1. A method of measuring chemical ionization reaction time, comprising the steps of:

applying a pulse voltage signal to a chemical ionization source to generate main ions;

acquiring a mass spectrum TTL feedback signal of the main ions;

acquiring a sequence chart of signals changing along with time, wherein the signals comprise the pulse voltage signals and the mass spectrum TTL feedback signals;

and calculating to obtain chemical ionization reaction time according to the time corresponding to the half-height of the mass spectrum TTL feedback signal in the sequence diagram and the time corresponding to the start of the pulse voltage signal.

2. The method of measuring chemical ionization reaction time of claim 1, wherein the generation of the pulsed voltage signal comprises the steps of:

setting the starting voltage to +200 volt current voltage;

the control voltage is converted to-400 vdc to produce a pulsed voltage signal.

3. The method of measuring chemical ionization reaction time of claim 2 wherein the pulse width of the pulsed voltage signal is between 40 and 50 milliseconds.

4. A method of measuring chemical ionization reaction time according to claim 2 or 3, further comprising:

after one pulse width, the dc voltage is reduced to-330 volts and held at this voltage value.

5. The method of measuring chemical ionization reaction time of claim 1, further comprising:

and after the mass spectrum TTL feedback signal of the main ions is obtained, filtering the mass spectrum TTL feedback signal to obtain a mass spectrum TTL feedback signal generated by a pulse voltage signal with the pulse width of 40-45 milliseconds.

6. A system for measuring chemical ionization reaction time, comprising:

the control computer is connected with the chemical ionization source and the oscilloscope and is used for sending pulse voltage signals to the chemical ionization source and the oscilloscope;

the chemical ionization source is connected with the control computer and the sampling tube and is used for receiving a pulse voltage signal sent by the control computer so as to generate main ions;

the sampling tube is connected with the chemical ionization source and the mass spectrometer and is used for transmitting the main ions to the mass spectrometer;

the mass spectrometer is connected with the sampling tube and the oscilloscope and is used for detecting the received main ions and sending mass spectrum TTL (transistor logic) feedback signals of the main ions to the oscilloscope;

and the oscilloscope is connected with the control computer and the mass spectrometer and is used for receiving the pulse voltage signal and the mass spectrum TTL feedback signal and displaying a sequence diagram of the signal changing along with time.

7. The system for measuring chemical ionization reaction time of claim 6, further comprising:

and the resistance-capacitance circuit is used for filtering the mass spectrum TTL feedback signal.

8. The system for measuring chemical ionization reaction time of claim 7, wherein the oscilloscope has at least two channels, wherein the first channel is connected to the control computer and the chemical ionization source, and the first channel receives and measures the change of the pulse voltage signal with time while the control computer sends the pulse voltage signal to the chemical ionization source and the chemical ionization source ionizes to generate main ions; and the second channel receives and detects a mass spectrum TTL feedback signal transmitted by the mass spectrometer, the mass spectrum TTL feedback signal is received by the second channel after being filtered by the resistor-capacitor circuit, and the change of the mass spectrum TTL feedback signal along with time is monitored by the second channel.

9. An apparatus for measuring chemical ionization reaction time, comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, the processor implementing the method of measuring chemical ionization reaction time as recited in any one of claims 1-5 when executing the computer program.

10. A computer-readable storage medium, in which a computer program is stored, which, when executed, implements a method of measuring chemical ionization reaction time according to any one of claims 1 to 5.

Background

Mass Spectrometry (Mass Spectrometry) is widely used for qualitative and quantitative detection of molecular composition of substances, and can be classified into Electron bombardment (Electron Impact), Electrospray Ionization (Electrospray Ionization), Chemical Ionization (Chemical Ionization) and the like according to Ionization methods, while Chemical Ionization Mass Spectrometry is a soft Ionization Mass Spectrometry widely used in recent years, and Chemical Ionization can be performed under vacuum or atmospheric pressure. The principle of the chemical ionization mass spectrometry is that ions to be detected are generated through chemical ionization reaction of main ions and molecules of substances to be detected, qualitative analysis is carried out according to spectrogram characteristics of the ions to be detected, and quantitative analysis is carried out according to information such as relative abundance, reaction rate constant and reaction time of the ions to be detected and the main ions. Therefore, in the quantitative analysis of the chemical ionization mass spectrum, the chemical ionization reaction time is an important index in a concentration quantitative equation, and particularly for the substance molecules which have no standard pure sample and cannot be accurately corrected, the concentration can be estimated only through the quantitative equation, so that the accurate measurement of the chemical ionization reaction time is very important.

The current reports on the chemical ionization reaction time measuring method are very limited, and the following methods are mainly used for common estimation: one is by estimating the flow length and velocity, assuming that under laminar flow conditions, the average reaction time is usually the distance the gas stream passes divided by its flow velocity; alternatively, drift techniques are used in the flow tube, and the velocity used in the equation for the reaction time is determined by both the flow velocity and drift velocity of the ions. However, for the case of short reaction time, there is a large error in the above two estimation methods, because the gas flow may have turbulence, even laminar flow, and there may be the case that the radial velocity is uniform and the gas flow is not uniform, resulting in inaccurate estimation of the reaction time. In addition, the ions are greatly affected by the electric field, and different voltage settings may cause different reaction times and inaccurate estimation.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides a method, a system, a device and a storage medium for measuring chemical ionization reaction time.

In one aspect, a method for measuring chemical ionization reaction time is provided, comprising the steps of:

a method of measuring chemical ionization reaction time, comprising the steps of:

applying a pulse voltage signal to a chemical ionization source to generate main ions;

acquiring a mass spectrum TTL feedback signal of the main ions;

acquiring a sequence chart of signals changing along with time, wherein the signals comprise the pulse voltage signals and the mass spectrum TTL feedback signals;

and calculating to obtain chemical ionization reaction time according to the time corresponding to the half-height of the mass spectrum TTL feedback signal in the sequence diagram and the time corresponding to the start of the pulse voltage signal.

Further, the generation of the pulse voltage signal comprises the following steps:

setting the starting voltage to + 200V DC voltage;

the control voltage is converted to-400 vdc to produce a pulsed voltage signal.

Further, the pulse width of the pulse voltage signal is between 40-50 milliseconds.

Further, still include:

after one pulse width, the dc voltage is reduced to-330 volts and held at this voltage value.

Further, still include:

and after the mass spectrum TTL feedback signal of the main ions is obtained, filtering the mass spectrum TTL feedback signal to obtain a mass spectrum TTL feedback signal generated by a pulse voltage signal with the pulse width of 40-45 milliseconds.

In one aspect, a system for measuring chemical ionization reaction time is provided, comprising:

the control computer is connected with the chemical ionization source and the oscilloscope and is used for sending pulse voltage signals to the chemical ionization source and the oscilloscope;

the chemical ionization source is connected with the control computer and the sampling tube and is used for receiving a pulse voltage signal sent by the control computer so as to generate main ions;

the sampling tube is connected with the chemical ionization source and the mass spectrometer and is used for transmitting the main ions to the mass spectrometer;

the mass spectrometer is connected with the sampling tube and the oscilloscope and is used for detecting the received main ions and sending mass spectrum TTL (transistor logic) feedback signals of the main ions to the oscilloscope;

and the oscilloscope is connected with the control computer and the mass spectrometer, and is used for receiving the pulse voltage signal and the mass spectrum TTL feedback signal and showing a sequence diagram of the signal changing along with time.

Further, still include:

and the resistance-capacitance circuit is used for filtering the mass spectrum TTL feedback signal.

Furthermore, the oscilloscope is provided with at least two channels, wherein the first channel is connected with the control computer and the chemical ionization source, and receives and measures the change of the pulse voltage signal along with time when the control computer sends the pulse voltage signal to the chemical ionization source and the chemical ionization source ionizes to generate main ions; and the second channel receives and detects a mass spectrum TTL feedback signal transmitted by the mass spectrometer, the mass spectrum TTL feedback signal is received by the second channel after being filtered by the resistor-capacitor circuit, and the change of the mass spectrum TTL feedback signal along with time is monitored by the second channel.

In one aspect, an apparatus for measuring chemical ionization reaction time is provided, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and the processor implements any one of the above methods for measuring chemical ionization reaction time when executing the computer program.

In one aspect, a computer readable storage medium is provided, having a computer program stored therein, which when executed, implements any of the above methods for measuring chemical ionization reaction time.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that: the invention provides a method, a system, a device and a storage medium for measuring chemical ionization reaction time.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a flow chart of a method of measuring chemical ionization reaction time according to the present invention;

FIG. 2 is a schematic diagram of generating a pulse voltage signal according to the present invention;

FIG. 3 is a time-varying sequence of a pulsed voltage signal and a mass spectrum TTL feedback signal in accordance with the present invention;

fig. 4 is a block diagram of a system for measuring chemical ionization reaction time in accordance with the present invention.

Detailed Description

The current reports on the chemical ionization reaction time measuring method are very limited, and the common estimation method is used for the situation of short reaction time, because the gas flow may have turbulence, even laminar flow, the radial velocity may be uniform, and the gas flow may not be uniform, so that the reaction time estimation is inaccurate. In addition, the ions are greatly affected by the electric field, and different voltage settings may cause different reaction times and inaccurate estimation.

According to the method, the system, the device and the storage medium for measuring the chemical ionization reaction time, the chemical ionization reaction time is determined according to the characteristics between the pulse voltage signal and the spectrogram of the mass spectrum TTL feedback signal, the accuracy of the measurement of the chemical ionization reaction time can be improved, and the method is simple and easy to implement.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.

In one embodiment, as shown in the flow chart of FIG. 1, the present invention provides a method for measuring chemical ionization reaction time, comprising the steps of:

s101, applying a pulse voltage signal to a chemical ionization source to generate main ions;

s102, acquiring mass spectrum TTL feedback signals of the main ions;

s103, acquiring a sequence chart of signals changing along with time, wherein the signals comprise the pulse voltage signals and the mass spectrum TTL feedback signals.

And S104, calculating to obtain chemical ionization reaction time according to the time corresponding to the half-height of the mass spectrum TTL feedback signal in the sequence diagram and the time corresponding to the start of the pulse voltage signal.

Sending a 200 v dc voltage to a chemical ionization source, which may be radioactive or soft X-ray ionization source, in a control computer (PC) by a self-programmed program, for example, using a Labview program, through a data acquisition control system (DAQ), wherein in this embodiment, for example, a soft X-ray ionization source is used, and the generated ions are nitrate ions and nitrate ion clusters with one or two nitrate molecules, and the method for generating the ions is as follows: a small amount of nitric acid vapor is added to the carrier gas stream under about 1-2 liters per minute of pure nitrogen carrier gas, typically less than about 10 milliliters per minute of pure nitrogen gas, into a sample bottle containing a solution of nitric acid, typically about 70 weight percent concentrated nitric acid, which is volatilized with the gas stream. Positive and negative ions are generated by soft X-ray ionization, and when a voltage of about 200 volts is applied, the ionization source generates positive ions, but the positive ions cannot be sent to the mass spectrometry system because the electric field of the sampling tube is set to measure the negative ions. Then when the computer is controlled to send an instruction that the voltage is changed from the positive voltage to-400V, the ionization source generates nitrate ions or ion clusters thereof, the ions are transmitted into a mass spectrometer through a sampling tube for detection, the mass selection is carried out, and signals are amplified after reaching the detector. Most of the ion mass is concentrated in m/z (mass to charge ratio) less than 200 according to the distribution characteristics of nitrate ions or ion clusters thereof, so that a mass spectrometer (a quadrupole mass spectrometer can be used herein) is required to perform mass-selection-free scanning (i.e. the quadrupole analyzer is in a state of applying only radio frequency without applying direct current voltage) for scanning ions with m/z less than 200. Therefore, the TTL signal output of the connection detector is a mass spectrum signal of all nitrate and ion clusters thereof, and the mass spectrum is fed back to the oscilloscope through the TTL signal.

As shown in fig. 2, the pulse voltage signal generation sequence is as follows: the initial voltage applied to the ion source was +200 vdc, then the computer programmed voltage was momentarily switched to-400 vdc, the pulse width was controlled between 40-50 ms, and finally the voltage was dropped to about-330 v and held at that voltage level.

Preferably, the pulse width of the pulse voltage signal is between 40-50 milliseconds, the narrower the pulse voltage signal is, the better theoretically, however, if the pulse voltage is too narrow, the signal can not be detected by mass spectrometry, so that the pulse width is preferably controlled between 40-50 milliseconds.

Preferably, after a pulse width, the dc voltage is reduced to-330 volts and held at a value, and the voltage applied to the chemical ionization source is set to 70 volts below the voltage after the pulse than before the pulse in order not to disturb the electric field of the sample tube, i.e. if the voltage is reduced too much, the electric field that has established equilibrium may be destroyed, leading to difficulties in ion transport.

Preferably, after the mass spectrum TTL feedback signal of the main ions is acquired, the mass spectrum TTL feedback signal is filtered to acquire a mass spectrum TTL feedback signal generated by a pulse voltage signal with a pulse width of 40-45 milliseconds, a resistance-capacitance circuit may be used as a filter circuit, and a passband is designed and set through the filter circuit to acquire a signal with a specific frequency, for example, the passband of the filter circuit in this embodiment may be set to 20-30 hz.

As shown in fig. 3, the mass spectrum TTL feedback signal received by the oscilloscope has a lag with respect to the start time of the pulse voltage due to the existence of ion transmission time, and the time when the ions reach the detector is significantly different due to the non-isotropy of the motion trajectory of the ions, so that the corresponding mass spectrum TTL feedback signal has the characteristics of slowly rising in the initial stage, falling to some extent after reaching the maximum value, and remaining stable. The chemical ionization reaction time can be defined as the difference value of the starting time of the pulse voltage signal and the time corresponding to the half-height of the mass spectrum TTL feedback signal, wherein the half-height refers to the position of the midpoint corresponding to the maximum value of the mass spectrum TTL feedback signal. In the implementation of the invention, the sampling gas of the sampling tube is indoor air, the flow rate is 10-30 liters per minute, and the chemical ionization source is positioned at different positions of the upstream area of the mass spectrum air inlet hole and corresponds to different reaction times.

The method comprises the steps of applying pulse voltage to a chemical ionization source to generate nitrate ions and ion clusters thereof, observing a time-varying sequence diagram of pulse voltage signals corresponding to short reaction time and long reaction time (about 0.2 and 0.6 seconds respectively) and mass spectrum TTL (transistor-transistor logic) feedback signals, and determining reaction time values corresponding to two reaction time settings from the diagram according to the definition of the chemical ionization reaction time.

In one embodiment, as shown in fig. 4, the present invention provides a system for measuring chemical ionization reaction time, comprising:

the control computer (104) is connected with the chemical ionization source (102) and the oscilloscope (101) and is used for sending pulse voltage signals to the chemical ionization source (102) and the oscilloscope (101);

the chemical ionization source (102) is connected with the control computer (104) and the sampling tube (106) and is used for receiving a pulse voltage signal sent by the control computer (104) so as to generate main ions;

a sampling tube (106) connected with the chemical ionization source (102) and the mass spectrometer (103) and used for transmitting the main ions to the mass spectrometer (103);

the mass spectrometer (103) is connected with the sampling tube (106) and the oscilloscope (101) and is used for detecting the received main ions and sending mass spectrum TTL (time to live) feedback signals of the main ions to the oscilloscope (101);

and the oscilloscope (101) is connected with the control computer (104) and the mass spectrometer (103) and is used for receiving the pulse voltage signal and the filtered mass spectrum TTL feedback signal and showing a sequence chart of the signal change along with time.

Preferably, the mass spectrometer further comprises a resistance-capacitance circuit (105) arranged between the mass spectrometer (103) and the oscilloscope (101) and used for filtering the mass spectrum TTL feedback signal and capturing a mass spectrum TTL feedback signal generated by a pulse voltage signal with a specific pulse width;

preferably, the oscilloscope (101) has at least two channels, wherein the first channel is connected with the control computer (104) and the chemical ionization source (102), and the first channel receives and measures the change of the pulse voltage signal along with the time when the control computer (104) sends the pulse voltage signal to the chemical ionization source (102) and the chemical ionization source (102) ionizes to generate main ions; and the second channel receives and detects a mass spectrum TTL feedback signal transmitted by the mass spectrometer (103), the mass spectrum TTL feedback signal is received by the second channel after being filtered by the resistance-capacitance circuit (105), and the change of the mass spectrum TTL feedback signal along with time is monitored by the second channel.

The functions and implementation manners of the system components in the above embodiment of the system of the present invention are the same as those in the above embodiment of measuring the chemical ionization reaction time, and for specific analysis, reference may be made to the above embodiment of the method of measuring the chemical ionization reaction time, and details are not repeated herein in order to avoid repetition.

In one embodiment, the present invention further provides an apparatus for measuring chemical ionization reaction time, the apparatus comprising a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, the processor implementing the method for measuring chemical ionization reaction time according to any one of the embodiments described above when executing the computer program.

In one embodiment, the present invention further provides a computer-readable storage medium having a computer program stored therein, the computer program when executed implementing the method for measuring chemical ionization reaction time according to any one of the embodiments.

The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory may be used to store the computer program and/or module, and the processor may implement the various functions of the control device for measuring chemical ionization reaction time by operating or executing the computer program and/or module stored in the memory and calling up the data stored in the memory. The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required by at least one function (such as a sound playing function, an image playing function, etc.), and the like; the storage data area may store data (such as audio data, a phonebook, etc.) created according to the use of the cellular phone, and the like. In addition, the memory may include high speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), at least one magnetic disk storage device, a Flash memory device, or other volatile solid state storage device.

Wherein the device-integrated module/unit for measuring chemical ionization reaction time may be stored in a computer-readable storage medium if it is implemented in the form of a software functional unit and sold or used as a stand-alone product. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying said computer program code, recording medium, U-disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signal, telecommunications signal, and software distribution medium, etc

The foregoing is a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present application, and these modifications and decorations are also regarded as the protection scope of the present application.