Chromatography-based pulsed flame photometric detection apparatus and differential detection method

Abstract

The application discloses a kind of based on chromatography's pulsed flame photometric detection device and differential detection method, including combustion reaction chamber component, light signal transmission component and light signal processing component. Combustion reaction chamber component is by flange-like base, reaction tower seat, combustion chamber main part, combustion chamber, ignition chamber is formed;Light signal transmission component includes double-end quartz light guide rod, plano-convex lens, optical filter;Light signal processing component includes photomultiplier tube, cooling pipeline and corresponding auxiliary power supply seat. Using differential principle, light signal is transmitted to two identical light signal processing components, two kinds of high and low wavelength light are detected simultaneously, using time as contrast process, the interference substance wavelength of high wavelength light in the time period of low wavelength is extracted, and the lower wavelength light further deducts interference wavelength, the present application can break through the detection lower limit of traditional pulsed flame photometric detector, and solve the interference problem of equipment temperature to photomultiplier tube, further improve detection precision.

Description

Technical Field

[0001] This invention relates to a gas chromatography detection device, specifically a pulsed flame photometric detector, which can utilize differential technology to optimize the detection limit. Background Technology

[0002] Gas chromatography is used to detect specific elements (and their compounds) in a sample. It is a qualitative analysis method and is generally used in conjunction with various detectors. Different detectors can selectively detect specific elements (and their compounds). Commonly used detectors include thermal conductivity detectors, flame ionization detectors, electron capture detectors, and flame photometric detectors. Among them, thermal conductivity detectors have relatively low sensitivity and are often used as general-purpose detectors; flame ionization detectors mainly detect organic compounds related to combustion in a hydrogen flame and are prone to damaging the sample, so they are often used as detectors for organic compounds; electron capture detectors are often used as dedicated detectors; flame photometric detectors have good selectivity and high sensitivity and are suitable for various occasions, but the combined equipment is relatively complex. Among flame photometric detectors, pulsed flame photometric detectors have the highest sensitivity and the best selectivity.

[0003] Generally, a pulsed flame photometric detector is used to detect the concentration of an analyte containing a specific element. It utilizes the diffused flame at the end of the combustion chamber 13, where the gas phase reaction generated by the diffused flame emits light with a specific spectrum and lifetime. This light is then amplified by a photomultiplier tube 21, converting the optical signal into an electrical signal for data analysis, and outputting a spectrum that characterizes the concentration of the substance. Different elements can be detected by adjusting the signal reception time and by using filters, photomultiplier tubes, and microcurrent amplifiers.

[0004] The detector operates at a temperature no lower than 250℃. Furthermore, the photomultiplier tube is located close to the detector, and the combustion chamber temperature can cause the photomultiplier tube's operating temperature to rise, generating background noise and significantly impacting detection accuracy. Currently, most photomultiplier tube applications use cooling pads, but the cooling effect still does not meet the requirements of the precision instrument's operating environment. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a pulsed flame photometric detector that differentially processes the optical signal while avoiding the influence of background noise from the photomultiplier tube, thereby reducing the detection limit and improving the stability of the detector.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A pulsed flame photometric detection device, characterized in that it comprises a combustion reaction chamber assembly, a light signal transmission assembly, and a light signal processing assembly connected in sequence; the combustion reaction chamber assembly includes a flange-like base, a reaction tower base, a combustion chamber, a combustion chamber main body, and an ignition chamber; the light signal transmission assembly passes through the side wall of the combustion chamber main body and collects light signals through a single-sided window, and includes a double-ended quartz light guide, a plano-convex lens, and a filter; the light signal processing assembly includes a photomultiplier tube and a cooling pipe.

[0007] As a further improvement of the present invention, a chromatographic column is inserted into the bottom of the flange-like base, the chromatographic column passes through the reaction tower base, and its end is fixed on the reaction tower base. A combustion chamber is provided on the reaction tower base, the main body of the combustion chamber is provided outside the combustion chamber and is fixed to the flange-like base by a first bolt, and the ignition chamber is fixed to the upper part of the main body of the combustion chamber by a second bolt. An ignition coil is connected at the welding window.

[0008] As a further improvement of the present invention, a gasket for sealing is provided between the combustion chamber body and the flange-like base; a gasket for sealing is provided between the combustion chamber body and the ignition chamber; and a flame arrester is also installed on the ignition chamber.

[0009] As a further improvement of the present invention, the flange-like base is provided with a heating component and a temperature measuring element inside; the flange base acts as a sample injection connection device, with a chromatographic column inserted into the bottom; the flange-like base is provided with a gas injection port on the side, a hydrogen injection port at the top, and an air injection port at the bottom.

[0010] As a further improvement of the present invention, the combustion chamber is welded to the second sleeve, which is a stainless steel sleeve with a special quartz tube inside.

[0011] As a further improvement of the present invention, the double-ended quartz light guide rod is fitted with a first tube sleeve. The left end of the first tube sleeve is welded and fixed to the combustion chamber body, and the right end is welded and fixed to the fixing component. The external thread of the bolt is screwed and fixed to the central internal thread of the fixing component. The right end of the double-ended quartz light guide rod is located at the focal point of the plano-convex lens, so that the light enters the filter parallel after passing through the plano-convex lens. The plano-convex lens is fixed in the lens holder by a washer, and the right side is pressed and fixed by a ring fixing component. The left side of the lens holder is connected to the fixing component by four third bolts, and the right side is connected to the photomultiplier tube sleeve by four fourth bolts. An O-ring is placed between the filter and the photomultiplier tube to protect the filter. The filter is placed at the incident light port of the photomultiplier tube to ensure that the light enters the photomultiplier tube perpendicularly. The photomultiplier tube includes a base and a power cord.

[0012] As a further improvement of the present invention, the input end of the double-ended quartz light guide rod is connected to an optical signal splitter, which receives the optical signal at the first moment and then splits it into two for output.

[0013] As a further improvement of the present invention, the cooling pipe includes an auxiliary heat sink, and the outside of the pipe is provided with cooling patches. The end of the photomultiplier tube is provided with a corresponding auxiliary power supply socket. The cooling pipe includes a motor exhaust cooling chamber placed at the front end of the pipe and cooling patches around the rear end of the pipe sleeve.

[0014] As a further improvement of the present invention, there are two working modes: When the optical signal transmission component is connected to a set of optical signal processing components, that is, the combustion reaction chamber component, the optical signal transmission component, and the optical signal processing component are connected in sequence, a filter is used, and the selectivity of the time coordinate is utilized to distinguish different substances, and the light intensity is detected to represent the concentration of the substance; When the optical signal transmission component is connected to two sets of optical signal processing components, that is, the combustion reaction chamber component is connected to two sets of optical signal transmission components through an optical signal splitter, the optical signal transmission component is connected to the optical signal processing component, the optical signal splitter is placed on a double-ended quartz light guide rod, and the double-ended quartz light guide rod is changed from a straight structure to a horizontal Y-shaped structure, so that it receives the optical signal at the first time and splits it into two outputs. The differential principle is used to simultaneously detect two kinds of high and low wavelength light, and time is used as a comparison processing to extract the interference wavelength of the high wavelength light in the time period of the low wavelength, and the interference wavelength of the lower wavelength light is further subtracted.

[0015] This invention also provides a pulsed flame photometric detection method, characterized by the following steps: the sample to be tested, air, and hydrogen are respectively introduced into a combustion reaction assembly, where they are decomposed into electronically excited states in the flame, emitting energy and photons emitted when returning to the ground state. Different elements emit different wavelengths of light, and the emission time varies. By adjusting the signal reception time, the light intensity is quantitatively analyzed through a filter and a photomultiplier tube. Based on this, the detection limit is further reduced by eliminating interfering light sources, that is, by using a differential method to subtract all possible interfering light sources that may exist at the same time within the time period of the target element.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Good working stability: By utilizing the principle of reducing thermal conductivity, the heat transferred out of the combustion chamber is reduced, thereby lowering the working environment temperature of the photomultiplier tube.

[0017] 2. Excellent interference removal capability: It utilizes the principle of difference to remove interfering light sources when detecting target elements. Attached Figure Description

[0018] Figure 1 This is a product image of a pulsed flame photometric detector; Figure 2 This is a product image of a pulsed flame photometric differential detector; Figure 3This is an exploded view of the pulsed flame photometric detector. Figure 4 This is a schematic diagram of the principle of a differential optical path splitter; Figure 5 This is a cross-sectional schematic diagram of a differential optical path splitter; Figure 6 This is a schematic diagram of a differential optical path splitter.

[0019] The diagram shows the following components: 1. Flange-like base; 2. Ignition chamber; 3. Combustion chamber main body; 4. Reaction chamber tower base; 5. Fixing component; 6. Bolt component; 7. Lens mounting bracket; 8. Circular ring fixing component; 9. Photomultiplier tube sleeve; 10. First sleeve; 11. Double-ended quartz light guide rod; 12. Gasket; 13. Combustion chamber; 14. First bolt; 15. Second bolt; 16. Third bolt; 17. Fourth bolt; 18. Second sleeve; 19. Flame arrester; 21. Photomultiplier tube; 22. Filter; 23. Plano-convex lens; 24. Washer; 25. O-ring; 26. Optical signal splitter. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings.

[0021] The present invention and its embodiments are described below. This description is not restrictive, and the actual embodiments are not limited thereto. This is the limitation. In conclusion, if anyone skilled in the art, inspired by this invention, designs a similar structure and embodiment without departing from the spirit of the invention, and without creative effort, such design should fall within the scope of protection of this invention.

[0022] Example 1

[0023] like Figure 1 As shown, this embodiment discloses a pulsed flame photometric detector, including: a combustion reaction chamber assembly, an optical signal transmission assembly, and an optical signal processing assembly.

[0024] The combustion reaction chamber assembly includes a flange-like base 1, which is locked to the chromatographic column by a graphite gasket ring to ensure a bottom seal. The flange-like base 1 includes two air inlets, corresponding to gas path one and gas path two, into which mixed gases of hydrogen and air in different proportions flow respectively.

[0025] Gas path one is the chromatographic column precipitate and mixed gas that flows through reaction tower base 4 to combustion chamber 13; The reaction tower base 4 and the flange-like base 1 are fixed by threads and sealed by a flange. Combustion chamber 13 is fixed to reaction tower base 4 by a pipe sleeve to ensure the stability of combustion chamber 13; Gas path two is that the mixed gas flows out from the upper part of the flange-like base 1, flows into the combustion chamber main body 3, and then into the ignition chamber 2; The combustion chamber main body 3 is fixed to the flange base 1 by two bolts, and a gasket 12 is provided between the two parts for sealing.

[0026] The combustion chamber main body 3 is fixed to the ignition chamber 2 by two bolts 14, and a gasket 12 is provided between the two parts for sealing.

[0027] Ignition chamber 2 is equipped with a spiral tube to prevent the flame light from the ignition coil from reaching the photomultiplier tube 21. At the same time, the ignition coil is inserted into the tube. When the gas mixture of appropriate proportion reaches the heated coil, the flame is ignited. The flame diffuses downward through the spiral tube and enters combustion chamber 13. After the analyte is eluted from the chromatographic column, it burns in a hydrogen-rich flame. During combustion, when it returns to the ground state, it emits light of a specific wavelength, which enters the photomultiplier tube 21 through the optical signal transmission component. When the gas in combustion chamber 13 is exhausted, the flame is extinguished. When the gas in ignition chamber 2 reaches the ignition coil again, it is reignited, forming a pulse ignition phenomenon.

[0028] The optical signal transmission component includes a quartz light guide rod 11 and a plano-convex lens 23. The left end of the tube sleeve 10 is welded to the combustion chamber main body 3, and the right end is welded to the fixing component 5. The double-ended quartz light guide rod 11 is placed inside the tube sleeve 10. The external thread of the fixing component 6 matches the central internal thread of the fixing component 5 for fixation. The output end of the light guide rod is located at the focal point of the plano-convex lens 23, allowing light to pass parallel to the filter 22 after passing through the plano-convex lens 23. The plane of the plano-convex lens 23 is fixed in the lens mounting bracket 7 by a washer 24, and the right side is pressed and fixed by a ring fixing component 8. The left side of the lens mounting bracket 7 is connected to the fixing component 5 by four bolts 16, and the right side is connected to the photomultiplier tube sleeve 9 by four bolts. An O-ring 25 is placed between the filter 22 and the photomultiplier tube 21 to protect the filter 22. The filter 22 is placed at the light inlet of the photomultiplier tube 21, ensuring that light enters the photomultiplier tube 21 perpendicularly. The photomultiplier tube 21 includes a base and a power cord.

[0029] The lens holder 7, the fastener 6, the ring fastener 8, and the photomultiplier tube sleeve 9 are all made of aluminum and require oxidation treatment to ensure that other interfering light sources are isolated during the transmission of the light source.

[0030] A thermally conductive silicone pad is placed between the photomultiplier tube sleeve 9 and the photomultiplier tube 21 to dissipate the heat generated by the photomultiplier tube 21 during operation. Meanwhile, a heat sink can be installed outside the photomultiplier tube sleeve 9 for cooling, further reducing background noise.

[0031] Example 2

[0032] like Figure 2As shown, this embodiment also discloses a pulsed flame photometric differential detector, including: a combustion reaction chamber assembly, an optical signal transmission assembly, and an optical signal processing assembly.

[0033] Combustion reaction chamber components, optical signal processing components and Figure 1 The detector shown is the same, but the optical signal transmission component adds an optical signal splitter 26. The optical signal enters the optical signal splitter through the left end of the light guide rod, is split by the optical fiber, and is output from the right end, thus splitting the optical signal into two. The remaining components are the same. Figure 1 Detector.

[0034] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention.

Claims

1. A pulsed flame photometric detection device, characterized in that, It includes a combustion reaction chamber assembly, an optical signal transmission assembly, and an optical signal processing assembly connected in sequence; the combustion reaction chamber assembly includes a flange-like base (1), a reaction tower base (4), a combustion chamber (13), a combustion chamber main body (3), and an ignition chamber (2); the optical signal transmission assembly passes through the side wall of the combustion chamber main body (3) and includes a double-ended quartz light guide rod (11), a plano-convex lens (23), and a filter (22); the optical signal processing assembly includes a photomultiplier tube (21) and a cooling pipe; wherein, the flange-like base (11) 1) The interior is equipped with heating components and temperature measuring elements. The flange-like base (1) has a gas inlet on its side, a hydrogen inlet at the top and an air inlet at the bottom. A chromatographic column is inserted into the bottom of the flange-like base (1). The chromatographic column passes through the reaction tower base (4) and its end is fixed on the reaction tower base (4). The ignition chamber (2) is equipped with a spiral pipe to prevent the flame light at the ignition coil from reaching the photomultiplier tube (21) and to allow the flame to diffuse downwards into the combustion chamber (13) through the spiral pipe, forming a pulse ignition.

2. The pulsed flame photometric detection device according to claim 1, characterized in that, The reaction tower base (4) is covered with a combustion chamber (13). The main body of the combustion chamber (3) is covered outside the combustion chamber (13) and fixed to the flange base (1) by the first bolt (14). The ignition chamber (2) is fixed to the upper part of the main body of the combustion chamber (3) by the second bolt (15). The ignition coil is connected at the welding window.

3. The pulsed flame photometric detection device according to claim 2, characterized in that, A gasket (12) for sealing is provided between the combustion chamber main body (3) and the flange base (1); a gasket (12) for sealing is provided between the combustion chamber main body (3) and the ignition chamber (2); a flame arrester is also installed on the ignition chamber (2).

4. The pulsed flame photometric detection device according to claim 2, characterized in that, The combustion chamber (13) is welded to the second sleeve (18), which is a stainless steel sleeve with a special quartz tube inside.

5. The pulsed flame photometric detection device according to claim 1, characterized in that, The double-ended quartz light guide rod (11) is fitted with a first sleeve (10). The left end of the first sleeve (10) is welded and fixed to the combustion chamber main body (3), and the right end is welded and fixed to the fixing part (5). The external thread of the bolt (6) is screwed and fixed to the central internal thread of the fixing part (5). The right end of the double-ended quartz light guide rod (11) is located at the focal point of the plano-convex lens (23), so that the light is parallel to the filter (22) after passing through the plano-convex lens (23). The plano-convex lens (23) is fixed in the lens holder (7) by a washer (24), and the right side is fixed by a ring. The fixing component (8) presses and fixes the lens; the left side of the lens fixing bracket (7) is connected to the fixing component (5) by four third bolts (16), and the right side is connected to the photomultiplier tube sleeve (9) by four fourth bolts (17); an O-ring (25) is placed between the filter (22) and the photomultiplier tube (21) to protect the filter (22); the filter (22) is placed at the light entrance of the photomultiplier tube (21) to ensure that the light enters the photomultiplier tube (21) perpendicularly. The photomultiplier tube (21) includes a base and a power cord.

6. The pulsed flame photometric detection device according to claim 1, characterized in that, The cooling pipe includes an auxiliary radiator, and the outside of the pipe is provided with cooling patches. The end of the photomultiplier tube (21) is provided with a corresponding auxiliary power supply seat. The cooling pipe includes a motor exhaust cooling chamber placed at the front end of the pipe and cooling patches around the rear end of the pipe.

7. The pulsed flame photometric detection device according to claim 1, characterized in that, When the optical signal transmission component is connected to a set of optical signal processing components, namely the combustion reaction chamber component, the optical signal transmission component and the optical signal processing component are connected in sequence, a filter is used, and the selectivity of the time coordinate is utilized to distinguish different substances, and the light intensity is detected to represent the concentration of the substance.

8. The pulsed flame photometric detection device according to claim 1, characterized in that, When the optical signal transmission component is connected to two sets of optical signal processing components, the combustion reaction chamber component is connected to two sets of optical signal transmission components through the optical signal separator (26). The optical signal transmission component is connected to the optical signal processing component. The optical signal separator (26) allows the double-ended quartz light guide rod (11) to receive the optical signal and then split it into two outputs. The differential principle is used to detect two kinds of high and low wavelength light at the same time. Time is used as a comparison process to extract the interference wavelength of the high wavelength light in the time period of the low wavelength light. The interference wavelength of the lower wavelength light is further subtracted.

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