Inductively coupled plasma mass spectrometry electron dilution sampling detection method and control system

Abstract

This invention relates to the field of elemental analysis and detection technology, specifically to an inductively coupled plasma mass spectrometry (ICP-MS) electronic dilution sample introduction and detection method and control system. The detection method includes: constructing an automatic dilution flow path; uniformly mixing the sample to be tested with the diluent; real-time acquisition of the detection signal intensity of a specified mass number of the target element; comparing the detection signal intensity with a preset upper limit threshold signal intensity; obtaining the effective detection signal based on the comparison result; and calculating the actual concentration of each target element in the original sample based on the actual dilution factor corresponding to the effective detection signal. The detection control system includes: a dilution flow path construction module, a dilution and sample introduction module, a real-time monitoring and feedback adjustment module, and a concentration calculation module. Through the above method, the concentration of the original sample can be accurately calculated based on the effective detection signal, combined with the actual dilution factor and standard curve parameters, thereby improving the accuracy and efficiency of ICP-MS detection of high-concentration and complex matrix samples.

Description

Technical Field

[0001] This invention relates to the field of elemental analysis and detection technology, and in particular to an inductively coupled plasma mass spectrometry (ICP-MS) electron dilution sample introduction detection method and control system. Background Technology

[0002] Inductively coupled plasma mass spectrometry (ICP-MS) is the mainstream technique for trace element analysis, boasting significant advantages such as high sensitivity, wide linear range, and simultaneous detection of multiple elements. In practical applications, ICP-MS typically requires sample pretreatment or dilution to accommodate the detection needs of samples with varying concentrations and matrix complexities.

[0003] For clean samples with appropriate concentrations of the analyte, simple acid digestion or direct dilution is sufficient for injection and detection, followed by quantitative analysis using the standard curve method. The basic procedure of the standard curve method is as follows: prepare a series of standard solutions of known concentrations, measure their signal intensities under identical detection conditions to the sample, establish a linear relationship between signal intensity and concentration, and then substitute the sample's detection signal into this equation to calculate the concentration of the target element in the sample. This method requires that the sample's detection signal must fall within the linear range of the standard curve; otherwise, the quantitative results are unreliable.

[0004] However, when the concentration of the target element in the sample is high or the matrix is ​​complex, direct injection or injection after fixed-fold dilution faces the following problems: First, the detection signal generated by high-concentration samples is very likely to exceed the upper limit of the linear range of the standard curve, leading to detector saturation or a deviation from linearity in the signal response. In this case, even if a standard curve is established, it is impossible to accurately convert the signal exceeding the limit into a concentration value. The traditional approach is to reduce the dilution factor or dilute the sample by a larger factor and then re-detect it. However, due to the lack of an effective mechanism for determining whether the diluted signal falls within the linear range of the standard curve, it is often necessary to repeatedly try different dilution factors, resulting in a lengthy and inefficient detection process.

[0005] Second, standard curves are typically established under fixed dilution conditions. When samples are manually diluted offline, factors such as the accuracy of the measuring instruments used, the operator's skill level, and environmental conditions can introduce errors, leading to discrepancies between the actual concentration of the diluted sample and the theoretically calculated value. This deviation is amplified when recalculating the original concentration, directly affecting the accuracy of the final result. Especially when multiple elements need to be detected simultaneously, with a wide range of element concentrations, a single dilution factor is insufficient to ensure that the detection signals of all elements fall within the linear range of the standard curve. Traditional recalculation methods cannot effectively handle such complex scenarios.

[0006] Third, existing methods mostly rely on a preset dilution factor for simple multiplication when calculating the original concentration, ignoring the difference between the actual dilution factor and the preset value. For example, manually transferring 1 ml of sample to 100 ml results in a theoretical dilution factor of 100. However, the actual volume transferred by the pipette might be 0.98 ml or 1.02 ml, and the volume adjustment might have an error of ±0.1 ml. These small deviations, when multiplied by 100, can lead to significant errors in the final concentration. For online dilution systems, flow drift in the proportional valve and elastic changes in the pump tubing can also cause deviations between the actual dilution factor and the preset value, and existing technologies lack a mechanism for real-time acquisition and calibration of the actual dilution factor.

[0007] Fourth, when the detected signal is below the lowest concentration point of the standard curve, existing methods typically report "below detection limit" or require reconcentration and detection, but ignore the possibility of bringing the signal into the linear range by reducing the dilution factor or extending the integration time. In other words, there is a lack of a technical means to dynamically guide the direction of dilution factor adjustment based on the relationship between signal intensity and the standard curve range.

[0008] Therefore, developing a method that can accurately calculate the original sample concentration based on the effective detection signal, combined with the actual dilution factor and standard curve parameters, is of great significance for improving the accuracy and efficiency of ICP-MS detection of high-concentration and complex matrix samples. Summary of the Invention

[0009] The purpose of this invention is to provide an inductively coupled plasma mass spectrometry (ICP-MS) electronic dilution sample introduction detection method and control system, which aims to accurately calculate the original sample concentration based on the effective detection signal, combined with the actual dilution factor and standard curve parameters, thereby improving the accuracy and efficiency of ICP-MS detection of high-concentration and complex matrix samples.

[0010] To achieve the above objectives, the present invention employs an inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method, comprising the following steps: An automated dilution flow path is constructed, which includes a sample pump, a diluent pump, a proportioning valve, a mixing tee, and connecting tubing. The sample pump connects the sample storage end to the first interface of the mixing tee, the diluent pump connects the diluent storage end to the second interface of the mixing tee, the third interface of the mixing tee connects to the sample inlet of the ICP-MS nebulizer, and the proportioning valve is connected to the signal of the sample pump and the diluent pump respectively. The initial dilution factor, the mass number corresponding to the target element, and the upper limit threshold of the signal strength are preset. The sample pump and the diluent pump are controlled by the proportional valve to extract the sample to be tested and the diluent according to the flow ratio corresponding to the initial dilution factor. They are then transported to the mixing tee to complete online uniform mixing and obtain the sample mixed diluent. The well-mixed sample dilution is fed into an ICP-MS nebulizer. After nebulization and plasma dissociation, elemental detection is completed. The detection signal intensity of the target element at a specified mass number is acquired in real time. The detection signal intensity is compared with the preset upper limit threshold of the signal intensity. The valid detection signal is obtained based on the comparison result. Based on the actual dilution factor corresponding to the effective detection signal, combined with the effective detection signal intensity and standard curve parameters, the actual concentration of each target element in the original sample to be tested is calculated.

[0011] The process of setting up an automated dilution flow path, which includes a sample pump, a diluent pump, a proportioning valve, a mixing tee, and connecting tubing, involves the following steps: The sample pump connects to the sample storage end of the analyte to the first interface of the mixing tee; the diluent pump connects to the diluent storage end to the second interface of the mixing tee; the third interface of the mixing tee connects to the sample inlet of the ICP-MS nebulizer; and the proportioning valve is connected to the signal terminals of the sample pump and the diluent pump. Connect the sample pump to the sample solution container via PTFE tubing, and connect the diluent pump to the diluent container. Connect the outputs of the sample pump and diluent pump to the two input ports of the proportional valve, respectively. Connect the output port of the proportional valve to the two corresponding inlets of the mixing tee through a pipeline. Connect the common outlet of the mixing tee directly to the inlet of the ICP-MS nebulizer through a pipeline. Establish a feedback control link for the control signal line of the proportional valve; The entire flow path was tested for air tightness and calibrated for flow rate. The actual flow rate ratio between the sample end and the diluent end was calibrated using a standard solution at different valve openings, thus completing the construction and initialization of the automatic dilution flow path.

[0012] In the step of setting an initial dilution factor, the mass number corresponding to the target element, and the upper limit threshold of the signal intensity, the sample pump and the diluent pump are controlled by a proportional valve to extract the sample to be tested and the diluent according to the flow ratio corresponding to the initial dilution factor, and then transported to the mixing tee to complete online uniform mixing to obtain the sample mixed diluent: Set the initial dilution factor for the sample to be tested, set the mass number of the target element to be analyzed, and set the upper limit threshold of the signal intensity based on the factory linear range of the ICP-MS detector and the background noise level. The flow ratio of the sample pump to the diluent pump is calculated based on the initial dilution factor. The flow ratio is then converted into a control signal for the proportional valve, which is used to drive the proportional valve to operate according to the corresponding time and opening ratio. Simultaneously start the sample pump and diluent pump to draw liquid from the sample storage end and diluent storage end, respectively. The two liquid streams meet and mix thoroughly inside the mixing tee to form a sample mixed diluent with uniform concentration.

[0013] In the process of feeding a uniformly mixed sample dilution into an ICP-MS nebulizer, performing nebulization and plasma dissociation to complete elemental detection, acquiring the detection signal intensity of the target element at a specified mass number in real time, comparing the detection signal intensity with a preset upper limit threshold, and obtaining the valid detection signal based on the comparison result: The sample mixture and dilution solution is introduced into the ICP-MS nebulizer at a stable flow rate. Under the action of argon, it is broken down into tiny aerosols. The aerosols are carried into the high-temperature plasma torch by the carrier gas, and after dissociation, atomization and ionization, they form a positively charged ion beam. The ion beam enters the mass spectrometry analysis chamber through a sampling cone and a truncation cone, and is separated according to the mass-to-charge ratio. The ICP-MS detector collects the ion count of the target element with a specified mass number in real time. The ion count is output after analog-to-digital conversion. The output includes the number of pulses per second and the signal intensity value. The system continuously reads the strength of the detected signal, compares the detected signal strength with a preset upper limit threshold for signal strength, and outputs the comparison result.

[0014] In the step of continuously reading the detected signal strength, comparing the detected signal strength with a preset upper limit threshold for signal strength, and outputting the comparison result: If the current signal strength is less than or equal to the upper limit threshold, then the current signal strength is determined to be a valid detection signal.

[0015] In the step of continuously reading the detected signal strength, comparing the detected signal strength with a preset upper limit threshold for signal strength, and outputting the comparison result: If the current signal strength is higher than the upper limit threshold, the signal is determined to be out of limit, the out-of-limit status is recorded, the dilution factor is increased, and the online dilution and detection process is re-executed until a valid detection signal that is not out of limit is obtained.

[0016] In the step of back-calculating the actual concentration of each target element in the original sample based on the actual dilution factor corresponding to the effective detection signal, combined with the effective detection signal intensity and standard curve parameters: The actual dilution factor used to obtain a valid detection signal is read. This actual dilution factor is calculated from the real-time flow ratio of the sample pump to the diluent pump in this detection. Extract the signal intensity value of the target element corresponding to the effective detection signal, as well as the signal intensity value of the internal standard element in the same detection batch, and use the internal standard signal to correct the signal fluctuations caused by short-term instrument drift and matrix effect; Establish the parameters for the standard curve. The standard curve is plotted by measuring standard solutions of known concentrations using the same online dilution process. Substitute the corrected effective detection signal intensity into the standard curve equation to calculate the apparent concentration of the target element in the sample mixture dilution.

[0017] Among them, after substituting the corrected effective detection signal intensity into the standard curve equation to calculate the apparent concentration of the target element in the sample mixed dilution: Multiply the apparent concentration by the actual dilution factor to obtain the actual concentration of the target element in the original sample.

[0018] In the step of substituting the corrected effective detection signal intensity into the standard curve equation to calculate the apparent concentration of the target element in the sample mixed dilution: Read the standard curve parameters, including the slope, intercept, and correlation coefficient of the standard curve; The effective detection signal intensity of the target element after internal standard correction is used as the vertical axis value. It is substituted into the standard curve equation to calculate the horizontal axis value corresponding to the signal intensity. This value is the apparent concentration of the target element in the sample mixed dilution. If the signal intensity of the target element exceeds the upper limit of the linear range of the standard curve, increase the dilution factor and re-detect; if the signal intensity is below the lowest concentration point of the standard curve, decrease the dilution factor and extend the integration time to improve detection sensitivity.

[0019] This invention also provides an inductively coupled plasma mass spectrometry (ICP-MS) electronic dilution sample introduction and detection control system, comprising a dilution flow path construction module, a dilution and sample introduction module, a real-time monitoring and feedback adjustment module, and a concentration back-calculation module; wherein: The dilution flow path construction module is used to build an automatic dilution flow path, which includes a sample pump, a diluent pump, a proportioning valve, a mixing tee, and connecting tubing. The sample pump connects the sample storage end to the first interface of the mixing tee, the diluent pump connects the diluent storage end to the second interface of the mixing tee, the third interface of the mixing tee connects to the ICP-MS nebulizer inlet, and the proportioning valve is connected to the sample pump and the diluent pump for signal connection. The dilution and injection module is used to preset the initial dilution factor, the mass number corresponding to the target element, and the upper limit threshold of the signal intensity. It controls the sample pump and the diluent pump to extract the sample to be tested and the diluent respectively according to the flow ratio corresponding to the initial dilution factor through the proportional valve, and deliver them to the mixing tee to complete online uniform mixing to obtain the sample mixed diluent. The real-time monitoring and feedback adjustment module is used to send the uniformly mixed sample dilution into the ICP-MS nebulizer, and after nebulization and plasma dissociation, element detection is completed. The module collects the detection signal intensity of the target element at a specified mass number in real time, compares the detection signal intensity with the preset upper limit threshold of the signal intensity, and obtains the effective detection signal based on the comparison result. The concentration back-calculation module is used to back-calculate the actual concentration of each target element in the original sample based on the actual dilution factor corresponding to the effective detection signal, combined with the effective detection signal intensity and standard curve parameters.

[0020] This invention discloses an inductively coupled plasma mass spectrometry (ICP-MS) electronic dilution sample introduction and detection method and control system. The method comprises a dilution flow path construction module, a dilution and sample introduction module, a real-time monitoring and feedback adjustment module, and a concentration back-calculation module, performing the following steps: An automatic dilution flow path is constructed, comprising a sample pump, a diluent pump, a proportional valve, a mixing tee, and connecting tubing. The sample pump connects the sample analyte storage end to the first interface of the mixing tee; the diluent pump connects the diluent storage end to the second interface of the mixing tee; the third interface of the mixing tee connects to the ICP-MS nebulizer sample introduction end; and the proportional valve is connected to the signal terminals of the sample pump and the diluent pump. An initial dilution factor, the mass number corresponding to the target element, and a signal intensity upper limit threshold are preset. The proportional valve controls the flow rate ratio of the sample pump and the diluent pump according to the initial dilution factor. For example, the sample to be tested and the diluent are extracted separately and transported to a mixing tee for online uniform mixing to obtain a sample mixed diluent. The uniformly mixed sample mixed diluent is then sent to an ICP-MS nebulizer. After nebulization and plasma dissociation, elemental detection is performed. The detection signal intensity of the target element at a specified mass number is acquired in real time and compared with a preset upper limit threshold. The valid detection signal is obtained based on the comparison result. Based on the actual dilution factor corresponding to the valid detection signal, combined with the valid detection signal intensity and standard curve parameters, the actual concentration of each target element in the original sample to be tested is calculated. In this way, the concentration of the original sample can be accurately calculated based on the valid detection signal, combined with the actual dilution factor and standard curve parameters, thereby improving the accuracy and efficiency of ICP-MS detection of high-concentration and complex matrix samples. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of the steps of the inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method of the present invention.

[0023] Figure 2 This is a flowchart of steps S100 of the present invention.

[0024] Figure 3 This is a flowchart of steps S200 of the present invention.

[0025] Figure 4 This is a flowchart of steps S300 of the present invention.

[0026] Figure 5 This is a flowchart of steps S400 of the present invention.

[0027] Figure 6 This is a schematic diagram of the structure of the inductively coupled plasma mass spectrometry electronic dilution sample introduction and detection control system of the present invention.

[0028] Figure 7 This is a schematic diagram of the electronic device of the present invention. Detailed Implementation

[0029] 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.

[0030] 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.

[0031] 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."

[0032] Please see Figures 1-5 This invention provides an inductively coupled plasma mass spectrometry (ICP-MS) electron dilution sample introduction and detection method, comprising the following steps: S100: Establish an automated dilution flow path, which includes a sample pump, a diluent pump, a proportioning valve, a mixing tee, and connecting tubing. The sample pump connects the sample storage end to the first interface of the mixing tee; the diluent pump connects the diluent storage end to the second interface of the mixing tee; the third interface of the mixing tee connects to the ICP-MS nebulizer inlet; and the proportioning valve is connected to the signal terminals of both the sample pump and the diluent pump. The specific process is as follows: S101: Connect the sample pump to the sample solution container and the diluent pump to the diluent container via PTFE tubing. S102: Connect the outputs of the sample pump and the diluent pump to the two input ports of the proportional valve, respectively. Connect the output port of the proportional valve to the two corresponding inlets of the mixing tee through a pipeline. Connect the common outlet of the mixing tee directly to the inlet of the ICP-MS nebulizer through a pipeline. S103: Establish a feedback control link for the control signal line of the proportional valve; S104: Perform airtightness testing and flow calibration on the entire flow path. Use standard solutions to calibrate the actual flow ratio between the sample end and the diluent end under different proportional valve openings, and complete the construction and initialization of the automatic dilution flow path.

[0033] In the above process, a PTFE tubing with an inner diameter of 0.8 mm is used. The inlet end of the sample pump is immersed 2 cm below the bottom of the sample solution container, and the outlet end is connected to the tubing through a sealing sleeve. Similarly, the inlet end of the diluent pump is connected to the diluent container using a PTFE tubing, ensuring that there are no bends or air bubbles trapped at the tubing joints.

[0034] Connect the output line of the sample pump to the first input port of the proportional valve, and connect the output line of the diluent pump to the second input port of the proportional valve. Connect the output port of the proportional valve to the first and second inlets of the mixing tee (connected in parallel) via a 10 cm long PTFE tube with an inner diameter of 0.5 mm. Connect the common outlet of the mixing tee directly to the inlet of the ICP-MS nebulizer via a 15 cm long PTFE tube. All interfaces are secured with flared nuts and sealing washers.

[0035] Connect the control signal line of the proportional valve to the analog output port of the programmable logic controller (PLC). The PLC communicates with the host computer via an RS232 serial port. Establish a feedback control link in the control software of the host computer. This link includes a signal reading module, a ratio calculation module, and a valve control signal output module to form a closed-loop control, which can automatically adjust the opening time ratio of the proportional valve according to the preset dilution ratio.

[0036] An airtightness test was performed on the entire flow path: the mixing tee outlet was closed, pure water was injected into the sample end and pressurized to 0.2 MPa, and the pressure was maintained for 30 seconds to observe for any leakage; then the flow rate was calibrated: a mixed standard solution of lithium, cobalt, indium and bismuth with a concentration of 10 μg / L was prepared as the test solution. Under the condition that the proportional valve opening was 10%, 30%, 50%, 70% and 90% respectively, pure water was used as the diluent, and the actual flow rate at the sample end and the diluent end was measured. Each opening was repeated three times and the average value was taken to obtain the opening-flow rate ratio calibration table. The calibration table was stored in the control software in the form of an interpolation function to complete the construction and initialization of the automatic dilution flow path.

[0037] S200: Presets the initial dilution factor, the mass number of the target element, and the upper limit threshold of the signal strength. A proportional valve controls the sample pump and diluent pump to extract the sample and diluent respectively according to the flow ratio corresponding to the initial dilution factor, delivering them to the mixing tee for online uniform mixing to obtain the sample-diluted mixture. The specific process is as follows: S201: Set the initial dilution factor for the sample to be tested, set the mass number of the target element to be analyzed, and set the upper limit threshold of the signal intensity based on the factory linear range of the ICP-MS detector and the background noise level. S202: Calculate the flow ratio of the sample pump and the diluent pump based on the initial dilution factor, convert the flow ratio into a control signal for the proportional valve, and drive the proportional valve to operate according to the corresponding time ratio and opening ratio. S203: Simultaneously start the sample pump and diluent pump to draw liquid from the sample test liquid storage end and the diluent storage end respectively. The two liquid streams meet and mix thoroughly inside the mixing tee to form a sample mixed diluent with uniform concentration.

[0038] In the above process, based on the estimated concentration range of the sample to be tested, the initial dilution factor is set to the upper limit of the estimated concentration. For example, if the estimated maximum concentration is 10 mg / L and the detector linear upper limit is 100 μg / L, then the initial dilution factor is set to 100 times. At the same time, the mass number of the target element to be analyzed (such as lead 208, cadmium 111, arsenic 75) is selected, and the upper limit threshold of the signal intensity is set according to 80% of the factory linear range of the ICP-MS detector. For example, if the detector linear counting upper limit is 10 to the power of 7 per second, then the threshold is set to 8 × 10 to the power of 6 per second.

[0039] The flow ratio of the sample pump to the diluent pump is calculated based on the initial dilution factor. The formula is: the dilution factor equals the sum of the sample pump flow rate and the diluent pump flow rate divided by the sample pump flow rate. The sample pump flow rate ratio is then calculated. This ratio is converted into the duty cycle of the pulse width modulation signal of the proportional valve, with a duty cycle range of 0% to 100%, which drives the proportional valve to open the sample end and the diluent end according to the corresponding time ratio.

[0040] Simultaneously start the sample pump and diluent pump. The sample pump draws the sample to be tested at the calculated flow rate, and the diluent pump draws the diluent (such as 2% dilute nitric acid) at the supplemental flow rate. The two liquid streams enter along the tangential inlet inside the mixing tee, forming a vortex in the cavity. After passing through a spiral mixing channel with a length of 2 cm, they are completely mixed to form a sample mixed diluent with uniform concentration.

[0041] S300: The uniformly mixed sample dilution is fed into the ICP-MS nebulizer. After nebulization and plasma dissociation, elemental detection is completed. The detection signal intensity of the target element at a specified mass number is acquired in real time, and the detection signal intensity is compared with a preset upper limit threshold. The valid detection signal is obtained based on the comparison result. The specific process is as follows: S301: The sample mixture dilution is introduced into the ICP-MS nebulizer at a stable flow rate. Under the action of argon, it is broken down into tiny aerosols. The aerosols are carried into the high-temperature plasma torch by the carrier gas. After dissociation, atomization and ionization, they form a positively charged ion beam. S302: The ion beam enters the mass spectrometry analysis chamber through the sampling cone and the truncation cone, and is separated according to the mass-to-charge ratio. The ICP-MS detector collects the ion count of the target element with a specified mass number in real time. The ion count is output after analog-to-digital conversion. The output includes the number of pulses per second and the signal intensity value. S303: Continuously read the detection signal strength, compare the detection signal strength with the preset upper limit threshold of signal strength, and output the comparison result; if the current signal strength is less than or equal to the upper limit threshold, the current signal strength is determined to be a valid detection signal; if the current signal strength is higher than the upper limit threshold, the signal is determined to be out of limit, the out-of-limit status is recorded, the dilution factor is increased and the online dilution and detection process is re-executed until a valid detection signal that has not exceeded the limit is obtained.

[0042] In the above process, the sample mixture dilution is introduced into the ICP-MS nebulizer at a stable flow rate of 0.4 mL per minute. Under the shearing action of high-purity argon gas (flow rate 1.0 L per minute), it is broken into tiny aerosols with an average particle size of less than 5 micrometers. The aerosols are carried by the carrier gas into an argon plasma torch at a temperature of approximately 8000 to 10000 Kelvin. After three steps of dissociation, atomization, and ionization, a positively charged ion beam is formed.

[0043] The ion beam enters the mass spectrometry analysis chamber through a sampling cone (1.0 mm aperture) and a truncation cone (0.4 mm aperture), and is separated according to the mass-to-charge ratio in a quadrupole mass analyzer. The ICP-MS detector (electron multiplier or Faraday cup) collects the ion counts of the target element at a specified mass number in real time. These ion counts are converted into digital signals by an analog-to-digital converter, and the output includes pulses per second (unit: counts per second) or the converted signal intensity value (unit: millivolts or microamps).

[0044] The detection signal strength is continuously read at a sampling period of 0.5 seconds. The signal strength of each sampling point is compared with the upper limit threshold preset in step S201. If the current signal strength is less than or equal to the upper limit threshold, the signal is determined to be a valid detection signal, the signal value is recorded, and the process proceeds to step S400. If the current signal strength is higher than the upper limit threshold, the signal is determined to be out of limit. The system records the out-of-limit status, the current out-of-limit signal value, and the excess ratio. Then, according to a preset step size (such as the initial dilution factor multiplied by 1.5) or according to the excess ratio, a new dilution factor is calculated once (the new factor is equal to the current factor multiplied by the ratio of the out-of-limit signal value to the threshold). The online dilution and detection process is restarted from step S200 until a valid detection signal that does not exceed the limit is obtained.

[0045] S400: Based on the actual dilution factor corresponding to the effective detection signal, combined with the effective detection signal intensity and standard curve parameters, the actual concentration of each target element in the original sample is calculated; the specific process is as follows: S401: Read the actual dilution factor used when a valid detection signal is obtained. This actual dilution factor is calculated from the real-time flow ratio of the sample pump and the diluent pump in this detection. S402: Extract the signal intensity value of the target element corresponding to the effective detection signal, as well as the signal intensity value of the internal standard element in the same detection batch, and use the internal standard signal to correct the signal fluctuations caused by short-term instrument drift and matrix effect; S403: Establish standard curve parameters. The standard curve is plotted by measuring standard solutions of known concentrations using the same online dilution process. S404: Substitute the corrected effective detection signal intensity into the standard curve equation to calculate the apparent concentration of the target element in the sample mixture dilution. S405: Multiply the apparent concentration by the actual dilution factor to obtain the actual concentration of the target element in the original sample.

[0046] Furthermore, in the step of substituting the corrected effective detection signal intensity into the standard curve equation to calculate the apparent concentration of the target element in the sample mixture dilution: Read the standard curve parameters, including the slope, intercept, and correlation coefficient of the standard curve; The effective detection signal intensity of the target element after internal standard correction is used as the vertical axis value. It is substituted into the standard curve equation to calculate the horizontal axis value corresponding to the signal intensity. This value is the apparent concentration of the target element in the sample mixed dilution. If the signal intensity of the target element exceeds the upper limit of the linear range of the standard curve, increase the dilution factor and re-detect; if the signal intensity is below the lowest concentration point of the standard curve, decrease the dilution factor and extend the integration time to improve detection sensitivity.

[0047] In the above process, the actual dilution factor used when obtaining a valid detection signal is read from the data buffer of the control software. This actual dilution factor is calculated by the ratio of the real-time flow rate of the sample pump to that of the diluent pump in this detection. The calculation formula is: the actual dilution factor equals the real-time flow rate of the sample pump plus the real-time flow rate of the diluent pump, and then divided by the real-time flow rate of the sample pump. The real-time flow rate is determined by the actual opening degree of the proportional valve and the flow calibration interpolation function obtained in step S104. It is updated once per second, and the average value after three seconds of stabilization is taken as the final actual dilution factor.

[0048] Extract the target element signal intensity value (unit: counts per second) corresponding to the effective detection signal from the detection data file, and simultaneously extract the signal intensity value of the internal standard element (such as rhodium 103 or indium 115) in the same detection batch; calculate the correction coefficient using the internal standard correction formula, which is equal to the signal intensity of the internal standard element at the midpoint of the standard curve divided by the measured signal intensity of the internal standard element in the current sample; then multiply the original signal intensity of the target element by the correction coefficient to obtain the corrected effective detection signal intensity, which is used to eliminate signal fluctuations caused by short-term instrument drift and matrix effects.

[0049] The specific process for establishing the parameters of the standard curve is as follows: First, prepare at least three standard solutions of different concentrations, for example, 1 microgram per liter, 10 micrograms per liter, 50 micrograms per liter, and 100 micrograms per liter. Secondly, each standard solution was diluted and detected online according to the same steps S200 and S300 as the sample, and the detection signal intensity corresponding to each concentration point after dilution was recorded. Then, with the theoretical concentration of the standard solution after dilution (i.e., the original concentration divided by the actual dilution factor) as the x-axis and the measured signal intensity as the y-axis, the least squares method was used to perform linear fitting, and the standard curve equation was obtained in the form that the signal intensity equals the slope multiplied by the apparent concentration plus the intercept. Simultaneously calculate the correlation coefficient; the correlation coefficient must be greater than 0.999 for the application to be valid. The slope, intercept, and correlation coefficient are stored as standard curve parameters in the system database.

[0050] If the internal standard method is used, the ratio of the concentration of the diluted standard solution to the concentration of the internal standard is used as the x-axis, and the ratio of the signal intensity of the target element to the signal intensity of the internal standard is used as the y-axis for fitting.

[0051] Read the standard curve parameters established in step S403 from the database, including slope a, intercept b, and correlation coefficient r.

[0052] The effective detection signal strength of the target element after correction in step S402 is denoted as I. correcedSubstitute into the standard curve equation to solve for the apparent concentration C. apparen The calculation formula is: C apparen =(I correced -b) / a.

[0053] If the internal standard method is used, the ratio of the target signal to the internal standard signal is first substituted into the corresponding equation to solve for the concentration ratio, and then multiplied by the internal standard concentration to obtain the apparent concentration.

[0054] Validate the solution results: If C apparen If C is negative, the signal is determined to be below the detection limit, and the apparent concentration is recorded as below the detection limit; if C apparen If the concentration exceeds 120% of the highest concentration point on the standard curve, it is determined to exceed the upper limit of the linear range. The system automatically records this and triggers an instruction to increase the dilution factor and retest; if C apparen If the concentration is below 50% of the lowest concentration point of the standard curve, it is determined to be outside the lower limit of the linear range. The system will suggest reducing the dilution factor or extending the integration time (e.g., from 0.5 seconds to 2 seconds) and then retesting.

[0055] For multiple target elements (such as simultaneous detection of lead, cadmium, and arsenic), the corrected signal intensity corresponding to each element is substituted into its respective independent standard curve equation in turn, and the apparent concentration of each target element in the mixed dilution is calculated and temporarily stored in the data buffer in the form of element name-apparent concentration key-value pairs.

[0056] Read the apparent concentration C of each target element from the data buffer. apparen Multiply by the actual dilution factor D obtained in step S401 acual Calculate the actual concentration C of the target element in the original sample to be tested. original The calculation formula is: C original =C apparen ×D acual .

[0057] After calculating each of the multiple target elements, all results are summarized to generate a test report containing the sample number, element name, actual concentration, concentration unit, test date, and dilution factor. The report is output to the display interface in tabular form and can be optionally saved as a CSV file.

[0058] Corresponding to the aforementioned embodiments of the inductively coupled plasma mass spectrometry (ICP-MS) electron dilution sample introduction and detection method, this application also provides embodiments of an ICP-MS electron dilution sample introduction and detection control system.

[0059] Figure 6 This is a schematic diagram illustrating the structural principle of an inductively coupled plasma mass spectrometry (ICP-MS) electron dilution sample introduction and detection control system according to an exemplary embodiment. (Refer to...) Figure 6 The system may include: a dilution flow path construction module, a dilution and injection module, a real-time monitoring and feedback adjustment module, and a concentration back-calculation module; wherein: The dilution flow path construction module is used to build an automatic dilution flow path, which includes a sample pump, a diluent pump, a proportioning valve, a mixing tee, and connecting tubing. The sample pump connects the sample storage end to the first interface of the mixing tee, the diluent pump connects the diluent storage end to the second interface of the mixing tee, the third interface of the mixing tee connects to the ICP-MS nebulizer inlet, and the proportioning valve is connected to the sample pump and the diluent pump for signal connection. The dilution and injection module is used to preset the initial dilution factor, the mass number corresponding to the target element, and the upper limit threshold of the signal intensity. It controls the sample pump and the diluent pump to extract the sample to be tested and the diluent respectively according to the flow ratio corresponding to the initial dilution factor through the proportional valve, and deliver them to the mixing tee to complete online uniform mixing to obtain the sample mixed diluent. The real-time monitoring and feedback adjustment module is used to send the uniformly mixed sample dilution into the ICP-MS nebulizer, and after nebulization and plasma dissociation, element detection is completed. The module collects the detection signal intensity of the target element at a specified mass number in real time, compares the detection signal intensity with the preset upper limit threshold of the signal intensity, and obtains the effective detection signal based on the comparison result. The concentration back-calculation module is used to back-calculate the actual concentration of each target element in the original sample based on the actual dilution factor corresponding to the effective detection signal, combined with the effective detection signal intensity and standard curve parameters.

[0060] In this embodiment, the dilution flow path construction module establishes an automatic dilution flow path, which includes a sample pump, a diluent pump, a proportioning valve, a mixing tee, and connecting tubing. The sample pump connects the sample storage end to the first interface of the mixing tee, the diluent pump connects the diluent storage end to the second interface of the mixing tee, and the third interface of the mixing tee connects to the ICP-MS nebulizer inlet. The proportioning valve is connected to both the sample pump and the diluent pump via signal connections. The dilution and injection module presets an initial dilution factor, the mass number corresponding to the target element, and a signal strength upper limit threshold. The proportioning valve controls the sample pump and the diluent pump to extract the sample and diluent at the flow rate ratio corresponding to the initial dilution factor, respectively, and delivers them to the mixing tee for online uniform mixing, resulting in a sample mixed dilution. The real-time monitoring and feedback adjustment module delivers the uniformly mixed sample dilution into the ICP-MS nebulizer. After nebulization and plasma dissociation, elemental detection is completed. The module acquires the detection signal intensity of the target element at a specified mass number in real time, compares the detection signal intensity with a preset upper limit threshold, and obtains the valid detection signal based on the comparison result. The concentration back-calculation module calculates the actual concentration of each target element in the original sample based on the actual dilution factor corresponding to the valid detection signal, combined with the valid detection signal intensity and standard curve parameters. In this way, the concentration of the original sample can be accurately calculated based on the valid detection signal, combined with the actual dilution factor and standard curve parameters, thereby improving the accuracy and efficiency of ICP-MS detection of high-concentration and complex matrix samples.

[0061] Regarding the system in the above embodiments, the specific ways in which each module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated here.

[0062] For the system embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0063] Accordingly, this application also provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; and, when the one or more programs are executed by the one or more processors, causing the one or more processors to implement the inductively coupled plasma mass spectrometry electron dilution injection detection method as described above. Figure 7The diagram shown is a hardware structure diagram of any device with data processing capabilities, which is part of an inductively coupled plasma mass spectrometry electron dilution sample introduction detection and control system provided in an embodiment of the present invention. Except for... Figure 7 In addition to the processor, memory, and network interface shown, any data processing device in the embodiment may also include other hardware depending on the actual function of the data processing device, which will not be described in detail here.

[0064] Accordingly, this application also provides a computer-readable storage medium storing computer instructions thereon, which, when executed by a processor, implement the inductively coupled plasma mass spectrometry electron dilution sample introduction detection method as described above. The computer-readable storage medium can be an internal storage unit of any data processing device as described in any of the foregoing embodiments, such as a hard disk or memory. The computer-readable storage medium can also be an external storage device, such as a plug-in hard disk, smart media card (SMC), SD card, flash card, etc., equipped on the device. Furthermore, the computer-readable storage medium can include both internal storage units of any data processing device and external storage devices. The computer-readable storage medium is used to store the computer program and other programs and data required by the data processing device, and can also be used to temporarily store data that has been output or will be output.

[0065] 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.

[0066] 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. A method for electron dilution sample introduction and detection in inductively coupled plasma mass spectrometry, characterized in that, Includes the following steps: An automated dilution flow path is constructed, which includes a sample pump, a diluent pump, a proportioning valve, a mixing tee, and connecting tubing. The sample pump connects the sample storage end to the first interface of the mixing tee, the diluent pump connects the diluent storage end to the second interface of the mixing tee, the third interface of the mixing tee connects to the sample inlet of the ICP-MS nebulizer, and the proportioning valve is connected to the signal of the sample pump and the diluent pump respectively. The initial dilution factor, the mass number corresponding to the target element, and the upper limit threshold of the signal strength are preset. The sample pump and the diluent pump are controlled by the proportional valve to extract the sample to be tested and the diluent according to the flow ratio corresponding to the initial dilution factor. They are then transported to the mixing tee to complete online uniform mixing and obtain the sample mixed diluent. The well-mixed sample dilution is fed into an ICP-MS nebulizer. After nebulization and plasma dissociation, elemental detection is completed. The detection signal intensity of the target element at a specified mass number is acquired in real time. The detection signal intensity is compared with the preset upper limit threshold of the signal intensity. The valid detection signal is obtained based on the comparison result. Based on the actual dilution factor corresponding to the effective detection signal, combined with the effective detection signal intensity and standard curve parameters, the actual concentration of each target element in the original sample to be tested is calculated.

2. The inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method as described in claim 1, characterized in that, In setting up an automated dilution flow path, which includes a sample pump, a diluent pump, a proportioning valve, a mixing tee, and connecting tubing; wherein the sample pump connects the sample storage end to the first interface of the mixing tee, the diluent pump connects the diluent storage end to the second interface of the mixing tee, the third interface of the mixing tee connects to the ICP-MS nebulizer inlet, and the proportioning valve is connected to the signal connections of the sample pump and the diluent pump respectively: Connect the sample pump to the sample solution container via PTFE tubing, and connect the diluent pump to the diluent container. Connect the outputs of the sample pump and diluent pump to the two input ports of the proportional valve, respectively. Connect the output port of the proportional valve to the two corresponding inlets of the mixing tee through a pipeline. Connect the common outlet of the mixing tee directly to the inlet of the ICP-MS nebulizer through a pipeline. Establish a feedback control link for the control signal line of the proportional valve; The entire flow path was tested for air tightness and calibrated for flow rate. The actual flow rate ratio between the sample end and the diluent end was calibrated using a standard solution at different valve openings, thus completing the construction and initialization of the automatic dilution flow path.

3. The inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method as described in claim 1, characterized in that, In the step of setting the initial dilution factor, the mass number corresponding to the target element, and the upper limit threshold of the signal strength, the sample pump and the diluent pump are controlled by a proportional valve to extract the sample to be tested and the diluent according to the flow ratio corresponding to the initial dilution factor, and then transported to the mixing tee to complete online uniform mixing to obtain the sample mixed diluent: Set the initial dilution factor for the sample to be tested, set the mass number of the target element to be analyzed, and set the upper limit threshold of the signal intensity based on the factory linear range of the ICP-MS detector and the background noise level. The flow ratio of the sample pump to the diluent pump is calculated based on the initial dilution factor. The flow ratio is then converted into a control signal for the proportional valve, which is used to drive the proportional valve to operate according to the corresponding time and opening ratio. Simultaneously start the sample pump and diluent pump to draw liquid from the sample storage end and diluent storage end, respectively. The two liquid streams meet and mix thoroughly inside the mixing tee to form a sample mixed diluent with uniform concentration.

4. The inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method as described in claim 3, characterized in that, In the process of feeding a uniformly mixed diluted sample solution into an ICP-MS nebulizer, performing nebulization and plasma dissociation to complete elemental detection, and acquiring the detection signal intensity of the target element at a specified mass number in real time, comparing the detection signal intensity with a preset upper limit threshold, and obtaining the valid detection signal based on the comparison result: The sample mixture and dilution solution is introduced into the ICP-MS nebulizer at a stable flow rate. Under the action of argon, it is broken down into tiny aerosols. The aerosols are carried into the high-temperature plasma torch by the carrier gas, and after dissociation, atomization and ionization, they form a positively charged ion beam. The ion beam enters the mass spectrometry analysis chamber through a sampling cone and a truncation cone, and is separated according to the mass-to-charge ratio. The ICP-MS detector collects the ion count of the target element with a specified mass number in real time. The ion count is output after analog-to-digital conversion. The output includes the number of pulses per second and the signal intensity value. The system continuously reads the strength of the detected signal, compares the detected signal strength with a preset upper limit threshold for signal strength, and outputs the comparison result.

5. The inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method as described in claim 4, characterized in that, In the step of continuously reading the detected signal strength, comparing the detected signal strength with a preset upper limit threshold for signal strength, and outputting the comparison result: If the current signal strength is less than or equal to the upper limit threshold, then the current signal strength is determined to be a valid detection signal.

6. The inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method as described in claim 5, characterized in that, In the step of continuously reading the detected signal strength, comparing the detected signal strength with a preset upper limit threshold for signal strength, and outputting the comparison result: If the current signal strength is higher than the upper limit threshold, the signal is determined to be out of limit, the out-of-limit status is recorded, the dilution factor is increased, and the online dilution and detection process is re-executed until a valid detection signal that is not out of limit is obtained.

7. The inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method as described in claim 1, characterized in that, In the step of back-calculating the actual concentration of each target element in the original sample based on the actual dilution factor corresponding to the effective detection signal, combined with the effective detection signal intensity and standard curve parameters: The actual dilution factor used to obtain a valid detection signal is read. This actual dilution factor is calculated from the real-time flow ratio of the sample pump to the diluent pump in this detection. Extract the signal intensity value of the target element corresponding to the effective detection signal, as well as the signal intensity value of the internal standard element in the same detection batch, and use the internal standard signal to correct the signal fluctuations caused by short-term instrument drift and matrix effect; Establish the parameters for the standard curve. The standard curve is plotted by measuring standard solutions of known concentrations using the same online dilution process. Substitute the corrected effective detection signal intensity into the standard curve equation to calculate the apparent concentration of the target element in the sample mixture dilution.

8. The inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method as described in claim 7, characterized in that, After substituting the corrected effective detection signal intensity into the standard curve equation to calculate the apparent concentration of the target element in the sample mixture dilution: Multiply the apparent concentration by the actual dilution factor to obtain the actual concentration of the target element in the original sample.

9. The inductively coupled plasma mass spectrometry electron dilution sample introduction and detection method as described in claim 8, characterized in that, In the step of substituting the corrected effective detection signal intensity into the standard curve equation to calculate the apparent concentration of the target element in the sample mixture dilution: Read the standard curve parameters, including the slope, intercept, and correlation coefficient of the standard curve; The effective detection signal intensity of the target element after internal standard correction is used as the vertical axis value. It is substituted into the standard curve equation to calculate the horizontal axis value corresponding to the signal intensity. This value is the apparent concentration of the target element in the sample mixed dilution. If the signal intensity of the target element exceeds the upper limit of the linear range of the standard curve, increase the dilution factor and re-detect; if the signal intensity is below the lowest concentration point of the standard curve, decrease the dilution factor and extend the integration time to improve detection sensitivity.

10. An inductively coupled plasma mass spectrometry (ICP-MS) electron dilution sample introduction and detection control system, employing the ICP-MS electron dilution sample introduction and detection method as described in claim 1, characterized in that, This includes a dilution flow path construction module, a dilution and injection module, a real-time monitoring and feedback adjustment module, and a concentration back-calculation module; among which: The dilution flow path construction module is used to build an automatic dilution flow path, which includes a sample pump, a diluent pump, a proportioning valve, a mixing tee, and connecting tubing. The sample pump connects the sample storage end to the first interface of the mixing tee, the diluent pump connects the diluent storage end to the second interface of the mixing tee, the third interface of the mixing tee connects to the ICP-MS nebulizer inlet, and the proportioning valve is connected to the sample pump and the diluent pump for signal connection. The dilution and injection module is used to preset the initial dilution factor, the mass number corresponding to the target element, and the upper limit threshold of the signal intensity. It controls the sample pump and the diluent pump to extract the sample to be tested and the diluent respectively according to the flow ratio corresponding to the initial dilution factor through the proportional valve, and deliver them to the mixing tee to complete online uniform mixing to obtain the sample mixed diluent. The real-time monitoring and feedback adjustment module is used to send the uniformly mixed sample dilution into the ICP-MS nebulizer, and after nebulization and plasma dissociation, element detection is completed. The module collects the detection signal intensity of the target element at a specified mass number in real time, compares the detection signal intensity with the preset upper limit threshold of the signal intensity, and obtains the effective detection signal based on the comparison result. The concentration back-calculation module is used to back-calculate the actual concentration of each target element in the original sample based on the actual dilution factor corresponding to the effective detection signal, combined with the effective detection signal intensity and standard curve parameters.

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