch is provided on the blowing tube, which is connected to the blowing tube as a bypass, and the other end of the blowing tube bypass is connected to the inlet of an ion mobility spectrometer; an online dilution interface connected to a dilution gas source is provided on the blowing tube bypass;

[0008] The exhaled air of a person or animal, which enters the air tube through the sampling nozzle, is diluted with dilution gas in the bypass of the air tube and then introduced into the ion mobility spectrometer through the injection port.

[0009] Ion mobility spectrometry includes an ion mobility tube, which comprises a reaction zone and a migration zone. An inlet is located in the reaction zone, where sample molecules are primarily ionized, while product ions are primarily separated in the migration zone. An ionization source is positioned at the front end of the reaction zone (the end furthest from the migration zone) to effectively ionize molecules. An ion gate is located between the reaction and migration zones; pulsed activation of the ion gate enables periodic separation and detection of ions. A detector is positioned at the rear end of the migration zone (the end furthest from the reaction zone) to convert current signals into voltage signals and amplify them.

[0010] The sampling nozzle is a disposable sampling nozzle, which is detachably connected to the blowing tube.

[0011] By setting an online dilution gas path at the front end of the inlet, the exhaled gas sample can be diluted in real time. Depending on the set dilution flow rate, the humidity of the exhaled gas can be reduced from 100%RH to 20-50%RH (20-30℃), thus avoiding the influence of high humidity in the exhaled gas. In addition, it can further expand the quantitative linear range of high humidity components in exhaled breath, which is more conducive to real-time online monitoring of exhaled gas samples.

[0012] The online dilution sampling device continuously supplies a stream of dry, clean air to dilute and purge the exhaled air sample. The flow rate of the dilution air is a certain proportion of the sampling flow rate, which can dilute the exhaled air sample to different degrees, thereby reducing the humidity of the exhaled air. Depending on the dilution ratio, the humidity can be reduced to 20-50% RH (20-30℃).

[0013] Since the humidity of exhaled air changes in real time with the breathing rate, ammonia in exhaled air is simulated by configuring ammonia standard gases with different humidity levels. Ion mobility spectrometry is used to detect ammonia standard gases with different humidity levels in the collected reaction zone to obtain ion mobility spectra of ammonia under different humidity levels.

[0014] An online purge sampling device was used to sample and detect ammonia standard gas at different humidity levels. Simultaneously, an online dilution purge gas was installed at the sampling pipeline end to further dilute the humidity, thus obtaining the change of the ammonia quantitative factor with humidity. Since the humidity is further diluted during the online dilution sampling process, this online dilution sampling device further eliminates the influence of humidity on the detection of ammonia gas at constant concentrations with different humidity levels, making the quantitative factor basically unchanged with humidity changes. It can be used for real-time monitoring of exhaled ammonia concentration.

[0015] The flow rate of the sampling tube is 100-200 ml / min, the flow rate of the diluent gas is 50-150 ml / min, and the flow rate of the exhaled air entering the bypass of the blowing tube is about 50-100 ml / min. By adjusting the different flow rates of the exhaled air entering the bypass of the blowing tube and the diluent gas, the humidity of the exhaled air can be effectively diluted.

[0016] The flow rate in the sampling tubing and the flow rate in the diluent gas can effectively dilute the humidity of exhaled air.

[0017] The exhaled air of a person or animal, which enters the air tube through the sampling nozzle, is diluted with dilution gas in the bypass of the air tube and then introduced into the ion mobility spectrometer for detection through the injection port; the other opening of the air tube is vented.

[0018] This sampling method can be used not only for the detection of ammonia in exhaled breath, but also for the detection of other components in exhaled breath such as acetone, isoprene, or other small molecules.

[0019] This invention employs online dilution sampling and purge detection technology based on ion mobility spectrometry. Through an online dilution sampling device, exhaled breath samples are simultaneously diluted, reducing the impact of exhaled breath humidity on accurate quantitative detection and further improving the quantitative linear range of exhaled ammonia. Simultaneously, the ion molecular reaction is unaffected by other components in the exhaled breath, exhibiting very high sensitivity and specificity for low concentrations of ppbv ammonia in exhaled breath. It allows for real-time monitoring of changes in exhaled ammonia concentration, significantly improving both qualitative separation sensitivity and quantitative analysis accuracy. This provides technical support for clinical monitoring of exhaled ammonia and organ function such as the liver and kidneys. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a direct exhaled breath sampling device.

[0021] Among them, 1: a mouthpiece for single-use exhaled air sampling; 2: an exhaled air tube bypass; 3: an exhaled air sampling tube; 4: an ionization source for ion mobility spectrometry; 5: an ion molecular reaction region; 6: an ion gate for controlling the periodic entry of ions; 7: a migration region for ion mobility spectrometry; 8: an ion receiving electrode; 9: a drift gas flow; and 10: a pump exhaust outlet.

[0022] Figure 2 This is a schematic diagram of an online exhaled breath sampling device for diluting and eliminating the effects of humidity.

[0023] Among them, 1: a mouthpiece for single-use exhaled air sampling; 2: an exhaled air tube bypass; 3: online dilution purge gas; 4: an exhaled air sampling line; 5: an ionization source for ion mobility spectrometry; 6: an ion molecular reaction region; 7: an ion gate for controlling the periodic entry of ions; 8: a migration region for ion mobility spectrometry; 9: an ion receiving electrode; 10: a drift gas flow; and 11: a pump exhaust outlet.

[0024] Figure 3 The ion migration spectra of ammonia in exhaled gas under different humidity levels;

[0025] Figure 4 The quantitative factor of exhaled ammonia varies with humidity under different humidity conditions using a direct injection device;

[0026] Figure 5 The quantitative factor of exhaled ammonia varies with humidity under different humidity conditions using an online dilution injection device;

[0027] Figure 6 Quantitative calibration curves for 100% RH ammonia at different concentrations;

[0028] Figure 7 This is a real-time tracking curve of changes in exhaled ammonia concentration. Detailed Implementation

[0029] Ion mobility spectrometry includes a reaction region and a migration region. The reaction region is mainly used for the ionization of sample molecules, while the migration region is mainly used for the separation of product ions. An ionization source is placed at the front end of the reaction region to effectively ionize molecules. An ion gate is placed between the reaction region and the migration region. The pulse opening of the ion gate enables the periodic separation and detection of ions. A detector is placed at the rear end of the migration region to convert the current signal into a voltage signal and amplify it.

[0030] Example 1

[0031] like Figure 1The diagram shows a schematic of a direct-injection exhaled gas sampling device. The direct-injection device includes a disposable sampling nozzle, a sampling tube, and a sampling tube bypassing the sampling tube. After exhaled gas enters the sampling tube, it enters the ion mobility spectrum in real time through the sampling tube bypassing the sampling tube. Among them, 1 is the disposable exhaled gas sampling nozzle, 2 is the exhaled gas sampling tube bypass, 3 is the exhaled gas sampling tube, 4 is the ionization source of the ion mobility spectrum, 5 is the ion molecular reaction region, 6 is the ion gate that controls the periodic entry of ions, 7 is the migration region of the ion mobility spectrum, 8 is the ion receiving electrode, 9 is the drift gas flow, and 10 is the pump exhaust outlet.

[0032] The device includes a sampling air tube with two open ends. A sampling air nozzle is provided at one open end of the air tube. The nozzle is a tube with a truncated cone-shaped hollow through hole. One end of the upper bottom surface of the truncated cone-shaped through hole (the radial cross-sectional area of ​​the lower bottom surface at the other end of the through hole is larger than the radial cross-sectional area of ​​the upper bottom surface) is connected to one open end of the air tube. The other end of the air tube bypass is connected to the inlet of the ion mobility spectrometer. The other open end of the air tube is vented to the atmosphere.

[0033] The exhaled air of a person entering the air tube through the sampling nozzle is diluted with dilution gas in the bypass of the air tube and then introduced into the ion mobility spectrometer through the injection port.

[0034] Example 2

[0035] like Figure 2 The diagram shows a schematic of an online dilution device for eliminating the influence of humidity in exhaled air sampling. The online dilution device includes a disposable sampling nozzle, a sampling tube, a sampling tube bypassing the sampling tube, and an online dilution line installed on the sampling line, enabling real-time online dilution of exhaled air samples. Specifically, 1 is the disposable exhaled air sampling nozzle, 2 is the exhaled air tube bypass, 3 is the online dilution purge gas, 4 is the exhaled air sampling line, 5 is the ionization source for ion mobility spectrometry, 6 is the ion molecular reaction region, 7 is the ion gate controlling the periodic entry of ions, 8 is the migration region of the ion mobility spectrometry, 9 is the ion receiving electrode, 10 is the drift gas flow, and 11 is the pump exhaust outlet.

[0036] The apparatus includes a sampling blowing tube with two open ends. A sampling blowing nozzle is provided at one open end of the blowing tube. The nozzle is a pipe with a truncated cone-shaped hollow through hole. One end of the upper base of the truncated cone-shaped through hole (the radial cross-sectional area of ​​the lower base at the other end of the through hole is larger than the radial cross-sectional area of ​​the upper base) is connected to one open end of the blowing tube. A branch is provided on the blowing tube, which is connected to the blowing tube as a bypass. The other end of the blowing tube bypass is connected to the inlet of the ion mobility spectrometer. An online dilution interface connected to a dilution gas source is provided on the blowing tube bypass. The other open end of the blowing tube is vented to the atmosphere.

[0037] The exhaled air of a person entering the air tube through the sampling nozzle is diluted with dilution gas in the bypass of the air tube and then introduced into the ion mobility spectrometer through the injection port.

[0038] The online dilution sampling device continuously purges the exhaled air sample with clean air through its dilution pipeline. The flow rate of the dilution air is a certain proportion of the sampling flow rate, which can dilute the exhaled air sample to different degrees, thereby reducing the humidity of the exhaled air. When the sampling flow rate of the ion mobility spectrometry is set to 200 ml / min, and the flow rates of the exhaled air and the online dilution air are set to 100 ml / min respectively, the humidity of the exhaled air can be reduced to 50% RH. When the flow rate of the exhaled air is set to 50 ml / min and the flow rate of the online dilution air is set to 150 ml / min, the humidity of the exhaled air can be reduced to 25%. Depending on the set dilution ratio, the humidity of the exhaled air can be greatly diluted, thereby avoiding the influence of high humidity in the exhaled air on the detection of low concentration ammonia.

[0039] An online purge sampling device was used to sample and detect ammonia standard gases at different humidity levels. Simultaneously, an online dilution purge gas was installed at the sampling line end to further dilute the humidity, allowing for the measurement of the ammonia quantitative factor as a function of humidity. Because the humidity is further diluted during the online dilution sampling process, this online dilution sampling device further eliminates the influence of humidity on the detection of ammonia gases at constant concentrations with different humidity levels. This ensures that the quantitative factor remains essentially constant with humidity changes, making it suitable for real-time monitoring of exhaled ammonia concentrations. Results are as follows: Figure 5 As shown.

[0040] Example 3

[0041] The process and conditions are the same as in Example 2, except that since the humidity of exhaled air changes in real time with the breathing rate, ammonia in exhaled air is simulated by preparing ammonia standard gases with different humidity levels. The concentration of the ammonia standard gas is 200 ppb. Ion mobility spectrometry is used to detect the ammonia standard gases collected in the reaction zone at different humidity levels, and ion mobility spectra of 200 ppb ammonia at different humidity levels are obtained. The results are as follows. Figure 3 As shown.

[0042] Example 4

[0043] The apparatus includes a sampling air tube with two open ends. A sampling air nozzle is provided at one open end of the air tube. The nozzle is a tube with a truncated cone-shaped hollow through hole. One end of the upper bottom surface of the truncated cone-shaped through hole (the radial cross-sectional area of ​​the lower bottom surface at the other end of the through hole is larger than the radial cross-sectional area of ​​the upper bottom surface) is connected to one open end of the air tube. A branch is provided on the air tube, which is connected to the air tube as a bypass. The other end of the air tube bypass is connected to the inlet of the ion mobility spectrometer. The other open end of the air tube is vented to the atmosphere.

[0044] Unlike Examples 2 and 3, the exhaled air of the person entering the air tube through the sampling nozzle is directly introduced into the ion mobility spectrometer through the injection port in the air tube bypass. There is no dilution gas to dilute the exhaled air sample online. The sampling flow rate of the ion mobility spectrometer directly collects the exhaled air at 200 ml / min.

[0045] This direct injection method was used to sample and detect ammonia standard gases at different humidity levels. The change in the ammonia quantitative factor with humidity was obtained. Since humidity has a certain promoting effect on ammonia detection, the signal intensity of ammonia gradually increases with increasing humidity. However, the influence of humidity changes on the ammonia quantitative signal response cannot be effectively eliminated. The results are as follows: Figure 4 As shown, as the humidity of the 200ppb ammonia standard gas changes from 0%RH to 100%RH, the quantification factor increases from 0.12 to 0.35, indicating that it is greatly affected by humidity and cannot accurately quantify the ammonia concentration under humidity changes in a single respiration cycle.

[0046] Example 5

[0047] The process and conditions are the same as in Example 2, except that an online purge sampling device is used to sample and detect ammonia standard gases with different humidity levels. Simultaneously, an online dilution purge gas is installed at the sampling pipeline end to further dilute the humidity, thus obtaining the change in the ammonia quantitative factor with humidity. Because the humidity is further diluted during the online dilution sampling process, this online dilution sampling device further eliminates the influence of humidity on the detection of ammonia gases at constant concentrations with different humidity levels, making the quantitative factor essentially unchanged with humidity changes. The results are as follows: Figure 5 As shown, within the RH range of 0%-100% RH, the quantitative ratio of 200 ppb ammonia standard gas remains relatively constant at around 0.05, demonstrating that humidity changes within a single respiratory cycle do not significantly affect the accurate quantitative detection of ammonia concentration, and this method can be used for real-time monitoring of exhaled ammonia concentration.

[0048] Example 6

[0049] The process and conditions were the same as in Example 2, except that an online dilution sampling device was used to detect ammonia gas at different concentrations: 100 ppb, 200 ppb, 500 ppb, 800 ppb, 1000 ppb, 1200 ppb, 1500 ppb, 1800 ppb, and 2000 ppb. The corresponding quantitative factor values ​​were 0.036, 0.062, 0.146, 0.228, 0.286, 0.338, 0.412, 0.501, and 0.539, respectively. A quantitative calibration curve was plotted, yielding the calibration equation y = 2.71 * 10^6. -4 x+0.01, where R 2 =99.9%, the result is as follows Figure 6 As shown.

[0050] Example 7

[0051] The process and conditions were the same as in Example 2, except that an online dilution sampling device and ion mobility spectrometry were used to sample and detect ammonia in human exhaled breath in real time, obtaining a concentration tracking curve for exhaled ammonia. Five consecutive monitoring sessions were conducted to obtain the concentration change curve for exhaled ammonia, with a concentration of 450 ppbv and a time resolution of only 40 ms. The results are as follows: Figure 7 As shown.

Claims

1. An exhaled breath sampling device that eliminates the influence of humidity, characterized in that: The device includes a sampling air blowing tube with two open ends. A sampling air blowing nozzle is provided at one open end of the air blowing tube. The nozzle is a pipe with a truncated cone-shaped hollow through hole. One end of the upper base of the truncated cone-shaped through hole is connected to one open end of the air blowing tube. The radial cross-sectional area of ​​the lower base of the other end of the truncated cone-shaped through hole is larger than the radial cross-sectional area of ​​the upper base. A branch is provided on the air blowing tube, which is connected to the air blowing tube as a bypass. The other end of the bypass is connected to the inlet of the ion mobility spectrometer. An online dilution interface connected to a dilution gas source is provided on the bypass of the air blowing tube. The exhaled air of a person or animal, which enters the air tube through the sampling nozzle, is diluted with dilution gas in the bypass of the air tube and then introduced into the ion mobility spectrometer through the injection port.

2. The exhaled breath sampling device for eliminating the influence of humidity according to claim 1, characterized in that: Ion mobility spectrometry includes an ion mobility tube, which comprises a reaction zone and a migration zone. An inlet is located in the reaction zone, where sample molecules are ionized, and product ions are separated in the migration zone. An ionization source is placed at the front end of the reaction zone, away from the migration zone, to effectively ionize the molecules. An ion gate is located between the reaction and migration zones; pulsed opening of the ion gate enables periodic separation and detection of ions. A detector is placed at the rear end of the migration zone, away from the reaction zone, to convert the current signal into a voltage signal and amplify it.

3. The exhaled breath sampling device for eliminating the influence of humidity according to claim 1, characterized in that: The sampling nozzle is a disposable sampling nozzle, which is detachably connected to the blowing tube.

4. A method for real-time detection of ammonia concentration in exhaled breath using an exhaled breath sampling device that eliminates the influence of humidity as described in any one of claims 1-3, characterized in that: The exhaled air sampling device continuously supplies a stream of dry, clean air to dilute and purge the exhaled air sample. The flow rate of the diluent air is a certain proportion of the sampling flow rate, which dilutes the exhaled air sample to different degrees, thereby reducing the humidity of the exhaled air to 20-50% RH, depending on the dilution ratio.

5. The method for real-time detection of ammonia concentration in exhaled breath using the exhaled breath sampling device for eliminating the influence of humidity according to claim 4, characterized in that: By simulating ammonia in exhaled breath using ammonia standard gases with different humidity levels, ion mobility spectrometry was used to detect the ammonia standard gases with different humidity levels collected in the reaction zone, and ion mobility spectra of ammonia under different humidity levels were obtained.

6. The method for real-time detection of ammonia concentration in exhaled breath using the exhaled breath sampling device for eliminating the influence of humidity according to claim 4, characterized in that: The flow rate of the sampling tube is 100-200 ml / min, the flow rate of the diluent gas is 50-150 ml / min, and the flow rate of the exhaled air entering the bypass of the blowing tube is about 50-100 ml / min. By adjusting the different flow rates of the exhaled air entering the bypass of the blowing tube and the diluent gas, the humidity of the exhaled air can be effectively diluted.

7. The method for real-time detection of ammonia concentration in exhaled breath using the exhaled breath sampling device for eliminating the influence of humidity according to claim 4, characterized in that: The exhaled air of a person or animal, which enters the air tube through the sampling nozzle, is diluted with dilution gas in the bypass of the air tube and then introduced into the ion mobility spectrometer for detection through the injection port; the other opening of the air tube is vented.

8. A method for real-time detection of ammonia concentration in exhaled breath using an exhaled breath sampling device that eliminates the influence of humidity according to any one of claims 4-7, characterized in that: This sampling method can be used to detect ammonia in exhaled breath.

9. A method for real-time detection of acetone concentration in exhaled breath, characterized in that: This method uses the exhaled air sampling device described in claims 1-3 to eliminate the influence of humidity to detect the concentration of acetone in exhaled air.

10. A method for real-time detection of exhaled isoprene concentration, characterized in that: This method uses the exhaled breath sampling device described in claims 1-3 to eliminate the influence of humidity to detect the concentration of isoprene in exhaled breath.

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