Sample ion detection methods and sample dilution methods

Abstract

This invention proposes a sample ion detection method and a sample dilution method, belonging to the field of trace detection technology. The method includes: obtaining the conductivity of the sample to be tested; substituting the conductivity into a preset dilution relationship function to obtain the dilution factor of the sample; diluting the sample according to the dilution factor to obtain a diluted sample; and then testing the diluted sample to obtain the ion concentration. Thus, after obtaining the sample, only the conductivity needs to be measured, and the accurate dilution factor can be obtained by substituting the conductivity into the dilution relationship function for sample dilution and testing. This achieves precise dilution and testing of different samples, that is, adaptably using appropriate dilution factors for different samples, thereby making the test data more accurate and the testing efficiency higher.

Description

Technical Field

[0001] This application relates to the field of trace detection technology, and more specifically, to a sample ion detection method and a sample dilution method. Background Technology

[0002] Ionic substance analysis is an indispensable indicator in research fields such as geography, environment, hydrology, chemical engineering, and materials science. Ion chromatography, due to its advantages such as fast analysis speed, high detection sensitivity, good selectivity, and simultaneous analysis of multiple ions, is currently an important instrument for analyzing ionic substances. When using ion chromatography to analyze anions and cations, the concentration of ions is often calculated based on the change in conductivity of the detection solution. Therefore, the conductivity of the sample is a crucial factor affecting the accuracy of the detection data. Too low a sample conductivity will lead to increased analytical errors, even falling below the detection limit, resulting in undetectable samples and wasted time; too high a conductivity indicates an excessively high sample concentration, which can overload the chromatographic column, cause peak tailing distortion, and even produce a memory effect that affects the analysis of subsequent samples.

[0003] When using ion chromatography to test anions and cations, unknown samples are typically injected after a 100-fold dilution. However, in studies across various fields such as geography, water resources, and materials science, the ion content of samples varies greatly, making it difficult to obtain satisfactory analytical samples using this method. This results in significant errors in the test data and low testing efficiency. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a sample ion detection method and a sample dilution method, which improves the accuracy of detection data and detection efficiency by more accurately diluting the sample.

[0005] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0006] In a first aspect, this application provides a method for detecting ions in a sample, the method comprising:

[0007] Obtain the conductivity of the sample to be tested, substitute the conductivity into a preset dilution relationship function, and use the dilution relationship function to obtain the dilution factor of the sample to be tested;

[0008] The test sample is diluted according to the dilution factor to obtain a diluted sample;

[0009] The diluted sample was tested to obtain the ion concentration.

[0010] Optionally, the step of obtaining the dilution relation function includes:

[0011] Multiple historical sample sets are obtained; wherein each historical sample set includes the conductivity of an original sample and the dilution factor of the original sample to the optimal detection concentration range.

[0012] Based on the historical sample set, the relationship between conductivity and dilution factor was fitted and trained to obtain the dilution relationship function.

[0013] Optionally, the step of fitting and training the relationship between conductivity and dilution factor based on the historical sample group to obtain the dilution relationship function includes:

[0014] Based on conductivity, the historical sample groups are divided into multiple segment groups; wherein the conductivity of each historical sample group in each segment group is within the same segment range.

[0015] For each of the segment groups, the conductivity of each of the historical sample groups in the segment group is fitted with the dilution factor to obtain the dilution relationship function.

[0016] Optionally, the step of fitting the conductivity and dilution factor of each historical sample group in the segmented group to obtain the dilution relationship function includes:

[0017] Multiple fitting methods were used to fit the conductivity and dilution factor of each historical sample group in the segmented group, resulting in multiple intermediate functions;

[0018] For each intermediate function, multiple verification sample groups are used to verify the intermediate function and obtain the error value;

[0019] The intermediate function with the smallest error value is selected as the dilution relationship function corresponding to the segment group.

[0020] Optionally, the step of testing the diluted sample to obtain the ion concentration includes:

[0021] The diluted sample was subjected to chromatographic testing to obtain test data;

[0022] Based on the blank signal, blank correction is performed on the test data to obtain corrected data;

[0023] Using the calibration data and a preset standard function, the test concentrations of various ions in the diluted sample are obtained; wherein, the standard function characterizes the relationship between the chromatographic test values ​​in the multi-ion mixed standard solution and the concentrations of ions in the multi-ion mixed standard solution;

[0024] Based on the test concentration and the dilution factor, the actual concentration of each ion in the test sample is obtained.

[0025] Optionally, the step of testing the diluted sample to obtain the ion concentration includes:

[0026] The diluted sample was subjected to chromatographic testing to obtain test data;

[0027] Using the test data and a preset standard function, the test concentrations of various ions in the diluted sample are obtained; wherein, the standard function characterizes the relationship between the chromatographic test value of the multi-ion mixed standard solution and the concentration of ions in the multi-ion mixed standard solution;

[0028] The test concentration is corrected based on the blank concentration to obtain the corrected concentration;

[0029] The actual concentration of each ion in the test sample is obtained based on the correction concentration and the dilution factor.

[0030] Optionally, the step of obtaining the standard function includes:

[0031] Configure the chromatographic test conditions for ions;

[0032] For each ion, under the corresponding chromatographic test conditions, the solution of the ion is subjected to chromatographic testing to obtain the upper limit of the linear response range of the chromatographic column to the ion;

[0033] The blank solution was subjected to multiple chromatographic tests to obtain the lower limit of determination of the concentration of each ion by the ion chromatograph;

[0034] Based on the upper limit of the linear response range and the lower limit of concentration determination of each ion, a variety of multi-ion mixed standard solutions with different concentrations were prepared.

[0035] Chromatographic tests were performed on each of the multi-ion mixed standard solutions, and a standard function was obtained based on the chromatographic test results and the ion concentrations in each of the multi-ion mixed standard solutions.

[0036] Optionally, the step of performing chromatographic testing on the solution of the ions under the corresponding chromatographic test conditions to obtain the upper limit of the linear response range of the chromatographic column to the ions includes:

[0037] Prepare a series of standard single-ion solutions for the ion; wherein the series of standard single-ion solutions includes multiple standard single-ion solutions;

[0038] Under the corresponding chromatographic test conditions, each of the standard single ion solutions is subjected to chromatographic testing to obtain the chromatographic peak characteristic value of each standard single ion solution; wherein, the chromatographic peak characteristic value includes peak height and peak area. Based on the chromatographic peak characteristic value and concentration of each of the standard single ion solutions, a relationship curve is obtained for sample ion detection.

[0039] Based on the changes in the relationship curve, the upper limit of the linear response range of the chromatographic column to the ion is obtained.

[0040] Optionally, the step of performing multiple chromatographic tests on the blank solution to obtain the lower limit of determination of the concentration of each ion by the ion chromatograph includes:

[0041] Perform multiple chromatographic tests on the blank solution and obtain the blank concentration of each ion for each test;

[0042] Based on the blank concentration, the standard deviation of each ion concentration is obtained;

[0043] For each ion, the lower limit of concentration determination for that ion is obtained by the ion chromatograph based on the standard deviation of the ion's concentration and the detection limit formula.

[0044] Secondly, this application provides a sample dilution method, the method comprising:

[0045] Obtain the conductivity of the sample to be tested, substitute the conductivity into a preset dilution relationship function, and use the dilution relationship function to obtain the dilution factor of the sample to be tested;

[0046] The test sample is diluted according to the dilution factor to obtain a diluted sample.

[0047] The sample ion detection method and sample dilution method provided in this application include: obtaining the conductivity of the sample to be tested; substituting the conductivity into a preset dilution relationship function to obtain the dilution factor of the sample to be tested using the dilution relationship function; diluting the sample to be tested according to the dilution factor to obtain a diluted sample; and then testing the diluted sample to obtain the ion concentration. Thus, after obtaining the sample to be tested, only the conductivity of the sample needs to be measured, and the accurate dilution factor can be obtained by substituting the conductivity into the dilution relationship function for sample dilution and testing. This achieves accurate dilution and testing of different samples, that is, adaptably using appropriate dilution factors for different samples to be tested, thereby making the test data more accurate and the testing efficiency higher.

[0048] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 One of the schematic flowcharts of the sample ion detection method provided in the embodiments of this application is shown.

[0051] Figure 2 The second schematic flowchart of the sample ion detection method provided in the embodiments of this application is shown.

[0052] Figure 3 It shows Figure 2 A flowchart illustrating some of the sub-steps in step 23.

[0053] Figure 4 It shows Figure 3 A flowchart illustrating some sub-steps of step 233.

[0054] Figure 5 It shows Figure 1 One of the flowcharts for some sub-steps in step 15.

[0055] Figure 6 It shows Figure 1 The second flowchart of some sub-steps in step 15.

[0056] Figure 7 The third schematic diagram of the sample ion detection method provided in the embodiments of this application is shown.

[0057] Figure 8 The diagram illustrates a relationship curve provided by an embodiment of this application.

[0058] Figure 9 It shows Figure 7 A flowchart illustrating some of the sub-steps in step 33.

[0059] Figure 10 It shows Figure 7 A flowchart illustrating some of the sub-steps in step 35. Detailed Implementation

[0060] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0061] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0062] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0063] The sample ion detection method provided in this application embodiment can be implemented using the sample ion detection system shown in the figure. The sample ion detection system includes an ion chromatograph, sample cups, test tubes, and computer equipment. The ion chromatograph includes components such as a high-pressure pump, a storage tank, an injection valve, an autosampler, a chromatographic column (including a pre-column, a guard column, and an analytical column), an inhibition system, a conductivity detector, and data processing software.

[0064] High-pressure infusion pump: Provides a stable flow rate to deliver the eluent to the chromatographic column. Ion chromatography eluents are often acidic or alkaline solutions, therefore the pump head is typically made entirely of PEEK material to prevent corrosion.

[0065] Storage tank: Used to store the rinsing solution, it is required to have a large enough volume and be easy to deaerate.

[0066] Sample injection valve: Used to introduce the sample into the system, it is usually made of full PEEK material to prevent corrosion. Sample injection valves can be manual or electric; autosamplers offer the best sample injection consistency.

[0067] Autosampler: Enables high-precision, highly repeatable sample injection operations, suitable for high-throughput analysis.

[0068] Guard column: Similar to analytical column packing, it is used to remove impurities in the sample that may damage the analytical column packing.

[0069] Analytical column: It is the core component of an ion chromatograph and is used to separate different ionic components in a sample.

[0070] The suppression system is one of the core components of ion chromatography, and its main function is to reduce background conductivity and improve detection sensitivity. Common suppression methods include column-gel suppression, ion exchange membrane suppression, and electrolytic self-regenerating membrane suppression.

[0071] Conductivity detector: The most commonly used detector, based on the principle of limiting molar conductivity, is used to detect inorganic anions and cations, organic acids and organic amines, etc.

[0072] Data processing software: used to record, process, and save detected signals.

[0073] When using ion chromatography to test anions and cations, unknown samples are typically diluted 100-fold before injection. However, in research fields such as geography, water resources, and materials science, the ion content of samples varies greatly. Directly diluting the sample 100-fold makes it difficult to obtain a good analytical sample, leading to large test data errors and low testing efficiency. To address these issues, this application provides a sample ion detection method, referring to... Figure 1 This includes steps 11 to 15. Furthermore, steps 11 to 15 are implemented using the sample ion detection system provided above.

[0074] Step 11: Obtain the conductivity of the sample to be tested, substitute the conductivity into the preset dilution relationship function, and use the dilution relationship function to obtain the dilution factor of the sample to be tested.

[0075] Step 13: Dilute the test sample according to the dilution factor to obtain the diluted sample.

[0076] Step 15: Test the diluted sample to obtain the ion concentration.

[0077] The test sample can be a solution from any research field such as geography, water resources, or materials. The dilution relationship function, obtained through a series of construction processes, characterizes the relationship between samples with different conductivity and the dilution factor of the optimal detection concentration range of the ion chromatograph. It can be a formula, a small program, or a relationship curve, and its form is not limited.

[0078] For example, using the sample ion detection system provided above, the sample to be tested is extracted and placed in a centrifuge tube. The conductivity of the sample is then measured at room temperature using a portable multi-parameter instrument. Furthermore, the testing personnel can use computer equipment to run a dilution function, substituting the conductivity into the function, and the computer equipment will calculate the dilution factor.

[0079] After obtaining the dilution factor, the testing personnel dilute the sample with deionized water according to the dilution factor and the volume of the sample to be tested, obtaining a diluted sample. Next, the testing personnel inject an appropriate amount of the diluted sample into the injection valve of the ion chromatograph for manual injection, or use an autosampler for automatic injection, to inject the diluted sample into the chromatographic column. After injection, chromatographic analysis is performed to obtain the ion concentration.

[0080] In steps 11 to 15 of the sample ion detection method, after obtaining the sample to be tested, it is only necessary to measure the conductivity of the sample and substitute the conductivity into the dilution relationship function to obtain the accurate dilution factor for sample dilution and testing. This achieves accurate dilution and testing of different samples, that is, it adaptively adopts appropriate dilution factors for different samples to be tested, thereby making the test data more accurate and the test efficiency higher.

[0081] The method of obtaining the dilution relationship function in step 11 above can be flexibly set. For example, it can be a function constructed by the inspector based on historical experience and skill level, or it can be a function constructed according to certain rules. Its implementation method is not restricted.

[0082] To quickly obtain accurate dilution factors, the sample ion detection method provided in this application also incorporates the concept of fitting and training historical data to obtain a coefficient relationship function. (Refer to...) Figure 2 The sample ion detection method provided in this application embodiment further includes steps 21 to 23.

[0083] Step 21: Obtain multiple historical sample groups.

[0084] Each historical sample group includes the conductivity of the original sample and the dilution factor of the original sample to the optimal detection concentration range. The original sample refers to the sample solution before dilution.

[0085] Step 23: Based on the historical sample groups, the relationship between conductivity and dilution factor is fitted and trained to obtain the dilution relationship function.

[0086] Steps 21 and 23 described above can be executed on a computer device. The number of historical sample groups can be any number, such as 1000, 2000, or 10000, and there is no limitation on the number. In addition, the historical sample groups can belong to the same field as the test samples in steps 11 to 15, or they can belong to different fields, which is also unrestricted.

[0087] In step 23, when performing fitting training, regression analysis methods such as linear fitting, polynomial regression, and nonlinear regression can be used, as well as curve fitting methods such as least squares, polynomial fitting, and curve straightening. Machine learning methods such as decision trees and random forests can also be used, and their implementation is unrestricted.

[0088] When expressed mathematically, the above dilution relationship function can include only one mathematical expression, that is, the same dilution relationship function is used to calculate the conductivity for all ranges, or different dilution relationship functions are used for different conductivity ranges.

[0089] To improve the accuracy of the dilution relationship function and obtain a more accurate dilution multiple, in step 23, the range segment of the specific conductivity is introduced, and the idea of fitting and training the dilution relationship function is proposed. Refer to Figure 3 , step 23 includes steps 231 to 233.

[0090] Step 231: Divide multiple historical sample groups into multiple segmented groups according to the specific conductivity.

[0091] Among them, the specific conductivity of each historical sample group in each segmented group is within the same segmented range.

[0092] Step 233: For each segmented group, fit the specific conductivity and the dilution multiple of each historical sample group in the segmented group to obtain the dilution relationship function.

[0093] The number of segments and the segmented range in step 231 can be set flexibly. For example, it can be divided into four segments, namely SEC < 150 us / cm, 150 us / cm < SEC < 1000 us / cm, 1000 us / cm < SEC < 5000 us / cm, and 5000 us / cm < SEC < 20000 us / cm. It can also be divided into three segments, namely SEC < 150 us / cm, 150 us / cm < SEC < 3000 us / cm, and 3000 us / cm < SEC < 20000 us / cm. The implementation method is not limited.

[0094] In step 233, any fitting method can be used for fitting and training, or it can be fitted and trained according to a preset rule. The implementation method is not limited.

[0095] To obtain a more accurate dilution relationship function, in step 233, the idea of using multiple fitting methods for each segmented group to fit and selecting the optimal one from the fitting results as the dilution relationship function is introduced. Refer to Figure 4 , the process of obtaining the dilution relationship function by fitting in step 233 includes steps 2331 to 2335.

[0096] Step 2331: Use multiple fitting methods to fit the specific conductivity and the dilution multiple of each historical sample group in the segmented group to obtain multiple intermediate functions.

[0097] Step 2333: For each intermediate function, use multiple verification sample groups to verify the intermediate function to obtain the error value.

[0098] The

[0099] Among them, similar to the historical sample group, each verification sample group includes the conductivity of an original sample and the actual dilution multiple of the original sample diluted to the optimal detection concentration range.

[0100] In step 2333, substitute the conductivity in the verification sample group into the intermediate function, solve the intermediate function to obtain the calculated dilution multiple. Furthermore, methods such as root mean square error and standard deviation are used to calculate the error value of the intermediate function based on the calculated dilution multiple and the actual dilution multiple.

[0101] For example, if the segmented groups are SEC < 150 us / cm, 150 us / cm < SEC < 1000 us / cm, 1000 us / cm < SEC < 5000 us / cm, and 5000 us / cm < SEC < 20000 us / cm respectively, the finally obtained dilution relationship function can be:

[0102]

[0103] Among them, y represents the dilution multiple, x represents the conductivity, and the unit is us / cm.

[0104] In the process of calculating the dilution multiple of the test sample using the dilution relationship function, the final dilution multiple can be obtained by rounding.

[0105] In an example, when the conductivity of the test sample is in the range of 150 us / cm < x ≤ 1000 us / cm, after rounding the solution result of the dilution relationship function to an integer, the final dilution multiple (i.e., the y value) is obtained. For example, if the solution result is 8.4, the dilution multiple is finally 8. When the conductivity of the test sample is in the range of 1000 us / cm < x ≤ 5000 us / cm or 5000 us / sm < x ≤ 20000 us / cm, after rounding the solution result of the dilution relationship function to a multiple of ten, the final coefficient multiple (i.e., the y value) is obtained. For example, if the solution result is 84, the dilution multiple is finally 80, and if the solution result is finally 85, the dilution multiple is finally 90.

[0106] Through the above method, the dilution relationship functions of each segmented group make the dilution relationship function more accurate, which helps to further improve the accuracy and test efficiency of test data. Thus, in step 11, the segmented range into which the conductivity of the test sample falls can be determined, and the dilution relationship function corresponding to this segmented range is used to obtain the dilution multiple of the test sample. In step 13, the test sample is diluted according to this dilution multiple to obtain a diluted sample. Furthermore, in step 15, the diluted sample is tested to obtain the ion concentration.

[0107] In step 15, the diluted sample is tested, and the method for obtaining the ion concentration can be flexibly selected. For example, the diluted sample can first be chromatographically tested using an ion chromatogram, and the ion chromatogram outputs test data (including the peak area and peak height of the ion chromatogram output signal, usually a chromatogram). After that, the test data can be analyzed by the testing personnel to obtain the ion concentration, or the actual concentration of each ion can be obtained by processing it using preset rules. The implementation method is not limited.

[0108] In one example, to obtain highly accurate ion concentrations, a pre-constructed standard function is introduced in step 15 (this standard function characterizes the relationship between the chromatographic test value of the multi-ion mixed standard solution and the concentration of each ion in the multi-ion mixed standard solution, the chromatographic test value including the peak height and peak area of ​​the signal output by the ion chromatograph after the chromatographic test) to calculate the ion concentration in combination with the test data of blank correction and diluted sample.

[0109] The blank correction method can be flexibly selected. For example, the background subtraction method, the standard curve method, or the internal standard method can be used for blank correction. The implementation method is not limited.

[0110] When using background subtraction for blank correction, refer to Figure 5 The process of obtaining ion concentration in step 15 includes steps 151A to 157A.

[0111] Step 151A: Perform chromatographic testing on the diluted sample to obtain test data.

[0112] The test data includes the peak height and peak area of ​​the output signal of the ion chromatograph, which is a chromatogram. The peak area is proportional to the concentration of each component (i.e., the ions contained) in the sample, and the peak height is also related to the concentration of each component in the sample.

[0113] Step 153A: Based on the blank signal, perform blank correction on the test data to obtain the corrected data.

[0114] The blank signal here refers to the signal output by the ion chromatograph after performing chromatographic analysis on the blank solution (deionized water), and it represents background interference. The calibration data includes calibration peak height and calibration peak area. Calibration peak height = peak height of the ion chromatograph output signal in the test data - peak height of the blank signal; calibration peak area = peak area of ​​the ion chromatograph output signal in the test data - peak area of ​​the blank signal.

[0115] Step 155A: Using the calibration data and the preset standard function, the test concentrations of various ions in the diluted sample are obtained.

[0116] The standard function characterizes the relationship between the chromatographic test results of the multi-ion mixed standard solution and the concentration of ions in the multi-ion mixed standard solution.

[0117] Step 157A: Based on the test concentration and dilution factor, obtain the actual concentration of each ion in the test sample.

[0118] When the standard function is a function relating peak area to the concentration of various ions, in step 155A, the corrected peak area is substituted into the standard function to determine the test concentration of various ions in the diluted sample.

[0119] When the standard function is a function relating peak height to the concentration of various ions, in step 153, the corrected peak height is substituted into the standard function to determine the test concentration of various ions in the diluted sample.

[0120] The ions used in this application may include chloride ions, nitrate ions, sulfate ions, sodium ions, potassium ions, calcium ions, and magnesium ions, etc. The specific types of ions are not limited.

[0121] Blank correction is performed using the standard curve method. The blank concentration is obtained beforehand using the standard curve method, and then used for correction in step 15. At this point, refer to... Figure 6 The process of obtaining ion concentration in step 15 includes steps 151B to 157B.

[0122] Step 151B: Perform chromatographic testing on the diluted sample to obtain test data.

[0123] Step 153B: Using the test data and a preset standard function, obtain the test concentration of various ions in the diluted sample.

[0124] Step 155B: Based on the blank concentration, the test concentration is corrected to obtain the corrected concentration.

[0125] Step 157B: Based on the calibration concentration and dilution factor, obtain the actual concentration of each ion in the test sample.

[0126] The principle of the standard curve method is as follows: by plotting the relationship curve between a series of standards with known concentrations and the instrument response, a standard curve is established. The concentration corresponding to the response value of the blank sample is found on the standard curve and used as the blank concentration.

[0127] In step 155B, the calibration concentration is obtained by subtracting the blank concentration from the test concentration.

[0128] It should be noted that in step 15, the internal standard method can also be used for blank correction. This involves adding a known amount of internal standard and performing quantitative analysis by measuring the signal ratio between the analyte and the internal standard. The internal standard method can correct errors caused by factors such as sample matrix effects and instrument fluctuations. When using the internal standard method, the same amount of internal standard is also added to the blank sample to correct the blank signal.

[0129] The standard function in steps 151A to 157A and steps 151B to 157B above may include multiple functions, each corresponding to the relationship between the concentration of an ion and the peak height or peak area of ​​the ion chromatograph output signal. The standard function may also be a single function, corresponding to the relationship between the peak height or peak area of ​​the ion chromatograph output signal and the concentration of various ions.

[0130] Through transformation, standard functions can have various forms of representation. For example, they can be represented as curves on graphs, expressed as mathematical formulas, developed as software tools running on computer devices, or as library functions, etc., and their form is not limited.

[0131] Furthermore, the method of obtaining the standard function can be flexibly chosen. For example, it can be obtained by fitting test data from historical experiments, or it can be obtained by constructing according to preset rules. The method of obtaining it is unrestricted.

[0132] To make the standard function more accurate, the sample ion detection method provided in this application introduces the concept of configuring a series of multi-ion mixed standard solutions with concentration gradients, and fitting and constructing a standard function based on their chromatographic test results. (Refer to...) Figure 7 The sample ion detection method provided in this application embodiment further includes steps 31 to 39.

[0133] Step 31: Configure the chromatographic test conditions for the ions.

[0134] Ions include both anions and cations. Chromatographic test conditions include those for anions and those for cations. Specific parameters for chromatographic test conditions include, but are not limited to: column type, eluent type, concentration, flow rate, suppressor type, suppressor current, and injection volume. The specific parameters of chromatographic test conditions vary depending on the ion chromatograph or testing requirements, and are not limited in scope.

[0135] In one example, the chromatographic parameters for cation analysis could be: CS12A column type, 20 mM methanesulfonic acid eluent, eluent flow rate of 1.0 mL / min, injection volume of 20 μL, CSRS-4 mm suppressor, and suppressor current of 59 mA. The parameters for anion analysis could be: AS14 column type, 3.5 mM / 1.0 mM sodium carbonate / sodium bicarbonate eluent, eluent flow rate of 1.2 mL / min, ASRS-4 mm suppressor, and suppressor current of 24 mA.

[0136] Step 33: For each ion, perform chromatographic testing on the ion solution under the corresponding chromatographic test conditions to obtain the upper limit of the linear response range of the chromatographic column to the ion.

[0137] Step 35: Perform multiple chromatographic tests on the blank solution to obtain the lower limit of determination of the concentration of each ion by the ion chromatograph.

[0138] Step 37: Based on the upper limit of the linear response range and the lower limit of concentration determination of each ion, prepare a variety of multi-ion mixed standard solutions with different concentrations.

[0139] Step 39: Perform chromatographic tests on the mixed standard solutions of each ion, and obtain the standard function based on the chromatographic test results and the ion concentrations in the mixed standard solutions of each ion.

[0140] The upper limit of the linear response range is a concentration value. It refers to the maximum ion concentration value within the range where the output signal of the chromatographic test and the ion concentration of the solution change linearly. For example... Figure 8 As shown, there is a relationship curve. The AB segment of the relationship curve shows a linear relationship, and B is the upper limit of the linear response range.

[0141] The lower limit of concentration determination is the lowest concentration that an ion chromatograph can detect.

[0142] In step 33, the chromatographic test conditions corresponding to the ion are determined by the charge it carries. For example, when the ion is a negatively charged anion, the corresponding chromatographic test conditions are those for anions. Conversely, if the ion is a positively charged anion, the corresponding chromatographic test conditions are those for cations.

[0143] In step 33, the method for obtaining the upper limit of the linear response range of the ions can be flexibly chosen. For example, it can be obtained manually by the detection personnel, or it can be obtained after processing according to preset rules; the method of implementation is unrestricted.

[0144] In one example, refer to Figure 9In step 33, the upper limit of the linear response range of the ion is obtained through steps 331 to 337.

[0145] Step 331: Prepare a series of standard single-ion solutions of ions.

[0146] The series of standard single-ion solutions includes multiple standard single-ion solutions with varying ion concentrations. The number of standard single-ion solutions in the series can be flexibly selected; for example, there can be at least five or at least seven, without limitation.

[0147] In step 331, multiple test solutions for the ions can be prepared manually by the testing personnel or automatically by automated equipment, with the ion concentrations of the multiple test solutions exhibiting a gradient. Then, matching chromatographic testing conditions are selected, and chromatographic tests are performed on each test solution to obtain the test results for each solution. Here, the obtained test results are still the peak height and peak area of ​​the ion chromatograph output signal.

[0148] Step 333: Under the corresponding chromatographic test conditions, perform chromatographic tests on each standard single ion solution to obtain the chromatographic peak characteristic values ​​of each standard single ion solution.

[0149] Among them, the characteristic value of chromatographic peak refers to the characteristic value of the output signal during chromatographic testing, including peak height and peak area.

[0150] Step 335: Obtain the relationship curve based on the chromatographic peak characteristic values ​​and concentrations of each standard single ion solution.

[0151] Step 337: Based on the changes in the relationship curve, obtain the upper limit of the linear response range of the chromatographic column to ions.

[0152] Here, the concentration in step 335 refers to the concentration of ions. In step 335, either plotting or function fitting is used to obtain a relationship curve. The maximum concentration in the linear segment of the relationship curve is the upper limit of the linear response range of the chromatographic column to the ions.

[0153] Using the above method, the upper limit of the linear response range of the chromatographic column to ions can be obtained quickly and accurately.

[0154] In step 35, the number of chromatographic tests on the blank solution can be adjusted as needed. For example, it can be at least five times, at least seven times, or at least 20 times, and the number is not limited.

[0155] Furthermore, the method for obtaining the lower limit of concentration determination (also known as the minimum measurable concentration) can be flexibly set, and its implementation is unrestricted.

[0156] In one example, under the chromatographic test conditions for ions, multiple blank tests were performed. The standard deviation of the output signal of the ion chromatograph during the multiple blank tests was then substituted into the detection limit formula to obtain the lower limit of concentration determination.

[0157] In another example, refer to Figure 10 The process of obtaining the lower limit of concentration determination includes steps 351 to 355.

[0158] Step 351: Perform multiple chromatographic tests on the blank solution and obtain the blank concentration of each ion for each test.

[0159] Here, blank concentration refers to the concentration of ions in the blank solution (which can be deionized water), and these ions are the ions to be measured in the test sample.

[0160] Step 353: Based on the blank concentration, obtain the standard deviation of the concentration of each ion.

[0161] Step 355: For each ion, based on the standard deviation of ion concentration and the detection limit formula, obtain the lower limit of ion concentration determination for the ion chromatograph.

[0162] In step 353, the standard deviation formula is used to calculate the concentration standard deviation for each ion. For example, if the blank test is performed 7 times, each ion has 7 blank concentrations (obtained in each blank test). For each ion, the standard deviation formula is used to calculate the standard deviation of the ion based on the 7 blank concentrations.

[0163] The formula for the detection limit is: MDL = t (n-1,0.99) ×S, MDL characterizes the detection limit, t (n-1,0.99) The degrees of freedom are represented by S, the standard deviation is represented by S, and the number of blank experiments (i.e., the number of parallel determinations) is represented by n.

[0164] The values ​​for degrees of freedom can be found in Table 1 below.

[0165] Table 1

[0166] n 7 8 9 10 11 16 21 n-1 6 7 8 9 10 15 20 <![CDATA[t (n-1,0.99) ]]> 3.143 2.998 2.896 2.821 2.764 2.602 2.528

[0167] Substituting the standard deviation of the signal into the formula for the limit of detection (LOD) yields the LOD. Multiplying the LOD by a preset multiple gives the lower limit of ion concentration determination for the ion chromatograph. For example, the lower limit of ion concentration determination can be four times the LOD. This preset multiple can also be three, or any other value; there are no restrictions.

[0168] In other examples, the blank concentration mentioned above can also be replaced with blank content, which is not restricted.

[0169] Using the above method, the lower limit of ion concentration determination for ion chromatography can be obtained quickly and accurately.

[0170] Furthermore, in step 37, based on the upper limit of the linear response range and the lower limit of concentration determination of each ion, a variety of multi-ion mixed standard solutions with different concentrations are prepared.

[0171] The rules for preparing multi-ion mixed standard solutions are as follows: (1) The maximum standard concentration of each ion (in actual detection, the maximum standard concentration is generally less than or equal to 20 mg / L) is equal to 70% of the upper limit of its linear response range, and the minimum standard concentration is equal to the lower limit of concentration determination; (2) Based on the maximum and minimum standard concentrations of each ion, prepare a series of multi-ion mixed standard solutions with concentration gradients (at least 5).

[0172] In one example, the maximum standard concentration can also be determined by combining the upper limit of the linear response range, the expected concentration of the analyte, and the need to achieve high-precision quantitative analysis.

[0173] The 70% mentioned above is just an example; other values ​​can be used instead.

[0174] After preparing the multi-ion mixed standard solutions, step 39 involves sequentially performing chromatographic tests on each multi-ion mixed standard solution. Based on the chromatographic test results (peak height / peak area of ​​the output signal) and the ion concentrations in each multi-ion mixed standard solution, a standard function is fitted. The method for fitting the standard function is similar to the method for obtaining the dilution relationship function described above, and will not be repeated here.

[0175] Therefore, by using the sample ion detection method provided above, given the known conductivity of the test sample solution, the dilution factor of the test solution can be quickly calculated without the need for dilution experiments. This simple method greatly improves the detection efficiency of the ion chromatograph.

[0176] Based on the same concept as the above-described sample ion detection method, this application embodiment also provides a sample dilution method, including steps 11 to 13 provided above.

[0177] Step 11: Obtain the conductivity of the sample to be tested, substitute the conductivity into the preset dilution relationship function, and use the dilution relationship function to obtain the dilution factor of the sample to be tested.

[0178] Step 13: Dilute the test sample according to the dilution factor to obtain the diluted sample.

[0179] The implementation methods and effects of steps 11 to 13 above can be found in the relevant descriptions above, and will not be repeated here.

[0180] The sample dilution method provided in this application is simple to operate and highly operable. It can quickly provide suitable dilution factors for different test samples, greatly improving experimental efficiency. Furthermore, it helps to improve the accuracy and efficiency of chromatographic testing.

[0181] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for detecting ions in a sample, characterized in that, The method includes: Obtain the conductivity of the sample to be tested, substitute the conductivity into a preset dilution relationship function, and use the dilution relationship function to obtain the dilution factor of the sample to be tested; The test sample is diluted according to the dilution factor to obtain a diluted sample; The diluted sample was tested to obtain the ion concentration; The steps for obtaining the dilution relation function include: Multiple historical sample sets are obtained; wherein each historical sample set includes the conductivity of an original sample and the dilution factor of the original sample to the optimal detection concentration range. Based on conductivity, the historical sample groups are divided into multiple segment groups; wherein the conductivity of each historical sample group in each segment group is within the same segment range. For each of the segment groups, multiple fitting methods are used to fit the conductivity and dilution factor of each of the historical sample groups in the segment group to obtain multiple intermediate functions; For each intermediate function, multiple verification sample groups are used to verify the intermediate function and obtain the error value; The intermediate function with the smallest error value is selected as the dilution relationship function corresponding to the segment group.

2. The sample ion detection method according to claim 1, characterized in that, The step of testing the diluted sample to obtain the ion concentration includes: The diluted sample was subjected to chromatographic testing to obtain test data; Based on the blank signal, blank correction is performed on the test data to obtain corrected data; Using the calibration data and a preset standard function, the test concentrations of various ions in the diluted sample are obtained; wherein, the standard function characterizes the relationship between the chromatographic test value of the multi-ion mixed standard solution and the concentration of each ion in the multi-ion mixed standard solution. Based on the test concentration and the dilution factor, the actual concentration of each ion in the test sample is obtained.

3. The sample ion detection method according to claim 1, characterized in that, The step of testing the diluted sample to obtain the ion concentration includes: The diluted sample was subjected to chromatographic testing to obtain test data; Using the test data and a preset standard function, the test concentrations of various ions in the diluted sample are obtained; wherein, the standard function characterizes the relationship between the chromatographic test value of the multi-ion mixed standard solution and the concentration of ions in the multi-ion mixed standard solution; The test concentration is corrected based on the blank concentration to obtain the corrected concentration; The actual concentration of each ion in the test sample is obtained based on the correction concentration and the dilution factor.

4. The sample ion detection method according to claim 2 or 3, characterized in that, The steps for obtaining the standard function include: Configure the chromatographic test conditions for ions; For each ion, under the corresponding chromatographic test conditions, the solution of the ion is subjected to chromatographic testing to obtain the upper limit of the linear response range of the chromatographic column to the ion; The blank solution was subjected to multiple chromatographic tests to obtain the lower limit of determination of the concentration of each ion by the ion chromatograph; Based on the upper limit of the linear response range and the lower limit of concentration determination of each ion, a variety of multi-ion mixed standard solutions with different concentrations were prepared. Chromatographic tests were performed on each of the multi-ion mixed standard solutions, and a standard function was obtained based on the chromatographic test results and the ion concentrations in each of the multi-ion mixed standard solutions.

5. The sample ion detection method according to claim 4, characterized in that, The step of performing chromatographic testing on the solution of the ions under the corresponding chromatographic test conditions to obtain the upper limit of the linear response range of the chromatographic column to the ions includes: Prepare a series of standard single-ion solutions for the ion; wherein the series of standard single-ion solutions includes multiple standard single-ion solutions; Under the corresponding chromatographic test conditions, each of the standard single ion solutions is subjected to chromatographic testing to obtain the chromatographic peak characteristic value of each standard single ion solution; wherein, the chromatographic peak characteristic value includes peak height and peak area. Based on the chromatographic peak characteristic value and concentration of each of the standard single ion solutions, a relationship curve is obtained for sample ion detection. Based on the changes in the relationship curve, the upper limit of the linear response range of the chromatographic column to the ion is obtained.

6. The sample ion detection method according to claim 4, characterized in that, The step of performing multiple chromatographic tests on the blank solution to obtain the lower limit of determination of each ion concentration by the ion chromatograph includes: Perform multiple chromatographic tests on the blank solution and obtain the blank concentration of each ion for each test; Based on the blank concentration, the standard deviation of each ion concentration is obtained; For each ion, the lower limit of concentration determination for that ion is obtained by the ion chromatograph based on the standard deviation of the ion's concentration and the detection limit formula.

7. A sample dilution method, characterized in that, The method includes: Obtain the conductivity of the sample to be tested, substitute the conductivity into a preset dilution relationship function, and use the dilution relationship function to obtain the dilution factor of the sample to be tested; The test sample is diluted according to the dilution factor to obtain a diluted sample; The steps for obtaining the dilution relation function include: Multiple historical sample sets are obtained; wherein each historical sample set includes the conductivity of an original sample and the dilution factor of the original sample to the optimal detection concentration range. Based on conductivity, the historical sample groups are divided into multiple segment groups; wherein the conductivity of each historical sample group in each segment group is within the same segment range. For each of the segment groups, multiple fitting methods are used to fit the conductivity and dilution factor of each of the historical sample groups in the segment group to obtain multiple intermediate functions; For each intermediate function, multiple verification sample groups are used to verify the intermediate function and obtain the error value; The intermediate function with the smallest error value is selected as the dilution relationship function corresponding to the segment group.

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