CN114755290A - Method and system for automatically tuning an inductively coupled plasma mass spectrometer - Google Patents
Method and system for automatically tuning an inductively coupled plasma mass spectrometer Download PDFInfo
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Abstract
The present invention provides a method and system for automatically tuning an inductively coupled plasma mass spectrometer. The method in standard mode comprises: step 101, adjusting the relative position of plasma flame and a sampling cone mouth; step 102, adjusting the flow rate of atomization air; step 103, adjusting the extraction lens; step 104, adjusting a focusing lens; step 105, adjusting a deflection lens; step 106, the atomization airflow rate is adjusted again. The automatic tuning of the invention can completely replace manual tuning; the automatic tuning is fully automatic, and can be automatically executed according to a set flow without manual interference, so that the professional requirements on operators are greatly reduced, and a beginner can well use instruments; meanwhile, the automatic tuning of the invention adopts an open design, so that the user can edit according to the self requirement, and the user can meet the use requirements in different scenes.
Description
Technical Field
The invention belongs to the technical field of inductively coupled plasma mass spectrometry, and particularly relates to a method and a system for automatically tuning an inductively coupled plasma mass spectrometer.
Background
The more and less trace elements of human body can have obvious influence on human health, and the current research proves that the deficiency or excess of partial elements has direct relation with various diseases. Meanwhile, the trace elements are a dynamic balance process in the human body. Therefore, the method has important significance for accurately, quickly and conveniently detecting the trace elements of the human body, namely health management and clinical disease diagnosis and treatment. ICP-ms (inductively coupled plasma mass spectrometry) is an analytical instrument combining ICP technology and mass spectrometry, collectively called an inductively coupled plasma mass spectrometer, which employs an inorganic multi-element analysis technology using inductively coupled plasma as an ion source and performing detection by mass spectrometry. Because the method can simultaneously measure dozens of trace inorganic elements, the method has a good position in an inorganic laboratory. At present, ICP-MS in medical treatment is mainly used for measuring the content of trace elements in a human body, so that diagnosis of certain occupational diseases is performed. The ICP-MS can measure almost all samples, can collect and measure multiple elements at one time, provides isotope information, and can be widely applied to other fields such as metallurgy, environment, biology, geology, microelectronics, food safety and the like.
But ICP-MS is interfered by various mass spectrums and non-mass spectrums in the analysis process, wherein polyatomic molecular ion interference is serious mass spectrum interference, the accuracy of the analysis result is greatly reduced due to the existence of the polyatomic molecular ion interference, the detection capability of an ICP-MS instrument is influenced, and the application range of the ICP-MS is limited. Currently, methods that can be used to address the interference of polyatomic molecular ions are: carrying out mathematical correction; separating interfering ions by adopting technologies such as flow injection, electrothermal evaporation, chromatography and the like; changing the ionization conditions of the plasma source portion by cold plasma, shielded torch technology to reduce polyatomic formation; and collision/reaction cell technology. Of these, collision/reaction cell technology is currently the most dominant and most effective means of addressing this interference. The collision/reaction pool technology improves the capability of ICP-MS for detecting trace ultra-trace elements and carrying out isotope analysis and morphological analysis, and widens the application range of ICP-MS.
To obtain good mass spectral data, the parameters of the mass spectrometer should be optimized before sample analysis, which is the tuning of the mass spectrometer. The tuning will set parameters of the ion source components; good ionization degree is obtained, and the voltage of the ion optical component is set, so that good ion transmission rate is obtained.
The aim of optimizing the response values (maximum signal, minimum noise), minimizing interferences (oxides, double charges, polyatomic ion interferences) and checking whether the ion ratios are correct (oxidation rate, double charge rate) is achieved by tuning.
The instrument operating conditions are optimized by instrument tuning. For multi-element analysis, a compromise is generally taken. The main indicators of tuning are sensitivity, stability, and interference levels such as oxides. The optimization tuning experiment is usually performed by using a mixed solution containing elements In the light, medium and heavy weight ranges (such as Li, Be, Co, In, Rh, Ce, Th, Bi, U, concentration ranges are generally 1-10 ng/mL). Instrument parameters tuned include lens group voltage, plasma sampling position (up, down, left, right positioning), carrier gas flow rate, impinging gas flow rate, etc.
However, the manual tuning process may be slow and require a significant amount of time dedicated to performing manual tuning. This is valuable time that could be used to analyze the sample, and manual tuning has high professional requirements for the operator. So that some users may skip performing manual tuning or perform manual tuning procedures with less than ideal results.
Disclosure of Invention
In view of the above, it is an object of the present invention to provide a method and system for automatically tuning an inductively coupled plasma mass spectrometer. The automatic tuning method of the present invention can replace manual tuning of the instrument to optimize the instrument to a good state for analysis. In addition, the invention can be edited by user-defining, and different users can adjust according to own needs, thus meeting different requirements of different users.
In a first aspect, an embodiment of the present invention provides a method for automatically tuning an inductively coupled plasma mass spectrometer, including:
According to some exemplary embodiments of the invention, wherein: the step 101 comprises:
the lateral position and/or the longitudinal position of the plasma is changed stepwise,
detecting the response value of the preset target object in the step,
and taking the position of the corresponding plasma when the response value of the target object is maximum as the adjusted position.
According to some exemplary embodiments of the invention, wherein: the step 102 comprises:
gradually changing the flow rate of the atomizing gas, and detecting the response value of the preset target object in the step;
the preset target comprises a first target and a second target, and when the response value of the first target meets a preset condition and the response value of the second target reaches the maximum value, the atomized air flow rate is taken as the adjusted optimal atomized air flow rate.
According to some exemplary embodiments of the invention, wherein: and when the response value of the first target meets a preset condition, and the ratio of the double charges of the oxide is not higher than the preset value, and the response value of the second target reaches the maximum value, taking the flow rate of the atomizing gas as the adjusted optimal flow rate of the atomizing gas.
According to some exemplary embodiments of the invention, wherein: the step 103 comprises:
gradually changing the voltage of the extraction lens, and detecting the response value of the preset target object in the step;
the preset target object comprises a third target object and a fourth target object, and when the response value of the third target object meets a preset condition and the response value of the fourth target object reaches the maximum value, the voltage of the extraction lens is used as the adjusted optimal voltage of the extraction lens.
According to some exemplary embodiments of the invention, wherein: the step 104 comprises:
gradually changing the voltage of the focusing lens, and detecting the response value of the preset target object in the step;
the focus lens voltage when the response value of the target object reaches the maximum value is preset as the adjusted optimum focus lens voltage.
According to some exemplary embodiments of the invention, wherein: the preset target in step 104 is a low-mass element.
According to some exemplary embodiments of the invention, wherein: the step 105 comprises:
gradually changing the voltage of the deflection lens, and detecting the response value of the preset target object in the step;
the deflection lens voltage when the response value of the target object reaches the maximum value is preset as the adjusted optimum deflection lens voltage.
According to some exemplary embodiments of the invention, wherein: step 106 comprises:
gradually changing the flow rate of the atomizing gas, and detecting the response value of the preset target object in the step;
and the preset target comprises a first target and a second target, and when the ratio of the double charges of the oxide is not higher than a preset value, the atomized gas flow speed when the response value of the first target meets a preset condition and the response value of the second target reaches the maximum value is taken as the adjusted optimal atomized gas flow speed.
According to some exemplary embodiments of the invention, wherein: between step 102 and step 103, further comprising:
According to some exemplary embodiments of the invention, wherein: in a collision mode of the inductively coupled plasma mass spectrometer, the method comprises:
According to some exemplary embodiments of the invention, wherein: the step 201 comprises:
gradually changing the collision airflow speed, and detecting the response value of a preset target in a collision mode;
the preset target object comprises a fifth target object and a sixth target object, and the collision airflow speed when the response values of the fifth target object and the sixth target object both meet the preset condition and the ratio of the response values of the fifth target object and the sixth target object reaches the maximum value is taken as the adjusted optimal collision airflow speed;
the step 202 comprises:
gradually adjusting the voltage of a deflection lens group, and detecting a response value of a preset target object in a collision mode;
the preset target object comprises a fifth target object and a sixth target object, and when the response values of the fifth target object and the sixth target object both meet preset conditions and the ratio of the response values of the fifth target object and the sixth target object reaches the maximum value, the deflection lens group voltage is used as the adjusted optimal deflection lens group voltage;
the step 203 comprises:
gradually changing the collision airflow speed, and detecting the response value of a preset target in a collision mode;
The preset target objects include a fifth target object and a sixth target object, and the collision airflow speed when the response values of the fifth target object and the sixth target object both satisfy a preset condition and the ratio of the response values of the fifth target object and the sixth target object reaches a maximum value is taken as the adjusted optimum collision airflow speed.
According to some exemplary embodiments of the invention, wherein: the fifth target is Co and the sixth target is ArO.
In a second aspect, embodiments of the present invention provide a system for automatically tuning an inductively coupled plasma mass spectrometer, comprising:
a processor;
and a memory storing executable instructions;
wherein the executable instructions, when executed by the processor, perform a method for automatically tuning an inductively coupled plasma mass spectrometer as described above.
Compared with the prior art, the invention has the following beneficial technical effects:
first, automatic tuning can completely replace manual tuning. The automatic tuning controlled by the computer optimizes the instrument more accurately than the manual tuning, and can lead the performance of the instrument to reach a better state.
Second, autotune full automation, will be according to the flow automatic execution that has set for, need not artificial interference, very big reduction to operating personnel's professional demand, make the instrument of use that beginner also can be fine.
And thirdly, the open design of automatic tuning enables a user to edit according to the self requirement, and the user can meet the use requirements in different scenes.
Drawings
FIG. 1 is a flow chart of a method for auto-tuning in standard mode according to an embodiment of the present invention;
fig. 2 is a schematic diagram illustrating a determination process of each stage in the automatic tuning method according to the embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating the principle of ICP flame formation in an auto-tuning method provided by an embodiment of the invention;
FIG. 4 is a schematic diagram of an X-Y tuning result display interface provided by an embodiment of the present invention;
FIG. 5 is a schematic view of a carrier gas flow rate tuning interface provided by an embodiment of the present invention;
FIG. 6 is a schematic diagram of an extraction lens tuning interface provided by an embodiment of the present invention;
FIG. 7 is a schematic view of a focusing lens tuning interface provided by an embodiment of the present invention;
FIG. 8 is a schematic view of a deflection lens tuning interface provided by an embodiment of the present invention;
FIG. 9 is a schematic view of a re-tuning interface for carrier gas flow rate provided by an embodiment of the present invention;
FIG. 10 is a flow chart of a method for auto-tuning in standard mode according to an embodiment of the present invention;
FIG. 11 is a flow chart of a method for auto-tuning in bump mode provided by an embodiment of the present invention;
FIG. 12 is a schematic view of a impinging airflow velocity tuning interface provided in accordance with an embodiment of the present invention;
FIG. 13 is a schematic diagram of a tuning interface of the deflection lens provided in the present embodiment;
FIG. 14 is a schematic view of a re-impinging airflow rate tuning interface provided in accordance with this embodiment;
fig. 15 is a schematic block diagram of the structure of the system for automatically tuning an inductively coupled plasma mass spectrometer according to the present embodiment.
Detailed Description
The present invention will be described in further detail below with reference to the drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Unless otherwise defined, all terms (including technical and scientific terms) used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present specification and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It should be noted that in the description of the present specification, reference to descriptions of expressions "one embodiment", "some embodiments", "exemplary embodiments", "specific examples", or "some examples", etc., means that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the schematic descriptions herein above for representations are not necessarily intended to be directed to the same embodiment or example only. Rather, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Example one
The present embodiments provide a method for automatically tuning an inductively coupled plasma mass spectrometer in standard mode.
Fig. 1 is a flowchart of a method for standard mode auto-tuning provided in this embodiment. The inductively coupled plasma mass spectrometer (hereinafter also referred to as an instrument) is stable for at least 15min after ignition, and the instrument parameter optimization debugging is carried out by using a tuning solution containing 1ng/mL of each element In Li, Be, Mg, Co, Y, In, Ce, Tl and U.
In the automatic tuning process, the judgment principle of each condition is as follows:
and (4) setting a judgment condition for each automatic tuning stage, and entering the next stage after the judgment is successful. The judgment condition includes one major condition (maximum value, minimum value), and several minor conditions (greater than, less than).
As shown in fig. 2, the determination process includes:
step (1) acquiring all scanning data at the stage;
step (2) starting to judge from the first group of data in sequence;
step (3) judging whether the main conditions pass or not;
step (4) judging whether the first secondary condition passes or not in sequence;
and (5) selecting the best data from the passing data groups according to the setting of the main conditions.
In the actual operation process, if the automatic tuning is successful, the execution of the process step (5) is judged to be finished;
There may also be instances where auto-tuning fails, including:
case 1: and (4) judging whether all the data do not meet the process step (3) or step (4), and outputting that the judgment condition does not meet.
Case 2: some of the data satisfy a part of the conditions in the judgment process step (4), some of the data satisfy another part of the conditions in the judgment process step (4), and secondary condition conflicts and sets of possible optimal values are output.
Case 3: all data do not reach the minimum required value, and the output scanning data are inaccurate.
In this embodiment, coarse adjustment and fine adjustment are also set. In the process of collecting scanning data, in order to shorten the tuning time, part of parameter setting is iterated for multiple times to further reduce the parameter step range. In general, 2-3 iterations are set in one stage, the first iteration is coarse adjustment, the used parameter step length is wider, the scanning times are fewer, and the second iteration is fine adjustment, the parameter step length is narrower, and the scanning times are more.
Fig. 4-9 illustratively show a progress window for presenting an inductively coupled plasma mass spectrometer auto-tuning state. In the progress window, the last column of 'yes' of the target judgment result indicates that the current result meets the judgment condition. Some windows are also provided with a calculation result RSD (standard deviation) representing the fluctuation degree of the response value on the left side of the 'YES', and the smaller the RSD, the more stable the response value is. The example given in this embodiment shows 0 because this calculation is not enabled.
In some embodiments, these progress windows are also provided with dialog boxes or command areas to allow the user to command to skip a step at any time during auto-tuning, or to stop after the current step is completed, or to stop the auto-tuning process immediately.
As shown in fig. 1, the method may include the steps of:
The first step of auto-tuning is to optimize the position of the lateral and longitudinal motors, i.e. "X-Y tuning", which corresponds to the relative position of the plasma flame and the sampling cone on the instrument (lateral and longitudinal).
The ICP-MS is provided with a two-dimensional module, the main body of the whole module is a movable mounting plate, and the two motors are used for respectively controlling the movement in the X direction and the Y direction. The X motor controls the movement of the two-dimensional module in the X direction, and the Y motor controls the movement of the two-dimensional module in the Y direction.
ICP-MS uses inductively coupled plasma as the ion source. There are three conditions for the formation of an ICP flame: high-frequency electromagnetic field, working gas and quartz torch tube capable of maintaining stable discharge of gas. As shown in FIG. 3, a water-cooled induction coil is wound around the upper portion of the tube, and when a high-frequency generator is supplied with power, a strongly oscillating magnetic field is generated in the direction of the coil axis. The working gas flowing in the middle is ionized by means of a high frequency spark or the like, and the generated ions and electrons are further acted on with the fluctuating magnetic field generated by the induction coil, and the interaction causes the ions and electrons in the coil to flow along a closed loop shown in the figure. Their resistance to this motion then results in ohmic heating effects. The gas is heated due to the high temperature created by the strong current, thereby forming a torch-like plasma. And the sample is carried by the atomizing gas in the form of aerosol, and is thermally ionized through the center of the plasma, so that ions generated by ionization of the sample exist mainly in the center portion of the plasma.
The interface is the most critical part of the whole ICP-MS system. Its function is to efficiently transfer ions in the plasma out to the mass spectrum. The interface usually consists of a sampling cone and an intercepting cone, the sampling cone is in direct contact with plasma, and the sampling cone has the function of sucking most of carrier gas flow, namely ion flow, from a central channel of the plasma into a cone hole and then enters a first-stage vacuum chamber. In order to reduce the vacuum load of the instrument, the taper hole of the sampling cone is small, usually about 1 mm.
An interface of a typical inductively coupled plasma mass spectrometer (e.g., ICP-MS analyzer SQ60, n.v. mechanical fiducial 20212220150) is a vacuum interface module that includes at least a sampling cone, a skimmer cone, and an extraction lens from upstream to downstream of the plasma stream. Generally, the sampling cone has an upstream conical outer surface and a downstream conical inner surface, and the intersection between the outer and inner surfaces is provided with a sampling aperture. The skimmer cone includes a generally conical portion and a generally cylindrical portion. The tapered portion has an upstream tapered outer surface and a downstream tapered inner surface, with a skimmer orifice at the intersection. The conical portion and the cylindrical portion constitute a channel for the plasma to continue flowing to the downstream extraction lens. An extraction lens is used to extract sample ions from the plasma for downstream analysis.
Therefore, in order to better collect the sample into the mass spectrum for detection, X-Y tuning is required so that the plasma center is aligned with the sampling cone.
When the X-Y tuning is started, the instrument will gradually change the X-Y position of the plasma according to the set X-Y range and step length, and will detect the response value of the In element of the set target object. As shown in fig. 4, the response value of the measured target is displayed in real time, and the point at which the response value of the target is the maximum is selected as the optimized value. Meanwhile, the user can customize an X-Y range (default-2-2 mm), a step length (default 0.02mm) and an adopted target object according to needs. Since the effect of X-Y tuning is the same for all elements, only a medium mass number of In elements is chosen here.
By changing the atomizing air flow rate, different elements can reach good ionization degree.
The atomizing gas transforms the liquid sample into an aerosol state by the atomizer. Atomization is that when liquid passes through an atomizer, the mechanical force of atomizing gas overcomes the surface tension between liquid molecules and separates the liquid molecules into smaller particles, thereby generating the atomization effect.
The carrier gas carries the sample through the center of the plasma, causing the sample to be heated and ionized. The magnitude of the carrier gas flow rate directly affects the final response value. The carrier gas flow velocity is too high, the ionization degree is reduced due to the fact that the sample stays in the plasma for a short time, the carrier gas flow velocity is too small, the sample cannot penetrate through the plasma, and therefore the sample ions cannot be collected by the sampling cone.
FIG. 5 is a schematic view of a carrier gas flow rate tuning interface. When the adjustment of the carrier gas flow rate is started, the apparatus gradually changes the carrier gas flow rate according to the set step length of the carrier gas flow rate range, and detects the response value of the set target object. Since the influence of the carrier gas flow rate on the elements of different mass numbers is different, and the optimum gas flow rates required for the different elements are different, the present embodiment sets the detected values of four elements of different mass numbers of low, medium, and high levels as necessary. The staging results are shown in fig. 5.
Meanwhile, the accuracy of the ICP-MS detection result is also influenced by interferences such as double charges of the oxide, and in order to reduce the influence of the oxide and the double charges on the detection result as much as possible, the influence of the oxide and the double charges needs to be considered when the atomization airflow speed is adjusted. In the case where the ratio of the double electric charges of the oxide is not higher than 3%, the higher the response value of the detected element is, the better.
Because the atomizing gas has different influences on the final performance of the instrument and elements, the atomizing gas and other partial parameters are adjusted for the second time, meanwhile, in order to reduce the time of automatic tuning, the two times of adjustment in the adjustment are set to be coarse adjustment and fine adjustment, and meanwhile, the percentage of the fine adjustment is set, so that the time is saved while the result is ensured.
Adjusting the extraction lens, i.e. by adjusting the voltage of the extraction lens, extracts ions into subsequent components.
An extraction lens is located directly on the base of the skimmer cone immediately behind the skimmer cone, the function of the extraction lens being to extract ions passing through the skimmer cone and accelerate them into the deflection lens. Because the ions to be detected have single positive charge, the negative pressure is applied to the extraction lens, and electrons can be repelled while the positive ions are accelerated, so that the electrons collide on the interception cone or the wall of the vacuum chamber, and neutral particles and photons can continue to enter the subsequent lens without being influenced by the extraction lens. In a typical inductively coupled plasma mass spectrometer as described above, the entrance of the extraction lens is a channel with a diameter of 10mm, and then gradually changes to a channel with a diameter of 25mm, and the outer surface of the entrance is a conical surface, which is used for extracting ions and accelerating the ions.
Fig. 6 is a schematic diagram of an extraction lens tuning display interface provided in the present embodiment.
When the adjustment of the extraction lens is started, the instrument gradually changes the voltage of the extraction lens according to the set step length of the range of the extraction lens, and simultaneously detects the response value of the set target object. Since the effect of the extraction lens on the elements with different mass numbers is different, and the optimum extraction lens voltage required for different elements is different, the present embodiment sets the detection values of four elements with different mass numbers of low, medium, and high levels as needed. The display interface is shown in fig. 6.
Adjusting the focusing lens, i.e. by adjusting the voltage of the focusing lens, focuses the ions into the subsequent component.
A focusing lens is located immediately after the collision cell and before the differential aperture, and this focusing lens acts to focus ions passing through the collision cell so that they enter the differential aperture. Because the ions to be detected have a single positive charge, a positive voltage is applied to the focusing lens, which can attract electrons while focusing the positive ions.
In ion collection systems, "mass discrimination" due to the "space charge effect" is an important factor that directly affects ion transport efficiency and ion transport uniformity across the mass range. This effect is particularly severe when the mass of the matrix ions is greater than the analyte ions. In plasma and ultrasonic jet, the ion current is balanced by an equal electron current, so that the entire ion beam is substantially electrically neutral. But after the ion flow leaves the skimmer cone, the electric field established by the lens will collect the ions and repel the electrons, which will no longer be present. So that the ions are bound in a narrow beam which is not quasi-neutral at the moment but still very high in ion density. The total number of ions in the ion beam is limited by the mutual repulsion between like-charged ions. The space charge effect in ICP-MS is significant at a total ion current of 1 μ a, which means that the higher the matrix concentration, the higher the number of heavy ions, the more significant the space charge effect. If the same space charge force is applied to all the ions, the light ions are most affected and most deflected (discriminated), and the sensitivity is low. Space charge effects are a major source of ICP-MS bulk effects, and higher mass-to-charge ions will dominate the ion beam, while lighter mass-to-charge ions are rejected, if not compensated for in any way. The high kinetic energy of ions (heavy elements) is more efficient at transport than medium and light elements.
Fig. 7 is a schematic diagram of a tuning interface of the focusing lens provided in this embodiment.
When the focus lens adjustment is started, the instrument will gradually change the focus voltage according to the set focus lens range step size, and will detect the response value of the set target object. The focusing lens affects different numbers of elements differently, and the optimum focusing lens voltage required by different elements differs. In addition, due to the influence of the space charge effect, the element with higher quality has high transmission efficiency, and the element with lower quality has low transmission efficiency. Therefore, according to actual needs, the element Co at the low and medium quality is set as the detection value in the present embodiment, so that the high response value at the medium and high quality is ensured, and the element response value at the low quality is not low.
The deflection lens is adjusted, namely, the ions are deflected to enter a subsequent component by adjusting the deflection voltage, and meanwhile, neutrons and photons in the ion flow are eliminated or reduced.
In ICP-MS only 1 out of the 1000,000 ions typically produced can eventually reach the detector, as determined by the efficiency of each stage, and with such low efficiency of transmission it becomes more important to remove various interferences, the primary purpose of the deflection being to remove the effects of electrons and neutral particles. The deflection lens is composed of four lenses in total, different voltages are applied to the two deflection lenses, so that the track of ions in the deflection lens is deflected, neutrons and photons are removed without being influenced by an electric field, and the voltage on the deflection lens influences the interference removing result and influences the ion transmission efficiency.
Fig. 8 is a schematic view of a deflection lens tuning interface.
When the adjustment of the deflection lens is started, the instrument gradually changes the voltage of the deflection lens according to the set step length of the range of the deflection lens, and detects the response value of the set target object. Three elements at low, medium and high quality are set as detection values due to the effect of the deflection lenses on different elements, and tuning of the deflection lenses requires iteration to reach an optimal value due to the fact that two groups of lenses in the deflection lenses are mutually associated in an interaction manner. In the tuning of the deflection lens, the deflection lens 1 and the deflection lens 2 are firstly and sequentially subjected to primary coarse tuning, and then the range is narrowed according to the adjusted value, and then the deflection lens 1 and the deflection lens 2 are subjected to primary fine tuning.
The final step of the auto-tuning method in standard mode will be the atomizing air tuning again.
Fig. 9 is a schematic interface diagram of a second tuning of the carrier gas flow rate.
When the adjustment of the carrier gas flow rate is started, the apparatus gradually changes the carrier gas flow rate according to the set step length of the carrier gas flow rate range, and detects the response value of the set target object. Since the influence of the carrier gas flow rate on the elements of different mass numbers is different, and the optimum gas flow rates required for the different elements are different, the present embodiment sets the detected values of four elements of different mass numbers of low, medium, and high levels as necessary. The user display interface is shown in fig. 9.
Meanwhile, the accuracy of the ICP-MS detection result is also influenced by interferences such as double charges of the oxide, and in order to reduce the influence of the oxide and the double charges on the detection result as much as possible, the influence of the oxide and the double charges needs to be considered when the atomization airflow speed is adjusted. In the case where the ratio of the double electric charges of the oxide is not higher than 3%, the higher the response value of the detected element is, the better.
Because the atomizing gas has different influences on the final performance of the instrument and elements, the atomizing gas and other partial parameters are adjusted for the second time, meanwhile, in order to reduce the time of automatic tuning, the two times of adjustment in the adjustment are set to be coarse adjustment and fine adjustment, and meanwhile, the percentage of the fine adjustment is set, so that the time is saved while the result is ensured.
Example two
The present embodiment provides a preferred auto-tuning method in standard mode.
Based on the automatic tuning method provided in the first embodiment, after the atomization gas flow rate is adjusted in step 102, step 102A of adjusting the temperature of the atomization chamber is added, and the flow is shown in fig. 10, which is specifically as follows:
By varying the atomization chamber temperature, the amount of aerosol introduced into the plasma is varied.
At present, the ICP-MS almost totally adopts a pneumatic atomization sampling technology. Of course, the pneumatic atomization sampling mode has the advantages of simplicity and convenience, but the element measurement is seriously influenced by the solvent, and particularly the interference of polyatomic ions and oxide ions is obvious. Therefore, the temperature of the atomizing chamber is adjusted to reduce the introduction amount of water vapor, namely the load amount of water in the plasma, so that the aim of reducing the interference of polyatomic ions and oxide ions is fulfilled, and the response value of elements is ensured.
When the temperature of the atomizing chamber is adjusted, the instrument gradually changes the temperature of the atomizing chamber according to the set step length of the temperature range of the atomizing chamber, and simultaneously detects the response value of the set target object. Since the degree of influence of the temperature of the atomizing chamber on the elements of different mass numbers is different, the present embodiment sets the detected values of four elements of different mass numbers of low, medium, and high levels as necessary.
The purpose of the temperature adjustment of the atomizing chamber is to reduce the influence of interference on the detection result, particularly, the influence of the interference of polyatomic ions formed by elements such as H, O on the accuracy of the detection result of the ICP-MS is large, and in order to maximize the influence of the interference of polyatomic ions on the detection result, the index of the interference needs to be considered when the temperature adjustment of the atomizing chamber is carried out. In the case of the element response value reaching the standard, the lower the interference value, the better.
By adding the steps, the interference is further reduced, and the accuracy of the detection result of the ICP-MS is improved.
EXAMPLE III
The present embodiments provide a method of auto-tuning in bump mode.
The ICP-MS detection process can be interfered by mass spectra generated by polyatomic ions, the analysis accuracy is greatly influenced, and the method can be generally used for eliminating the polyatomic ion interference: the method for removing the multi-atomic ion interference has certain limitations, for example, the interference correction equation is limited in applicable samples, the requirements of a shielded torch technology on experience and skill of an operator are high, the analysis sensitivity is greatly reduced, and the like. The performance of the collision reaction tank is closely related to the parameters of the collision reaction tank, and the performance of the collision reaction tank is optimized to be optimal through automatic tuning.
Fig. 11 is a flowchart of a method for automatic tuning of a crash mode according to this embodiment.
Fig. 12-14 illustratively show a progress window for presenting an inductively coupled plasma mass spectrometer auto-tuning state. Preferably, these progress windows may also be provided with a dialog box or command area to allow the user to command at any time during auto-tuning to skip a step, or to stop after the current step is completed, or to stop the auto-tuning process immediately.
As shown in fig. 11, the method includes the steps of:
The first step of auto-tuning in the KED mode (Kinetic Energy Discrimination) is to adjust the collision gas flow rate, and by adjusting the collision gas flow rate, the Kinetic energies of the ions to be measured and the interfering ions are changed.
The KED mode operates based on the following basic principles.
(1) All molecular ions contain two or more atoms and have a larger collision cross-section than a monoatomic ion. When colliding with the same gas under the same conditions, the number of collisions of ions having a large collision cross section with the collision gas is larger than that of ions having a small collision cross section.
(2) Assuming that the collisions are elastic collisions, the ions transfer kinetic energy to the gas molecules. The molecular ions with a high number of collisions lose more kinetic energy than the ions to be measured with a low number of collisions.
Setting the potential energy of the mass spectrometer quadrupole mass analyser to be higher than that of the collision/reaction cell, when the potential barrier is higher than the kinetic energy of the molecular ions, they will not enter the quadrupole and thus will not form interference; and ions to be detected with higher kinetic energy can pass through potential energy difference to enter the quadrupole rod mass analyzer and can be detected by an instrument.
Fig. 12 is a schematic diagram of a collisional airflow rate tuning interface provided by this embodiment.
When the collision airflow speed adjustment is started, the instrument will gradually change the collision airflow speed according to the set collision airflow speed range step length, and will detect the response value of the set target object, the response value of the disturbance. Since the impact gas has different influences on the element to be measured and the interfering object, response values of the target object and the interfering object are set respectively. Wherein in the case where Co > 30000 is satisfied, the larger the Co/ArO ratio, the better.
The deflection lens group is automatically adjusted, namely the response value of Co is optimized by adjusting the deflection lens group after colliding with the reaction tank, thereby improving the Co/ArO ratio.
In the collision reaction cell, ions collide with gas introduced into the collision reaction cell, so that kinetic energy changes, and therefore, the lens voltage in the standard mode is not suitable for ion transmission in the KED mode. In addition, new neutral particles may be generated in the ion flow due to violent collisions or other reactions. Therefore, the voltage of the deflecting lens group needs to be optimized again, so that the ion transmission efficiency is improved and the interference is reduced.
Fig. 13 is a schematic diagram of a tuning interface of the deflection lens provided in this embodiment.
When the adjustment of the deflection lens is started, the instrument will gradually change the voltage of the extraction lens according to the set step length of the range of the deflection lens, and since we pay more attention to the response value of Co and the Co/ArO ratio in the collision mode, the larger the Co/ArO ratio is, the better the Co/ArO ratio is when Co > 30000 is set as required. Since the two groups of lenses in the deflection lens are interactively interrelated, the tuning of the deflection lens needs to be iterated to reach an optimal value. In the tuning of the deflection lens, the deflection lens 1 and the deflection lens 2 are firstly and sequentially subjected to primary coarse tuning, and then the range is narrowed according to the adjusted value, and then the deflection lens 1 and the deflection lens 2 are subjected to primary fine tuning.
The collision airflow speed is adjusted again because the collision airflow causes the response value to have a certain fluctuation, and the collision airflow speed is adjusted again to ensure that the collision airflow speed reaches an optimal value.
Fig. 14 is a schematic diagram of a re-impinging airflow rate tuning interface provided in this embodiment.
When the collision airflow rate adjustment is started, the instrument will gradually change the collision airflow rate according to the set collision airflow rate range step size, while detecting the response value of the set target object, the response value of the disturbance. Since the impact gas has different influences on the element to be measured and the interfering object, response values of the target object and the interfering object are set respectively. Wherein in the case where Co > 30000 is satisfied, the larger the Co/ArO ratio, the better.
Example four
The embodiment provides a system for automatically tuning an inductively coupled plasma mass spectrometer, which is used as an upper computer to control the inductively coupled plasma mass spectrometer and is suitable for automatically tuning the mass spectrometer in a standard mode and a collision mode.
Fig. 15 shows a schematic block diagram of a system 100 for automatically tuning an inductively coupled plasma mass spectrometer provided in accordance with an exemplary embodiment of the present embodiment. System 100 for automatically tuning an inductively coupled plasma mass spectrometer includes a processor 110 and a memory 130.
The memory 130 includes a computer-readable storage medium 140 that may be configured to store executable instructions that, when executed by the processor 110, may implement the methods for automatically tuning an inductively coupled plasma mass spectrometer described above. Computer-readable storage media 140 may include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer-readable executable instructions, data, and so forth. Computer-readable storage media 140 may include, without limitation, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD), or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other storage medium which can be used to store information.
Similarly, system 100 for automatically tuning an inductively coupled plasma mass spectrometer may also include a system bus or other data and command transfer system to connect processor 110 and memory 130 to each other. A system bus can include any one or combination of different bus structures, such as a memory bus or memory controller, a peripheral bus, a universal serial bus, and/or a processor or local bus that utilizes any of a variety of bus architectures.
The system 100 for automatically tuning an inductively coupled plasma mass spectrometer establishes a wired and/or wireless communication connection with the inductively coupled plasma mass spectrometer, thereby enabling actual control of the inductively coupled plasma mass spectrometer components when the processor 110 executes the aforementioned method for automatically tuning an inductively coupled plasma mass spectrometer.
In some possible embodiments, the memory 130 of the system 100 for automatically tuning an inductively coupled plasma mass spectrometer stores instructions that, when executed, cause the processor 110 to: receiving user data input about automatic tuning to be performed on the inductively coupled plasma mass spectrometer ICP-MS, wherein the user data input comprises selection of an operation mode of the inductively coupled plasma mass spectrometer and setting of parameters such as types, detection ranges and threshold values of target objects (various elements and compounds involved in automatic tuning), so that a user can edit according to self requirements, and the use requirements of the user under different scenes can be met. The operation modes include a standard mode and a collision mode. The user input means may include one or a combination of mouse clicks, keystrokes, and graphical user interface component selections.
The foregoing description is that of exemplary embodiments of the invention only, and such illustration and description are to be considered illustrative and exemplary and the scope of the invention is not limited thereto. Any person skilled in the art can easily conceive of various changes or substitutions under the teaching of the present disclosure, and these should be considered as falling within the scope of the present disclosure. Therefore, the protection scope of the present invention should be subject to the scope of the appended claims.
Claims (14)
1. A method for automatically tuning an inductively coupled plasma mass spectrometer, characterized by:
in a standard mode of the inductively coupled plasma mass spectrometer, the method comprises:
step 101, adjusting the relative position of plasma flame and a sampling cone to enable the center of the plasma to be aligned with a sampling cone hole;
step 102, adjusting the flow velocity of atomizing gas to the optimal flow velocity of atomizing gas so as to enable different elements to reach the expected ionization degree, wherein the atomizing gas carries a sample;
step 103, adjusting the extraction lens;
step 104, adjusting a focusing lens;
step 105, adjusting a deflection lens;
step 106, the atomization airflow rate is adjusted again.
2. The method of claim 1, wherein:
the step 101 comprises:
the lateral position and/or the longitudinal position of the plasma is changed stepwise,
detecting the response value of the preset target object in the step,
and taking the position of the corresponding plasma when the response value of the target object is maximum as the adjusted position.
3. The method of claim 1, wherein:
the step 102 comprises:
gradually changing the flow rate of the atomizing gas, and detecting the response value of the preset target object in the step;
the preset target comprises a first target and a second target, and when the response value of the first target meets a preset condition and the response value of the second target reaches the maximum value, the atomized air flow rate is taken as the adjusted optimal atomized air flow rate.
4. The method of claim 3, wherein:
and when the response value of the first target object meets a preset condition, and the ratio of the double charges of the oxide is not higher than a preset value, and the response value of the second target object reaches the maximum value, taking the atomized gas flow rate as the adjusted optimal atomized gas flow rate.
5. The method of claim 1, wherein:
the step 103 comprises:
Gradually changing the voltage of the extraction lens, and detecting the response value of the preset target object in the step;
the preset target object comprises a third target object and a fourth target object, and when the response value of the third target object meets a preset condition and the response value of the fourth target object reaches the maximum value, the voltage of the extraction lens is used as the adjusted optimal voltage of the extraction lens.
6. The method of claim 1, wherein:
the step 104 comprises:
gradually changing the voltage of the focusing lens, and detecting the response value of the preset target object in the step;
the focus lens voltage when the response value of the target object reaches the maximum value is preset as the adjusted optimum focus lens voltage.
7. The method of claim 6, wherein:
the preset target in step 104 is a low-mass element.
8. The method of claim 1, wherein:
the step 105 comprises:
gradually changing the voltage of the deflection lens, and detecting the response value of the preset target object in the step;
the deflection lens voltage when the response value of the target object reaches the maximum value is preset as the adjusted optimum deflection lens voltage.
9. The method of claim 1, wherein:
Step 106 comprises:
gradually changing the flow rate of the atomizing gas, and detecting the response value of the preset target object in the step;
and the preset target comprises a first target and a second target, and when the ratio of the double charges of the oxide is not higher than a preset value, the atomized gas flow speed when the response value of the first target meets a preset condition and the response value of the second target reaches the maximum value is taken as the adjusted optimal atomized gas flow speed.
10. The method of claim 1, wherein:
between step 102 and step 103, further comprising:
step 102A, the temperature of the aerosolizing chamber is adjusted to vary the amount of aerosol introduced into the plasma.
11. The method according to any one of claims 1-10, wherein:
in a collision mode of the inductively coupled plasma mass spectrometer, the method comprises:
step 201, adjusting collision airflow speed;
step 202, adjusting a deflection lens group;
step 203, the impinging airflow rate is again adjusted.
12. The method of claim 11, wherein:
the step 201 comprises:
gradually changing the collision airflow speed, and detecting the response value of a preset target object in a collision mode;
The preset target object comprises a fifth target object and a sixth target object, and the collision airflow speed when the response values of the fifth target object and the sixth target object both meet the preset condition and the ratio of the response values of the fifth target object and the sixth target object reaches the maximum value is taken as the adjusted optimal collision airflow speed;
the step 202 comprises:
gradually adjusting the voltage of a deflection lens group, and detecting a response value of a preset target object in a collision mode;
the preset target object comprises a fifth target object and a sixth target object, and when the response values of the fifth target object and the sixth target object both meet preset conditions and the ratio of the response values of the fifth target object and the sixth target object reaches the maximum value, the deflection lens group voltage is used as the adjusted optimal deflection lens group voltage;
the step 203 comprises:
gradually changing the collision airflow speed, and detecting the response value of a preset target object in a collision mode;
the preset target objects include a fifth target object and a sixth target object, and the collision airflow speed when the response values of the fifth target object and the sixth target object both satisfy a preset condition and the ratio of the response values of the fifth target object and the sixth target object reaches a maximum value is taken as the adjusted optimum collision airflow speed.
13. The method of claim 12, wherein:
the fifth target is Co and the sixth target is ArO.
14. A system for automatically tuning an inductively coupled plasma mass spectrometer, comprising:
a processor;
and a memory storing executable instructions;
wherein the executable instructions, when executed by the processor, perform a method for automatically tuning an inductively coupled plasma mass spectrometer as recited in any of claims 1 to 13.
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| CN116593570A (en) * | 2023-06-15 | 2023-08-15 | 瑞莱谱(杭州)医疗科技有限公司 | Trace element analyzer detection limit performance test method and device and electronic equipment |
| WO2023184910A1 (en) * | 2022-03-31 | 2023-10-05 | 瑞莱谱(杭州)医疗科技有限公司 | Method and system for automatically tuning inductively coupled plasma mass spectrometer |
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| JP2598566B2 (en) * | 1990-10-26 | 1997-04-09 | 株式会社日立製作所 | Mass spectrometer |
| US5838002A (en) * | 1996-08-21 | 1998-11-17 | Chem-Space Associates, Inc | Method and apparatus for improved electrospray analysis |
| US8481923B1 (en) * | 2012-06-29 | 2013-07-09 | Agilent Technologies, Inc. | Atmospheric pressure plasma mass spectrometer |
| CN106463329B (en) * | 2014-02-14 | 2019-09-24 | 珀金埃尔默健康科学公司 | The system and method for automation optimization for multi-mode icp ms |
| CN104576289B (en) * | 2014-12-31 | 2017-08-25 | 聚光科技(杭州)股份有限公司 | A kind of icp mses of adjustable vacuum pressure |
| FI20165251A (en) * | 2016-03-24 | 2017-09-25 | Univ Helsinki | Process and arrangement for verification, optimization or calibration of a particle detector |
| EP3784768A4 (en) * | 2018-04-27 | 2022-01-19 | Fluidigm Canada Inc. | Reagents and methods for elemental mass spectrometry of biological samples |
| CN112946056A (en) * | 2021-01-29 | 2021-06-11 | 山东省食品药品检验研究院 | Method for detecting aluminum element in alanyl glutamine injection |
| CN114755290A (en) * | 2022-03-31 | 2022-07-15 | 瑞莱谱(杭州)医疗科技有限公司 | Method and system for automatically tuning an inductively coupled plasma mass spectrometer |
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| CN116593570A (en) * | 2023-06-15 | 2023-08-15 | 瑞莱谱(杭州)医疗科技有限公司 | Trace element analyzer detection limit performance test method and device and electronic equipment |
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