An automatic analyzer for detecting aniline compounds in a liquid and a method for measuring the same

Abstract

The application discloses an automatic analyzer for detecting aniline compounds in liquid and a determination method, and realizes automatic and rapid determination of aniline compounds in liquid samples through the design, connection and control of flow paths and structures, and the analysis processes such as automatic sampling, reagent adding, mixing reaction and spectrophotometric detection, so that reagent consumption and waste liquid discharge are reduced, and the analysis detection sensitivity, accuracy and precision are improved.

Description

Technical Field

[0001] This invention relates to the technical field of compound detection and analysis, and in particular to an automated analyzer and method for detecting aniline compounds in liquids. Background Technology

[0002] As an important organic raw material in industry, aniline compounds are widely used in dyes, printing and dyeing, rubber, pharmaceuticals, plastics, and paints. With the rapid growth of the domestic market, the demand for products using aniline compounds as raw materials has also increased significantly, making my country a major producer and consumer of aniline compounds in the world. Aniline compounds belong to the organic amine class, are slightly soluble in water, and readily soluble in ethanol, ether, and acetone. They can enter the human body through the respiratory and digestive tracts, and can also be absorbed through the skin. They can convert oxygen and hemoglobin in the body into methemoglobin, affecting the oxygen supply to tissue cells and causing internal asphyxiation. They are toxic to humans and are a priority pollutant for control in my country, as well as a key organic pollutant indicator for monitoring. my country's "Surface Water Environmental Quality Standard" (GB3838), "Water Pollutant Discharge Standard for Textile Dyeing and Finishing Industry" (GB4287-2012), and "Integrated Wastewater Discharge Standard" (GB8978-1996) all clearly stipulate limits for aniline compounds.

[0003] Currently, the determination of aniline compounds mainly adopts the manual spectrophotometric method of the national standard GB / T 11889-1989 Determination of Aniline Compounds in Water - N-(1-Naphthyl)ethylenediamine azo Spectrophotometric Method. This method is greatly affected by temperature, requires a large amount of water sample and reagents, and is cumbersome, has many steps, is time-consuming, and has low precision, making it difficult to determine large batches of samples. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide an automatic analyzer and method for detecting aniline compounds in liquids.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] An automated analyzer for detecting aniline compounds in liquids includes a peristaltic pump, a detector, a controller, and flow paths; the flow paths sequentially include a reaction flow path, a gas-liquid separation flow path, a quantitative flow path, and a colorimetric flow path.

[0007] The reaction flow path includes several pump tubes, tees and reaction coils, and is used to obtain reactants such as the liquid sample to be tested, potassium hydrogen sulfate solution, sodium nitrite solution and ammonium aminosulfonate solution.

[0008] The gas-liquid separation flow path is connected to the outlet of the reaction flow path, including a gas-liquid separator. The gas outlet of the gas-liquid separator is connected to an exhaust channel, and the liquid outlet is connected to a metering flow path.

[0009] The quantitative flow path includes a quantitative loop, a multi-port injection valve, and a current-carrying branch. The multi-port injection valve is used to switch the input and output of the quantitative loop, and the current-carrying branch is used to push the reactant solution from the quantitative loop to the colorimetric flow path during output.

[0010] The colorimetric flow path includes a three-way valve, a temperature-controlled reactor, and an N-(1-naphthyl)ethylenediamine hydrochloride solution branch. The two inlets of the three-way valve are respectively connected to the N-(1-naphthyl)ethylenediamine hydrochloride solution branch and the quantitative flow path, and the outlet is connected to the temperature-controlled reactor.

[0011] The detector is a spectrophotometer equipped with a flow cell, which is connected to the outlet of the temperature-controlled reactor;

[0012] The controller is used to control the peristaltic pump, the multi-port injection valve, the temperature-controlled reactor, and the detector, and to receive information from the spectrophotometer.

[0013] Optionally, the gas-liquid separator has a cavity, which includes a bottom interface, a top interface, and a middle interface. The middle interface is connected to the outlet of the reaction flow path, the top interface is the gas outlet, and the bottom interface is the liquid outlet.

[0014] Optionally, the gas-liquid separator includes upper and lower fixed blocks and a microporous hydrophobic membrane sandwiched between the upper and lower fixed blocks. The upper and lower fixed blocks are provided with flow channels that communicate with each other through the microporous hydrophobic membrane. The flow channels have A and B interfaces located on both sides of the lower fixed block, and C interface located on the same side of the upper fixed block as the second interface. The A interface is connected to the reaction flow path, the B interface is the liquid outlet, and the C interface is the gas outlet.

[0015] Optionally, the exhaust channel includes a first pump pipe, the inlet of which is connected to the gas outlet, and the outlet is connected to a waste liquid bottle.

[0016] Optionally, the reaction flow path includes a second pump tube for inputting the liquid sample to be tested, a third pump tube for inputting potassium bisulfate solution, a fourth pump tube for inputting sodium nitrite solution, and a fifth pump tube for inputting ammonium aminosulfonate solution. It also includes a first tee, a second tee, a third tee, a first reaction coil, a second reaction coil, and a third reaction coil. The two inlets of the first tee are connected to the second and third pump tubes, respectively, and the outlet is connected to the first reaction coil. The two inlets of the second tee are connected to the first reaction coil and the fourth pump tube, respectively, and the outlet is connected to the second reaction coil. The two inlets of the third tee are connected to the second reaction coil and the fifth pump tube, respectively, and the outlet is sequentially connected to the third reaction coil and the gas-liquid separation flow path.

[0017] Optionally, the multi-port injection valve can switch between input and output states. In the input state, the inlet of the quantitative loop is connected to the liquid outlet of the gas-liquid separation flow path, and the outlet is connected to the back pressure tube and the waste bottle in sequence. In the output state, the inlet of the quantitative loop is connected to the flow-carrying branch, and the outlet is connected to the colorimetric flow path.

[0018] Optionally, the current-carrying branch includes a sixth pump tube for current-carrying input, and the N-(1-naphthyl)ethylenediamine hydrochloride solution branch includes a seventh pump tube for N-(1-naphthyl)ethylenediamine hydrochloride solution input.

[0019] Optionally, it also includes an autosampler connected to the second pump tube, the autosampler being controlled by the controller.

[0020] A method for determining aniline compounds in liquids includes using the aforementioned automated analyzer to prepare a series of standard solutions of aniline compounds with known concentrations. The automated analyzer is then used to sequentially test the absorbance of each standard solution to obtain the relationship between concentration and absorbance, and to fit a working curve and equation. The automated analyzer is also used to test the absorbance of samples of liquids with unknown concentrations, and the concentration of aniline compounds is calculated by substituting the absorbance into the equation. Each individual test specifically includes the following steps:

[0021] The peristaltic pump is activated by the controller to pump the sample and reagents into the reaction flow path. After mixing and reaction, the mixture enters the gas-liquid separation flow path for gas-liquid separation. The separated reactant solution enters the quantitative flow path. The multi-port injection valve is switched to the input state to fill the quantitative loop with the reactant solution. The multi-port injection valve is then switched to the output state to allow the carrier flow to push the reactant solution out of the quantitative loop into the colorimetric flow path. The N-(1-naphthyl)ethylenediamine hydrochloride solution enters the colorimetric flow path and merges with the reactant solution. They are then mixed in the temperature-controlled reactor and a colorimetric reaction occurs. The colorimetric solution enters the flow cell and the absorbance is measured by the detector. The controller receives the absorbance data.

[0022] Optionally, the concentration of the potassium hydrogen sulfate solution is 35 g / L, the concentration of the sodium nitrite solution is 10 g / L, the concentration of the ammonium aminosulfonate solution is 50 g / L, the concentration of the N-(1-naphthyl)ethylenediamine hydrochloride solution is 15 g / L, and the carrier is deionized water.

[0023] The beneficial effects of this invention are as follows:

[0024] (1) The sample processing and analysis detection process is fully automated;

[0025] (2) An online gas-liquid separation device is used to efficiently eliminate the influence of gases generated during the reaction;

[0026] (3) Low reagent consumption is beneficial for energy conservation, emission reduction and cost reduction;

[0027] (4) The present invention has excellent sensitivity and accuracy, and is simple to operate and fast to analyze. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of an automated analyzer for detecting aniline compounds in liquids according to an embodiment;

[0029] Figure 2 This is a schematic diagram of the structure of a gas-liquid separator according to one embodiment;

[0030] Figure 3 This is a schematic diagram of a gas-liquid separator according to another embodiment. Detailed Implementation

[0031] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0032] like Figure 1 As shown, an automated analyzer for detecting aniline compounds in liquids according to one embodiment includes an autosampler 1, a peristaltic pump 2, at least 7 peristaltic pump tubes (3-1 to 3-7), a light-proof refrigeration device 4, a gas-liquid separator 7, a multi-port injection valve 8, 4 tees (5-1 to 5-4), 3 reaction coils (6-1 to 6-3), a quantitative loop 9, a back pressure tube 10, a temperature-controlled reactor 11, a detector 12, polytetrafluoroethylene tubing, various reagent bottles and waste liquid bottles 13, and a controller 14.

[0033] The autosampler 1 is used to automatically select samples for analysis according to a set sequence. Alternatively, the autosampler can be replaced with a manual sample injector.

[0034] Peristaltic pump 2, used for continuous delivery of samples and reagents, is equipped with at least 7 peristaltic pump tubes, including a vacuum pump tube 3-1, a sample pump tube 3-2, a flow carrier pump tube 3-6, and pump tubes for 4 reagents (3-3, 3-4, 3-5, and 3-7). The inner diameter of the pump tubes ranges from 0.38 mm to 2.72 mm.

[0035] The light-proof refrigeration unit 4 is used to place reagent bottles and ensure the stability of the reagents. It contains 5 reagent bottles: potassium hydrogen sulfate solution 4-1, sodium nitrite solution 4-2, ammonium aminosulfonate solution 4-3, a carrier bottle 4-4, and N-(1-naphthyl)ethylenediamine hydrochloride solution 4-5.

[0036] The three-way valve is used for the online mixing of two solutions.

[0037] The reaction coil is used to promote the mixing reaction of solutions. Its inner diameter is 0.5 mm to 4 mm, outer diameter is 1.5 mm to 6 mm, and length is 0.5 m to 12 m.

[0038] refer to Figure 2 In this embodiment, the gas-liquid separator 7 is a cylindrical or cuboid module with an internal conical cavity 701. The diameter of the conical cavity is 2mm to 25mm, and the height is 5mm to 30mm. The gas-liquid separator is installed vertically with the bottom surface of the conical cavity facing upwards. It includes a bottom interface 7-3, a top interface 7-2, and a middle interface 7-1. The distance between the middle interface 7-1 and the top interface 7-2 is 1 to 10mm. The gas-liquid separator 7 can be made of glass or quartz, or it can be made of inert plastics such as polytetrafluoroethylene, plexiglass, or polyetheretherketone.

[0039] The multi-port injection valve 8 is a six-way valve or a quantitative injection valve with a similar structure, and has two states: loading sample and injecting sample; it is equipped with a quantitative ring 9 with an inner diameter of 0.5mm to 1.5mm, an outer diameter of 1.5mm to 6mm, and a length of 0.5m to 5m, which is used to measure the volume of the sample.

[0040] The back pressure tube 10 is a polytetrafluoroethylene tube with an inner diameter of 0.5mm to 1.5mm, an outer diameter of 1.5mm to 6mm, and a length of 0.5m to 10m. It is used to maintain the stability of the solution pressure in the pipeline.

[0041] The temperature-controlled reactor 11 consists of a temperature-controlled heating rod and a polytetrafluoroethylene (PTFE) tube wound around the heating rod, and is equipped with an insulation shell. During operation, the temperature is controlled at 28℃ ± 0.5℃. The inner diameter of the PTFE tube is 0.5mm to 3mm, and the length is 0.5m to 10m. The temperature-controlled reactor 11 can also be heated by a water bath or an oil bath.

[0042] The detector 12 is a spectrophotometer equipped with a flow cell with an optical path of 10 mm to 500 mm.

[0043] Waste liquid bottle 13 is used to collect the waste liquid generated after the reaction.

[0044] The above components are connected by PTFE tubing to form a liquid flow path. The inner diameter of the PTFE tubing is 0.5mm to 4mm and the outer diameter is 1.5mm to 6mm.

[0045] The controller 14 is used to control the autosampler, peristaltic pump, injection valve, temperature-controlled reactor and detector, and to record the absorbance data output by the detector to achieve automated detection.

[0046] According to their functions, the flow paths are sequentially divided into a reaction flow path, a gas-liquid separation flow path, a quantitative flow path, and a colorimetric flow path. The reaction flow path is used to obtain the reactants, namely the liquid sample to be tested, potassium hydrogen sulfate solution, sodium nitrite solution, and ammonium aminosulfonate solution. The gas-liquid separation flow path is connected to the outlet of the reaction flow path and is used to separate the gas and liquid reactants. The quantitative flow path is connected to the liquid outlet of the gas-liquid separation flow path and is used to quantify the reactant solution. The colorimetric flow path is used to mix the quantified reactant solution with the colorimetric reagent for reaction. After color development, the solution enters the detector to measure the absorbance, thereby obtaining the correspondence between concentration and absorbance.

[0047] Specifically, such as Figure 1 As shown, the inlet of the first pump tube 3-1 on the peristaltic pump 2 is connected to the top interface 7-2 of the gas-liquid separator 7, and the outlet is connected to the waste liquid bottle 13; the inlet of the second pump tube 3-2 is connected to the sampling needle of the autosampler 1, and the outlet is connected to the first interface of the first three-way valve 5-1; the inlet of the third pump tube 3-3 is connected to the potassium bisulfate solution reagent bottle 4-1, and the outlet is connected to the second interface of the first three-way valve 5-1; the inlet of the fourth pump tube 3-4 is connected to the sodium nitrite solution reagent bottle 4-2, and the outlet is connected to the second interface of the second three-way valve 5-2; the inlet of the fifth pump tube 3-5 is connected to the ammonium sulfamate solution reagent bottle 4-3, and the outlet is connected to the second interface of the third three-way valve 5-3; the inlet of the sixth pump tube 3-6 is connected to the carrier bottle 4-4, and the outlet is connected to the first interface 8-1 of the injection valve 8; the inlet of the seventh pump tube 3-7 is connected to the N-(1-naphthyl)ethylenediamine hydrochloride solution reagent bottle 4-5, and the outlet is connected to the second interface of the fourth three-way valve 5-4. The third port of the first three-way valve 5-1 is connected to the inlet of the first reaction coil 6-1, and the outlet of the first reaction coil 6-1 is connected to the first port of the second three-way valve 5-2; the third port of the second three-way valve 5-2 is connected to the inlet of the second reaction coil 6-2, and the outlet of the second reaction coil 6-2 is connected to the first port of the third three-way valve 5-3; the third port of the third three-way valve 5-3 is connected to the middle port 7-1 of the gas-liquid separator 7, and the bottom port 7-3 of the gas-liquid separator 7 is connected to the third port 8-3 of the injection valve 8; The second port 8-2 and the fifth port 8-5 of the sample valve 8 are connected to the inlet and outlet of the quantitative loop 9, respectively; the fourth port 8-4 of the sample valve 8 is connected to the inlet of the back pressure tube 10, and the outlet of the back pressure tube 10 is connected to the waste bottle 13; the sixth port 8-6 of the sample valve 8 is connected to the first port of the fourth three-way valve 5-4, and the third port of the fourth three-way valve 5-4 is connected to the inlet of the temperature-controlled reactor 11; the outlet of the temperature-controlled reactor 11 is connected to the inlet of the flow cell of the detector 12, and the outlet of the flow cell is finally connected to the waste bottle 13.

[0048] In operation, the sampling needle of the autosampler 1 moves to the first sample position, and the peristaltic pump is activated, continuously pumping the sample and reagents into the analyzer. The sample and potassium bisulfate solution are combined at the first three-way connector 5-1 and then mixed in the first reaction coil 6-1. Afterward, the sample and sodium nitrite solution are combined at the second three-way connector 5-2 and then mixed in the second reaction coil 6-2. Finally, the sample and ammonium aminosulfonate solution are combined at the third three-way connector 5-3 and mixed in the third reaction coil 6-3 before entering the gas-liquid separator 7. Upon entering the gas-liquid separator 7, the gas produced by the reaction is extracted from the top interface through the first pump tube 3-1, while the liquid flows out from the bottom interface under gravity and enters the sample injection valve 8.

[0049] At this time, the injection valve 8 is in the sample loading state (input state), with its second port 8-2 connected to the third port 8-3, its fourth port 8-4 connected to the fifth port 8-5, and its first port 8-1 connected to the sixth port 8-6. The solution coming out of the bottom port of the gas-liquid separator 7 enters the metering loop 9 through the third port 8-3 and the second port 8-2 of the injection valve 8. After the metering loop 9 is filled, it enters the back pressure tube 10 through the fifth port 8-5 and the fourth port 8-4 of the injection valve and is finally discharged into the waste liquid bottle 13. After the metering loop 9 is filled with sample solution, the injection valve switches to the sample injection state (output state), with its second port 8-2 connected to the first port 8-1, its fifth port 8-5 connected to the sixth port 8-6, and its third port 8-3 connected to the fourth port 8-4. The carrier fluid enters through the first port 8-1 of the injection valve, pushing out the solution in the quantitative loop 9. It then flows through the fifth port 8-5 and the sixth port 8-6 of the injection valve into the first port of the fourth three-way valve 5-4, where it mixes with the N-(1-naphthyl)ethylenediamine hydrochloride solution. The mixture then enters the temperature-controlled reactor 11, where it mixes and undergoes a colorimetric reaction. The resulting solution finally enters the flow cell, and the absorbance is recorded by the detector 12. By preparing a series of standard solutions with known concentrations and measuring the absorbance of each standard solution using the analyzer of this invention, the relationship between concentration and absorbance can be obtained. By then measuring the absorbance of a sample with an unknown concentration, the concentration of aniline in the sample can be determined.

[0050] The automatic analyzer for aniline compounds in water of the present invention can continuously and automatically measure at a rate of more than 20 samples per hour, and has excellent sensitivity, accuracy and precision.

[0051] Example 1: Determination of aniline compounds in water.

[0052] Chemical reaction principle: Aniline compounds are diazotized with nitrite under acidic conditions, and then coupled with N-(1-naphthyl)ethylenediamine to generate a purple-red dye. The absorbance is measured at a wavelength of 545 nm for quantification.

[0053] Implementation steps: such as Figure 1As shown, an automatic analyzer for aniline compounds in water has the following components: the inner diameters of the first pump tube 3-1 and the second pump tube 3-2 are both 1.52 mm; the inner diameters of the third pump tube 3-3, the fourth pump tube 3-4, the fifth pump tube 3-5, and the seventh pump tube 3-7 are all 0.76 mm; the inner diameter of the sixth pump tube 3-6 is 1.02 mm; and the peristaltic pump 2 rotates at 15 rad / min. The inner diameters of the first, second, and third reaction coils 6-1, 6-2, and 6-3 are all 0.8 mm, the outer diameters are all 1.6 mm, and the lengths are 0.5 m, 2 m, and 5 m, respectively.

[0054] The gas-liquid separator 7 adopts a polytetrafluoroethylene cylindrical module with an internal conical cavity. The conical cavity has a diameter of 10mm and a height of 25mm. It is installed vertically with the bottom surface of the conical cavity facing upwards. The distance between the middle interface and the top interface is 10mm.

[0055] The injection valve 8 is a two-position six-way valve driven by a stepper motor.

[0056] The metering ring 9 is a polytetrafluoroethylene tube with an inner diameter of 0.8 mm, an outer diameter of 1.6 mm, and a length of 2 m.

[0057] The back pressure tube 10 is a polytetrafluoroethylene tube with an inner diameter of 0.5 mm, an outer diameter of 1.6 mm, and a length of 2 m.

[0058] The temperature-controlled reactor 11 is a device in which a polytetrafluoroethylene tube with an inner diameter of 0.8 mm, an outer diameter of 1.6 mm, and a length of 4 m is wound around a temperature-controlled heating rod, and the temperature is set to 28℃±0.5℃.

[0059] The detector 12 is a spectrophotometer equipped with a 10mm optical path flow cell and a detection wavelength of 545nm.

[0060] The pipes connecting the various components are polytetrafluoroethylene pipes with an inner diameter of 0.8 mm and an outer diameter of 1.6 mm.

[0061] A computer is used as the controller 14 to control the autosampler 1, peristaltic pump 2, injection valve 8, temperature-controlled reactor 11 and detector 12, and to record the data output by the detector.

[0062] All reagents used were of analytical grade, and all solutions were prepared with deionized water. Specifically, the concentrations of potassium hydrogen sulfate solution were 35 g / L, sodium nitrite solution 10 g / L, ammonium aminosulfonate solution 50 g / L, and N-(1-naphthyl)ethylenediamine hydrochloride solution 15 g / L. Deionized water was used as the carrier fluid.

[0063] Seven standard solutions with aniline concentrations of 0 mg / L, 0.01 mg / L, 0.25 mg / L, 0.50 mg / L, 1.00 mg / L, 1.50 mg / L, and 2.00 mg / L were prepared and placed in an injector for testing. Each concentration of the sample was measured in triplicate, and the average value of the absorbance peak height was taken to plot a standard curve.

[0064] After the instrument is started, the sampling needle of the autosampler 1 moves to the first sample position, and the peristaltic pump 2 starts running, continuously pumping in the sample and reagents. The injection valve is initially in the sample loading state. The sample and potassium bisulfate solution are combined at the first three-way valve 5-1 and then enter the first reaction coil 6-1 for mixing and reaction; then they are combined with sodium nitrite solution at the second three-way valve 5-2 and enter the second reaction coil 6-2 for mixing and reaction; finally, they are combined with ammonium aminosulfonate solution at the third three-way valve 5-3 and enter the third reaction coil 6-3 for mixing and reaction. At this time, the gas-liquid mixture generated by the reaction enters the gas-liquid separator 7 from the middle interface. The gas is drawn out from the top interface by the first pump tube 3-1, while the liquid flows out from the bottom interface under the action of gravity and enters the injection valve 8.

[0065] At this time, the injection valve is in the sample loading state. Its second port 8-2 is connected to the third port 8-3, the fourth port 8-4 is connected to the fifth port 8-5, and the first port 8-1 is connected to the sixth port 8-6. The solution coming out of the bottom port of the gas-liquid separator 7 enters the metering loop 9 through the third port 8-3 and the second port 8-2 of the injection valve. After the metering loop 9 is filled, it enters the back pressure tube 10 through the fifth port 8-5 and the fourth port 8-4 of the injection valve and is finally discharged into the waste liquid bottle 13.

[0066] After the quantitative loop 9 is filled with the sample solution, the injection valve 8 switches to the sample injection state. Its second port 8-2 communicates with the first port 8-1, the fifth port 8-5 communicates with the sixth port 8-6, and the third port 8-3 communicates with the fourth port 8-4. The carrier flow enters from the first port 8-1 of the injection valve, pushing the solution in the quantitative loop 9 out. The solution then flows through the fifth and sixth ports 8-5 and 8-6 of the injection valve to the first port of the fourth three-way valve 5-4, where it merges with the N-(1-naphthyl)ethylenediamine hydrochloride solution and enters the temperature-controlled reactor 11 for mixing and a colorimetric reaction. The colorimetric solution finally enters the flow cell, and the absorbance is recorded by the detector 12.

[0067] The above standard solution series was measured using the analyzer of this invention, and the results are shown in the table below. The linear equation of the fitted working curve is A = 0.1482C - 0.0008(R). 2 =0.9998), where A is the absorbance peak height measured by the analyzer, C is the concentration of aniline in mg / L, and the linear range is 0.01 mg / L to 2.0 mg / L.

[0068] Aniline concentration C (mg / L) Absorbance average peak height A 0.00 0.0008 0.01 0.0025 0.25 0.0338 0.50 0.0718 1.00 0.1472 1.50 0.2205 2.00 0.2970

[0069] The method detection limit (MDL) is calculated using the formula MDL = t (n-1，α＝0.99) ×S, where t (n-1，α＝0.99) The t-value is given with a confidence level of 99% and degrees of freedom of n-1, and S is the standard deviation of n parallel determinations. The detection limit of the automatic analyzer for aniline compounds in water according to the present invention is calculated to be 0.002 mg / L.

[0070] Using the analyzer of this invention, the spiked recovery rate of aniline compounds in actual water samples was found to be 95%–110%.

[0071] In another embodiment, the gas-liquid separator 7' can also be as follows: Figure 3 The membrane separation device shown comprises a clamp, two polytetrafluoroethylene (PTFE) blocks 702 and 703 as upper and lower fixing blocks, and a microporous hydrophobic membrane 704. The clamp holds the two PTFE blocks 702 and 703 and the microporous hydrophobic membrane 704 in the middle, and the adjacent surfaces of the two PTFE blocks are engraved with identical flow channels. The lower PTFE block 703 has interfaces A and B on opposite sides for solution entry and exit; the upper PTFE block 702 has interface C on the same side as interface B for gas discharge. In this invention, replacing the cylindrical gas-liquid separator in the embodiment with a membrane separation device can achieve the same effect.

[0072] The above embodiments are only used to further illustrate the automatic analyzer and determination method for detecting aniline compounds in liquids according to the present invention. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An automated analyzer for detecting aniline compounds in liquids, characterized in that: It includes a peristaltic pump, a detector, a controller, and flow paths; the flow paths sequentially include a reaction flow path, a gas-liquid separation flow path, a quantitative flow path, and a colorimetric flow path; The reaction flow path includes several pump tubes, tees and reaction coils, and is used to obtain reactants such as the liquid sample to be tested, potassium hydrogen sulfate solution, sodium nitrite solution and ammonium aminosulfonate solution. The gas-liquid separation flow path is connected to the outlet of the reaction flow path, and includes a gas-liquid separator; the gas-liquid separator includes upper and lower fixed blocks and a microporous hydrophobic membrane sandwiched between the upper and lower fixed blocks. The upper and lower fixed blocks are provided with flow path channels that communicate through the microporous hydrophobic membrane. The flow path channels have A and B interfaces located on both sides of the lower fixed block, and C interface located on the same side of the upper fixed block as the second interface. The A interface is connected to the reaction flow path, the B interface is the liquid outlet, the C interface is the gas outlet, the gas outlet is connected to the exhaust channel, and the liquid outlet is connected to the metering flow path. The quantitative flow path includes a quantitative loop, a multi-port injection valve, and a current-carrying branch. The multi-port injection valve is used to switch the input and output of the quantitative loop. When the multi-port injection valve is switched to the input state, the reactant solution fills the quantitative loop. When the multi-port injection valve is switched to the output state, the current-carrying branch is used to push the reactant solution from the quantitative loop to the colorimetric flow path when outputting. The colorimetric flow path includes a three-way valve, a temperature-controlled reactor, and an N-(1-naphthyl)ethylenediamine hydrochloride solution branch. The two inlets of the three-way valve are respectively connected to the N-(1-naphthyl)ethylenediamine hydrochloride solution branch and the quantitative flow path, and the outlet is connected to the temperature-controlled reactor. The detector is a spectrophotometer equipped with a flow cell, which is connected to the outlet of the temperature-controlled reactor; The controller is used to control the peristaltic pump, the multi-port injection valve, the temperature-controlled reactor, and the detector, and to receive information from the spectrophotometer.

2. The automatic analyzer according to claim 1, characterized in that: The exhaust channel includes a first pump pipe, the inlet of which is connected to the gas outlet, and the outlet is connected to a waste liquid bottle.

3. The automatic analyzer according to claim 1, characterized in that: The reaction flow path includes a second pump tube for inputting the liquid sample to be tested, a third pump tube for inputting potassium bisulfate solution, a fourth pump tube for inputting sodium nitrite solution, and a fifth pump tube for inputting ammonium aminosulfonate solution. It also includes a first tee, a second tee, a third tee, a first reaction coil, a second reaction coil, and a third reaction coil. The two inlets of the first tee are connected to the second and third pump tubes, respectively, and the outlet is connected to the first reaction coil. The two inlets of the second tee are connected to the first reaction coil and the fourth pump tube, respectively, and the outlet is connected to the second reaction coil. The two inlets of the third tee are connected to the second reaction coil and the fifth pump tube, respectively, and the outlet is sequentially connected to the third reaction coil and the gas-liquid separation flow path.

4. The automatic analyzer according to claim 1, characterized in that: The multi-port injection valve switches between input and output states. In the input state, the inlet of the quantitative loop is connected to the liquid outlet of the gas-liquid separation flow path, and the outlet is connected to the back pressure tube and the waste bottle in sequence. In the output state, the inlet of the quantitative loop is connected to the flow-carrying branch, and the outlet is connected to the colorimetric flow path.

5. The automatic analyzer according to claim 1, characterized in that: The current-carrying branch includes a sixth pump tube for current input, and the N-(1-naphthyl)ethylenediamine hydrochloride solution branch includes a seventh pump tube for N-(1-naphthyl)ethylenediamine hydrochloride solution input.

6. The automatic analyzer according to claim 3, characterized in that: It also includes an autosampler connected to the second pump tube, the autosampler being controlled by the controller.

7. A method for determining aniline compounds in liquid, characterized in that: Using the automatic analyzer described in any one of claims 1 to 6, a series of standard solutions of aniline compounds with known concentrations are prepared. The absorbance of each standard solution is tested sequentially using the automatic analyzer to obtain the relationship between concentration and absorbance. A working curve and equation are obtained by fitting the results. The absorbance of a sample of liquid with unknown concentration is tested using the automatic analyzer, and the concentration of aniline compounds is calculated by substituting the results into the equation. A single test specifically includes the following steps: The peristaltic pump is activated by the controller to pump the sample and reagents into the reaction flow path. After mixing and reaction, the mixture enters the gas-liquid separation flow path for gas-liquid separation. The separated reactant solution enters the quantitative flow path. The multi-port injection valve is switched to the input state to fill the quantitative loop with the reactant solution. The multi-port injection valve is then switched to the output state to allow the carrier flow to push the reactant solution out of the quantitative loop into the colorimetric flow path. The N-(1-naphthyl)ethylenediamine hydrochloride solution enters the colorimetric flow path and merges with the reactant solution. They are then mixed in the temperature-controlled reactor and a colorimetric reaction occurs. The colorimetric solution enters the flow cell and the absorbance is measured by the detector. The controller receives the absorbance data.

8. The method for determining aniline compounds in liquid according to claim 7, characterized in that: The concentration of the potassium hydrogen sulfate solution is 35 g / L, the concentration of the sodium nitrite solution is 10 g / L, the concentration of the ammonium aminosulfonate solution is 50 g / L, the concentration of the N-(1-naphthyl)ethylenediamine hydrochloride solution is 15 g / L, and the carrier is deionized water.

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