Nylon sample residue detection device

Abstract

This utility model discloses a device for detecting residues in nylon samples, relating to the field of detection equipment technology. The device comprises a moisture analyzer, a gas storage chamber, a flue gas separator, a cold trap, a drying tube, and a gas chromatography-mass spectrometry (GC-MS) instrument connected sequentially via pipelines. A booster pump is installed between the cold trap and the drying tube, and a pressure regulating valve, a flow meter, and a flow control valve are installed between the drying tube and the GC-MS instrument. This device enables integrated detection of moisture and residues, eliminating the need for complex pretreatment. It features multi-stage purification and dehydration, pressure and flow stabilization, improved detection accuracy and efficiency, instrument protection, and reduced maintenance costs. It is suitable for rapid batch detection of nylon samples.

Description

Technical Field

[0001] This utility model relates to the field of testing equipment technology, specifically to a device for detecting residues in nylon samples. Background Technology

[0002] As a widely used engineering plastic, nylon is prone to leaving volatile substances such as monomers, solvents, and additives during production, processing, and use. At the same time, the moisture content in the material directly affects its processing performance and product quality. Therefore, accurate detection of moisture and residues in nylon samples is a key link to ensure product quality and safety.

[0003] Currently, the industry generally uses a separate detection mode for nylon samples, which has obvious technical defects: the moisture content is measured separately using a moisture analyzer, while indicators such as residual monomers, solvents, additives, low molecular weight volatiles and thermally degraded small molecules need to be detected separately using a gas chromatography-mass spectrometry system. The two sets of equipment operate independently, the detection process is cumbersome and time-consuming, and it is impossible to achieve integrated rapid analysis.

[0004] When using gas chromatography-mass spectrometry (GC-MS) to detect nylon residues, a complex sample pretreatment process is required: first, the nylon sample is dissolved in formic acid, and then an extractant is added to extract the target substance; subsequently, the supernatant is purified by centrifugation through a solid-phase extraction column to remove interfering impurities; for components that are difficult to vaporize, derivatization is also necessary to improve the instrument response; finally, the sample is filtered through a 0.22 μm filter membrane and brought to a constant volume before being analyzed. This entire pretreatment process involves numerous steps, is time-consuming, and requires a high level of expertise from the operators. Improper operation can easily introduce detection biases, or even lead to pretreatment failures requiring repeated attempts, resulting in poor reproducibility and difficulty in ensuring the accuracy of the test results.

[0005] In addition, traditional detection systems do not integrate functions such as gas purification, moisture separation, pressure control and flow stabilization. Moisture and solid dust in the sample volatile gas can easily enter the detection instrument, causing pipeline contamination and abnormal chromatographic peak shape. This not only affects the detection accuracy, but also reduces the service life of the instrument, increases laboratory operation and maintenance costs and equipment space occupation, and cannot meet the needs of efficient, stable and accurate batch detection of nylon sample residues. Utility Model Content

[0006] The technical problem to be solved by this utility model is to overcome the shortcomings of the existing technology and provide a nylon sample residue detection device that can realize integrated detection of moisture and residues, without the need for complicated pretreatment, multi-stage purification and dehydration, pressure and flow stabilization, improve detection accuracy and efficiency, protect the instrument, reduce operation and maintenance costs, and is suitable for rapid batch detection of nylon samples.

[0007] The technical solution of this utility model is as follows:

[0008] The nylon sample residue detection device includes a moisture analyzer, a gas storage chamber, a flue gas separator, a cold trap, a drying tube, and a gas chromatography-mass spectrometry (GC-MS) instrument connected in sequence by pipelines. A booster pump is installed on the pipeline between the cold trap and the drying tube, and a pressure regulating valve, a flow meter, and a flow control valve are installed on the pipeline between the drying tube and the GC-MS instrument.

[0009] Preferably, a one-way valve is installed on the pipeline between the cold trap and the drying tube.

[0010] Preferably, the drying tube is filled with molecular sieves or anhydrous calcium chloride.

[0011] Preferably, the bottom of the cold trap is connected to a drain pipe, and a drain valve is installed on the drain pipe.

[0012] Preferably, the temperature of the cold trap is 0-5°C.

[0013] Preferably, a glass frit is installed inside the flue gas separator.

[0014] Preferably, the tubing between the drying tube and the gas chromatograph-mass spectrometer is made of stainless steel capillary, while the remaining tubing is made of Teflon tubing.

[0015] Compared with the prior art, this utility model has the following advantages:

[0016] 1. This invention integrates moisture determination and residue detection into a single unit, enabling simultaneous detection of moisture and organic residues. It eliminates the need for two separate systems, significantly shortening the detection cycle and resolving the cumbersome and inefficient nature of traditional separate detection processes. This invention employs an online direct sample introduction design, eliminating multiple pretreatment steps such as sample dissolution, extraction, purification, derivatization, and filtration. This reduces the skill requirements for operators, avoids biases introduced by manual operation, and greatly improves the reproducibility and accuracy of the detection results.

[0017] 2. This invention removes impurities and moisture from the gas through a multi-stage process: a flue gas separator filters dust, a cold trap condenses and removes water, and a drying tube performs deep drying. This prevents impurities and moisture from entering the gas chromatograph-mass spectrometer, avoiding pipeline contamination and abnormal chromatographic peak shapes, extending the instrument's lifespan, and reducing maintenance costs. The cold trap is equipped with a drainage structure that quickly drains condensate, preventing backflow; a one-way valve prevents carrier gas backflow, ensuring stable system pressure and equipment safety, and improving the device's continuous operating capability and ease of maintenance.

[0018] 3. This utility model is equipped with a booster pump, pressure stabilizing valve, flow meter, and flow regulating valve, which can precisely control gas pressure and flow rate, match the optimal sample injection requirements of the instrument, ensure stable sample injection, and further improve the accuracy and repeatability of test data. The overall structure of this utility model is compact and highly integrated, reducing the space occupied by the equipment and eliminating the need for additional pretreatment equipment, thus reducing the initial investment and subsequent maintenance costs of the laboratory and meeting the needs of batch, efficient, and stable testing. In this utility model, key pipelines use stainless steel capillary tubes to reduce organic adsorption and improve peak shape; the remaining pipelines use Teflon tubing, which is corrosion-resistant, non-adsorbent, and non-leaching, ensuring the authenticity and reliability of test results and making it suitable for long-term continuous use. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the nylon sample residue detection device of this utility model.

[0020] In the diagram, 1. Moisture analyzer; 2. Gas storage chamber; 3. Flue gas separator; 4. Cold trap; 5. Drying tube; 6. Gas chromatograph-mass spectrometer; 7. Booster pump; 8. Pressure regulator; 9. Flow meter; 10. Flow control valve; 11. Check valve; 12. Drain pipe; 13. Drain valve.

[0021] Figure 2 The total ion chromatogram is obtained by detecting residues in a nylon sample using the apparatus of Example 1.

[0022] Figure 3 The mass spectrum in positive ion mode is obtained by detecting nylon sample residues using the apparatus of Example 1.

[0023] Figure 4 The mass spectrum is obtained in negative ion mode by detecting nylon sample residue using the apparatus of Example 1. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of this utility model will be clearly and completely described below in conjunction with the embodiments of this utility model.

[0025] Example 1

[0026] This embodiment provides a nylon sample residue detection device, which adopts an online direct sample injection design, eliminating the need for complex pretreatment, and can simultaneously detect moisture and organic residues in nylon samples in one go.

[0027] like Figure 1 As shown, the device includes a moisture analyzer 1, a gas storage chamber 2, a flue gas separator 3, a cold trap 4, a drying tube 5, and a gas chromatograph-mass spectrometer 6, which are sequentially and sealed together by pipelines.

[0028] The moisture analyzer 1 employs a rapid moisture determination module based on thermal loss of mass, which can quickly heat nylon samples to release moisture and volatile residues simultaneously. The output gas is then temporarily stored in the gas storage chamber 2. The gas storage chamber 2 is a 1L pressure-resistant sealed cavity that serves as a gas buffer, pressure stabilizer, and temporary storage unit, preventing gas flow fluctuations from interfering with subsequent detection. The flue gas separator 3 is internally equipped with a multi-layer glass frit filter structure, which efficiently filters out sample dust, small solid particles, and other impurities carried in the gas, preventing impurities from entering the cold trap 4 and the gas chromatography-mass spectrometry (GC-MS) instrument 6 and causing contamination or blockage. The temperature of the cold trap 4 is precisely controlled between 0-5℃, which rapidly condenses water vapor in the gas into liquid water, achieving efficient gas-water separation and preventing moisture from entering the chromatographic column and affecting separation efficiency and instrument lifespan. A booster pump 7 is installed on the pipeline between the cold trap 4 and the drying tube 5 to increase the gas pressure, ensuring the gas pressure meets the injection requirements of the GC-MS instrument 6. The drying tube 5 is filled with activated 4A molecular sieve or anhydrous calcium chloride to deeply dry the gas after it has been dehydrated by the cold trap 4, further removing trace amounts of residual moisture and improving detection stability. The 4A molecular sieve in the drying tube 5 is activated in a 350℃ oven for 4 hours before first use, and then quickly filled after cooling. A pressure regulator 8, a flow meter 9, and a flow control valve 10 are installed on the pipeline between the drying tube 5 and the gas chromatograph-mass spectrometer 6 to stably control the gas flow rate within the range of 10-50 mL / min, precisely matching the optimal injection flow rate requirements of the gas chromatograph-mass spectrometer 6 and ensuring the repeatability of detection data.

[0029] To further optimize system stability, this embodiment adds a one-way valve 11 to the pipeline between the cold trap 4 and the drying tube 5. The one-way valve 11 is strictly directed towards the gas chromatograph-mass spectrometer 6, which can effectively prevent the instrument carrier gas from flowing back to the front-end moisture analyzer 1 and the gas storage chamber 2, thus avoiding abnormal pipeline pressure, instrument damage or detection interference.

[0030] In terms of pipeline materials, a stainless steel capillary tube is used between the drying tube 5 and the gas chromatograph-mass spectrometer 6. The inner wall is smooth and inert, which can significantly reduce the adsorption of organic matter and effectively improve problems such as peak tailing and low response. The remaining pipelines are all made of Teflon tubing, which is resistant to acid and alkali corrosion, high and low temperature, and aging and cracking. It maintains good sealing and transmission stability even after long-term continuous use, with no adsorption or leaching, ensuring that the test results are true and reliable.

[0031] When actually setting up the device of this utility model, all pipe interfaces must be fixed with clamps or sealing rings to prevent air leakage. After the device is set up, the interfaces should be coated with soapy water. If there are no air bubbles or leaks, the device is considered qualified.

[0032] The device in this embodiment integrates moisture determination and residue detection. The sample is directly placed into the moisture analyzer 1 for heating and volatilization. The gas is purified, dehydrated, pressure-stabilized, and flow-stabilized before being directly analyzed by the gas chromatograph-mass spectrometer 6. The entire process eliminates the need for cumbersome pretreatment, significantly shortening the detection time, reducing human error, and significantly improving the reproducibility and accuracy of the detection results. At the same time, the device has a high degree of integration, occupies little space, and requires no additional pretreatment equipment, reducing laboratory investment and maintenance costs.

[0033] The nylon sample is tested using the apparatus of this embodiment. Figure 2 As can be seen, the device in this embodiment exhibits excellent separation performance: high peak resolution, no overlap, and no tailing, proving that the multi-stage purification system of flue gas separator 3 + cold trap 4 + drying tube 5 in this embodiment effectively removes dust, moisture, and impurities, ensuring stable chromatographic separation conditions. A clean baseline with no extraneous peaks indicates no adsorption or dissolution in the Teflon tube + stainless steel capillary, demonstrating high system airtightness and cleanliness. Symmetrical and sharp peaks with strong response indicate strong target residue signals and high sensitivity, validating that online direct injection without pretreatment still achieves high response, demonstrating outstanding detection efficiency and sensitivity. Stable peaks and good reproducibility: consistent retention times reflect the precise flow and pressure stabilization achieved by pressure regulating valve 8, flow control valve 10, and booster pump 7, with data repeatability meeting batch detection requirements. The absence of moisture interference peaks proves successful deep water removal by the 0-5℃ cold trap 4 and drying tube 5, preventing moisture from affecting the chromatographic column and detection results.

[0034] Depend on Figure 3 As can be seen, the mass spectrometry peaks are clear and the signal-to-noise ratio is high: the characteristic ion peaks are obvious and the background noise is low, indicating that the mass spectrometry detection environment is pure and the ionization efficiency is stable after the gas is purified and dried. Qualitative analysis is accurate and reliable: the molecular ion peaks and fragment peaks have a high degree of matching, enabling precise qualitative analysis of residual monomers, solvents, and additives in nylon. There is no water-related interference: the absence of water cluster ion interference verifies that the cold trap 4 + drying tube 5 thoroughly removes water, effectively protecting the mass spectrometer. The signal is stable and highly consistent: the injection pressure and flow rate are stable, ensuring stable mass spectrometry signal intensity, suitable for quantitative analysis.

[0035] Depend on Figure 4 As can be seen, the negative ion detection effect is excellent: the characteristic peaks are clear and the background is clean, proving that the device has good detection capabilities for residues of different polarities and types, and has a wide range of applications. Complementary to the positive ion mode: The combination of positive and negative ion modes can cover a variety of volatile residues in nylon samples, resulting in more complete detection. No residue, no cross-contamination: There are no residual peaks or memory effects, making it suitable for batch continuous detection and meeting the needs of rapid industrial detection. Strong system stability: The signal remains stable even in negative ion mode, further verifying the reliability of the voltage and flow stabilization system and the water and impurity removal system.

[0036] therefore, Figure 2-4Together, they proved that the device in this embodiment does not require complex pretreatment, multi-stage purification and dehydration, pressure and flow stabilization, and direct online sample injection, and can realize integrated, high-precision, high-stability, and high-efficiency detection of moisture and residues in nylon samples.

[0037] Example 2

[0038] Based on Example 1, this example optimizes the drainage structure of the cold trap 4 to improve the continuous working capability and ease of maintenance of the device.

[0039] like Figure 1 As shown, in this embodiment, a drain pipe 12 is installed at the bottom of the cold trap 4, and a drain valve 13 is installed on the drain pipe 12. When the cold trap 4 is working, water vapor in the sample gas continuously condenses into liquid water at 0-5℃, which collects in the bottom cavity of the cold trap 4. After each batch of samples is tested, the drain valve 13 is opened to quickly and completely drain the condensate, preventing liquid water from accumulating in the cold trap 4 and preventing it from being carried into the subsequent drying tube 5 and gas chromatography-mass spectrometry instrument 6 due to excessive water level, thus ensuring the long-term stable operation of the system.

Claims

1. A nylon sample residue detection device characterized by, The instrument includes a moisture analyzer (1), a gas storage chamber (2), a flue gas separator (3), a cold trap (4), a drying tube (5), and a gas chromatograph-mass spectrometer (6) connected in sequence by pipelines. A booster pump (7) is installed on the pipeline between the cold trap (4) and the drying tube (5), and a pressure regulating valve (8), a flow meter (9), and a flow regulating valve (10) are installed on the pipeline between the drying tube (5) and the gas chromatograph-mass spectrometer (6).

2. The nylon sample residue detection apparatus of claim 1, wherein, A one-way valve (11) is installed on the pipeline between the cold trap (4) and the drying tube (5).

3. The nylon sample residue detection device as described in claim 1, characterized in that, The drying tube (5) is filled with molecular sieves or anhydrous calcium chloride.

4. The nylon sample residue detection device as described in claim 1, characterized in that, The bottom of the cold trap (4) is connected to a drain pipe (12), and a drain valve (13) is installed on the drain pipe (12).

5. The nylon sample residue detection device as described in claim 1, characterized in that, The temperature of the cold trap (4) is 0-5℃.

6. The nylon sample residue detection device as described in claim 1, characterized in that, The flue gas separator (3) is equipped with a glass frit core.

7. The nylon sample residue detection device as described in claim 1, characterized in that, The tubing between the drying tube (5) and the gas chromatograph-mass spectrometer (6) is made of stainless steel capillary tube, and the remaining tubing is made of Teflon tubing.

Images