Inductively coupled plasma mass spectrometry detection method with online automatic dilution function

Abstract

The present application relates to the technical field of mass spectrometry, and particularly relates to an inductively coupled plasma mass spectrometry detection method with an online automatic dilution function. An original sample solution is introduced into an online dilution module comprising a sample inlet, a diluent inlet and a mixing chamber. The sample and the diluent are simultaneously pumped according to an initial dilution ratio instruction. The mixed dilution sample is uniformly mixed by a dynamic mixing tube and then sent to an atomizer to generate characteristic ions through atomization and ionization. The characteristic ions are separated and counted, and a signal intensity is output in real time. The signal intensity is compared with pre-stored upper and lower threshold values. When the signal exceeds the linear range, a new dilution ratio is automatically calculated, the pumping flow rate is adjusted, and the detection is repeated until the signal falls within the linear range. The present application realizes integrated continuous operation of dilution and detection, automatically adjusts the dilution ratio without manual intervention, significantly improves the detection efficiency and accuracy, and reduces human error.

Description

Technical Field

[0001] This invention relates to the field of mass spectrometry analysis technology, and in particular to an inductively coupled plasma mass spectrometry detection method with online automatic dilution function. Background Technology

[0002] Inductively coupled plasma mass spectrometry (ICP-MS) is a highly sensitive detection technique for the simultaneous analysis of trace and ultra-trace multi-element samples, widely used in environmental monitoring, food safety, geological exploration, and biomedicine. In actual sample analysis, the concentrations of target elements in the samples often vary significantly. When the concentrations of certain elements in the sample exceed the linear response range of the ICP-MS detector, the instrument will be unable to provide accurate quantitative results, and may even cause detector saturation or contamination, affecting subsequent analyses.

[0003] In existing technologies, for samples with known high concentrations, operators typically need to manually dilute them offline before injection. This involves pre-mixing the sample with the stock solution or deionized water in a specific ratio using glassware such as pipettes and volumetric flasks, ensuring uniform dilution, and then transferring the diluted sample to the injection tube for analysis. This approach has the following inherent drawbacks: First, the dilution and detection operations are performed separately, failing to achieve an integrated continuous "dilution-detection" process, significantly extending the total analysis time for a single sample, especially inefficient for large-scale sample analysis. Second, the manual dilution process involves multiple liquid transfers, which not only easily introduces volumetric errors but also increases the risk of sample cross-contamination or external contamination, adversely affecting the accuracy of trace analysis results. Third, if the initial dilution factor is inappropriately selected, resulting in the detection signal still exceeding the linear range or excessive dilution causing an excessively low signal, resampling and manual dilution are necessary, further exacerbating the repetitiveness and human intervention in the detection process. Furthermore, the existing technology lacks a closed-loop control mechanism that can automatically adjust the dilution ratio based on actual signal feedback and complete repeated detection in real time, which limits the automation level of ICP-MS technology in the field of rapid analysis of high-concentration samples. Summary of the Invention

[0004] The purpose of this invention is to provide an inductively coupled plasma mass spectrometry detection method with online automatic dilution function, which realizes integrated continuous operation of dilution and detection, and can adaptively adjust the dilution ratio without manual intervention, significantly improving detection efficiency and accuracy, and reducing human error.

[0005] To achieve the above objectives, the present invention provides an inductively coupled plasma mass spectrometry detection method with online automatic dilution function, comprising the following steps: The original sample solution is introduced into an online dilution module, which includes at least one sample inlet, one diluent inlet, and a mixing chamber. The original sample solution and the diluent are simultaneously pumped into the mixing chamber according to the initial dilution ratio command via a dual-channel fluid drive device, wherein the dual-channel fluid drive device is driven synchronously at the sample flow rate and the diluent flow rate, respectively. The diluted sample after mixing flows sequentially through a dynamic mixing tube and is then fed into an atomizer. After atomization and ionization, characteristic ions are generated, and the characteristic ions are separated and counted, with the signal intensity output in real time. The signal intensity is compared with a pre-stored upper and lower threshold. When the signal intensity exceeds the linear range defined by the upper and lower thresholds, a new dilution ratio is automatically calculated, and the sample flow rate and diluent flow rate are readjusted to trigger repeated detection until the obtained signal intensity falls within the linear range.

[0006] The initial dilution ratio instruction is obtained through one of the following methods: standard library matching based on sample matrix parameters, or intelligent prediction based on rapid pre-scan detection; wherein, the intelligent prediction based on rapid pre-scan detection includes: taking a small amount of the original sample solution and the diluent and quickly mixing them according to a conservative high dilution factor, performing a pre-scan, and calculating and outputting the initial dilution ratio instruction in reverse based on the ratio of the pre-scan signal intensity to the upper limit threshold.

[0007] The dual-channel fluid drive device is a dual-channel injection pump or a dual-channel peristaltic pump. When a dual-channel injection pump is used, the synchronous drive is achieved by simultaneously sending start pulse signals to the sample injection pump driver and the diluent injection pump driver at the same time, and the pistons of the two pumps advance synchronously after the pre-compression step, so that the flow rate ratio of the sample solution and the diluent reaches the ratio required by the initial dilution ratio command when they first come into contact at the inlet of the mixing chamber.

[0008] The dynamic mixing tube is a spirally coiled or serpentine capillary tube with an inner diameter of 1 to 3 mm and a length of 0.5 to 2 meters; the mixed liquid generates a Dean vortex effect when flowing through the dynamic mixing tube.

[0009] The upper and lower thresholds are established through the following steps: obtaining the instrument's nominal range from the factory; automatically preparing gradient standard solutions and performing system linear calibration using the online dilution module to determine the concentration range where the correlation coefficient between signal intensity and concentration is greater than 0.995; using the minimum signal intensity corresponding to this range as the lower threshold and 90% of the maximum signal intensity corresponding to this range as the upper threshold; and automatically updating the upper and lower thresholds dynamically using calibration standard solutions every time a predetermined number of samples are analyzed or every predetermined time interval during daily operation.

[0010] The method further includes, after separating and counting the characteristic ions: Construct a standard peak shape template library; collect signal intensity values ​​within a set range of the target element feature peaks in real time and generate grayscale images; compare the grayscale images with the standard peak shape templates for structural similarity; if the similarity index is greater than or equal to the first threshold, directly use the original signal intensity value; if the similarity index is between the second threshold and the first threshold, correct the signal intensity value through a peak shape recovery algorithm; if the similarity index is less than the second threshold, determine that the data is invalid.

[0011] The method for automatically calculating the new dilution ratio is as follows: when the signal strength is greater than the upper limit threshold, the new dilution factor = current dilution factor × (current signal strength / upper limit threshold) × safety factor α, where α ranges from 0.9 to 0.95; when the signal strength is less than the lower limit threshold, the new dilution factor = current dilution factor × (current signal strength / lower limit threshold) × amplification factor β, where β ranges from 1.05 to 1.1; and the new dilution factor is limited to between the preset minimum dilution factor and the maximum dilution factor.

[0012] The method further includes: A standard stock solution of known concentration and a blank matrix solution are placed on an autosampler; the standard stock solution and the blank matrix solution are mixed online according to multiple predetermined dilution ratios to generate a series of standard working solutions with a gradient concentration distribution; Each standard working solution was tested sequentially and the corresponding signal intensity was recorded; a linear regression was performed with concentration as the independent variable and signal intensity as the dependent variable to obtain the standard curve equation; the standard curve equation was used to convert the effective signal intensity falling within the linear range into the concentration of the target element in the original sample.

[0013] In the process of adjusting the dilution ratio and triggering repeated testing, the propulsion speed of the sample injection pump and the diluent injection pump in the dual-channel fluid drive device is directly changed; after a transition time, repeated testing is performed, and this transition time is equal to twice the time obtained by dividing the dynamic mixing tube volume by the total flow rate.

[0014] When the signal strength still fails to fall within the linear range after eight consecutive adjustments to the dilution ratio, it is determined that it cannot be detected, the adjustment is stopped and a warning message is issued; when the signal strength falls within the linear range, the final dilution ratio and the corresponding signal strength are recorded, the original sample concentration is calculated, and an online cleaning process is executed: pure water is pumped at a high flow rate through the sample inlet pipeline, the diluent inlet pipeline, the mixing chamber and the dynamic mixing tube, and the system is continuously cleaned for a preset time before automatically resetting to standby mode.

[0015] This invention discloses an inductively coupled plasma mass spectrometry (ICP-MS) detection method with online automatic dilution. The method involves introducing the original sample solution into an online dilution module comprising a sample inlet, a diluent inlet, and a mixing chamber. Simultaneously, the sample and diluent are pumped according to an initial dilution ratio command. The diluted sample is then uniformly mixed via a dynamic mixing tube and fed into an nebulizer, where it is atomized and ionized to generate characteristic ions. These characteristic ions are separated, counted, and their signal intensity is output in real time. The signal intensity is compared with pre-stored upper and lower thresholds. When the signal exceeds the linear range, a new dilution ratio is automatically calculated, and the pumping flow rate is adjusted. This process is repeated until the signal falls within the linear range. This invention achieves integrated continuous operation of dilution and detection, adaptively adjusting the dilution ratio without manual intervention, significantly improving detection efficiency and accuracy, and reducing human error. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0017] Figure 1 This is a schematic diagram of the steps of an inductively coupled plasma mass spectrometry detection method with online automatic dilution function provided by the present invention.

[0018] Figure 2 This is a schematic flowchart of an inductively coupled plasma mass spectrometry detection method with online automatic dilution function provided by the present invention. Detailed Implementation

[0019] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application.

[0020] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0021] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0022] Please see Figures 1-2 This invention provides an inductively coupled plasma mass spectrometry detection method with online automatic dilution function, comprising the following steps: S1. Introduce the original sample solution into an online dilution module.

[0023] Specifically, the core functional unit of the online dilution module used in this invention is an integrated automatic dilution and sample introduction system, specifically the prepFAST 6 fully automatic online diluent manufactured by Elemental Scientific. This module is physically installed upstream of the nebulizer of the inductively coupled plasma mass spectrometer and achieves bidirectional signal transmission with the mass spectrometer's control unit via a dedicated communication cable.

[0024] The internal structure of this online dilution module includes the following key components: First, the sample inlet port and the diluent inlet port.

[0025] The front of the module features a sample inlet connector for connecting an autosampler probe and a diluent inlet connector for connecting to a diluent reservoir. The sample inlet connector is connected to the first port of a six-port selector valve via a 0.5 mm inner diameter polyetheretherketone (PEEK) tubing; the diluent inlet connector is connected to the second port of the same six-port selector valve via a PEEK tubing of the same inner diameter. The diluent reservoir is pre-filled with ultrapure water or matrix-matched diluent with a resistivity of not less than 18.2 megohm-cm.

[0026] Second, a dual-channel injection pump drive unit.

[0027] The module integrates two high-precision syringe pumps, each with a volume of 10 ml and a step resolution of 0.1 μL. These two pumps are designated as a sample syringe pump and a diluent syringe pump, respectively. The outlet of the sample syringe pump is connected to the sample inlet line via a switching valve, while the outlet of the diluent syringe pump is connected to the diluent inlet line via the same switching valve. The control unit can independently control the piston suction and discharge rates of the two pumps by sending pulse commands, thereby achieving precise ratio adjustment of the sample and diluent flow rates. Compared to peristaltic pumps, syringe pumps provide pulsation-free, highly repeatable micro-step flow control, making them particularly suitable for dilution requirements ranging from sub-milliliter to tens of times.

[0028] Third, the mixing chamber and the dynamic mixing tube.

[0029] The third port of the six-port selector valve connects to a micro-mixing chamber with an internal volume of approximately 0.2 ml. This mixing chamber has a cylindrical structure with three spiral guide channels along its inner wall to induce radial mixing between the two liquid streams. The outlet of the mixing chamber is connected to a dynamic mixing tube via a 1.0 mm inner diameter, 1.5 m long polyetheretherketone (PEEK) capillary. This dynamic mixing tube is coiled into a planar spiral shape with a diameter of approximately 5 cm. It contains no static mixing elements; instead, it relies on the Dean vortex effect generated by the liquid flowing through the curved channel to achieve continuous reorganization of the laminar cross-section, ensuring complete and uniform mixing of sample molecules and diluent molecules at the microscale. The end of the dynamic mixing tube is directly connected to the sample inlet of the nebulizer.

[0030] Fourth, the communication and feedback interface of the control unit.

[0031] The control circuit board of the online dilution module is connected to the main control unit of the inductively coupled plasma mass spectrometer via a serial interface. The mass spectrometer control unit can read the currently detected ion signal intensity value in real time and send this value to the microprocessor of the online dilution module. The microprocessor has a dilution ratio calculation algorithm pre-programmed inside, which can automatically calculate the new sample to diluent flow rate ratio based on the ratio of the signal intensity to a preset linear upper limit threshold, and drive the dual-channel syringe pumps to adjust their respective dispensing rates accordingly.

[0032] After the autosampler inserts its sampling needle into the test tube containing the original sample solution, the control unit sends a start-of-detection command to the online dilution module. The module first executes the "sample loading" sub-step: the six-port selector valve switches to the state where the sample injection pump is connected to the sample inlet, and the sample injection pump draws 2.0 ml of the original sample solution at a rate of 0.5 ml / s, storing it in the pump cylinder. Subsequently, the module executes the "diluent loading" sub-step: the switching valve actuates, connecting the diluent injection pump to the diluent inlet, and the diluent injection pump also draws 2.0 ml of diluent.

[0033] After loading is complete, the module enters the "synchronous discharge and mixing" sub-step: the switching valve simultaneously connects the outlets of the sample injection pump and the diluent injection pump to the inlet of the mixing chamber. The control unit, according to the initially set dilution ratio (e.g., 1:10, i.e., sample flow rate of 0.1 ml / min and diluent flow rate of 0.9 ml / min), instructs both injection pumps to synchronously push their pistons forward at the set flow rates. The two liquid flows converge at the T-junction at the inlet of the mixing chamber and then enter the spiral guide channel area of ​​the mixing chamber, where the first turbulent mixing occurs. The mixed liquid flows out from the outlet of the mixing chamber and enters a 1.5-meter-long dynamic mixing tube. During its flow through the spirally coiled dynamic mixing tube, the liquid continuously experiences centrifugal force due to changes in direction, causing the sample and diluent to repeatedly exchange positions in the radial direction, ultimately forming a homogeneous and stable diluted sample solution upon exiting the dynamic mixing tube.

[0034] The diluted sample solution requires no intermediate storage or manual transfer; it enters the nebulizer's sample capillary in a continuous flow and is carried by the carrier gas into the inductively coupled plasma torch for subsequent nebulization, ionization, and mass spectrometry detection. The entire "loading-mixing-delivery" process is completed within 45 seconds, is completely closed, and involves no manual pipetting.

[0035] S2. Using a dual-channel fluid drive device, the original sample solution and the diluent are simultaneously pumped into the mixing chamber according to the initial dilution ratio command.

[0036] Specifically, before the sample is formally injected, the control unit needs to first determine an initial dilution ratio. This invention provides three acquisition methods that can be used in parallel or selectively: The first method: based on user-inputted experience values.

[0037] The operator manually inputs a desired dilution factor in the control software interface of the inductively coupled plasma mass spectrometer, based on the sample source, historical detection data, or estimated matrix concentration. For example, for a wastewater sample with a known total dissolved solids content exceeding 0.2%, the operator can directly input a dilution factor of 20. The control unit converts this value into the ratio of sample flow rate to diluent flow rate (sample:diluent = 1:19) and stores it as the initial command.

[0038] The second method: matching based on a standard library of sample matrix parameters.

[0039] The control unit internally maintains a matrix-recommended dilution ratio reference table, stored in non-volatile memory. The table records the typical dilution factor ranges for different sample types (e.g., seawater, blood, urine, soil digest, high-salt food extracts, etc.). Before sample analysis, the operator selects the sample category via a drop-down menu. The control unit automatically retrieves the recommended initial dilution factor for that category; for example, 40 times for seawater and 50 times for blood. This method reduces manual input and improves the success rate of the first dilution.

[0040] The third method: intelligent prediction based on fast pre-scan signals.

[0041] This invention incorporates a micro-flow divider valve and a bypass rapid detection capillary between the online dilution module and the nebulizer. Before the large-volume pumping in step two, the control unit first instructs the sample injection pump to draw only a very small amount (e.g., 50 microliters) of the original sample solution, while simultaneously instructing the diluent injection pump to draw an equal volume of diluent. The two pumps are rapidly and synchronously driven at a conservative high dilution factor (e.g., 100 times), directly delivering the extremely small volume of diluted sample to the nebulizer via the bypass for a rapid pre-scan detection lasting only a few seconds.

[0042] The control unit rapidly reads the total ion current intensity or the signal intensity of a specific target element output by the mass spectrometer detection unit. If the signal intensity is significantly lower than the upper limit threshold of the linear range, the control unit determines that the initial dilution factor can be appropriately reduced (i.e., the sample concentration increased), and calculates a more reasonable initial dilution factor using the formula: "New dilution factor = Upper limit threshold / Current signal intensity × Current dilution factor". Conversely, if the pre-scan signal still exceeds the upper limit, the initial dilution factor is further increased. This pre-scan-based adaptive initial dilution command acquisition method significantly reduces the number of repeated adjustments due to lack of experience, and is particularly suitable for the first analysis of samples with unknown concentrations.

[0043] Regardless of which method is used, the control unit will ultimately generate a specific initial dilution ratio command. This command is internally expressed as two flow rate parameters: the target discharge rate of the sample syringe pump and the target discharge rate of the diluent syringe pump. The ratio of these two is strictly equal to the ratio of the sample volume to the diluent volume in the initial dilution factor.

[0044] Once the initial dilution ratio command is generated, the control unit sends it to the microprocessor of the online dilution module. The microprocessor calculates the stepper motor drive pulse frequencies for the sample injection pump and the diluent injection pump based on two target dispensing rates. The specific control flow is as follows: Step 1: Quantitative loading of sample and diluent.

[0045] Before the actual pumping, the six-port selector valve is switched to the "loading" position. In this position, the sample injection pump's inlet is connected to the sample inlet tubing, and its outlet is disconnected from the mixing chamber; the diluent injection pump's inlet is connected to the diluent inlet tubing, and its outlet is also disconnected from the mixing chamber. The control unit instructs the piston of the sample injection pump to move backward, drawing a certain volume of the original sample solution at a suction rate of 0.2 ml per second. The volume drawn is determined based on the expected number of tests and the dead volume of the tubing, typically two ml. Simultaneously, the diluent injection pump also draws the same volume of diluent at the same rate. After the loading process is complete, both pump cylinders are filled with the liquid to be mixed.

[0046] Step 2: Switch to the drainage position.

[0047] The microprocessor issues a command to drive the rotor of the six-port selector valve to the "drain" position. In this position, the passage between the sample injection pump outlet and the mixing chamber inlet is opened, while the diluent injection pump outlet is also connected to the same mixing chamber inlet via a Y-tee connector. The sample channel and diluent channel remain independent before entering the mixing chamber, converging only immediately adjacent to the mixing chamber inlet, thus preventing uncontrolled mixing before pumping.

[0048] Step 3: Drive the two pumps separately according to the target flow rate.

[0049] The microprocessor sends pulse signals of corresponding frequencies to the stepper motor drivers of the two pumps based on the target sample dispensing rate (e.g., 0.1 ml / min) and the target diluent dispensing rate (e.g., 0.9 ml / min) in the initial instructions. The piston of the sample injection pump advances forward at a constant speed, expelling the sample solution from the cylinder through the sample channel; the piston of the diluent injection pump also advances forward at a constant speed, expelling the diluent. Since the pistons of the two pumps have the same diameter, the ratio of dispensing rates is strictly equal to the ratio of piston advance rates, thus achieving precise control of the flow ratio. The microprocessor also monitors the piston position in real time through a built-in photoelectric encoder, forming a closed-loop position-velocity feedback to ensure that the deviation between the actual dispensing rate and the target rate is less than one percent.

[0050] The key to achieving synchronous start-up of the sample injection pump and diluent injection pump in this invention lies in the fact that the control unit sends start-up pulse signals to the drivers of both injection pumps at the same time, and the mechanical response times of the two injection pumps are calibrated to be consistent.

[0051] Specifically, after the loading and switching valves are fully operational, the control unit executes a "synchronous trigger" procedure. This procedure first checks whether the pistons of both pumps have reached their starting positions (i.e., fully filled with liquid). Once confirmed, the control unit reads an internal microsecond-level timer, waiting for the next integer second boundary. At the instant the boundary is reached, the control unit simultaneously outputs a start-level signal to both the sample injection pump driver and the diluent injection pump driver via two independent hardware trigger lines. Both drivers begin outputting drive pulses within the same clock cycle of receiving the signal, driving the stepper motors to rotate.

[0052] Because both syringe pumps use the exact same stepper motor model and mechanical transmission mechanism, and their drive circuits have the same delay characteristics (total delay less than ten microseconds), the pistons of both pumps begin to move forward almost simultaneously. This ensures that the flow rate ratio of the two liquid streams has stabilized at the initial command setting the moment the sample solution and diluent first come into contact at the mixing chamber inlet, avoiding distortion of the front-end ratio caused by sequential startup.

[0053] To further eliminate potential asynchrony caused by elastic deformation of the pipeline, this invention also includes a miniature damper in both the sample channel and the diluent channel, ensuring identical flow resistance in both channels. Before formal pumping, the control unit performs a pre-compression step: both pumps advance at an extremely low speed (0.01 ml / min) for 50 microliters to raise the pressure within the pipeline to a set threshold, before returning to the starting position to restart formal pumping. This pre-compression step ensures that the liquid is immediately output in a laminar flow state upon formal startup, without lag or creep.

[0054] S3. The diluted sample after mixing flows through a dynamic mixing tube and is then fed into an atomizer. After atomization and ionization, characteristic ions are generated. The characteristic ions are then separated and counted, and the signal intensity is output in real time.

[0055] Specifically, the sample solution and diluent first undergo turbulent mixing within the mixing chamber. Due to the presence of several staggered baffles or spiral guide channels within the mixing chamber, the two liquid streams come into full contact and undergo initial mixing within a limited space. Subsequently, the mixed liquid flows out from the mixed sample outlet and into a dynamic mixing tube with an inner diameter of 1 to 3 mm and a length of 0.5 to 2 meters. This dynamic mixing tube employs a spiral or serpentine geometry, generating continuous transverse secondary flow and Dean's vortex effect as the liquid flows within it, further disrupting the laminar boundary layer and achieving complete and homogeneous mixing of the sample and diluent at the microscale. The diluted sample solution after mixing is then ready for direct introduction into ICP-MS, with its total dissolved solids reduced to within the limits allowed by the mass spectrometry detection unit.

[0056] The outlet of the dynamic mixing tube is directly connected to the sample capillary inlet of a concentric nebulizer via a short polyetheretherketone (PEEK) tube with an inner diameter of 0.5 mm and a length not exceeding 10 cm. This concentric nebulizer is made of standard quartz and its internal structure consists of a central capillary and a surrounding argon nozzle. The central capillary has an inner diameter of 0.2 mm and is used to deliver the diluted sample solution; the surrounding annular slit has a width of 0.1 mm and is used to eject the nebulizing gas at high speed.

[0057] When the uniformly mixed diluted sample solution enters the central capillary of the concentric nebulizer at a stable flow rate of 0.5 to 1.0 mL per minute, the control unit simultaneously activates the high-purity argon gas path, allowing argon to flow through the annular slit at a rate of approximately 1.0 L per minute. The argon gas forms a high-speed jet at the nozzle exit, generating a strong shear force on the liquid column flowing out of the central capillary. Under this shear force, the liquid column is torn into numerous tiny droplets, forming a primary aerosol.

[0058] The primary aerosol enters a swirling atomization chamber with a volume of approximately 50 cubic centimeters. The inner wall of the atomization chamber is hydrophilically treated. Large droplets (typically larger than 10 micrometers in diameter) collide with the inner wall of the atomization chamber under the influence of centrifugal force and gravity, condensing into a liquid film and being discharged through the exhaust pipe. Meanwhile, fine droplets with a diameter of less than 5 micrometers escape from the outlet at the top of the atomization chamber with the argon gas flow, forming a uniform and stable fine aerosol. The concentrated droplet size distribution in this fine aerosol is beneficial for subsequent complete evaporation and dissociation in the plasma. The fine aerosol is then fed into the central channel of the inductively coupled plasma torch through a heat-insulated transfer tube approximately 1 meter long.

[0059] The inductively coupled plasma torch consists of three concentric quartz tubes: an outer cooling gas tube, a middle auxiliary gas tube, and an inner central tube. Fine aerosol is ejected from the central tube along with argon carrier gas. A load coil powered by a radio frequency generator surrounds the torch, operating at a frequency of 27.12 MHz or 40.68 MHz, with an output power typically set to 1.2 to 1.6 kW.

[0060] When radio frequency current passes through the load coil, a strong alternating electromagnetic field is generated inside the coil. Argon gas introduced into the torch (as a cooling gas, auxiliary gas, and carrier gas) is ionized in the electromagnetic field, producing a small number of electrons and argon ions, forming a "seed" plasma. These charged particles are accelerated in the alternating electromagnetic field, colliding with and ionizing neutral argon atoms, producing an avalanche effect, and ultimately forming a stable argon plasma in the shape of a torch at a temperature of approximately 8,000 to 10,000 Kelvin at the top of the torch.

[0061] After the fine aerosol enters the central channel of the plasma along with the carrier gas, it undergoes the following four consecutive stages: Desolventization: The droplets evaporate rapidly at high temperatures, and the water is completely vaporized, leaving solid particles (usually less than 2 micrometers in diameter) composed of non-volatile substances.

[0062] Melting and vaporization: Solid particles melt at temperatures of thousands of degrees and then vaporize to form gaseous molecules or atoms.

[0063] Dissociation: Chemical bonds in gaseous molecules break under the bombardment of high-energy electrons and argon ions, decomposing into neutral atoms.

[0064] Ionization: Neutral atoms collide with high-energy electrons and argon ions in the plasma, losing one or more outer electrons to form positively charged ions (i.e., characteristic ions). For most metallic elements, the ionization efficiency can reach over 90%, generating single-charged ions. These characteristic ions, carrying information about the original elemental concentration in the sample, are propelled by the plasma gas flow from the torch exit into the ion extraction interface of the mass spectrometer.

[0065] Characteristic ions enter the high-vacuum mass spectrometry analysis chamber from atmospheric pressure plasma, where they undergo transmission and focusing by a series of ion optical elements. The specific separation and counting process is as follows: Step 1: Ion extraction and focusing.

[0066] Characteristic ions enter the first-stage vacuum chamber (pressure approximately 200 Pa) through a water-cooled sampling cone (approximately 1.0 mm in diameter). They then pass through a smaller-diameter intercepting cone (approximately 0.4 mm in diameter) into the second-stage vacuum chamber (pressure approximately 0.1 Pa). In the region between the two cones, the ions form a supersonic expanding ion beam. This ion beam is captured and focused by a set of electrostatic lenses (including extraction lenses, focusing lenses, and deflection lenses), while neutral particles (such as argon atoms) are deflected or removed, allowing only positive ions to pass through.

[0067] Step 2: Mass spectrometry separation – quadrupole mass analyzer.

[0068] The focused ion beam enters a quadrupole mass analyzer. This analyzer consists of four parallel hyperboloid or cylindrical metal rods, with opposite rods connected, and radio frequency (RF) and DC voltages applied to them respectively. The control unit changes the ratio of the DC to RF voltages applied to the quadrupoles, allowing only ions with a specific mass-to-charge ratio (m / z) to pass through the quadrupoles with stable oscillating trajectories. Ions with other mass-to-charge ratios are neutralized and filtered out as their amplitude increases. The control unit sequentially allows characteristic ions with different mass-to-charge ratios to pass through the quadrupoles according to a set mass scan range (e.g., 2 to 260 atomic mass units) and scan speed (e.g., 1000 mass-to-charge ratio points per second), thereby achieving the separation of different elements.

[0069] Step 3: Ion detection and counting – electron multiplier.

[0070] Characteristic ions are guided through a quadrupole to an electron multiplier. This electron multiplier typically employs a discontinuous dinter structure; when an ion strikes the surface of the first dinter, it generates secondary electrons. These secondary electrons are multiplied sequentially between subsequent dinters, ultimately forming a measurable current pulse. The intensity of this pulse is proportional to the number of ions arriving per unit time. The control unit converts the current pulse into a digital pulse, which is then accumulated by a high-speed counter. For samples with extremely low concentrations, the electron multiplier operates in pulse counting mode, generating one pulse per ion, and the count directly provides the ion flux. For samples with higher concentrations, it can switch to analog mode to measure the average current.

[0071] In traditional signal acquisition, the control unit directly reads the signal intensity value output by the electron multiplier and calculates the element concentration based on this value. However, in actual detection, signal distortion may occur due to short-term plasma fluctuations, minor blockages in the nebulizer, or overlap of mass spectral peaks of adjacent elements. To improve the reliability of the counting results, this invention introduces an innovative method based on mass spectral peak shape image recognition in the data processing stage of step four, specifically including the following sub-steps: Sub-step A: Construct a standard peak shape template library.

[0072] During the instrument calibration phase, the control unit acquires ideal mass spectrometry peak shapes for various elements (such as lead, cadmium, arsenic, and mercury) under optimal instrument conditions. Each peak shape contains continuous data points with the mass-to-charge ratio on the x-axis and the signal intensity on the y-axis. After normalization, these peak shapes are stored as binarized edge contour image templates, forming a standard peak shape template library. The template library also records the theoretical peak width, peak symmetry, and typical offset of adjacent interfering peaks for each element's characteristic isotopes.

[0073] Sub-step B: Acquire raw mass spectrometry data in real time and generate grayscale images.

[0074] During sample detection, the mass spectrometry detection unit acquires signal intensity values ​​within a window (e.g., 0.5 atomic mass units before and after the peak center) around the characteristic peak of the target element in steps of 0.01 atomic mass units, forming a continuous discrete data vector. The control unit maps this vector into a grayscale image: the horizontal axis represents the mass-to-charge ratio (in pixels), and the vertical axis represents the signal intensity (mapped to grayscale values ​​from 0 to 255). This grayscale image is generated in real time and stored in the control unit's buffer.

[0075] Sub-step C: Image recognition – peak matching and anomaly detection.

[0076] The control unit invokes a lightweight convolutional neural network or a template matching-based algorithm to compare the real-time generated grayscale image with the ideal peak image of the corresponding element in a standard peak template library. The comparison process calculates the structural similarity index between the two images, which comprehensively considers the degree of similarity in three dimensions: brightness, contrast, and structure.

[0077] If the structural similarity index is greater than or equal to a pre-stored threshold (e.g., 0.95), the current mass spectrum peak shape is determined to be normal, and the signal intensity value output by the electron multiplier is directly used as the valid signal to enter the concentration calculation process.

[0078] If the structural similarity index is between 0.80 and 0.95, it indicates a slight distortion in the peak shape (such as slight tailing or asymmetry). In this case, the control unit initiates a "peak shape recovery" subroutine: it uses the shape of the template peak shape to constrain and fit the real-time peak shape, adjusts the amplitude and center position of the real-time peak shape through an optimization algorithm, reconstructs a peak shape closer to the ideal state, and extracts the corrected peak area as the signal intensity value. This corrected value replaces the original reading for subsequent calculations.

[0079] If the structural similarity index is below 0.80, it indicates a severe peak shape anomaly (possibly caused by plasma quenching, nebulizer blockage, severe matrix inhibition, etc.). The control unit determines the detection data to be invalid and automatically triggers a system diagnostic procedure: suspending sample injection, checking parameters such as argon pressure, RF power, and nebulizer back pressure, and displaying a specific mass spectrometry peak shape image on the screen to prompt the operator to check. Simultaneously, the control unit saves the abnormal peak shape image in the log for subsequent fault tracing.

[0080] Sub-step D: Automatic learning and template updating.

[0081] When similar, slightly distorted peak shapes are detected multiple times consecutively (e.g., peak broadening caused by a specific matrix), and the actual sample concentration is confirmed to be reliable, the control unit can add the distorted peak shape to an auxiliary template library after labeling it, as an allowed variation pattern under that matrix condition. The next time a similar peak shape is detected, the system will no longer classify it as abnormal, but will directly use the fitted correction value. This self-learning mechanism allows the system to gradually adapt to the mass spectrometry behavior of different sample matrices, reducing human intervention.

[0082] S4. Compare the signal intensity with the pre-stored upper and lower thresholds. When the signal intensity exceeds the linear range defined by the upper and lower thresholds, automatically calculate the new dilution ratio, readjust the sample flow rate and diluent flow rate, and trigger repeated detection until the obtained signal intensity falls within the linear range.

[0083] Specifically, the upper and lower threshold values ​​define the linear dynamic range of the inductively coupled plasma mass spectrometry (ICP-MS) detection unit under specific operating conditions. This invention employs the following multi-level calibration method to determine these two key parameters: Step 1: Reading and verifying the instrument's factory-specified range.

[0084] Each inductively coupled plasma mass spectrometer (ICP-MS) is shipped with a manufacturer providing nominal linear range values ​​for its detector in different operating modes. For example, for pulse counting mode, the upper linear limit is typically about five million counts per second, and the lower linear limit is about one hundred counts per second; for analog mode, the upper linear limit can extend to about one billion counts per second, but the lower limit is limited by the noise floor. These factory-nominal values ​​are pre-stored in the non-volatile memory of the control unit as initial reference thresholds.

[0085] Step 2: System linear calibration based on gradient standard solutions.

[0086] To obtain the actual linear range of a specific instrument under real-world operating conditions, operators should perform the following calibration procedure during system installation, commissioning, or routine maintenance: Using high-purity single-element or multi-element mixed standard stock solutions (e.g., containing 1,000 micrograms per milliliter of internal standard elements such as yttrium, indium, or rhodium), the solutions are automatically diluted in an online dilution module at multiple ratios such as 1:1, 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, 1:128, 1:256, 1:512, and 1:1024 to obtain a series of standard solutions with concentrations decreasing from approximately 1,000 micrograms per milliliter to approximately 1 nanogram per milliliter.

[0087] These standard solutions were sequentially introduced into an ICP-MS for detection, and the signal intensity (count rate or analog voltage value) corresponding to each concentration point was recorded.

[0088] The control unit plots a response curve with concentration on the x-axis and signal intensity on the y-axis. In the low-concentration region, signal intensity and concentration are linearly related; as the concentration increases, the detector begins to saturate, and the curve gradually deviates from the straight line; when the signal intensity no longer increases with increasing concentration, the detector reaches its saturation limit.

[0089] The control unit uses linear regression analysis to determine the concentration range where the correlation coefficient between signal intensity and concentration is greater than 0.995. The minimum signal intensity corresponding to this range is the lower threshold, and the maximum value is the upper threshold. Typically, the upper threshold is set to 90% of the critical signal intensity value before the detector enters the saturation region, to provide a safety margin; the lower threshold is set to three times the standard deviation of the blank solution signal to ensure that signals below the detection limit are not misjudged.

[0090] Step 3: Dynamic threshold updates during daily operation.

[0091] During long-term continuous detection, plasma conditions, interface cone contamination levels, and detector aging can all cause drift in the linear range. This invention employs a periodic automatic calibration procedure: after analyzing every twenty samples or every two hours, the system automatically extracts a medium-concentration calibration standard solution (within the middle of the linear range) pre-placed on the autosampler for testing. If the detected signal intensity deviates from the known expected value of the standard solution by more than 5%, the control unit automatically triggers a rapid gradient calibration (using only three concentration points), recalculating and updating the upper and lower threshold values. The updated thresholds are immediately applied to the judgment of subsequent samples.

[0092] Through the above method, the present invention obtains real-time and accurate upper and lower threshold values, which serve as criteria for determining whether the signal strength falls within the effective linear range.

[0093] To convert the detected signal intensity into the concentration of the target element in the original sample, this invention employs a scheme based on an online dilution module to automatically establish a standard curve, completely avoiding the manual operation of preparing standard solutions. The specific process is as follows: Step A: Introduction of standard mother liquor and online dilution series preparation.

[0094] Place a test tube containing a standard stock solution of known concentration (e.g., a target element concentration of 100 μg / mL) and a test tube containing a blank matrix solution (containing no target element, but with a matrix composition similar to the sample) on the autosampler. The control unit instructs the online dilution module to mix the standard stock solution and the blank matrix solution online according to multiple pre-set dilution ratios (typically 5 to 8 different ratios, covering 0.2 to 2 times the expected sample concentration), automatically generating a series of standard working solutions. The concentration of the standard working solution corresponding to each dilution ratio is calculated by multiplying the stock solution concentration by the reciprocal of the dilution ratio.

[0095] Step B: Sequential testing and data acquisition of the standard working solution.

[0096] The online dilution module delivers each standard working solution sequentially to the nebulizer and mass spectrometry detection unit, from low to high concentration. For each concentration point, the mass spectrometry detection unit acquires the signal intensity of the target element (after subtracting the background signal from the blank matrix solution). The control unit records each concentration point and its corresponding signal intensity value, forming a raw dataset consisting of several data points.

[0097] Step C: Regression fitting and establishment of standard curve equation.

[0098] The control unit uses concentration as the independent variable (X-axis) and signal intensity as the dependent variable (Y-axis) to perform linear regression fitting on the original data points using the least squares method, obtaining the standard curve equation in the form: Y = A × X + B, where A is the sensitivity (i.e., the slope) and B is the intercept. The control unit simultaneously calculates the correlation coefficient; if the correlation coefficient is lower than 0.995, the standard curve is deemed unqualified, and the online dilution and detection process is automatically re-executed until a qualified fitting result is obtained. The established standard curve is stored in the control unit's cache for subsequent concentration calculations of all samples.

[0099] The standard curve is established using the same dilution module and fluid path as the online detection of samples, avoiding systematic errors caused by matrix mismatch or pipeline adsorption between offline preparation and online detection, thus improving the accuracy of quantitative analysis.

[0100] After mass spectrometry analysis of the diluted sample is completed, the mass spectrometry detection unit outputs a value representing the signal intensity of the target element. This value is transmitted to the control unit in real time. The control unit executes the following decision logic: First-level judgment: Signal validity verification.

[0101] The control unit first checks whether the signal strength is greater than the instrument's inherent electronic noise level (usually less than 5 counts per second). If the signal strength is below one-tenth of the lower threshold and there is no significant increase in three consecutive tests, it is determined that the concentration of the target element in the sample is extremely low or non-existent, and a "not detected" result is directly output, ending the detection process for this sample.

[0102] Second-level judgment: linear range judgment.

[0103] If the signal strength passes the validity check, the control unit compares it with the currently stored upper and lower thresholds: If the lower threshold ≤ signal strength ≤ upper threshold, the signal is considered valid and falls within the linear range. The control unit directly uses this signal strength value, substitutes it into the standard curve equation to calculate the original sample concentration, and then proceeds to step six for data output.

[0104] If the signal strength is greater than the upper limit threshold, it is determined that the signal is overloaded, indicating that the dilution factor is insufficient and the dilution factor needs to be increased before retesting.

[0105] If the signal intensity is less than the lower limit threshold, it is determined that the signal is too low, indicating that the dilution is excessive or the sample concentration itself is too low. It is necessary to reduce the dilution factor and re-detect (but if the signal intensity is already close to the lower limit threshold and the dilution factor is already at its minimum, it is directly determined to be below the detection limit).

[0106] Third-level judgment: Trend-assisted judgment.

[0107] To prevent misjudgments due to accidental plasma fluctuations, the control unit also records the signal intensity trend of the current sample over the past five consecutive detections. If the current signal intensity is only slightly above the upper limit threshold (e.g., less than 5%), and the previous two signals were within the linear range, the control unit considers the signal valid and makes no adjustments. This hysteresis range reduces unnecessary repeated detections.

[0108] When the signal strength is determined to be overloaded or too low, the control unit initiates a closed-loop process that automatically adjusts the dilution ratio. This process employs an adaptive algorithm based on an exponential decay ratio to ensure rapid convergence to the effective range.

[0109] Sub-step 1: Calculate the new dilution factor.

[0110] The control unit acquires the currently used dilution factor (denoted as D_current, defined as the ratio of the original sample volume to the total volume of the diluted sample, for example, 1:10, i.e., D_current=10) and the currently measured signal intensity (denoted as S_current), and calculates the new target dilution factor D_new according to the following formula: If the signal is overloaded (S_current > upper limit threshold): D_new = D_current × (S_current / upper limit threshold) × α; where α is a safety factor, ranging from 0.9 to 0.95, the purpose of which is to make the new dilution factor slightly greater than the theoretically calculated value, so as to ensure that the signal strength of the next detection falls within the upper limit threshold rather than exactly equal to the upper limit.

[0111] If the signal is too low (S_current < lower threshold): D_new = D_current × (S_current / lower threshold) × β; where β is an amplification factor, ranging from 1.05 to 1.1, the purpose of which is to make the new dilution factor slightly less than the theoretically calculated value, ensuring that the signal rises back above the lower threshold.

[0112] The control unit limits the calculated D_new to a preset feasible range (e.g., the minimum dilution factor is 1, i.e., no dilution; the maximum dilution factor is 2000, limited by the minimum sampling accuracy of the syringe pump). If the calculated D_new exceeds this range, the boundary value is taken.

[0113] Sub-step 2: Convert the new dilution factor into a flow rate command.

[0114] Based on the new dilution factor D_new, the control unit calculates the new flow rate ratio between the sample injection pump and the diluent injection pump. Keeping the total flow rate constant (e.g., 1.0 mL / min to ensure stable nebulizer operation), the sample flow rate = total flow rate / D_new, and the diluent flow rate = total flow rate × (1 - 1 / D_new). The control unit converts these two flow rate values ​​into the drive pulse frequency of the stepper motor.

[0115] Sub-step 3: No need to reload -- adjust flow rate and repeat detection in real time.

[0116] When adjusting the dilution ratio, there is no need to empty the syringe pump or re-absorb the sample. This is because sufficient amounts of the original sample solution and diluent have already been stored in the cylinders of the sample syringe pump and diluent syringe pump, respectively, in step two. The control unit directly drives the pistons of both pumps forward at the new speed under the new flow rate command. This operation can be completed within milliseconds while maintaining the continuity of liquid flow. The liquid in the mixing chamber and dynamic mixing tube will transition to a stable state at the new dilution ratio within seconds.

[0117] The control unit waits for a transition time (typically twice the time obtained by dividing the dynamic mixing tube volume by the total flow rate, approximately 10 seconds) to ensure that the diluted sample at the new ratio completely replaces the residual liquid at the old ratio. Subsequently, the control unit automatically instructs the repetition of step four (nebulization, ionization, mass spectrometry separation and counting) to obtain a new signal intensity S_new.

[0118] Sub-step four: Convergence judgment and loop control.

[0119] The control unit compares S_new with the upper and lower thresholds again: If S_new is still outside the linear range, repeat sub-steps one through three above to recalculate the new dilution factor and test again.

[0120] If S_new falls within the linear range, stop adjusting and record the final dilution factor D_final and the corresponding effective signal strength.

[0121] To improve convergence speed, this invention employs a variation of the dichotomy approach: the first adjustment uses the complete exponential calculation formula; in the second and subsequent adjustments, the control unit sets the target dilution factor to the geometric mean of the current value and the previous adjustment value, avoiding excessive oscillation. Actual testing shows that most samples obtain a valid signal within two adjustments, and for samples with extreme concentration variations, no more than five adjustments are needed.

[0122] Sub-step 5: Anomaly protection and alarm.

[0123] If the signal intensity cannot fall within the linear range after more than eight consecutive adjustments (e.g., the sample concentration is extremely high, exceeding the maximum dilution capacity, or extremely low, below the detection limit), the control unit determines that it cannot be detected, stops the adjustment, and issues a warning message. Simultaneously, the control unit saves the original signal curve and adjustment history of the sample, prompting the operator to use offline manual dilution or other methods.

[0124] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0125] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope.

Claims

1. An inductively coupled plasma mass spectrometry detection method with online automatic dilution function, characterized in that, Includes the following steps: The original sample solution is introduced into an online dilution module, which includes at least one sample inlet, one diluent inlet, and a mixing chamber. The original sample solution and the diluent are simultaneously pumped into the mixing chamber according to the initial dilution ratio command via a dual-channel fluid drive device, wherein the dual-channel fluid drive device is driven synchronously at the sample flow rate and the diluent flow rate, respectively. The diluted sample after mixing flows sequentially through a dynamic mixing tube and is then fed into an atomizer. After atomization and ionization, characteristic ions are generated, and the characteristic ions are separated and counted, with the signal intensity output in real time. The signal intensity is compared with a pre-stored upper and lower threshold. When the signal intensity exceeds the linear range defined by the upper and lower thresholds, a new dilution ratio is automatically calculated, and the sample flow rate and diluent flow rate are readjusted to trigger repeated detection until the obtained signal intensity falls within the linear range.

2. The inductively coupled plasma mass spectrometry detection method with online automatic dilution function as described in claim 1, characterized in that, The initial dilution ratio instruction is obtained through one of the following methods: standard library matching based on sample matrix parameters, or intelligent prediction based on rapid pre-scan detection; wherein, the intelligent prediction based on rapid pre-scan detection includes: taking a small amount of the original sample solution and the diluent and quickly mixing them according to a conservative high dilution factor, performing a pre-scan, and calculating and outputting the initial dilution ratio instruction in reverse according to the ratio of the pre-scan signal intensity to the upper limit threshold.

3. The inductively coupled plasma mass spectrometry detection method with online automatic dilution function as described in claim 1, characterized in that, The dual-channel fluid drive device is a dual-channel injection pump or a dual-channel peristaltic pump. When a dual-channel injection pump is used, the synchronous drive is achieved in the following way: a start pulse signal is sent to the sample injection pump driver and the diluent injection pump driver at the same time, and the pistons of the two pumps advance synchronously after the pre-compression step, so that the flow rate ratio of the sample solution and the diluent reaches the ratio required by the initial dilution ratio command when they first come into contact at the inlet of the mixing chamber.

4. The inductively coupled plasma mass spectrometry detection method with online automatic dilution function as described in claim 1, characterized in that, The dynamic mixing tube is a spirally coiled or serpentine capillary tube with an inner diameter of 1 to 3 mm and a length of 0.5 to 2 meters; the mixed liquid generates the Dean vortex effect when flowing through the dynamic mixing tube.

5. The inductively coupled plasma mass spectrometry detection method with online automatic dilution function as described in claim 1, characterized in that, The upper and lower thresholds are established through the following steps: obtaining the instrument's nominal range from the factory; automatically preparing gradient standard solutions and performing system linear calibration using the online dilution module to determine the concentration range where the correlation coefficient between signal intensity and concentration is greater than 0.995; using the minimum signal intensity corresponding to this range as the lower threshold and 90% of the maximum signal intensity corresponding to this range as the upper threshold; and automatically updating the upper and lower thresholds dynamically using calibration standard solutions every time a predetermined number of samples are analyzed or every predetermined time interval during daily operation.

6. The inductively coupled plasma mass spectrometry detection method with online automatic dilution function as described in claim 1, characterized in that, After separating and counting the characteristic ions, the method further includes: Construct a standard peak shape template library; collect signal intensity values ​​within a set range of the target element feature peaks in real time and generate grayscale images; compare the grayscale images with the standard peak shape templates for structural similarity; if the similarity index is greater than or equal to the first threshold, directly use the original signal intensity value; if the similarity index is between the second threshold and the first threshold, correct the signal intensity value through a peak shape recovery algorithm; if the similarity index is less than the second threshold, determine that the data is invalid.

7. The inductively coupled plasma mass spectrometry detection method with online automatic dilution function as described in claim 1, characterized in that, The method for automatically calculating the new dilution ratio is as follows: when the signal strength is greater than the upper threshold, the new dilution factor = current dilution factor × (current signal strength / upper threshold) × safety factor α, where α ranges from 0.9 to 0.95; when the signal strength is less than the lower threshold, the new dilution factor = current dilution factor × (current signal strength / lower threshold) × amplification factor β, where β ranges from 1.05 to 1.1; and the new dilution factor is limited to between the preset minimum dilution factor and the maximum dilution factor.

8. The inductively coupled plasma mass spectrometry detection method with online automatic dilution function as described in claim 1, characterized in that, The method further includes: A standard stock solution of known concentration and a blank matrix solution are placed on an autosampler; the standard stock solution and the blank matrix solution are mixed online according to multiple predetermined dilution ratios to generate a series of standard working solutions with a gradient concentration distribution; Each standard working solution was tested sequentially and the corresponding signal intensity was recorded; a linear regression was performed with concentration as the independent variable and signal intensity as the dependent variable to obtain the standard curve equation; the standard curve equation was used to convert the effective signal intensity falling within the linear range into the concentration of the target element in the original sample.

9. The inductively coupled plasma mass spectrometry detection method with online automatic dilution function as described in claim 1, characterized in that, During the process of adjusting the dilution ratio and triggering repeated testing, the advance speed of the sample injection pump and the diluent injection pump in the dual-channel fluid drive device is directly changed; after a transition time, repeated testing is performed, which is equal to twice the time obtained by dividing the dynamic mixing tube volume by the total flow rate.

10. The inductively coupled plasma mass spectrometry detection method with online automatic dilution function as described in claim 1, characterized in that, If the signal strength still cannot fall into the linear range after eight consecutive adjustments of the dilution ratio, it is determined that it cannot be detected, the adjustment is stopped and a warning message is issued; when the signal strength falls into the linear range, the final dilution ratio and the corresponding signal strength are recorded, the original sample concentration is calculated, and the online cleaning process is executed: pure water is pumped at a high flow rate through the sample inlet pipeline, the diluent inlet pipeline, the mixing chamber and the dynamic mixing tube, and the system is continuously cleaned for a preset time before automatically resetting to standby state.

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