Online floating electrochemical scanning and electrospray ionization mass spectrometry combined device

Abstract

The invention discloses an online floating electrochemical scanning and electrospray ionization mass spectrometry combined device, relates to the technical field of analytical chemistry, and can improve the electrochemical detection efficiency and detection accuracy. According to the device, a three-electrode probe is arranged in a reaction cavity and is used for containing a target solution to be detected; the floating type electrochemical controller comprises a high-voltage module, a power supply module, a floating electrochemical measurement and control circuit and a three-electrode probe, the high-voltage module raises the first potential of the floating ground end of the power supply module into a second potential; the power supply module is used for converting the voltage of the floating battery into a preset voltage and then supplying power to the floating electrochemical measurement and control circuit; the floating electrochemical measurement and control circuit is used for controlling the three-electrode probe to output a continuous high-voltage signal or a continuous current signal, the continuous high-voltage signal or the continuous current signal acts on a target solution to generate an electrochemical reaction and directly generate spray ions, and the three-electrode probe is used for detecting voltage and current in the electrochemical reaction process of the target solution; and detection voltage and detection current are obtained.

Description

Technical Field

[0001] The present application relates to the technical field of analytical chemistry, and in particular to an online floating electrochemical scanning electrospray mass spectrometry device. Background Art

[0002] In chemical detection and analysis, electrochemistry can effectively distinguish substances with large differences in electroactivity with its advantages of rapidity, sensitivity and quantification. However, electrochemistry itself does not have the ability to perform structural analysis, while mass spectrometry is very powerful in structural analysis. Therefore, combining electrochemistry with mass spectrometry can not only improve the efficiency and accuracy of analysis, but also produce a synergistic effect and complete tasks that cannot be achieved by a single technology. For example, electrochemistry can distinguish species with the same mass-to-charge ratio by differences in electroactivity, while the structural analysis capability of mass spectrometry can reveal intermediates and products in electrochemical reactions. This combination provides important help for studying the mechanism of electrochemical reactions and further enhances the application value of electrochemistry in analysis and synthesis. However, due to the large differences in the operating conditions of electrochemical systems and electrospray ionization (ESI) systems, how to effectively combine electrochemistry, electrospray ionization and mass spectrometry to build an integrated combined device has become a key issue that needs to be solved urgently. Summary of the invention

[0003] The present application provides an online floating electrochemical scanning electrospray mass spectrometry device, which can realize the combination of electrochemistry, electrospray and mass spectrometry devices, and can improve the electrochemical detection efficiency and detection accuracy.

[0004] In order to achieve the above objectives, this application adopts the following technical solutions:

[0005] In a first aspect of an embodiment of the present application, an online floating electrochemical scanning electrospray mass spectrometry device is provided, the device comprising:

[0006] A reaction chamber, wherein a three-electrode probe is disposed in the reaction chamber, the reaction chamber is used to contain a target solution to be detected, and the three-electrode probe is in contact with the target solution;

[0007] A floating electrochemical controller, the floating electrochemical controller comprising: a high voltage module, a power module connected in series with the high voltage module, and a floating electrochemical measurement and control circuit connected to the power module, the floating electrochemical measurement and control circuit being connected to the three-electrode probe;

[0008] The high-voltage module is used to increase the first potential of the floating terminal of the power module to a second potential, wherein the second potential is greater than 500V, so that the power module operates at the second potential;

[0009] The power module includes a floating battery and a voltage stabilizing circuit, wherein the voltage stabilizing circuit is used to convert the voltage of the floating battery into a preset voltage to supply power to the floating electrochemical measurement and control circuit;

[0010] The floating electrochemical measurement and control circuit is used to control the three-electrode probe to output a continuous high-voltage signal or a continuous current signal, the continuous high-voltage signal or the continuous current signal acts on the target solution to produce an electrochemical reaction and directly generate spray ions, and at the same time, the three-electrode probe is used to detect the voltage and current during the electrochemical reaction of the target solution to obtain a detection voltage and a detection current;

[0011] The output port of the reaction chamber is close to the input port of the mass spectrometer, and is used for the spray ions to enter the mass spectrometer.

[0012] As a possible implementation, the floating electrochemical measurement and control circuit includes: a main control chip, a voltage and current generator, a voltage detection module, a current detection module and a synchronous trigger module, and the main control chip is connected to the host computer through wireless communication;

[0013] The host computer is used to input electrochemical parameters to the main control chip and receive, process and display the electrochemical detection results obtained by the main control chip;

[0014] The main control chip is used to generate a corresponding digital signal according to the electrochemical parameter and transmit the digital signal to the voltage and current generator;

[0015] The voltage and current generator is used to generate a corresponding continuous high-voltage signal or a continuous current signal according to the digital signal, and output the continuous high-voltage signal or the continuous current signal from the three-electrode probe;

[0016] The synchronous trigger module is respectively connected to the main control chip, the voltage and current generator and the mass spectrometer;

[0017] The main control chip is further used to control the synchronization trigger module to generate a synchronization signal before controlling the output of the continuous high voltage signal or the continuous current signal from the three-electrode probe;

[0018] The synchronization trigger module is used to send the synchronization signal to the voltage and current generator and the mass spectrometer, so that the voltage and current generator and the mass spectrometer are started after receiving the synchronization signal.

[0019] As a possible implementation, the three-electrode probe includes: a working electrode, a reference electrode and a counter electrode, and the end of the working electrode is close to the output port of the reaction chamber;

[0020] The voltage and current generator is connected to the working electrode, the voltage detection module is connected to the reference electrode and the working electrode, and the current detection module is connected to the counter electrode;

[0021] The continuous high voltage signal or continuous current signal generated by the voltage and current generator is output from the working electrode. The voltage detection module is used to detect the comparative voltage signal of the working electrode relative to the reference electrode to obtain the detection voltage. The current detection module is used to collect the current signal generated by the counter electrode to obtain the detection current.

[0022] As a possible implementation, the voltage detection module includes a first analog-to-digital converter, and the current detection module includes a resistor and a second analog-to-digital converter;

[0023] The voltage detection module is specifically used to convert the comparison voltage signal into a first digital signal by using the first analog-to-digital converter, and then transmit the first digital signal to the host computer through the main control chip to obtain the detection voltage;

[0024] The current detection module is specifically used to convert the current signal generated by the electrode into a voltage signal using the resistor, then convert the voltage signal into a second digital signal using the second analog-to-digital converter, and then transmit the second digital signal to the host computer through the main control chip to obtain the detection current.

[0025] As a possible implementation manner, the high voltage module includes a voltage regulating unit, which is used to adjust the output voltage of the high voltage module.

[0026] As a possible implementation manner, the power module includes a protection unit, and the protection unit is used to prevent the voltage of the high-voltage module from breaking down the power module.

[0027] As a possible implementation manner, the device further includes a first connecting component and a second connecting component;

[0028] The first connecting component is used to connect the reaction chamber and the mass spectrometer;

[0029] The second connecting component is used to connect the floating electrochemical controller and the reaction chamber.

[0030] As a possible implementation manner, the first connecting component includes a movable platform, and the movable platform is used to adjust the position of the reaction chamber along the input port direction of the mass spectrometer device.

[0031] As a possible implementation, the reaction chamber is a nanospray needle.

[0032] As a possible implementation, the host computer is also connected to the mass spectrometer;

[0033] The host computer is also used to obtain the mass spectrometry detection result of the mass spectrometry device.

[0034] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0035] The embodiment of the present application provides an online floating electrochemical scanning electrospray mass spectrometry device, which includes a reaction chamber, a three-electrode probe is arranged in the reaction chamber, the reaction chamber is used to hold a target solution to be detected, and the three-electrode probe is in contact with the target solution; a floating electrochemical controller, the floating electrochemical controller includes: a high-voltage module, a power module connected in series with the high-voltage module, and a floating electrochemical measurement and control circuit connected to the power module, the floating electrochemical measurement and control circuit is connected to the three-electrode probe; the high-voltage module is used to increase the first potential of the floating end of the power module to a second potential, the second potential is greater than 500V, so that the power module works at a second potential. Potential; the power module includes a floating battery and a voltage stabilizing circuit, the voltage stabilizing circuit is used to convert the voltage of the floating battery into a preset voltage to power the floating electrochemical measurement and control circuit; the floating electrochemical measurement and control circuit is used to control the output of a continuous high-voltage signal or a continuous current signal in the three-electrode probe, the continuous high-voltage signal or the continuous current signal acts on the target solution to produce an electrochemical reaction and directly generate spray ions, and at the same time, the three-electrode probe is used to detect the voltage and current during the electrochemical reaction of the target solution to obtain the detection voltage and detection current; the output port of the reaction chamber is close to the input port of the mass spectrometer, which is used to spray ions into the mass spectrometer. The online floating electrochemical scanning electrospray mass spectrometry device provided in the embodiment of the present application can realize the online combined detection of electrochemistry and mass spectrometry, can realize the detection of electrochemistry and mass spectrometry at the same time, and can improve the detection efficiency. In addition, a three-electrode system is introduced to continuously and accurately control the electrode potential during the electrochemical reaction, and combined with mass spectrometry analysis, the reactive intermediates in the process are captured and structurally identified. Furthermore, the power module uses a battery and is connected to a high-voltage module, and the first potential of the floating end of the power module is increased to a high potential, which can improve the portability of the online floating electrochemical scanning electrospray ionization mass spectrometry device. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of an online floating electrochemical scanning electrospray mass spectrometry device provided in the embodiment of the present application Figure 1 ;

[0037] Figure 2 An online floating electrochemical scanning electrospray mass spectrometry device structure provided in the embodiment of the present application Figure 2 ;

[0038] Figure 3Cyclic voltammetry test curves of the device provided in the embodiment of the present application and a commercial electrochemical workstation using a large electrode;

[0039] Figure 4 Cyclic voltammetry test curves of the device provided in the embodiment of the present application and a commercial electrochemical workstation using a microelectrode in a nanospray needle;

[0040] Figure 5 The reaction formula for producing dopaquinone by electro-oxidation of dopamine provided in the embodiments of the present application;

[0041] Figure 6 The electrochemical linear voltammetric scanning curve of the dopamine solution provided in the embodiment of the present application is Figure 1 ;

[0042] Figure 7 The electrochemical linear voltammetric scanning curve of the dopamine solution provided in the embodiment of the present application is Figure 2 ;

[0043] Figure 8 The mass voltammetric curve of dopamine and its oxidation product dopamine o-quinone provided in the examples of the present application;

[0044] Fig. 9 Mass spectrometry of the dopamine electrochemical reaction process provided in the present application example Figure 1 ;

[0045] Fig.10 Mass spectrometry of the dopamine electrochemical reaction process provided in the present application example Figure 2 .

[0046] Reference numerals:

[0047] 1-reaction chamber, 2-floating electrochemical controller, 3-three-electrode probe, 4-first connecting component, 5-mass spectrometer, 6-second connecting component, 7-host computer, 21-main control chip, 22-voltage detection module, 23-synchronous trigger module, 24-current detection module, 25-voltage and current generator, 26-high voltage module, 27-power module, 31-reference electrode, 32-working electrode, 33-counter electrode; 271-voltage stabilizing circuit, 272-floating battery. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0049] In the following, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0050] Additionally, the use of “based on” or “according to” is meant to be open and inclusive, as a process, step, calculation, or other action “based on” or “according to” one or more conditions or values ​​may, in practice, be based on additional conditions or beyond values.

[0051] Organic electrosynthesis has been widely used as a sustainable green synthesis method for decades. Its outstanding advantages lie not only in sustainability and atom economy, but also in the possibility of preparing unique reaction intermediates in a controllable and predictable manner. As with any chemical reaction, mechanism studies are crucial. Currently, the main methods for studying reaction mechanisms include electrochemical methods, spectroscopic methods, chromatographic techniques, and computational methods.

[0052] Cyclic voltammetry (CV) is one of the most widely used electrochemical methods and can provide rich information for a given electrochemical process. Although cyclic voltammetry can be used to determine the potential required to drive an electrochemical reaction and the appropriate potential window, and has the advantages of high sensitivity and convenience, it is still a great challenge to rely solely on electrical signals to study complex redox reaction mechanisms. Mass spectrometry is a high-precision and high-accuracy analytical technique that can directly obtain the mass-to-charge ratio (m / z) of the analyte, and multi-stage tandem mass spectrometry can obtain characteristic fragments of related substances to achieve rapid identification of structural features. Therefore, mass spectrometry, as a highly sensitive analytical method, can provide corresponding structural information for electrochemical reaction products or intermediates. Therefore, the combination of electrochemical (EC) and mass spectrometry (MS) has become a powerful tool for studying electrochemical reaction processes.

[0053] In recent years, in some studies using the electrochemical properties of electrospray ionization (ESI) or nanoelectrospray ionization (nESI) sources for EC-MS coupling, the electrochemical reaction process and the electrospray process are usually entangled. However, since the ESI source usually operates at a very high voltage (2-4 kilovolts), the EC-MS system must float under the high voltage of ESI or be decoupled from the ESI high voltage in a certain way. At the same time, the control of the potential during the electrochemical reaction is also very important, which is related to whether the reaction can occur and the distribution of products or intermediates.

[0054] The electrochemical system and the electrospray system have great differences in operating conditions and poor compatibility in circuit configuration. In order to eliminate the mutual interference between them and enable them to operate normally at the same time, EC-MS can continuously and accurately control the electrode potential of the reaction based on ESI.

[0055] Therefore, we proposed an online floating electrochemical scanning electrospray ionization mass spectrometry device, which continuously and precisely controls the electrode potential during the electrochemical (EC) reaction by introducing a three-electrode system into a floating electrochemical scanning device, and captures and structurally identifies the reactive intermediates in the process in combination with mass spectrometry analysis.

[0056] like Figure 1 As shown, an online floating electrochemical scanning electrospray mass spectrometry device provided in an embodiment of the present application comprises:

[0057] A reaction chamber 1, wherein a three-electrode probe 3 is disposed in the reaction chamber 1, and the reaction chamber 1 is used to contain a target solution to be detected, and the three-electrode probe 3 is in contact with the target solution;

[0058] A floating electrochemical controller 2, the floating electrochemical controller 2 comprising: a high voltage module 26, a power module 27 connected in series with the high voltage module 26, and a floating electrochemical measurement and control circuit connected to the power module 27, the floating electrochemical measurement and control circuit being connected to the three-electrode probe 3;

[0059] The high voltage module 26 is used to increase the first potential of the floating terminal of the power module 27 to a second potential, where the second potential is greater than 500V, so that the power module 27 works at the second potential;

[0060] The power module 27 includes a floating battery 272 and a voltage stabilizing circuit 271, wherein the voltage stabilizing circuit 271 is used to convert the voltage of the floating battery 272 into a preset voltage to supply power to the floating electrochemical measurement and control circuit;

[0061] The floating electrochemical measurement and control circuit is used to control the three-electrode probe 3 to output a continuous high-voltage signal or a continuous current signal, the continuous high-voltage signal or the continuous current signal acts on the target solution to produce an electrochemical reaction and directly generate spray ions, and at the same time, the three-electrode probe 3 is used to detect the voltage and current during the electrochemical reaction of the target solution to obtain the detection voltage and the detection current;

[0062] The output port of the reaction chamber 1 is close to the input port of the mass spectrometer 5 , so as to allow the spray ions to enter the mass spectrometer 5 .

[0063] Optionally, the reaction chamber 1 can be an electrolytic cell or a nanospray needle, and the nanospray needle can be drawn from a high borosilicate glass tube. The three-electrode probe 3 design includes a working electrode 32, a reference electrode 31, and a counter electrode 33. The substance generated by the working electrode 32 is ionized and transmitted into a mass spectrometer under high pressure. Among them, the reaction chamber 1 and the three electrodes can form an electrolytic cell for electrochemical reactions.

[0064] In the three-electrode layout, the working electrode 32 and the counter electrode 33 are Pt wires, and the reference electrode 31 is Ag / AgCl wire. We placed the working electrode 32 (WE) very close to the outlet of the nESI needle to ensure that the electrode reaction products are quickly transferred to the mass spectrometer. It is worth noting that to prevent short circuits, both electrodes are pre-inserted into fused silica capillaries.

[0065] It can be understood that the online floating electrochemical scanning electrospray mass spectrometry device in the embodiment of the present application can be combined not only with an electrospray ionization source, but also with other ion sources based on the principle of electrospray ionization source, such as paper spray, desorption electrospray and droplet electrospray ionization sources. The basic connection method remains unchanged, and only the electrolytic cell needs to be replaced from the nanospray needle to the corresponding paper, beaker and glass plate.

[0066] By connecting the floating end of the battery in the power module 27 in the floating electrochemical controller 2 to the high-voltage power module 26, the output voltage of the three electrodes is high voltage, that is, the voltage and current between the three electrodes are low voltage, which can control the generation of electrochemical reactions, but the three electrodes are all floating above the high voltage, and electrospray can be generated. The floating electrochemical controller 2 can realize the functions of voltage scanning and current scanning under high voltage. By connecting the output and input ends of the floating electrochemical controller 2 to the three-electrode probe 3, the detection of voltage and current can be realized.

[0067] Optionally, the floating electrochemical measurement and control circuit includes: a main control chip 21, a voltage and current generator 25, a voltage detection module 22, a current detection module 24 and a synchronous trigger module 23, and the main control chip 21 is connected to the host computer 7 through wireless communication;

[0068] The host computer 7 is used to input electrochemical parameters to the main control chip 21 and receive, process and display the electrochemical detection results obtained by the main control chip;

[0069] The main control chip 21 is used to generate corresponding digital signals according to the electrochemical parameters and transmit the digital signals to the voltage and current generator 25;

[0070] The voltage and current generator 25 is used to generate a corresponding continuous high voltage signal or a continuous current signal according to the digital signal, and output the continuous high voltage signal or the continuous current signal from the three-electrode probe 3;

[0071] The synchronous trigger module 23 is respectively connected to the main control chip 21, the voltage and current generator 25 and the mass spectrometer device 5;

[0072] The main control chip 21 is further used to control the synchronization trigger module 23 to generate a synchronization signal before controlling the output of the continuous high voltage signal or the continuous current signal from the three-electrode probe 3;

[0073] The synchronization trigger module 23 is used to send the synchronization signal to the voltage and current generator 25 and the mass spectrometer 5, so that the voltage and current generator 25 and the mass spectrometer 5 are started after receiving the synchronization signal.

[0074] The comparison voltage signal and the detection current signal obtained through real-time detection can generate the potential change during the electrochemical reaction of the target solution, and the electrochemical reaction process can be analyzed based on the potential change.

[0075] The comparison voltage signal and the detection current signal obtained through real-time detection can generate the potential change during the electrochemical reaction of the target solution, and the electrochemical reaction process can be analyzed based on the potential change.

[0076] Specifically, the voltage detection module 22 includes a first analog-to-digital converter, and the current detection module 24 includes a resistor and a second analog-to-digital converter;

[0077] The voltage detection module 22 is specifically used to convert the comparison voltage signal into a first digital signal by using the first analog-to-digital converter, and then transmit the first digital signal to the host computer 7 through the main control chip 21 to obtain the detection voltage;

[0078] The current detection module 24 is specifically used to convert the current signal generated by the electrode 33 into a voltage signal using the resistor, and then convert the voltage signal into a second digital signal using the second analog-to-digital converter, and then transmit the second digital signal to the host computer 7 through the main control chip 21 to obtain the detection current.

[0079] The indexes and specification parameters of the floating electrochemical controller 2 are shown in Table 1. In addition, the software control functions of the floating electrochemical controller 2 include: wireless communication with the control hardware circuit, electrochemical reaction parameter setting, mass spectrometry synchronization triggering, electrochemical information collection and data processing.

[0080] Table 1 Indexes and specifications of the floating electrochemical controller

[0081]

[0082] Optionally, the high voltage module 26 includes a voltage regulating unit for regulating the output voltage of the high voltage module 26 .

[0083] Optionally, the power module 27 includes a protection unit, and the protection unit is used to prevent the voltage of the high-voltage module 26 from breaking down the power module 27 .

[0084] Optionally, the device further includes a first connecting component 4 and a second connecting component 6; the first connecting component 4 is used to connect the reaction chamber 1 and the mass spectrometer 5; the second connecting component 6 is used to connect the floating electrochemical controller 2 and the reaction chamber 1.

[0085] Among them, the first connecting component 4 can be a fixing frame, which is used to fix the online floating electrochemical scanning electrospray mass spectrometry device provided in the embodiment of the present application at the input port of the mass spectrometer, and can adjust the position of the floating electrochemical controller 2 in the Z-axis direction.

[0086] Optionally, the first connecting component 4 includes a movable platform, and the movable platform is used to adjust the position of the reaction chamber 1 along the input port direction of the mass spectrometer 5 .

[0087] The second connecting component 6 includes a slide fixing plate and a three-dimensional moving platform, and the slide fixing plate includes a slide. A slide fixing plate is arranged above the first connecting component 4, which can initially adjust the x-axis position of the nanospray needle, and the slide inside the slide fixing plate can initially adjust the y-axis position of the nanospray needle; the fine control of the three directions of the nanospray needle is realized by the three-dimensional moving platform, so that the outlet of the nanospray needle can be aligned with the injection port of the mass spectrometer, and the electrode reaction product can be detected in real time.

[0088] Optionally, the host computer 7 is also connected to the mass spectrometer device 5 ; the host computer 7 is also used to obtain the mass spectrometer detection result of the mass spectrometer device 5 .

[0089] The present application provides an online floating electrochemical scanning electrospray mass spectrometry device, which can float the electrolytic cell to carry out the electrochemical process of the three-electrode system without interference while ionizing the substance, thereby continuously and accurately controlling the electrode potential during the electrochemical reaction and monitoring the changes in substance information in the electrochemical reaction through mass spectrometry technology.

[0090] The online floating electrochemical scanning electrospray mass spectrometry device includes a floating electrochemical controller 2 with three-electrode output, which is used to realize continuous measurement of three-electrode electrochemistry under high voltage; a three-electrode probe 3, which is used to combine electrochemistry with mass spectrometry ionization, and transmit the substances produced on the working electrode 32 to the mass spectrometer through high-voltage ionization; and by controlling the movement of the three-electrode probe 3, the substances ionized by high voltage on the working electrode 32 are aligned with the injection port of the mass spectrometer. Compared with the previous electrochemical-mass spectrometry method, the significant advantage of the online electrochemical electrospray mass spectrometry device 5 is that it can realize high-precision control and electrochemical scanning of electrochemistry under high voltage, and at the same time, the nanoampere current under the microelectrode can also have a good detection effect, ensuring the versatility of redox reactions in different scenarios. Furthermore, the power module 27 uses a battery and is connected to the high-voltage module 26, and the first potential of the floating end of the power module 27 is increased to a high potential, which can improve the portability of the online floating electrochemical scanning electrospray mass spectrometry device.

[0091] Based on the online floating electrochemical scanning electrospray ionization mass spectrometry device (hereinafter referred to as the device) provided in the embodiments of the present application, the present application conducts the following tests and verifications.

[0092] Example 1: Mainly verify the difference between the present device and the commercial electrochemical workstation in cyclic voltammetry test using a traditional large electrode.

[0093] The cyclic voltammetry test of ferrocene was carried out using traditional large electrodes (working electrode: platinum disk electrode Φ3mm, counter electrode: platinum sheet electrode 5*5*0.1mm, reference electrode: Φ0.1mmAg / AgCl electrode wire). The electrochemical test results are as follows: Figure 3 As shown, according to Figure 3 It can be observed that the test results of ferrocene by the device are basically consistent with those by a commercial electrochemical workstation.

[0094] Example 2: Mainly verify the difference between this device and a commercial electrochemical workstation in cyclic voltammetry testing using a microelectrode in a nanospray needle, and compare whether this device can perform electrochemical reactions under high voltage and whether high voltage affects the position of the electrochemical oxidation peak.

[0095] Based on the electrochemical oxidation test of ferrocene by the electrodes under the nanospray needle (working electrode: Φ0.2mm platinum wire, counter electrode: Φ0.2mm platinum wire, reference electrode: Φ0.1mmAg / AgCl electrode wire) of this device, the test results are as follows Figure 4 As shown, it was observed that the test results of ferrocene by the present device were basically consistent with those by a commercial electrochemical workstation, and the use of a smaller microelectrode did not change the oxidation peak voltage of ferrocene. Furthermore, under high pressure, the fluidity inside the nanospray needle did not affect the oxidation peak potential of ferrocene.

[0096] Example 3: In positive ion mode, the applied voltage is 0.0-1.2 V to monitor the oxidation of dopamine.

[0097] Example 3 mainly introduces that when the applied voltage is 0.0~1.2V, various electrochemical oxidation data of dopamine can be observed. Figure 5 is the reaction formula for the electrooxidation of dopamine to produce dopaquinone; Figure 6 This is the electrochemical linear voltammetric scanning curve of dopamine blank solution. Figure 7 1 mM dopamine (1 mM dopamine hydrochloride, 10 mM LiCl, MeCN / H 2 O=1 / 1) electrochemical linear voltammetric scanning curve, Figure 6 and Figure 7 All scans were performed at a rate of 50 mV / s in the range of 0-1.2 V. From the electrochemical linear voltammetric scanning curve, it can be seen that the electrochemical oxidation process of dopamine on the Pt disk electrode has a clear voltammetric response, with an initial oxidation potential of about 0.2 V and a peak potential of about 0.65 V.

[0098] The device was used to conduct online EC-MS experiments under potential scanning, and the mass voltammetry curves of dopamine and its oxidation product dopamine o-quinone were plotted, as shown in Figure 2. Figure 8 As shown, from Figure 8 It can be clearly seen that the initial oxidation potential of dopamine is about 0.2 V. In addition, the intensity of dopamine decreases with the increase of potential, while the intensity of dopamine o-quinone increases with the increase of potential. Fig. 9 and Fig.10 The high-resolution mass spectra at 0.1V and 0.8V are shown. It can be seen that at the initial scanning potential, only the proton addition peak of dopamine ([M+H] + , m / z154.0860), the intensity of m / z 154.0860 decreased with the increase of potential, and the proton addition peak of dopamine o-quinone ([M+H] + , m / z 152.0710) began to increase in intensity. In the mass spectrum, there was an ion with a relatively high intensity of m / z 137.0595. This is the result of protonated dopamine losing a molecule of NH during the ion transport process. 3 The fragment ions produced.

[0099] The online scanning experimental results of dopamine show that the mass voltammogram can reflect the initial oxidation potential of the reactant, helping us to better monitor the oxidation process. During this period, the electrochemical process in the nESI source has little effect on the electrochemical process in the floating electrolytic cell. Before the generation of dopamine o-quinone, the intensity of dopamine is not affected by the potential scan, which shows that the electrochemical system has little effect on the electrospray system.

[0100] The above examples fully demonstrate that the online floating electrochemical scanning electrospray ionization mass spectrometry device provided in the embodiments of the present application can monitor the electrochemical reaction process, and can capture and structurally identify active intermediates and products in the reaction process.

[0101] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0102] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. An online floating electrochemical scanning electrospray mass spectrometry device, characterized in that: The device comprises: A reaction chamber, wherein a three-electrode probe is disposed in the reaction chamber, the reaction chamber is used to contain a target solution to be detected, and the three-electrode probe is in contact with the target solution; A floating electrochemical controller, the floating electrochemical controller comprising: a high voltage module, a power module connected in series with the high voltage module, and a floating electrochemical measurement and control circuit connected to the power module, the floating electrochemical measurement and control circuit being connected to the three-electrode probe; The high-voltage module is used to increase the first potential of the floating terminal of the power module to a second potential, wherein the second potential is greater than 500V, so that the power module operates at the second potential; The power module includes a floating battery and a voltage stabilizing circuit, wherein the voltage stabilizing circuit is used to convert the voltage of the floating battery into a preset voltage to supply power to the floating electrochemical measurement and control circuit; The floating electrochemical measurement and control circuit is used to control the three-electrode probe to output a continuous high-voltage signal or a continuous current signal, the continuous high-voltage signal or the continuous current signal acts on the target solution to produce an electrochemical reaction and directly generate spray ions, and at the same time, the three-electrode probe is used to detect the voltage and current during the electrochemical reaction of the target solution to obtain a detection voltage and a detection current; The output port of the reaction chamber is close to the input port of the mass spectrometer, and is used for the spray ions to enter the mass spectrometer.

2. The device according to claim 1, characterized in that The floating electrochemical measurement and control circuit includes: a main control chip, a voltage and current generator, a voltage detection module, a current detection module and a synchronous trigger module, and the main control chip is connected to the host computer through wireless communication; The host computer is used to input electrochemical parameters to the main control chip and receive, process and display the electrochemical detection results obtained by the main control chip; The main control chip is used to generate a corresponding digital signal according to the electrochemical parameter and transmit the digital signal to the voltage and current generator; The voltage and current generator is used to generate a corresponding continuous high-voltage signal or a continuous current signal according to the digital signal, and output the continuous high-voltage signal or the continuous current signal from the three-electrode probe; The synchronous trigger module is respectively connected to the main control chip, the voltage and current generator and the mass spectrometer; The main control chip is further used to control the synchronization trigger module to generate a synchronization signal before controlling the output of the continuous high voltage signal or the continuous current signal from the three-electrode probe; The synchronization trigger module is used to send the synchronization signal to the voltage and current generator and the mass spectrometer, so that the voltage and current generator and the mass spectrometer are started after receiving the synchronization signal.

3. The device according to claim 2, characterized in that The three-electrode probe comprises: a working electrode, a reference electrode and a counter electrode, wherein the end of the working electrode is close to the output port of the reaction chamber; The voltage and current generator is connected to the working electrode, the voltage detection module is connected to the reference electrode and the working electrode, and the current detection module is connected to the counter electrode; The continuous high voltage signal or continuous current signal generated by the voltage and current generator is output from the working electrode. The voltage detection module is used to detect the comparative voltage signal of the working electrode relative to the reference electrode to obtain the detection voltage. The current detection module is used to collect the current signal generated by the counter electrode to obtain the detection current.

4. The device according to claim 3, characterized in that The voltage detection module includes a first analog-to-digital converter, and the current detection module includes a resistor and a second analog-to-digital converter; The voltage detection module is specifically used to convert the comparison voltage signal into a first digital signal by using the first analog-to-digital converter, and then transmit the first digital signal to the host computer through the main control chip to obtain the detection voltage; The current detection module is specifically used to convert the current signal generated by the electrode into a voltage signal using the resistor, then convert the voltage signal into a second digital signal using the second analog-to-digital converter, and then transmit the second digital signal to the host computer through the main control chip to obtain the detection current.

5. The device according to claim 1, characterized in that The high voltage module includes a voltage regulating unit, which is used to adjust the output voltage of the high voltage module.

6. The device according to claim 1, characterized in that The power module includes a protection unit, and the protection unit is used to prevent the voltage of the high-voltage module from breaking through the power module.

7. The device according to claim 1, characterized in that The device also includes a first connecting member and a second connecting member; The first connecting component is used to connect the reaction chamber and the mass spectrometer; The second connecting component is used to connect the floating electrochemical controller and the reaction chamber.

8. The device according to claim 7, characterized in that The first connecting component includes a movable platform, and the movable platform is used to adjust the position of the reaction chamber along the input port direction of the mass spectrometer.

9. The device according to claim 1, characterized in that The reaction chamber is a nanospray needle.

10. The device according to claim 2, characterized in that The host computer is also connected to the mass spectrometer; The host computer is also used to obtain the mass spectrometry detection result of the mass spectrometry device.

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