Method and system for automatic tuning of an inductively coupled plasma mass spectrometer

Abstract

The application provides a method and system for automatically tuning an inductively coupled plasma mass spectrometer. The method in the standard mode comprises the following steps: step 101, adjusting the relative position of the plasma flame and the sampling cone; step 102, adjusting the atomizing gas flow rate; step 103, adjusting the extraction lens; step 104, adjusting the focusing lens; step 105, adjusting the deflection lens; and step 106, adjusting the atomizing gas flow rate again. The automatic tuning of the application can completely replace manual tuning; the automatic tuning is fully automated and can be automatically executed according to a set process without manual intervention, greatly reducing the professional requirements for the operator, so that beginners can also use the instrument well; meanwhile, the automatic tuning of the application adopts an open design and can be edited according to the needs of the user, so that the user can use the application in different scenes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of inductively coupled plasma mass spectrometry, and particularly relates to a method and system for automatically tuning an inductively coupled plasma mass spectrometer. BACKGROUND

[0002] The too much or too little of trace elements in human body can significantly affect human health, and current research has proved that the deficiency or excess of some elements is directly related to a variety of diseases. At the same time, trace elements in the human body are in a dynamic balance process. Therefore, accurate, rapid and convenient detection of trace elements in the human body is of great significance to health management and clinical disease diagnosis and treatment. ICP-MS (Inductively coupled plasma mass spectrometry) is an analytical instrument that combines ICP technology and mass spectrometry together, and its full name is inductively coupled plasma mass spectrometer. It uses inductively coupled plasma as an ion source and mass spectrometry for detection of inorganic multi-element analysis technology. Because it can simultaneously determine dozens of trace inorganic elements, it has a strong position in inorganic laboratories. At present, ICP-MS in medical treatment is mainly used to measure the content of trace elements in the human body, so as to make some diagnosis of occupational diseases. Because ICP-MS can measure almost all samples, and can collect and determine multiple elements at one time, it can also provide isotopic information, and can be widely used in metallurgy, environment, biology, geology, microelectronics and food safety and other fields.

[0003] However, ICP-MS will be interfered by various mass spectrometry and non-mass spectrometry during analysis, and multi-atomic molecular ion interference is a more serious mass spectrometry interference. Its existence greatly reduces the accuracy of the analysis results, affects the detection capability of the ICP-MS instrument, and limits the application range of the ICP-MS. At present, the methods that can be used to solve the multi-atomic molecular ion interference include: numerical correction; separation of interfering ions by using flow injection, electric heating evaporation, chromatography and other technologies; changing the ionization conditions of part of the plasma source to reduce the formation of multi-atoms by cold plasma and shielding torch technology; and collision / reaction cell technology. Among them, the collision / reaction cell technology is the most important and effective means to solve this interference. The collision / reaction cell technology improves the ability of ICP-MS to detect trace and ultra-trace elements, and performs isotopic analysis and morphological analysis, thereby widening the application range of ICP-MS.

[0004] In order to obtain good mass spectrometry data, the parameters of the mass spectrometer should be optimized before sample analysis, and this process is the tuning of the mass spectrometer. In the tuning, the parameters of the ion source components are set; the ionization degree is obtained, and the voltage of the ion optical components is set to obtain a better ion transmission rate.

[0005] To optimize the response value (max signal, min noise), minimize the interference (oxide, double charged, polyatomic ion interference), and check the ion ratio is correct (oxidation rate, double charged rate).

[0006] The instrument working condition is optimized by instrument tuning. For multi-element analysis, the compromise condition is usually taken. The main indicators of tuning are sensitivity, stability, oxide, and interference level. A mixed solution containing elements with light, medium, and heavy mass range (e.g. Li, Be, Co, In, Rh, Ce, Th, Bi, U, the concentration range is generally 1-10 ng / mL) is usually used for optimization tuning experiment. The tuned instrument parameters include lens group voltage, plasma sampling position (up, down, left, right positioning), carrier gas flow rate, collision gas flow rate, etc.

[0007] However, the manual tuning process can be slow and requires a large amount of time dedicated to performing manual tuning. This is valuable time that could be used to analyze the analysis sample, and manual tuning requires a high level of expertise for the operator. This results in some users may skip performing manual tuning, or the effect of performing the manual tuning process is not ideal. SUMMARY

[0008] Therefore, the purpose of the present application is to provide a method and system for automatically tuning an inductively coupled plasma mass spectrometer. The automatic tuning method of the present application can replace manual tuning of the instrument, and optimize the instrument to a good state for analysis. In addition, the present application can be customized and edited, and different users can adjust it according to their needs to meet the different needs of different users.

[0009] In a first aspect, embodiments of the present application provide a method for automatically tuning an inductively coupled plasma mass spectrometer, comprising:

[0010] Step 101, adjusting the relative position of the plasma flame and the sampling cone to align the plasma center with the sampling cone hole;

[0011] Step 102, adjusting the atomizing gas flow rate to the optimal atomizing gas flow rate to achieve the desired ionization degree of different elements, and the atomizing gas carries the sample;

[0012] Step 103, adjusting the extraction lens;

[0013] Step 104, adjusting the focusing lens;

[0014] Step 105, adjusting the deflection lens;

[0015] Step 106, adjusting the atomizing gas flow rate again.

[0016] According to some exemplary embodiments of the present application, wherein: the step 101 comprises:

[0017] gradually changing the lateral position and / or the longitudinal position of the plasma,

[0018] detecting the response value of the preset target object in the step,

[0019] the position of the plasma corresponding to the maximum response value of the target object is taken as the adjusted position.

[0020] According to some exemplary embodiments of the present application, the step 102 comprises:

[0021] gradually changing the atomizing gas flow rate, and detecting the response value of the preset target object in the step;

[0022] The preset target object comprises a first target object and a second target object. When the response value of the first target object meets a preset condition, and the atomizing gas flow rate at which the response value of the second target object reaches a maximum value is taken as the adjusted optimal atomizing gas flow rate.

[0023] According to some exemplary embodiments of the present application, when the response value of the first target object meets a preset condition, and the atomizing gas flow rate at which the response value of the second target object reaches a maximum value is taken as the adjusted optimal atomizing gas flow rate, provided that the ratio of the double electric charge of the oxide is not higher than a preset value.

[0024] According to some exemplary embodiments of the present application, the step 103 comprises:

[0025] gradually changing the extraction lens voltage, and detecting the response value of the preset target object in the step;

[0026] The preset target object comprises a third target object and a fourth target object. When the response value of the third target object meets a preset condition, and the extraction lens voltage at which the response value of the fourth target object reaches a maximum value is taken as the adjusted optimal extraction lens voltage.

[0027] According to some exemplary embodiments of the present application, the step 104 comprises:

[0028] gradually changing the focusing lens voltage, and detecting the response value of the preset target object in the step;

[0029] The focusing lens voltage at which the response value of the preset target object in the step reaches a maximum value is taken as the adjusted optimal focusing lens voltage.

[0030] According to some exemplary embodiments of the present application, the preset target object in the step 104 is an element with a low mass number.

[0031] According to some exemplary embodiments of the present application, the step 105 comprises:

[0032] The deflection lens voltage is changed step by step, and the response value of the preset target object at each step is detected;

[0033] When the response value of the preset target object reaches the maximum value, the deflection lens voltage is taken as the adjusted optimal deflection lens voltage.

[0034] According to some example embodiments of the present application, wherein step 106 comprises:

[0035] The atomization gas flow rate is changed step by step, and the response value of the preset target object at each step is detected;

[0036] The preset target object includes a first target object and a second target object, and when the response value of the first target object meets the preset condition and the response value of the second target object reaches the maximum value, the atomization gas flow rate is taken as the adjusted optimal atomization gas flow rate, provided that the ratio of the double charges of the oxide is not higher than a preset value.

[0037] According to some example embodiments of the present application, wherein between the step 102 and step 103 further comprises:

[0038] Step 102A, adjusting the atomization chamber temperature to change the introduction amount of aerosol into the plasma.

[0039] According to some example embodiments of the present application, wherein in the collision mode of the inductively coupled plasma mass spectrometer, the method comprises:

[0040] Step 201, adjusting the collision gas flow rate;

[0041] Step 202, adjusting the deflection lens group;

[0042] Step 203, adjusting the collision gas flow rate again.

[0043] According to some example embodiments of the present application, wherein the step 201 comprises:

[0044] The collision gas flow rate is changed step by step, and the response value of the preset target object in the collision mode is detected;

[0045] The preset target object includes a fifth target object and a sixth target object, and when the response value 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, the collision gas flow rate is taken as the adjusted optimal collision gas flow rate.

[0046] The step 202 comprises:

[0047] The deflection lens group voltage is adjusted step by step, and the response value of the preset target object in the collision mode is detected;

[0048] The preset target objects include a fifth target object and a sixth target object, and the collision gas flow rate when the response values of the fifth target object and the sixth target object both satisfy preset conditions and the ratio of the response values of the fifth target object and the sixth target object reaches a maximum value is taken as an adjusted optimal collision gas flow rate.

[0049] The step 203 comprises:

[0050] The response value of the preset target object in the collision mode is detected by gradually changing the collision gas flow rate.

[0051] The preset target objects include a fifth target object and a sixth target object, and the collision gas flow rate when the response values of the fifth target object and the sixth target object both satisfy preset conditions and the ratio of the response values of the fifth target object and the sixth target object reaches a maximum value is taken as an adjusted optimal collision gas flow rate.

[0052] According to some example embodiments of the present application, the fifth target object is Co, and the sixth target object is ArO.

[0053] In a second aspect, embodiments of the present application provide a system for automatically tuning an inductively coupled plasma mass spectrometer, comprising:

[0054] a processor;

[0055] and a memory storing executable instructions;

[0056] When the executable instructions are executed by the processor, the method for automatically tuning an inductively coupled plasma mass spectrometer is performed.

[0057] Compared with the prior art, the present application has the following beneficial technical effects:

[0058] First, automatic tuning can completely replace manual tuning. The optimization of the instrument by automatic tuning controlled by a computer is more accurate and more precise than manual tuning, and can make the performance of the instrument reach a better state.

[0059] Second, automatic tuning is completely automated and can be automatically executed according to a set process without human intervention, greatly reducing the professional requirements for operators and enabling beginners to use the instrument well.

[0060] Third, the open design of automatic tuning enables users to edit according to their own needs and meet the use needs of users in different scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 is a method flowchart for automatic tuning in a standard mode provided by embodiments of the present application;

[0062] Figure 2 is a judgment flowchart of each stage in the automatic tuning method provided by the embodiment of the present application;

[0063] Figure 3 is a schematic diagram of the principle of ICP flame formation in the automatic tuning method provided by the embodiment of the present application;

[0064] Figure 4 is a schematic diagram of the X-Y tuning result display interface provided by the embodiment of the present application;

[0065] Figure 5 is a schematic diagram of the carrier gas flow rate tuning interface provided by the embodiment of the present application;

[0066] Figure 6 is a schematic diagram of the extraction lens tuning interface provided by the embodiment of the present application;

[0067] Figure 7 is a schematic diagram of the focusing lens tuning interface provided by the embodiment of the present application;

[0068] Figure 8 is a schematic diagram of the deflection lens tuning interface provided by the embodiment of the present application;

[0069] Figure 9 is a schematic diagram of the carrier gas flow rate tuning interface provided by the embodiment of the present application;

[0070] Figure 10 is a flowchart of another automatic tuning method in the standard mode provided by the embodiment of the present application;

[0071] Figure 11 is a flowchart of the automatic tuning method in the collision mode provided by the embodiment of the present application;

[0072] Figure 12 is a schematic diagram of the collision gas flow rate tuning interface provided by the embodiment of the present application;

[0073] Figure 13 is a schematic diagram of the deflection lens tuning interface provided by the embodiment of the present application;

[0074] Figure 14 is a schematic diagram of the collision gas flow rate tuning interface provided by the embodiment of the present application;

[0075] Figure 15 is a schematic block diagram of the structure of the system for automatically tuning the inductively coupled plasma mass spectrometer provided by the embodiment of the present application. DETAILED DESCRIPTION

[0076] The present application will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present application, and are not intended to limit the present application.

[0077] Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification are to be interpreted as is customary in the art to which this application pertains. 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.

[0078] It is to be noted that, in the description of the present specification, the description referring to the expressions "one embodiment", "some embodiments", "exemplary embodiments", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. Therefore, the illustrative description for the above expressions herein does not necessarily refer to the same embodiment or example. Rather, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples, without contradiction.

[0079] Embodiment One

[0080] The present embodiment provides a method for automatically tuning an inductively coupled plasma mass spectrometer in a standard mode.

[0081] Figure 1 The flow chart of the standard mode automatic tuning method provided in the present embodiment is shown. After the inductively coupled plasma mass spectrometer (hereinafter also referred to as "instrument") is ignited for at least 15 min, the instrument parameter optimization debugging is performed using a tuning solution containing 1 ng / mL of each of Li, Be, Mg, Co, Y, In, Ce, Tl, U.

[0082] The judgment principle of each condition in the automatic tuning process is as follows:

[0083] The judgment condition needs to be set for each stage of automatic tuning, and after successful judgment, the next stage is entered. The judgment condition includes a main condition (maximum value, minimum value) and several secondary conditions (greater than, less than).

[0084] As shown in Figure 2 The judgment process includes:

[0085] Step (1) obtains all scan data at this stage;

[0086] Step (2) starts judging from the first group of data in turn;

[0087] Step (3) judging whether the main condition is passed;

[0088] Step (4) judging whether the secondary condition is passed in sequence from the first secondary condition;

[0089] Step (5) selecting the best data from the passed data set according to the setting of the main condition.

[0090] In actual operation, if the automatic tuning is successful, the judging process step (5) is executed;

[0091] There can also be a case of automatic tuning failure, including:

[0092] Case 1: all data does not meet the judging process step (3) or step (4), and the output is that the judging condition is not met.

[0093] Case 2: some data meet part of the conditions in the judging process step (4), and some data meet another part of the conditions in the judging process step (4), and the output is that the secondary conditions conflict and several possible best values.

[0094] Case 3: all data does not reach the minimum required value, and the output is that the scanning data is inaccurate.

[0095] In this embodiment, the settings of coarse adjustment and fine adjustment are also made. In the process of collecting scanning data, in order to shorten the tuning time, part of the parameter settings are iterated several times to gradually simplify the parameter step range. Usually, 2-3 iterations are set in a stage, the first time is coarse adjustment, the parameter step is relatively wide, and the scanning times are relatively few, and from the second time, it is fine adjustment, the parameter step is relatively narrow, and the scanning times are relatively many.

[0096] Figures 4 to 9 Exemplarily, a progress window for presenting the automatic tuning state of the inductively coupled plasma mass spectrometer is shown. In the progress window, the last column of the target judging result "Yes" indicates that the current result meets the judging 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 "Yes". The smaller the RSD is, the more stable the response value is. The example given in this embodiment is displayed as 0 because this calculation is not enabled.

[0097] In some embodiments, these progress windows are also provided with a dialog box or command area to allow the user to command to skip a certain step, or stop after completing the current step, or immediately stop the automatic tuning process during the automatic tuning.

[0098] As Figure 1 shown, the method can include the following steps:

[0099] Step 101, adjusting the relative position of the plasma flame and the sampling cone port.

[0100] The first step of auto-tuning is to optimize the position of the transverse motor and the longitudinal motor, i.e., "X-Y tuning". X-Y corresponds to the relative position of the plasma flame and the sampling orifice on the instrument (transverse and longitudinal).

[0101] The ICP-MS has a two-dimensional module, the whole module body is a mobile mounting plate, a total of two motors, respectively control X-Y two direction movement. X motor control two-dimensional module X direction movement, Y motor control two-dimensional module Y direction movement.

[0102] ICP-MS is an inductively coupled plasma as the ion source. The formation of ICP flame has three conditions: high-frequency electromagnetic field, working gas, and quartz torch tube that can maintain stable discharge of gas. As shown in Figure 3 the upper part of the tube is surrounded by a water-cooled induction coil, when the high-frequency generator is powered, a strong oscillating magnetic field is generated in the axial direction of the coil. The working gas flowing in the middle is ionized by high-frequency spark and the like, and the generated ions and electrons interact with the fluctuating magnetic field generated by the induction coil. This interaction makes the ions and electrons in the coil flow along the closed loop shown in the figure. The resistance to this movement results in ohmic heating effect. Due to the high temperature generated by the strong current, the gas is heated, thereby forming a torch-shaped plasma. The sample is carried by the atomizing gas in the form of aerosol and is heated and ionized by passing through the center of the plasma, so the ions generated by the ionization of the sample mainly exist in the central part of the plasma.

[0103] The interface is the most critical part of the entire ICP-MS system. Its function is to effectively transmit the ions in the plasma to the mass spectrometer. The interface is usually composed of a sampling cone and a skimmer cone. The sampling cone is in direct contact with the plasma, and its function is to suck most of the ion flow from the central channel of the plasma into the first-stage vacuum chamber through the cone hole. In order to reduce the vacuum burden of the instrument, the cone hole of the sampling cone is very small, usually about 1 mm.

[0104] The interface of a typical inductively coupled plasma mass spectrometer (for example, ICP-MS Inspector SQ60, Zhejiang Instrumentation Approval 20212220150) is a vacuum interface module, which includes at least a sampling cone, a skimmer cone, and an extraction lens from the upstream to the downstream of the plasma flow. Generally, the sampling cone has a conical outer surface at the upstream and a conical inner surface at the downstream, and a sampling hole is arranged at the intersection between the outer surface and the inner surface. The skimmer cone includes a conical portion and a substantially cylindrical portion. The conical portion has a conical outer surface at the upstream and a conical inner surface at the downstream, and a skimmer hole is arranged at the intersection between the two. The conical portion and the cylindrical portion form a channel for the plasma flow to continue flowing downstream through the extraction lens. The extraction lens is used to extract sample ions from the plasma for downstream analysis.

[0105] Therefore, in order to better collect the sample into the mass spectrum for detection, X-Y tuning is needed to align the plasma center with the sampling cone hole.

[0106] When 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 size, while detecting the response value of the set target In element. As shown in Figure 4 , the measured target response value is displayed in real time on the graph, and the point with the maximum target response value is selected as the optimized value. At the same time, the user can also customize the X-Y range (default -2-2 mm), step size (default 0.02 mm), and the target used. Since the effect of X-Y tuning on all elements is the same, only the In element with medium mass number is selected here.

[0107] Step 102, adjust the nebulization gas flow rate.

[0108] By changing the nebulization gas flow rate, different elements can achieve good ionization degree.

[0109] The nebulization gas converts the liquid sample into an aerosol state through the nebulizer. When the liquid passes through the nebulizer, the mechanical force of the nebulization gas overcomes the surface tension between the liquid molecules to separate them into smaller particles, thereby producing the effect of nebulization.

[0110] The carrier gas carries the sample through the center of the plasma, so that the sample is heated to ionize. The size of the carrier gas flow rate directly affects the final response value. If the carrier gas flow rate is too high, the sample will stay in the plasma for a shorter time, resulting in reduced ionization degree. If the carrier gas flow rate is too small, the sample cannot pass through the plasma, resulting in the sampling cone failing to collect sample ions.

[0111] Figure 5 The carrier gas flow rate tuning interface is shown in the figure. When the carrier gas flow rate adjustment is started, the instrument will gradually change the carrier gas flow rate according to the set carrier gas flow rate range and step size, while detecting the response value of the set target. Since the effect of the carrier gas flow rate on elements of different mass numbers is different, the optimal gas flow rate required by different elements is different, so according to the need, the embodiment sets the detection values of four elements of different mass numbers, i.e. low, medium, and high. The stage results are shown in Figure 5 .

[0112] At the same time, oxides and double charges and other interferences will also affect the accuracy of the ICP-MS detection results. In order to minimize the influence of oxides and double charges on the detection results, the influence of oxides and double charges needs to be considered when adjusting the nebulization gas flow rate. In the case where the ratio of oxides and double charges is not higher than 3%, the higher the response value of the detected element is, the better.

[0113] Because of the importance of the atomizing gas to the final performance of the instrument and the different effects on elements, the embodiment adjusts the atomizing gas and other parameters for the second time, and in order to reduce the time of automatic tuning, the two adjustments in the adjustment are set as coarse adjustment and fine adjustment, and the fine adjustment percentage is set, so as to save time while ensuring the result.

[0114] Step 103, adjusting the extraction lens.

[0115] Adjusting the extraction lens means adjusting the voltage of the extraction lens to extract ions into subsequent components.

[0116] The extraction lens is directly located on the base of the skimmer cone after the skimmer cone, and the function of the extraction lens is to extract ions passing through the skimmer cone and accelerate them into the deflection lens. Because the measured ions have a single positive charge, a negative voltage is applied to the extraction lens, which can repel electrons while accelerating positive ions, so that the electrons collide with the skimmer cone or the wall of the vacuum chamber, and neutral particles and photons are not affected by the extraction lens and continue to enter the subsequent lens. As described in a typical inductively coupled plasma mass spectrometer, the inlet of the extraction lens is a channel with a diameter of 10 mm, which then gradually changes to a channel with a diameter of 25 mm, and the outer surface of the inlet is a conical surface, which functions to extract ions and accelerate ions.

[0117] Figure 6 The figure is a schematic diagram of the extraction lens tuning display interface provided by the embodiment.

[0118] When the extraction lens adjustment is started, the instrument will gradually change the extraction lens voltage according to the set extraction lens range step, and at the same time, the response value of the set target will be detected. Because the extraction lens has different effects on different mass number elements, the optimal extraction lens voltage required by different elements is different, so according to the need, the embodiment sets the detection values of four elements with different mass numbers, including low, medium and high. The display interface is as shown in Figure 6 .

[0119] Step 104, adjusting the focusing lens.

[0120] Adjusting the focusing lens means adjusting the voltage of the focusing lens to focus ions into subsequent components.

[0121] The focusing lens is directly located after the collision reaction cell and before the differential hole, and the function of the focusing lens is to focus ions passing through the collision reaction cell into the differential hole. Because the measured ions have a single positive charge, a positive voltage is applied to the focusing lens, which can focus positive ions while attracting electrons.

[0122] In ion focusing systems, the "mass discrimination" caused by the "space charge effect" is an important factor that directly affects the ion transmission efficiency and the uniformity of ion transmission in the entire mass range. This effect is particularly serious when the mass of the matrix ions is greater than that of the analyte ions. In plasmas and supersonic jets, the ion current is balanced by an equal electron current, so the entire ion beam is essentially electrically neutral. However, after the ion current exits the skimmer cone, the electric field established by the lens will collect ions and repel electrons, so that electrons will no longer exist. Thus, the ions are confined in a very narrow ion beam, and the ion beam is not instantaneously neutral, but the ion density is still very high. The mutual repulsion between ions of the same charge limits the total number of ions in the ion beam. The space charge effect in ICP-MS is significant when the total ion current is 1 μA, which means that the higher the matrix concentration, the more the number of heavy ions, and the more significant the space charge effect. If the same space charge force acts on all ions, the lightest ions are affected the most and are deflected (discriminated) the most severely, so the sensitivity is low. The space charge effect is the main source of the matrix effect in ICP-MS. If no compensation is taken, higher mass-to-charge ratio ions will dominate in the ion beam, and lighter mass-to-charge ratio ions will be repelled. High-energy ions (heavy mass elements) have higher transmission efficiency than medium and light mass elements.

[0123] Figure 7 The focusing lens tuning interface provided for the embodiment is shown in the figure.

[0124] When the focusing lens adjustment is started, the instrument will gradually change the focusing voltage according to the set focusing lens range step length, and at the same time, the response value of the set target object will be detected. The influence of the focusing lens on different mass number elements is different, and the best focusing lens voltage required by different elements is different. In addition, due to the influence of the space charge effect, the transmission efficiency of higher mass elements is high, and the transmission efficiency of lower mass elements is low. Therefore, according to the actual needs, the element Co at low and medium mass in the embodiment is set as the detection value, which not only ensures the high response value of high and medium mass, but also makes the response value of the element at low mass not low.

[0125] Step 105, adjust the deflection lens.

[0126] Adjusting the deflection lens means adjusting the voltage of the deflection to make the ions deflected into the subsequent components, while eliminating or reducing the neutrons and photons in the ion current.

[0127] In ICP-MS, only one of the 1000,000 ions generated can finally reach the detector, due to the efficiency of each stage, under such low efficiency transmission, it is more important to remove various interferences, the main purpose of deflection is to remove the influence of electrons and neutral particles. The deflection lens is composed of two groups of four lenses, by applying different voltages on the two groups of deflection lenses, the trajectory of ions in the deflection lens is deflected, while the neutrons and photons are not affected by the electric field and are removed, and the voltage on the deflection lens affects the result of interference removal and the efficiency of ion transmission.

[0128] Figure 8 The schematic diagram of the deflection lens tuning interface.

[0129] When starting to adjust the deflection lens, the instrument will gradually change the deflection lens voltage according to the set deflection lens range step length, while detecting the response value of the set target. Due to the effect of deflection lens on different elements, three elements at low, medium and high mass are set as detection values. Since the two groups of lenses in the deflection lens interact and correlate with each other, the tuning of the deflection lens needs to be iterated to achieve the best value. In the tuning of the deflection lens, the deflection lens 1 and the deflection lens 2 are sequentially adjusted once, and then according to the adjusted value, the range is reduced, and the deflection lens 1 and the deflection lens 2 are adjusted once.

[0130] Step 106, adjust the atomizing gas flow rate again.

[0131] The last step of the automatic tuning method in the standard mode will adjust the atomizing gas again.

[0132] Figure 9 The interface schematic diagram for the second time to adjust the carrier gas flow rate.

[0133] When starting to adjust the carrier gas flow rate, the instrument will gradually change the carrier gas flow rate according to the set carrier gas flow rate range step length, while detecting the response value of the set target. Since the influence of the carrier gas flow rate on elements of different mass numbers is different, the best gas flow rate required by different elements is different, therefore, according to the need, the embodiment sets the detection values of four elements of different mass numbers at low, medium and high. The user display interface is as shown in Figure 9 .

[0134] At the same time, the interference of oxide double charge also affects the accuracy of ICP-MS detection results, in order to minimize the influence of oxide and double charge on the detection results, the influence of oxide and double charge needs to be considered when adjusting the atomizing gas flow rate. In the case that the ratio of oxide double charge is not higher than 3%, the response value of the detected element is higher.

[0135] Because of the importance of the atomizing gas to the final performance of the instrument and the different effects on elements, the atomizing gas and other parameters are adjusted a second time in this embodiment. In order to reduce the time for automatic tuning, the two adjustments in the adjustment are set as coarse adjustment and fine adjustment, and the fine adjustment percentage is set, so as to ensure the results and save time.

[0136] Embodiment Two

[0137] This embodiment provides a preferred automatic tuning method in the standard mode.

[0138] On the basis of the automatic tuning method provided in Embodiment One, a step 102A of adjusting the atomizing chamber temperature is added after the step 102 of adjusting the atomizing gas flow rate, and the flow is as shown in Figure 10 The specific steps are as follows:

[0139] Step 102A, adjusting the atomizing chamber temperature.

[0140] By changing the atomizing chamber temperature, the introduction amount of aerosol into the plasma is changed.

[0141] At present, almost all ICP-MSs use pneumatic nebulization sampling technology. Of course, in addition to the advantages of simplicity and convenience, the pneumatic nebulization sampling method has the problem that the element determination is seriously affected by the solvent, especially the interference of polyatomic ions and oxide ions. Therefore, adjusting the atomizing chamber temperature is to reduce the introduction amount of water vapor, that is, to reduce the water load in the plasma, so as to reduce the interference of polyatomic ions and oxide ions, while ensuring the response value of the element.

[0142] When the atomizing chamber temperature adjustment is started, the instrument will gradually change the atomizing chamber temperature according to the set step of the atomizing chamber temperature range, and at the same time, the response value of the set target will be detected. Because the influence of the atomizing chamber temperature on elements of different mass numbers is different, according to the need, this embodiment sets the detection values of four elements of low, medium and high mass numbers.

[0143] The purpose of adjusting the atomizing chamber temperature is to reduce the influence of interference on the detection results, especially the influence of polyatomic ions formed by elements such as H and O on the accuracy of the ICP-MS detection results. In order to minimize the influence of these polyatomic ion interferences on the detection results, the interference index needs to be considered when adjusting the atomizing chamber temperature. In the case of meeting the element response value, the lower the interference value is, the better.

[0144] By adding the above steps, the interference is further reduced, and the accuracy of the ICP-MS detection results is provided.

[0145] Embodiment Three

[0146] This embodiment provides an automatic tuning method in the collision mode.

[0147] During the ICP-MS detection process, mass spectrum interference caused by polyatomic ions will greatly affect the analysis accuracy. Generally, the methods that can be used to eliminate the interference of polyatomic ions include cold plasma, pretreatment, correction equation, and high resolution. The above-mentioned methods for removing polyatomic ion interference have certain limitations, such as limited sample applicability for interference correction equation, higher requirements for operator experience and skills for shielding torch technology, and greatly reduced analysis sensitivity, etc. The collision / reaction cell technology is currently the most powerful means to solve the interference of polyatomic ions. This technology does not need to change the working state of the ion source, can effectively remove various polyatomic ion interferences, and greatly improves the detection performance of the ICP-MS instrument. The performance of the collision / reaction cell is closely related to its parameters, and the performance of the collision / reaction cell is optimized to the best through automatic tuning.

[0148] Figure 11 The method flowchart of the collision mode automatic tuning provided for the present embodiment is shown.

[0149] Figures 12 to 14 Exemplarily, progress windows for presenting the automatic tuning state of the inductively coupled plasma mass spectrometer are shown. Preferably, these progress windows can also set a dialog box or command area to allow the user to command to skip a certain step, or stop after completing the current step, or immediately stop the automatic tuning process during the automatic tuning.

[0150] As shown in Figure 11 , the method comprises the following steps:

[0151] Step 201, adjust the collision gas flow rate.

[0152] The first step of automatic tuning in KED mode (Kinetic Energy Discrimination) will adjust the collision gas flow rate. By adjusting the collision gas flow rate, the kinetic energy of the to-be-detected ions and the interfering ions is changed.

[0153] KED mode works based on the following basic principles.

[0154] (1) All molecular ions contain two or more atoms, and their collision cross sections are larger than those of single-atom ions. Under the same conditions, the ions with larger collision cross sections collide with the collision gas more frequently than the ions with smaller collision cross sections.

[0155] (2) Assuming that the collision is an elastic collision, the ion transfers kinetic energy to the gas molecules. Molecular ions that collide more frequently lose more kinetic energy than to-be-detected ions that collide less frequently.

[0156] The potential energy of the quadrupole mass analyzer of the mass spectrometer is set to be higher than the potential energy of the collision / reaction cell. When the potential energy barrier is higher than the kinetic energy of the molecular ions, they cannot enter the quadrupole, and thus interference cannot be formed. The kinetic energy of the to-be-tested ions is higher, and thus they can pass through the potential energy difference and enter the quadrupole mass analyzer, and can be detected by the instrument.

[0157] Figure 12 A collision gas flow rate tuning interface diagram is provided for the embodiment.

[0158] When the collision gas flow rate adjustment is started, the instrument gradually changes the collision gas flow rate according to the set collision gas flow rate range step length, and detects the response value of the set target and the response value of the interference. Because the collision gas has different effects on the to-be-tested elements and the interference, the response values of the target and the interference are set respectively. In the case of meeting Co>30000, the larger the Co / ArO ratio is, the better.

[0159] Step 202, adjust the deflection lens group.

[0160] The deflection lens group is automatically adjusted, that is, the deflection lens group after the collision reaction cell is adjusted, the response value of Co is optimized, and thus the Co / ArO ratio is improved.

[0161] In the collision reaction cell, ions collide with the gas introduced into the collision reaction cell, and thus the kinetic energy changes. Therefore, the lens voltage in the standard mode is not very suitable for ion transmission in the KED mode. In addition, new neutral particles may be generated in the ion flow due to violent collision or other reactions. Therefore, the voltage of the deflection lens group needs to be re-optimized to improve the ion transmission efficiency and reduce interference.

[0162] Figure 13 A deflection lens tuning interface diagram is provided for the embodiment.

[0163] When the deflection lens adjustment is started, the instrument gradually changes the extraction lens voltage according to the set deflection lens range step length. Because we pay more attention to the response value of Co and the Co / ArO ratio in the collision mode, we set the condition that Co>30000, and the larger the Co / ArO ratio is, the better. Because the two groups of lenses in the deflection lens interact and are related to each other, the tuning of the deflection lens needs to be iterated to achieve the best value. In the tuning of the deflection lens, the deflection lens 1 and the deflection lens 2 are first coarsely adjusted, and then according to the adjusted value, the range is narrowed, and the deflection lens 1 and the deflection lens 2 are finely adjusted again.

[0164] Step 203, adjust the collision gas flow rate again.

[0165] The collision gas flow rate is adjusted again because the collision gas makes the response value have a certain fluctuation, and by adjusting the collision gas flow rate again, the collision gas flow rate is ensured to reach an optimal value.

[0166] Figure 14 A second collision gas flow rate tuning interface diagram is provided for this embodiment.

[0167] When the collision gas flow rate adjustment is started, the instrument will gradually change the collision gas flow rate according to the set collision gas flow rate range step, while detecting the response value of the set target and the response value of the interference. Because the collision gas has different effects on the measured elements and the interference, the response values of the target and the interference are set respectively. Among them, in the case of meeting Co>30000, the larger the ratio of Co / ArO is, the better.

[0168] Embodiment Four

[0169] The embodiment provides a system for automatically tuning an inductively coupled plasma mass spectrometer. The system 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.

[0170] Figure 15 A schematic structural block diagram of a system 100 for automatically tuning an inductively coupled plasma mass spectrometer is shown, which is provided according to one exemplary embodiment of the present embodiment. The system 100 for automatically tuning the inductively coupled plasma mass spectrometer includes a processor 110 and a memory 130.

[0171] The processor 110 includes a hardware element 120 which can be configured as a processing unit, a functional block, etc. It can include other logic devices formed as application specific integrated circuits or using one or more semiconductors. The hardware element 120 is not limited by the material it is formed of or the processing mechanism employed therein. For example, the processor 110 can be composed of semiconductor(s) and / or transistors. The processor 110 can include a single processing unit or multiple processing units, all of which can include a single or multiple computing units or multiple cores. The processor 110 can be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, and / or any device based on operational instructions to manipulate signals. The processor 110 can be configured to obtain and execute executable instructions stored in the memory 130, so as to execute the aforementioned method for automatically tuning the inductively coupled plasma mass spectrometer.

[0172] Memory 130 includes a computer-readable storage medium 140 that can be configured to store executable instructions that, when executed by processor 110, can implement the method for automatically tuning an inductively coupled plasma mass spectrometer described above. Computer-readable storage medium 140 can 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 structures, and the like. Computer-readable storage medium 140 can include, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD), or other optical storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other storage medium which can be used to store information which can be accessed by processor 110.

[0173] Similarly, system 100 for automatically tuning an inductively coupled plasma mass spectrometer can also include a system bus or other data and command transfer system that couples processor 110 and memory 130 to each other. System bus can include any of a variety of bus structures including a memory bus or memory controller, a peripheral bus, a serial bus, a general purpose communications bus, and / or a processor or local bus that utilizes any of a variety of bus architectures.

[0174] System 100 for automatically tuning an inductively coupled plasma mass spectrometer establishes wired and / or wireless communication connection with the inductively coupled plasma mass spectrometer, so that when processor 110 executes the aforementioned method for automatically tuning an inductively coupled plasma mass spectrometer, actual control of the components of the inductively coupled plasma mass spectrometer is achieved.

[0175] In some possible embodiments, the instructions stored by memory 130 of system 100 for automatically tuning an inductively coupled plasma mass spectrometer, when executed, cause processor 110 to: receive user data input regarding performing automatic tuning on the inductively coupled plasma mass spectrometer ICP-MS, wherein the user data input includes selection of operation mode of the inductively coupled plasma mass spectrometer, and setting of parameters such as kind of target substance (various elements, compounds, etc. involved in the automatic tuning), detection range, threshold value, etc., so that the user can edit according to his own needs, and the user can use in different scenarios. The operation mode includes standard mode and collision mode. The user input method can include one or a combination of mouse click, key press, and graphical user interface component selection.

[0176] The above description is only a description and a description of the exemplary embodiments of the present application, but such description and description should be considered as illustrative and exemplary, and the protection scope of the present application is not limited thereto. Any skilled person in the art can easily think of various changes or replacements under the teaching of the present disclosure, and these changes and replacements should be considered as falling within the scope of the present disclosure. Therefore, the protection scope of the present application should be subject to the scope of the appended claims.

Claims

1. A method for automatically tuning an inductively coupled plasma mass spectrometer, characterized in that: In the standard mode of the inductively coupled plasma mass spectrometer, the method includes: Step 101: Adjust the relative position of the plasma flame and the sampling cone so that the center of the plasma is aligned with the cone hole of the sampling cone; Gradually change the lateral and / or longitudinal position of the plasma. This step involves detecting the response value of the preset target object. The position of the plasma corresponding to the maximum response value of the target object is taken as the adjusted position; Step 102: Adjust the atomizing gas flow rate to the optimal atomizing gas flow rate so that different elements achieve the desired degree of ionization, and the atomizing gas carries the sample; Gradually change the atomizing airflow rate and detect the response value of the preset target object in this step; The preset target includes a first target and a second target. When the response value of the first target meets the preset condition and the response value of the second target reaches the maximum value, the atomized airflow rate is taken as the adjusted optimal atomized airflow rate. or, The optimal atomizing gas flow rate is defined as the atomizing gas flow rate when the response value of the first target meets the preset conditions, the ratio of oxide double charge is not higher than the preset value, and the response value of the second target reaches the maximum value. Step 103: Adjust the extraction lens; Gradually change the extraction lens voltage and detect the response value of the preset target object in this step; The preset target includes a third target and a fourth target. The extraction lens voltage when the response value of the third target meets the preset condition and the response value of the fourth target reaches the maximum value is taken as the adjusted optimal extraction lens voltage. Step 104: Adjust the focusing lens; The focusing lens voltage is gradually changed, while the response value of the preset target object in this step is detected. The focusing lens voltage at which the response value of the target object reaches its maximum value in this step is taken as the adjusted optimal focusing lens voltage. Step 105: Adjust the deflection lens; The voltage of the deflection lens is gradually changed, and the response value of the preset target object in this step is detected at the same time. The deflection lens voltage at which the response value of the target object reaches its maximum value in this step is taken as the adjusted optimal deflection lens voltage. Step 106: Adjust the atomizing airflow rate again; Gradually change the atomizing airflow rate and detect the response value of the preset target object in this step; The preset target includes a first target and a second target. When the ratio of oxide double charge is not higher than a preset value, the atomized gas flow rate when the response value of the first target meets the preset condition and the response value of the second target reaches the maximum value is taken as the adjusted optimal atomized gas flow rate.

2. The method according to claim 1, characterized in that: The preset target in step 104 is a low-mass element.

3. The method according to claim 1, characterized in that: Between steps 102 and 103, the following is also included: Step 102A: Adjust the temperature of the atomization chamber to change the amount of aerosol introduced into the plasma.

4. The method according to any one of claims 1-3, characterized in that: In the collision mode of the inductively coupled plasma mass spectrometer, the method includes: Step 201: Adjust the collision airflow speed; Step 202: Adjust the deflection lens group; Step 203: Adjust the collision airflow speed again.

5. The method according to claim 4, characterized in that: Step 201 includes: Gradually change the collision airflow velocity and detect the response value of the target object in the preset collision mode; The preset target objects include a fifth target object and a sixth target object. The collision airflow velocity when the response values ​​of the fifth target object and the sixth target object both meet the preset conditions 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 velocity. Step 202 includes: Gradually adjust the voltage of the deflection lens group and detect the response value of the preset target object in the collision mode; The preset target objects include a fifth target object and a sixth target object. The deflection lens group voltage when the response values ​​of the fifth target object and the sixth target object both meet the preset conditions 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 optimal deflection lens group voltage after adjustment. Step 203 includes: Gradually change the collision airflow velocity and detect the response value of the target object in the preset collision mode; The preset target objects include a fifth target object and a sixth target object. The collision airflow velocity when the response values ​​of the fifth target object and the sixth target object both meet the preset conditions 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 velocity.

6. The method according to claim 5, characterized in that: The fifth target is Co, and the sixth target is ArO.

7. A system for automatically tuning an inductively coupled plasma mass spectrometer, characterized in that, include: processor; And memory, which stores executable instructions; When the executable instructions are executed by the processor, the method for automatically tuning an inductively coupled plasma mass spectrometer according to any one of claims 1 to 6 is performed.

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