Microfluidic titration device and titration method

Abstract

The invention discloses a microfluidic titration device and a titration method, and belongs to the technical field of test equipment. The device comprises a control unit, an acid solution tank, an alkaline solution tank, a first injection pump, a second injection pump, a first burette pipeline, a second burette pipeline, a three-way piece, a C4D detector and a waste liquid bottle, the acid solution tank, the first injection pump, the first burette pipeline and a first port of the three-way piece are connected in sequence; the alkaline solution tank, the second injection pump, the second burette pipeline and a second port of the three-way piece are connected in sequence; a third port of the three-way piece is connected with the C4D detector and then is connected with the waste liquid bottle; the control unit is connected with the C4D detector, the first injection pump and the second injection pump through data lines and is used for controlling the injection pumps and the detector to work. The method has the advantages of high automation degree, low solution consumption, high titration speed and high repeatability.

Description

Technical Field

[0001] The present invention belongs to the technical field of test equipment, and particularly relates to a microfluidic titration device and a titration method. Background Art

[0002] Acid-base titration is an important quantitative analysis method for accurately determining the concentration of an unknown acid or base in a solution. Traditional manual acid-base titration is carried out by manually controlling a burette, which has high accuracy and good repeatability, but there are many defects and deficiencies, including:

[0003] 1) A large amount of titrant and titrated solution are consumed, and a long time is required for adding the solution. After each titration, the titration container needs to be washed clean, which takes a long time;

[0004] 2) By manually controlling the flow rate of the titrant added by the operator, there are many uncontrollable factors, and the human eye judges the end point according to the color change of the indicator, which is subject to strong subjective judgment interference, resulting in inaccurate results;

[0005] 3) A certain amount of indicator needs to be added to determine the titration end point, but the indicator itself is a weak acid or weak base, which can dissociate by itself to bring a certain acidity or alkalinity, interfering with the judgment of the titration end point.

[0006] In addition to the above method of judging the titration end point by the color change of the indicator, the most common end point detection method is pH electrode measurement, which is more intuitive in indication, but the thin-walled glass bulb of the electrode body is easily affected by bubbles in the solution, causing certain interference.

[0007] Therefore, it is necessary to develop new titration methods or titration equipment to help acid-base titration overcome these technical problems. Summary of the Invention

[0008] The present invention aims to solve at least one of the technical problems in the above related technologies to some extent.

[0009] For this reason, the purpose of the present invention is to provide a microfluidic titration device and a titration method, which have the advantages of high automation, less solution consumption, fast titration speed, and high repeatability.

[0010] To solve the above technical problems, the present invention is implemented as follows:

[0011] An embodiment of the present invention provides a microfluidic titration device, which includes: a control unit, an acidic solution tank, a basic solution tank, a first injection pump, a second injection pump, a first titration pipeline, a second titration pipeline, a three-way joint, C 4 D detector and a waste liquid bottle;

[0012] The acidic solution tank, the first injection pump, the first titration pipeline, and the first port of the three-way piece are connected in sequence;

[0013] The alkaline solution tank, the second injection pump, the second titration pipeline, and the second port of the three-way piece are connected in sequence;

[0014] The third port of the three-way piece is connected to the detection window of the 4 C

[0015] D detector, and then connected to the waste liquid bottle; 4 The control unit is connected to the

[0016] C

[0017] D detector, the first injection pump, and the second injection pump through data lines, and is used to control the operation of the injection pump and the detector.

[0018] The first injection pump, the first corrosion-resistant connecting pipe, the first inverted cone joint, the first corrosion-resistant two-way joint, the second inverted cone joint, the second corrosion-resistant connecting pipe, the first capillary, the third corrosion-resistant connecting pipe, and the third inverted cone joint are connected in sequence.

[0019] In some embodiments, the second titration pipeline includes a second injection pump, a fourth corrosion-resistant connecting pipe, a fourth inverted cone joint, a second corrosion-resistant two-way joint, a fifth inverted cone joint, a fifth corrosion-resistant connecting pipe, a second capillary, a sixth corrosion-resistant connecting pipe, and a sixth inverted cone joint;

[0020] The second injection pump, the fourth corrosion-resistant connecting pipe, the third inverted cone joint, the second corrosion-resistant two-way joint, the fourth inverted cone joint, the fifth corrosion-resistant connecting pipe, the second capillary, the sixth corrosion-resistant connecting pipe, and the sixth inverted cone joint are connected in sequence.

[0021] In some embodiments, the left outlet of the corrosion-resistant three-way piece is connected to the first titration pipeline, the right outlet is connected to the second titration pipeline, and the upper outlet is connected to the seventh inverted cone joint, the seventh corrosion-resistant connecting pipe, the third capillary, the 4 detection window of the C

[0022] D detector and the waste liquid bottle.

[0023] In some of these embodiments, the outer diameter of the capillary is 360 μm and the inner diameter is 100 μm.

[0024] The outer diameter of the corrosion-resistant connecting tube connecting the right port of the injection pump is 1.6 mm and the inner diameter is 0.5 mm; the outer diameter of the corrosion-resistant connecting tube connecting the right port and the capillary is 1.6 mm and the inner diameter is 0.36 mm.

[0025] The embodiment of the present invention also provides a microfluidic titration method, which is implemented by using the microfluidic titration device described in any of the previous ones; the content of the method includes:

[0026] Add the acidic solution to be titrated into the acidic solution tank, and add the alkaline solution to be titrated into the alkaline solution tank.

[0027] Set the parameters of the titration experiment through the control unit, including the operating flow rate range and the single stroke time of the first injection pump and the second injection pump.

[0028] The control unit controls the first injection pump and the second injection pump to perform titration according to the set parameters.

[0029] Through the C 4 D detector detects the conductivity of the mixed solution, and then the control unit processes the experimental data and displays the experimental results.

[0030] In addition, according to the microfluidic titration method of the present invention, the following additional technical features may also be provided:

[0031] In some of these embodiments, during the titration process, the sum of the injection solution flow rates of the first injection pump and the second injection pump always remains constant.

[0032] In some of these embodiments, when the measured conductivity signal shows an inflection point, the acid-base solution is just neutralized. According to the flow rate of the acidic solution and the total flow rate at the time of acid-base neutralization, the flow rate ratio of the acid-base solution is obtained, and the concentration ratio of the acid-base solution is obtained according to this flow rate ratio.

[0033] In some of these embodiments, during the entire titration process, a graph is plotted with the flow rate of the acidic solution as the abscissa and the average value of the signal within the corresponding time of this flow rate as the ordinate. Linear fitting is performed on the regions before and after the inflection point respectively, and the flow rate corresponding to the intersection point of the two fitting straight lines is the flow rate of the acidic solution at the time of acid-base neutralization.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] In the embodiments of the present invention, the provided microfluidic titration device only consumes less than 100 μL of solution when titrating strong acids and strong bases, some strong acids and weak bases, and some weak acids and strong bases with similar titration concentrations. Only 3 mL of ultrapure water is consumed for flushing the capillary, reducing the reagent cost and solving the problem of large consumption of solution in traditional acid-base titration. At the same time, the titration time of some acid-base titrations can be controlled within 45 s, saving time cost.

[0036] In the embodiments of the present invention, the provided microfluidic titration device uses a programmed procedure to automatically and continuously control the entire titration process. Only by setting parameters can the entire titration process be completed and data be automatically processed, solving problems such as errors caused by the need for experimenters to manually control the addition of solution and subjectively judge the titration end point in traditional acid-base titration.

[0037] In the embodiments of the present invention, the provided microfluidic titration device can import the obtained data into the provided data processing program. After selecting the data range and setting parameters, the results can be automatically and quickly calculated. The judgment of the end point is fast and has less interference, solving the problem of interference caused by the need to add indicators in traditional acid-base titration.

[0038] In the embodiments of the present invention, the provided microfluidic titration device uses a capillary with an inner diameter of 100 μm in the pipeline, greatly reducing the volume of acid-base solution added. At the same time, the injection pump can accurately control the flow rate of the ejected liquid.

[0039] The microfluidic titration method of the present invention is implemented using the described microfluidic titration device, and thus has at least all the characteristics and advantages of the microfluidic titration device, which will not be elaborated here. The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic structural diagram of a microfluidic titration device disclosed in an embodiment of the present invention;

[0041] Figure 2 It is an interface diagram of a signal acquisition module disclosed in an embodiment of the present invention;

[0042] Figure 3 It is an interface diagram of a selection cursor module disclosed in an embodiment of the present invention;

[0043] Figure 4 It is an interface diagram of a module for deleting a certain point disclosed in an embodiment of the present invention;

[0044] Figure 5 It is an interface diagram of a calculation result module disclosed in an embodiment of the present invention;

[0045] Figure 6The physical diagram of the syringe pump disclosed in an embodiment of the present invention;

[0046] Figure 7 The example diagram of the selection cursor module interface disclosed in an embodiment of the present invention;

[0047] Figure 8 The example diagram of the module interface for deleting a certain point disclosed in an embodiment of the present invention;

[0048] Figure 9 The example diagram of the calculation result module interface disclosed in an embodiment of the present invention. Detailed implementation manners

[0049] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] Next, the embodiments of the present invention will be described in detail with reference to the accompanying drawings through specific embodiments and their application scenarios.

[0051] Please refer to Figure 1 As shown, in some embodiments of the present invention, a microfluidic titration device is provided, and its design mainly involves improvements in three aspects: reducing the titration volume, automating the program, and broadening the basis for endpoint judgment.

[0052] In some embodiments of the present invention, in terms of reducing the titration volume, introducing microscale analysis in acid-base titration can reduce the cost problem caused by large reagent consumption and improve the safety and portability of operation. The existing solutions currently include microfluidic chip titration, capillary electrophoresis coupled titration, reducing the volume of liquid discharged from the burette, etc. Microfluidic chip titration has been widely used in related fields of analytical chemistry including acid-base titration. For example, different micro-regions are designed on the filter paper by the wax printing method, the extract from juniper fruit peel is used as an acid-base indicator, and the pH value of the measured solution can be determined by combining its working curve of pH value and color to determine the titration endpoint. For example, the flow rate ratio of acid-base solutions is controlled by a pump, and the pH of the mixed solution is continuously measured by a probe to plot the titration curves of strong acid and strong base, strong base and weak acid, and strong base and polybasic acid. For another example, by ignoring the Faraday current and keeping the temperature constant, it is found that the current intensity in the capillary can reflect the change in solution conductivity, and an acid-base titration can be performed by using a commercially available capillary electrophoresis instrument to measure the current, with less consumption of titrant volume. For still another example, by reducing the volume of liquid discharged from the burette and the volume of titrant added, the reagent cost of titration is reduced. However, these means cannot well meet the requirements.

[0053] In some embodiments of the present invention, two SP60-1A industrial injection pumps (pump A and pump B) are used in the titration device to respectively extract and discharge acidic and alkaline solutions. The physical diagram of the injection pump is as shown in Figure 6 . In the present invention, other models of injection pumps or other types of devices capable of achieving the same functions can also be used. The injection pump has two ports on the left and right. The left port is used to suck the solution, and one end of a corrosion-resistant tube with an outer diameter of 1.6 mm and an inner diameter of 0.5 mm is connected through a reverse-taper joint. The other end of the tube is inserted into a solution storage tank, which is used to hold the acidic or alkaline solution to be sucked; the right port is used to discharge the solution. First, a corrosion-resistant connecting tube with an outer diameter of 1.6 mm and an inner diameter of 360 μm is connected through a reverse-taper joint. The other end of the corrosion-resistant connecting tube is connected to one end of a corrosion-resistant tee through a second reverse-taper joint. The other end of the tee is connected to another corrosion-resistant connecting tube. One end of this corrosion-resistant connecting tube is inserted with a capillary tube and has the same dimensions as the previous corrosion-resistant connecting tube; the outer diameter of the capillary tube is 360 μm and the inner diameter is 100 μm. To prevent liquid leakage at all threaded connections, a pipe cutter is used to make the cross-section flat, and the corrosion-resistant connecting tube needs to be slightly longer than the tip of the reverse-taper joint, and the capillary tube is slightly longer than the end of the corrosion-resistant connecting tube. When necessary, a suitable tool is used to tighten the threaded connections.

[0054] In some embodiments of the present invention, the corrosion-resistant tube can be a polytetrafluoroethylene tube (PTFE tube) or a polyetheretherketone tube (PEEK tube). The inner diameter of the PTFE tube can be 0.5 mm; the inner diameter of the PEEK tube can be 360 μm.

[0055] In some embodiments of the present invention, the pump and capillary tube for transporting the acidic solution are referred to as pump A and tube A, and the pump and capillary tube for transporting the alkaline solution are referred to as pump B and tube B. Tube A and tube B are connected to the left and right ends of the same corrosion-resistant three-way joint through corrosion-resistant connecting tubes and reverse-taper joints. The upper end of the three-way joint is connected to another capillary tube, referred to as tube C, for transporting the acid-base mixed solution, and then connected into the C 4 D detector. The C 4 D detector is then connected to a waste liquid bottle through a corrosion-resistant connecting tube.

[0056] In some embodiments of the present invention, the titration operation content of the microfluidic titration device includes:

[0057] During the entire titration process, the sum of the flow rates of the acidic and alkaline solutions is kept constant; that is, if the flow rate of one solution increases, the flow rate of the other solution decreases to keep the sum of the flow rates constant. Relevant parameters can be input through the control program in the control unit. The control unit is connected to the two injection pumps through data lines and can control the working states and titration speeds of the two pumps.

[0058] In the above-described embodiment, the control unit can set the total operating flow rate of the acidic solution and the alkaline solution, the time of a single stroke (i.e., a flow rate ratio), the initial speed and the end speed of pump A, the magnitude of the speed change of each stroke, and the adjustment factor. Among them, the adjustment factor is the waiting time after each pump operates for a set time. The setting of this value can prevent the pump with a smaller flow rate from missing the reception of the next instruction due to not stopping. The pump operation time difference is the measured time difference of the pump operation, which can be used for the display of images in subsequent data processing.

[0059] In the above-described embodiment, it is described that relevant parameters are input through the control unit. The parameters determined by the control unit actually include preset fixed parameters (that is, parameters applicable to all titration tests of this device) and variable parameters that need to be input for the current test. The baud rate and data bits are fixed parameters, which are preset in the control unit in advance and do not need to be set subsequently. The variable parameters include the pump serial port, the address of each pump, the total operating speed, the test time, as well as the initial speed, the end speed, the speed change, and the number of operating steps of each pump.

[0060] In some embodiments of the present invention, the address of pump A and the address of pump B come from the code disk on the back circuit board of the syringe pump, which can distinguish different pumps and enable selective signal transmission. The total operating speed is the sum of the flow rates of the acid and alkali solutions, corresponding to v in the following calculation; the initial speed of pump A and the end speed of pump A define the flow rate setting range of the acid solution. The operating time of each flow rate ratio is the single operating time of the pump, and the speed change is the flow rate difference of the pump between two strokes.

[0061] In some embodiments of the present invention, within a single stroke corresponding to each flow rate ratio, the obtained conductance data is averaged as the measured value of the conductance at this flow rate. Taking the titration of 0.1 mol / L hydrochloric acid and 0.1 mol / L sodium hydroxide as an example, when the flow rate of pump B is greater than that of pump A, the alkali solution is in excess, the solution is alkaline, and as the flow rate of pump A continuously increases, the amount of water generated in the solution increases but the total flow rate remains unchanged, and the conductance signal of the mixed solution decreases, which is manifested as an increase in the measured signal on the detector; when the flow rate of pump A is greater than that of pump B, the solution is acidic, but no more water is generated, and the conductance signal of the mixed solution increases, which is manifested as a decrease in the measured signal on the detector. Therefore, when the measured conductance signal is the largest, it corresponds to the exact neutralization of acid and alkali. Taking the flow rate of the acid solution as the abscissa and the average value of the signal as the ordinate, linear fitting can be performed on the two regions of conductance increase and decrease respectively. The intersection point of the two straight lines corresponds to the flow rate of the acid solution at the time of acid-base neutralization.

[0062] It is proved through formula derivation that when the sum of the flow rates of the acidic solution and the alkaline solution remains unchanged, the concentration ratio of the mixed solution is inversely proportional to the flow rate ratio. Therefore, the flow rate ratio of the acid and alkali solutions at this time can be obtained by using the flow rate of the acid solution and the total flow rate during acid-base neutralization. The reciprocal can be used to obtain the concentration ratio of the acid and alkali solutions. Combined with the concentration value of the known solution, the concentration value of the unknown solution can be calculated; or the concentration ratio of the two solutions can be directly obtained as the test result. The formula derivation process is as follows:

[0063] When a monobasic strong acid titrates a monobasic weak acid, let the concentration of the acid be c A , set the flow rate to v A , the concentration of the base is c B , set the flow rate to v B .

[0064] During the titration process, the concentration of acid and base and v remain unchanged, that is:

[0065] v A +v B =v

[0066] After the solutions are mixed, the acid concentration changes to c' A , the concentration of the base changes to c′ B ,have:

[0067]

[0068] When the concentrations of the changed acid and base solutions are equal, the titration reaches the stoichiometric point, and the acid and base concentrations and flow rates at this time satisfy:

[0069] c′ A =c′ B

[0070]

[0071] From this we can conclude that the conductivity of the solution has an inflection point at the titration endpoint, at which time the inverse of the flow rate ratio of the acid and base solutions is equal to the concentration ratio of the acid and base solutions.

[0072] In some embodiments of the present invention, for signal detection and data processing, a C 4 D detector to achieve, C 4 The D detector collects voltage-time signals and performs preliminary processing with the help of the signal acquisition program in the control unit to display the real-time signal curve. The collection and data processing of conductivity signals are concentrated in the same LabVIEW program, which includes four modules: signal acquisition, cursor selection, deletion of a point, and calculation of results.

[0073] In the above embodiment, if Figure 2As shown, the signal acquisition module can set some parameters during acquisition, display the acquired data in real time, and display the standard deviation of the data near the real-time value, which can reflect the noise level of the detector to a certain extent. After the data acquisition is completed, click "STOP" in the lower right corner to save the data, and then enter the next module.

[0074] Regarding the cursor: The cursor refers to Figure 7 the yellow vertical line in, which can move left and right within the abscissa range of the image to determine the selection range of valid data. When using the single cursor mode, when the cursor moves to t and the single cursor interval is set to a seconds (a is an appropriate integer value), the selected valid data interval is from t to t + a. For each flow rate ratio, this cursor needs to be moved to the start position of the valid data, and the data within this interval can be automatically selected. At this time, two t values will be displayed in the "Currently Added" column on the right as the displayed valid data interval.

[0075] When using the double cursor mode ( Figures 7 to 9 is the double cursor mode. The single cursor operation is simple, and the double cursor has higher controllability but the operation is slightly more complex), another yellow vertical line needs to be added. By moving the two yellow vertical lines to enclose the valid data to be selected, the valid data interval can be obtained and displayed on the right.

[0076] In the above embodiment, as Figure 3 shown, the selection cursor module includes two modes: single cursor and double cursor. The single cursor mode requires setting the single cursor interval (unit: s) below, and the valid data range is within the interval after the selected point; the double cursor mode requires adding a second cursor, and the selected data range is the data range to be processed. The selected cursor range and the added points can be displayed on the right. After confirming that it is correct, click "End" to enter the next module.

[0077] In the above embodiment, as Figure 4 shown, the module for deleting a certain point can be used to delete points with abnormal conductivity signals or not within the linear range, and set the titration parameters to prepare for the automatic calculation of data. After setting the parameters and inputting the sequence to be deleted, click "Delete", and the remaining flow rate of pump A, the flow rate values of pump A divided into the previous region and the subsequent region, will be displayed in the upper right. After confirming that the region is correct, click "End" to enter the next module. In this step, it is necessary to input the initial speed of the acid solution, the end speed of the acid solution, the speed change, and the total flow rate set during titration; the actual BA time difference is the pump operation time difference given on the right in the automatic control program, which can be automatically given, and the unit is milliseconds.

[0078] In the above embodiment, as Figure 5As shown, the calculation result module can set the number of significant digits, the value to be calculated, and the known value. Clicking "Start Calculation" will pop up a dialog box to display the fitting curve equations and correlation coefficients of the acid region and the base region. After clicking "OK", the automatically calculated results can be displayed. In this step, the number of significant digits to be set needs to be input, the unknown concentration to be calculated is selected, and the known concentration is input. The rest of the values can be automatically calculated by the program.

[0079] In the present invention, the capillary is connected to the syringe pump. The entire pipeline can be built through simple corrosion-resistant joints and corrosion-resistant connecting pipes for automatic acid-base titration in the capillary. And through testing, after the two are connected, the volume error of the transmitted solution is small, the loss is small, the mixing flow rate is accurate, and the mixing speed is also fast when the solution flow rate is low, which can meet the requirements of general acid-base titration experiments.

[0080] The present invention uses a titration control program and a data automatic processing program independently written by LabVIEW software. After setting the parameters in the titration control program and ensuring that the pipeline connection is correct, running the program can control the two syringe pumps simultaneously to complete the entire titration process. In the data processing program, only after importing the data, selecting the appropriate data range, and inputting the set parameters, the results of acid-base titration can be automatically calculated.

[0081] The third innovation point of the present invention is that the amount of acid and base solutions consumed is very small, the titration speed is fast, and the repeatability of the measured data is good. The test results of the present invention are shown in Table 1.

[0082] Table 1 Test Results of Capillary Titration Device

[0083]

[0084] It can be seen from the results in the table that in the titrations of strong acid and strong base, strong acid and some weak bases, and strong base and some weak acids, the present invention can achieve lower consumption, faster analysis speed, and good repeatability.

[0085] In some embodiments of the present invention, when using the program for data processing, first select the range with less fluctuation in the data and determine it as the effective data value; after clicking "End", this interface can display the selected cursor area and the thumbnail of the average value, as Figure 7 shown. Then enter the next module, that is, the module for deleting a certain point. Both the acid excess region (the right descending region) and the base excess region (the left ascending region) of this group of data have good linearity, so there is no need to delete the data, and appropriate parameters can be set, as Figure 8 shown. After confirming that all parameters are correct and clicking "End", the calculation result module can be entered. Clicking "Start Calculation" can automatically display the results, as Figure 9 shown. The calculation process of the calculation result module includes:

[0086] Linear fitting is performed on the acid region and the base region respectively. The calculation method is the least squares method. The fitting straight line equation for the acid region is y = k A v A + a, and the fitting straight line equation for the base region is y = k B v A + b.

[0087] When a strong acid titrates a strong base, in the region where the base is in excess, as the acid flow rate continuously increases, a certain amount of water is generated at the same time, and the concentration of OH - in the solution decreases, and the conductivity of the solution decreases; while in the region where the acid is in excess, as the acid flow rate continuously increases, no more water is generated, and the concentration of H + in the solution increases, and the conductivity increases. Therefore, the conductivity of the solution at the stoichiometric point is the lowest, and the signal shows an extreme value. From the two fitting straight line equations, the acid solution flow rate at the intersection point can be obtained:

[0088] k A v A + a = k B v A + b

[0089]

[0090] The flow rates of the acid and base solutions and v are known set values. Combining with the content deduced from the previous formulas, the concentration ratio can be obtained:

[0091]

[0092] When the concentration of one of the acid and base solutions is known, the unknown concentration can be obtained based on the known value.

[0093] For the parts not detailed in the present invention, reference can be made to the existing technologies in the art, or they are well-known technologies to those skilled in the art. This embodiment does not limit them and will not be described in detail here.

[0094] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims, and all of them fall within the protection scope of the present invention.

Claims

1. A microfluidic titration device, characterized in that, The device includes: a control unit, an acidic solution tank, a basic solution tank, a first injection pump, a second injection pump, a first titration pipeline, a second titration pipeline, a three-way joint, C 4 D detector and a waste liquid bottle; The acidic solution tank, the first injection pump, the first titration pipeline, and the first port of the three-way piece are connected in sequence; The alkaline solution tank, the second injection pump, the second titration pipeline, and the second port of the three-way piece are connected in sequence; The third port of the tee is connected to C 4 the detection window of the D detector, and then connected to the waste liquid bottle; The control unit is connected to the C 4 D detector, the first injection pump, and the second injection pump via a data cable, and is used to control the operation of the injection pumps and the detector.

2. The microfluidic titration device according to claim 1, wherein The first titration pipeline includes a first injection pump, a first corrosion-resistant connecting pipe, a first inverted cone joint, a first corrosion-resistant two-way joint, a second inverted cone joint, a second corrosion-resistant connecting pipe, a first capillary tube, a third corrosion-resistant connecting pipe, and a third inverted cone joint; The first injection pump, the first corrosion-resistant connecting pipe, the first inverted cone joint, the first corrosion-resistant connecting pipe, the second inverted cone joint, the second corrosion-resistant connecting pipe, the first capillary tube, the third corrosion-resistant connecting pipe, and the third inverted cone joint are connected in sequence.

3. The microfluidic titration device according to claim 1, wherein The second titration pipeline includes a second injection pump, a fourth corrosion-resistant connecting pipe, a fourth inverted cone joint, a second corrosion-resistant two-way joint, a fifth inverted cone joint, a fifth corrosion-resistant connecting pipe, a second capillary tube, a sixth corrosion-resistant connecting pipe, and a sixth inverted cone joint; The second injection pump, the fourth corrosion-resistant connecting pipe, the third inverted cone joint, the second corrosion-resistant two-way joint, the fourth inverted cone joint, the fifth corrosion-resistant connecting pipe, the second capillary tube, the sixth corrosion-resistant connecting pipe, and the sixth inverted cone joint are connected in sequence.

4. The microfluidic titration device according to claim 2 or 3, characterized in that, The outer diameters of the corrosion-resistant connecting pipes are all 1.6 mm, and the inner diameters are all 0.5 mm.

5. The microfluidic titration device according to claim 2 or 3, characterized in that, The outer diameter of the capillary tube is 360 μm, and the inner diameter is 100 μm.

6. A microfluidic titration method, characterized in that, It is realized by using the microfluidic titration device according to any one of claims 1-5; the content of the method includes: Add the acidic solution to be titrated into the acidic solution tank, and add the alkaline solution to be titrated into the alkaline solution tank; Set the parameters of the titration experiment through the control unit, including the operating flow rate range and the single stroke time of the first injection pump and the second injection pump; The control unit controls the first injection pump and the second injection pump to perform titration according to the set parameters; Through C 4 The conductivity of the mixed solution is detected by the D detector, and then the test data is processed by the control unit and the test results are displayed.

7. The microfluidic titration method according to claim 6, wherein During the titration process, the sum of the injection solution flow rates of the first injection pump and the second injection pump always remains unchanged.

8. The microfluidic titration method according to claim 6, wherein When the measured conductance signal shows an inflection point, the acid-base solution is just neutralized. According to the flow rate ratio of the acid solution to the total flow rate when the acid-base is neutralized, the concentration ratio of the acid-base solution is obtained.

9. The microfluidic titration method according to claim 6, wherein, During the whole titration process, a graph is plotted with the flow rate of the acidic solution as the abscissa and the average value of the signal within the time corresponding to this flow rate as the ordinate. Linear fitting is performed on the regions before and after the inflection point respectively, and the flow rate corresponding to the intersection point of the two fitting lines is the flow rate of the acidic solution when the acid-base is neutralized.

Images