A method for correcting matrix effect of graphite furnace atomic absorption method

Abstract

The application provides a correction method for matrix effect of graphite furnace atomic absorption method, comprising the following steps: checking the absorbance-time real-time signal of the highest concentration value of a standard curve according to a preset temperature rising program; if the absorbance-real-time signal is not ideal, optimizing the temperature rising program by using a sample to be measured to obtain an optimized temperature rising program; detecting the absorbance corresponding to the concentration point on the standard curve according to the optimized temperature rising program to obtain a standard curve; testing the standard curve; detecting the sample to be measured by using the standard curve method, correcting by using parallel samples and testing whether there is interference of matrix effect. In the application, the molecular absorption interference and light scattering interference phenomenon caused by the matrix effect can be partially displayed in the real-time signal of the graphite furnace atomic absorption spectrometer, and can be corrected and eliminated by optimizing the graphite furnace temperature rising program or combining the dilution enrichment program and the parallel sample detection method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of detection methods, and particularly relates to a correction method for matrix effect of a graphite furnace atomic absorption method. BACKGROUND

[0002] The matrix effect refers to various interferences caused by one or more components coexisting with the analyte in the sample. The graphite furnace temperature program is divided into four stages: drying, ashing, atomization, and cleaning; the drying can remove moisture; the ashing can remove the matrix solvent (matrix); the atomization can convert the target element in the sample into atoms; and the cleaning can remove the residual target element to be measured in the graphite tube. The background absorption interference includes molecular absorption, which can be generated in the atomization process or before the atom. The non-characteristic gas molecules, oxides and salt molecules generated by the matrix solution in the atomization process cause interference to the characteristic radiation absorption. The molecular absorption can also be generated before the atomic absorption signal, which is mainly caused by the uneven distribution of sample vapor in the graphite furnace, resulting in uneven spatial distribution of background absorption. The background absorption interference also includes light scattering, which is caused by solid particles and aerosols generated in the atomization process, so that the scattered light deviates from the light path and is not detected by the detector. In summary, the matrix effect causes background absorption interference, molecular absorption interference and light scattering interference, which can occur in the drying and ashing stages before atomization, or in the atomization process. If it occurs in the drying and ashing stages before atomization, it can reduce the atomization signal; if it occurs in the atomization process, it can increase / decrease the atomization signal, and if the interference is serious, the graphite furnace atomic absorption detection cannot be completed.

[0003] The detection method of matrix interference is suitable for samples with a certain concentration, specifically: two samples of the same sample are taken, one of which is diluted 5 times (1+4), and the measured value of the diluted sample (not less than 10 times the detection limit) is multiplied by the dilution multiple and compared with the measured value of the undiluted sample, and the relative deviation within ±10% is considered to have no interference; otherwise, it indicates that there is interference, and dilution or standard addition method can be used to eliminate; when the concentration of the diluted sample is lower than 10 times the detection limit, the relative deviation of the slope of the standard addition method curve and the slope of the standard curve within ±3% is considered to have no interference; otherwise, it indicates that there is matrix interference.

[0004] Methods for correcting interference include spectral-based methods such as the deuterium lamp method. Deuterium lamps are continuous light sources; if there is strong absorption by coexisting elements within the instrument's spectral passband, it will be mistakenly treated as "background" and subtracted from the total absorbance. This phenomenon is more pronounced in graphite furnaces. The Zeeman effect method corrects background interference, but the equipment is complex and cannot be applied to all atomic absorption spectrometers. The hollow cathode lamp self-absorption method corrects background interference by utilizing the broadening of the emission lines of the hollow cathode lamp under high current, which generates self-absorption to measure background absorption. However, some elemental spectral lines readily self-absorb, having little impact on sensitivity, while others are difficult to self-absorb from the hollow cathode lamp, resulting in significant sensitivity loss after background correction. The disadvantages of spectral-based interference correction are: complex operation and high requirements for the atomic absorption spectrometer; in terms of instrument management, background correction capabilities need to be tested, and only qualified instruments can be used.

[0005] Another method for correcting interference is the standard addition method. Specifically, four equal amounts of the same test sample are measured and four identical solutions are prepared. The first solution is not added to the standard solution. The second, third, and fourth solutions are added to standard solutions of different concentrations in proportions, namely: C... x C x +C0、C x +2C0、C x +3C0, the mass concentration of the added standard solution is approximately equal to 0.5 times the mass concentration of the sample, i.e., C x ≈0.5C0. Under the same test conditions, the absorbance of four solutions was measured. A calibration curve was established with the mass concentration of the added standard solution as the x-axis and the corresponding absorbance as the y-axis. The intersection of the inverse extension of the curve with the concentration axis is the mass concentration of the test sample. This method is only applicable to regions where mass concentration and absorbance are linearly related. Precautions for the standard addition method: The volume error caused by adding the standard solution should not exceed 0.5%; the standard addition method can only offset the influence of matrix effects, not eliminate the influence of background absorption; it is only applicable to regions where sample concentration and absorbance are linearly related. Standard addition method suitability assessment: Measure the absorbance of the test sample as A, find the concentration as x from the standard curve, add a standard solution to the test sample with a spiking concentration of S, measure its absorbance as B, and find the concentration as y from the standard curve. Use the standard addition method suitability assessment formula to determine if the standard addition method is applicable. When C = x, i.e., S / (yx) = 1, the standard solution calibration curve method (abbreviated as: standard curve method) can be used. When matrix effects exist, S / (yx) is between 0.5 and 1.5, and the standard addition method can be used. If S / (yx) exceeds this range, the standard addition method is no longer applicable, and the matrix must be separated before measurement.

[0006] In the existing atomic absorption technology detection, for the sample with a large amount of matrix and unknown matrix content, the standard addition method is generally used to eliminate the matrix interference. The standard addition method has more strict application scope, the calibration curve should be strictly in the linear range, and the absorbance value is preferably in the range of 0.100-0.200; and the standard addition method has large workload, and is not suitable for large batch sample analysis and determination; the standard addition method is to add standard solutions with different concentrations into the sample, so that each calibration curve can only measure one sample; if the concentration of the sample to be tested is too high or too low, the standard addition method is not suitable, and the matrix should be separated in advance, but the separation of the matrix is complicated and difficult when the matrix composition is unknown. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a correction method for the matrix effect of the graphite furnace atomic absorption method, and the method provided by the present application is simple and can accurately correct the matrix effect.

[0008] The present application provides a correction method for the matrix effect of the graphite furnace atomic absorption method, comprising:

[0009] checking the absorbance-time real-time signal of the highest concentration value of the standard curve according to the preset temperature rising program;

[0010] If the absorbance-real-time signal is not ideal, the absorbance-time real-time signal of the sample to be tested is used to optimize the temperature rising program to obtain an optimized temperature rising program;

[0011] detecting the absorbance corresponding to the concentration point on the standard curve according to the optimized temperature rising program to obtain the standard curve;

[0012] checking the standard curve;

[0013] detecting the sample to be tested by the standard curve method, and correcting and checking whether there is interference of the matrix effect by using parallel samples.

[0014] Preferably, before checking the absorbance-time real-time signal of the highest concentration value of the standard curve according to the preset temperature rising program, the method further comprises:

[0015] peak searching, and the energy of the peak searching is 98-102%;

[0016] energy checking, and the energy checking comprises:

[0017] adjusting the light path to be optimal, the energy checking is 100%, and after placing the graphite tube, the energy is not less than 75%.

[0018] Preferably, the preset temperature rising program comprises:

[0019] one-step drying, one-step ashing, atomization and cleaning;

[0020] The temperature rising time of the one-step drying is 4-6s, the drying temperature is 90-110℃, and the holding time is 8-12s;

[0021] The temperature rising time of the one-step ashing is 4-6s, the ashing temperature is the highest temperature without loss of the element to be detected, and the holding time is 8-12s;

[0022] The temperature of the atomization is the lowest temperature corresponding to the maximum absorbance signal of the element to be detected, and the holding time is 2-4s;

[0023] The temperature of the cleaning is 90-110℃ higher than the atomization temperature, and the holding time is 1-2s.

[0024] Preferably, the absorbance-time real-time signal of the highest concentration value of the standard curve checked according to the preset temperature rising program further comprises:

[0025] The absorbance-time real-time signal of the zero-point concentration value of the standard curve according to the preset temperature rising program; and / or;

[0026] The absorbance-time real-time signal of the empty burning graphite tube according to the preset temperature rising program.

[0027] Preferably, the method for optimizing the temperature rising program by using the absorbance-time real-time signal of the sample to be detected comprises:

[0028] The absorbance-time real-time signal of the sample to be detected is detected according to the preset temperature rising program, if the absorbance-time real-time signal is not ideal, the abnormal peak position in the absorbance-time real-time signal is checked, if the temperature corresponding to the abnormal peak position is <120℃, the drying stage is optimized, if the temperature corresponding to the abnormal peak position is ≥120℃ and <the atomization temperature, the ashing stage is optimized.

[0029] The method for optimizing the temperature rising program by using the absorbance-time real-time signal of the sample to be detected further comprises:

[0030] If the concentration corresponding to the absorbance of the sample to be detected is ≥the second highest concentration of the standard curve, the sample to be detected is diluted and then the temperature rising program is optimized, the concentration C1 after dilution satisfies: 3 times the lower limit of determination ≤C1 <the second highest concentration of the standard curve.

[0031] Preferably, the method for optimizing the drying stage comprises:

[0032] If the real-time absorbance-time signal is not ideal, continue to optimize, check the position of the abnormal peak of the real-time absorbance-time signal, if the temperature corresponding to the abnormal peak position is < 120℃, continue to increase one step drying, carry out three-step drying, check the real-time absorbance-time signal, if the real-time absorbance signal is still not ideal, continue to optimize, check the position of the abnormal peak of the real-time absorbance-time signal, if the temperature corresponding to the abnormal peak position is < 120℃, increase the temperature rising time and holding time of the corresponding drying stage without changing the three-step drying temperature;

[0033] The method for optimizing the ashing stage comprises:

[0034] If the real-time absorbance-time signal is not ideal, continue to optimize, check the position of the abnormal peak of the real-time absorbance-time signal, if the temperature corresponding to the abnormal peak position is ≥ 120℃ and < atomization temperature, continue to increase one step ashing, carry out three-step ashing, check the real-time absorbance-time signal, if the real-time absorbance signal is still not ideal, continue to optimize, check the position of the abnormal peak of the real-time absorbance-time signal, if the temperature corresponding to the abnormal peak position is ≥ 120℃ and < atomization temperature, increase the temperature rising time and holding time of the corresponding ashing stage without changing the three-step ashing temperature.

[0035] Preferably, the method for optimizing the temperature rising program by using the real-time absorbance-time signal of the sample to be tested further comprises:

[0036] If the total increase time of the optimized drying stage and the optimized ashing stage is > 90s, dilute the sample to be tested before optimizing the temperature rising program, and the dilution multiple is ≤ 20 times.

[0037] Preferably, the abnormal peak further comprises:

[0038] The atomization peak type abnormality comprises:

[0039] The atomization peak is not a sharp single peak, the atomization peak has a tailing phenomenon and / or the peak tail of the atomization peak is higher than the empty burning value level.

[0040] Preferably, the testing of the standard curve comprises:

[0041] Detecting the slope, intercept, regression standard deviation, and residual of the standard curve.

[0042] Preferably, the method for correcting and checking whether there is interference of matrix effect by using parallel samples comprises:

[0043] The concentration of the sample to be detected is C1 according to the optimized temperature rising procedure:

[0044] If 1-fold determination lower limit ≤ C1 < 2-fold determination lower limit, the parallel sample is treated by adding standard to obtain C2 solution, the adding standard multiple is not less than 1.25 times and not more than 3 times, the adding standard multiple is J 加标 ; if C1 = (85-115%) (1 / J 加标 ) × C2, it is considered that there is no interference during atomization;

[0045] If 2-fold determination lower limit ≤ C1 < 3-fold determination lower limit, the parallel sample is treated by adding standard or dilution to obtain C2 solution, the adding standard multiple is J 加标 , the dilution multiple is N 检测稀释 , the C2 solution treated by adding standard or dilution simultaneously satisfies: 2-fold determination lower limit ≤ C2 < 4-fold determination lower limit; if C1 = (90-110%) (N 检测稀释 or 1 / J 加标 ) × C2, it is considered that there is no interference during atomization;

[0046] If 3-fold determination lower limit ≤ C1 < the concentration of the second highest point of the standard curve, the parallel sample is treated by dilution to obtain C2, the dilution multiple is N 检测稀释 , 2-fold determination lower limit ≤ C2; if C1 = (95-105%) N 检测稀释 × C2, it is considered that there is no interference during atomization;

[0047] If the concentration of the second highest point of the standard curve ≤ C1, the parallel sample is treated by dilution twice to obtain solutions CC1 and CC2, the concentration of CC1 is greater than the concentration of CC2, the dilution multiples are N 检测稀释1 and N 检测稀释2 respectively; simultaneously satisfy: 3-fold determination lower limit ≤ CC1 < the concentration of the second highest point of the standard curve, 3-fold determination lower limit ≤ CC2 < the concentration of the second highest point of the standard curve; if N 检测稀释1 CC1 = (95-105%) N 检测稀释2 × CC2, it is considered that there is no interference during atomization;

[0048] If the detection limit ≤ C1 < determination lower limit, the parallel sample is treated by adding standard or dilution to obtain C2 solution, the adding standard multiple is not less than 1.25 times and not more than 3 times, the adding standard multiple is J 加标 ; the dilution multiple is not less than 1.25 times and not more than 2 times, the dilution multiple is N 检测稀释 ; the concentration of the C2 solution obtained by dilution should be not less than the detection limit; if C1 = (75-125%) (1 / J 加标 ) × C2, it is considered that there is no interference during atomization;

[0049] If C1 < MDL, and no dilution is performed when optimizing the temperature program, judge whether there is interference in atomization: if C1 solution is measured 7 times, t 单侧检验(7次，0.95) x S 7次C1溶液测定浓度值 ≤ MDL, it is considered that there is no interference in atomization.

[0050] If C1 < MDL, and dilution is performed when correcting the temperature program, 1 < N 升温稀释 ≤ 10, the enrichment program is performed until the concentration after enrichment is greater than the MDL, and the enrichment multiple is recorded as F 富集 , 1 < F 富集 ≤ 10, C 试样最终测定结果 = N 升温稀释 x (1 / F 富集 ) x C1; if the enrichment multiple exceeds 10 times and is still not greater than the MDL, stop enrichment, and the test result of the sample is not detected; judge whether there is interference in atomization: if C1 solution before enrichment is measured 7 times, t 单侧检验(7次，0.95) x S 7次未富集前C1溶液测定浓度值 ≤ MDL; at the same time, enrichment is performed twice, and CC1 and CC2 are obtained, if CC1 = (70-130%) CC2; if the above two conditions are met, it is considered that there is no interference in atomization.

[0051] The application is applied in the field of graphite furnace atomic absorption environmental sample detection, corrects the interference of the matrix in atomic absorption determination in the environmental sample, and in order to realize the precise correction method of the matrix effect, needs to test in the linear range of the monadic linear regression standard curve based on the least square method, ensures that the monadic linear regression standard curve of the least square method is a straight line, so that the matrix effect interference in the atomization process can be corrected. If the molecular absorption interference and light scattering interference caused by the matrix effect occur in the drying and ashing stage before the atomization signal, the real-time signal of the graphite furnace atomic absorption spectrometer can be displayed, the method of optimizing the graphite furnace temperature program alone or in combination with the dilution enrichment program can be used to eliminate the interference, and the dilution enrichment program is used to correct the matrix effect interference in the atomization process.

[0052] The matrix anti-interference method provided by the application directly uses the standard curve method, optimizes the graphite furnace temperature program, dilutes and enriches the sample matrix to correct the chemical interference, and a standard curve can realize detection of a large number of samples; when the concentration of the diluted sample is not suitable for the detection range of atomic absorption, the graphite furnace enrichment method can be used to concentrate the sample concentration to the suitable detection range of the graphite furnace. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 It is an ideal signal graph of Abs-time real-time signal in the application;

[0054] Figure 2 It is an ideal signal graph of Abs-time real-time signal in the application;

[0055] Figure 3 A sample absorbance-time real-time signal curve without dilution in the embodiment of the present application;

[0056] Figure 4 A sample absorbance-time real-time signal curve after dilution in the embodiment of the present application;

[0057] Figure 5 An absorbance-concentration standard curve obtained in the embodiment of the present application;

[0058] Figure 6 A concentration-absorbance standard curve obtained in the embodiment of the present application. DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0060] The present application provides a correction method for the matrix effect of graphite furnace atomic absorption method, comprising:

[0061] Checking the absorbance-time real-time signal of the highest concentration value of the standard curve according to a preset temperature rising program;

[0062] If the absorbance-real-time signal is not ideal, then the temperature rising program is optimized by using the absorbance-time real-time signal of the sample to be tested, and an optimized temperature rising program is obtained;

[0063] Detecting the absorbance corresponding to the concentration point on the standard curve according to the optimized temperature rising program, and obtaining the standard curve;

[0064] Testing the standard curve;

[0065] Detecting the sample to be tested by using the standard curve method, and correcting and testing whether there is the interference of the matrix effect by using the parallel sample.

[0066] In the present application, the checking of the absorbance-time real-time signal of the highest concentration value of the standard curve according to the preset temperature rising program preferably further comprises:

[0067] Adjusting the parameters of the graphite furnace instrument.

[0068] In the present application, the adjustment of the parameters of the graphite furnace instrument preferably comprises:

[0069] Performing peak searching.

[0070] In the present application, the peak searching result of the peak searching is preferably no more than ±0.15 of the characteristic value; in principle, the energy during peak searching is preferably 98-102%, more preferably no less than 99%; if the above conditions are not met, re-peak searching is preferably performed.

[0071] In the present application, the adjustment of the graphite furnace instrument parameters preferably further comprises:

[0072] Adjusting the graphite furnace light path and checking the energy.

[0073] In the present application, the integration mode during the energy checking process is preferably peak height method.

[0074] In the present application, the adjustment of the graphite furnace light path and the energy checking preferably comprises:

[0075] Before placing the graphite tube, the graphite furnace light path is adjusted to be optimal, and the energy checking is 100%; after placing the graphite tube, the energy is no less than 75%, preferably no less than 80%;

[0076] If the above conditions are not met, the graphite furnace light path is preferably re-adjusted, and the energy checking is 98-102% after the above conditions are met.

[0077] In the present application, the energy loss after placing the graphite tube is generally no more than 20%, and no more than 25% in special cases.

[0078] In the present application, the preset temperature rising program preferably comprises:

[0079] One-step drying, one-step ashing, atomization and cleaning.

[0080] In the present application, the temperature rising time of the one-step drying is preferably 4-6s, more preferably 5s; the drying temperature is preferably 90-110°C, more preferably 100°C; and the holding time is preferably 8-12s, more preferably 10s. In the present application, the temperature rising time of the one-step ashing is preferably 4-6s, more preferably 5s; the ashing temperature is preferably the highest temperature without loss of the measured element; and the holding time is preferably 8-12s, more preferably 10s. In the present application, the temperature of the atomization is preferably the lowest temperature corresponding to the maximum absorbance signal of the measured element (the lowest temperature corresponding to the highest peak of the absorbance signal), and the holding time is preferably 2-4s, more preferably 3s. In the present application, the temperature of the cleaning is preferably 90-110°C higher than the atomization temperature, more preferably 100°C higher than the atomization temperature; and the holding time is preferably 1-2s, more preferably 1s.

[0081] In the present application, the time of the preset temperature rising program is preferably 30-35s, more preferably 31-34s, most preferably 32-33s.

[0082] In the present application, the preset temperature rising procedure preferably comprises:

[0083] One-step drying (100℃: 5s+10s) + one-step ashing (the highest temperature without loss of the element to be detected: 5s+10s) + atomization (the lowest temperature with the largest atomization signal: 0s+3s) + cleaning (atomization temperature + 100℃: 0s+1s).

[0084] In the present application, the conditions under which the absorbance-time signal of the highest concentration point of the standard curve is an ideal signal preferably comprise:

[0085] The absorbance gradually decreases in the drying stage; the Abs (absorbance) is basically equal to the blank value (close to zero) in the ashing stage; the atomization peak appears in the last 10s in the atomization stage, and the peak type is visually sharp and narrow; the peak tail returns to the blank value (close to zero) in the cleaning stage.

[0086] In the present application, the ideal absorbance-time real-time signal has no matrix interference, and the peak in the last 10s is the atomization peak, and the small peak before the atomization peak is a false absorption peak in the drying and ashing stages, as shown in Figure 1 .

[0087] In the present application, the conditions under which the absorbance-time signal of the highest concentration point of the standard curve is an ideal signal preferably comprise:

[0088] There is an interference peak before the atomization peak.

[0089] In the present application, the ideal absorbance-time real-time signal has no matrix interference, and the peak in the last 10s is the atomization peak, and the small peak before the atomization peak is a false absorption peak in the drying and ashing stages, as shown in Figure 2 .

[0090] In the present application, the absorbance-time real-time signal of the highest concentration value of the standard curve according to the preset temperature rising procedure is checked before:

[0091] The absorbance-time real-time signal of the blank graphite tube is checked according to the preset temperature rising procedure.

[0092] In the present application, the number of times of the blank graphite tube is preferably 10-12 times, and more preferably 11 times.

[0093] In the present application, the Abs-time (absorbance-time) real-time signal when the blank graphite tube is preferably a flat straight line, otherwise the graphite tube is replaced.

[0094] In the present application, the absorbance value obtained when the blank graphite tube is preferably satisfied with the following conditions, otherwise the graphite tube is replaced:

[0095] If 1800℃≤T 原子化温度 <2000℃, then A空烧11次最大值 ≤0.005;

[0096] If 2000℃≤T 原子化温度 <2200℃, A 空烧11次最大值 ≤0.010;

[0097] If 2200℃≤T 原子化温度 <2500℃, A 空烧11次最大值 ≤0.015;

[0098] If 2500℃≤T 原子化温度 , A 空烧11次最大值 ≤0.018.

[0099] In the present application, the empty burning graphite tube can understand the baseline, since the subsequent detection of atomization peak type needs to return to the baseline, that is, the empty burning graphite tube is the absorbance value level.

[0100] In the present application, the absorbance-time real-time signal of the highest concentration value of the standard curve according to the preset temperature program is checked before the standard curve.

[0101] The absorbance-time real-time signal of the zero point concentration value of the standard curve is checked according to the preset temperature program.

[0102] In the present application, the zero point of the standard curve is a blank solution; the blank solution is preferably selected from water, nitric acid and hydrochloric acid mixture. In the present application, the water is preferably ultrapure water; the volume ratio of nitric acid and hydrochloric acid in the nitric acid and hydrochloric acid mixture is preferably 1:(98-99), more preferably 1:99; the nitric acid and hydrochloric acid are preferably of superior purity.

[0103] In the present application, the graphite furnace sample injection amount during the detection of the absorbance-time real-time signal is preferably 5-20 μL, more preferably 10 μL.

[0104] In the present application, the number of times of detecting the absorbance-time real-time signal of the zero point concentration value of the standard curve is preferably 7-21 times, more preferably 10-20 times, and most preferably 15 times.

[0105] In the present application, the Abs-time real-time signal of the zero point concentration value of the standard curve is preferably a flat straight line with an absorbance close to 0, otherwise the graphite furnace light path is repositioned and the energy is checked, and the graphite tube is repositioned and / or the standard curve blank solution is replaced. In the present application, the method of repositioning the graphite furnace light path and checking the energy is consistent with the method of adjusting the graphite furnace instrument parameters described in the above technical solution, which will not be described here.

[0106] In the present application, the absorbance value of the standard curve zero point concentration value preferably satisfies the following conditions, otherwise the blank solution of the standard curve is replaced or the Abs-time real-time signal of the standard curve blank solution is re-determined:

[0107] If 1800℃≤T 原子化温度 <2000℃, then A 标准曲线空白溶液21次最大值 ≤0.006;

[0108] If 2000℃≤T 原子化温度 <2200℃, then A 标准曲线空白溶液21次最大值 ≤0.012;

[0109] If 2200℃≤T 原子化温度 <2500℃, then A 标准曲线空白溶液21次最大值 ≤0.018;

[0110] If 2500℃≤T 原子化温度 , then A 标准曲线空白溶液21次最大值 ≤0.030; and / or;

[0111] A 单次标准曲线空白值 ∈ A n次标准曲线空白平均值 ±t 双侧检验(n-1，0.99) ×S n次标准溶液空白值吸光度标准偏差 .

[0112] In the present application, the absorbance of the standard curve zero point concentration value can be obtained by viewing the standard curve matrix, because the standard curve zero point solution is the standard curve matrix, but the sample matrix to be tested cannot be obtained at all.

[0113] In the present application, the method for optimizing the temperature program by using the absorbance-time real-time signal of the sample to be tested or combining with the dilution enrichment program comprises:

[0114] According to the preset temperature program, the absorbance-time real-time signal of the sample to be tested is detected, if the absorbance-time real-time signal is not ideal, the abnormal peak position in the absorbance-time real-time signal is viewed; if the temperature corresponding to the abnormal peak position is <120℃, the drying stage is optimized; if the temperature corresponding to the abnormal peak position is ≥120℃ and <atomization temperature, the ashing stage is optimized.

[0115] In the present application, the optimization of the temperature program by combining with the dilution enrichment program preferably comprises:

[0116] If the concentration corresponding to the absorbance of the sample to be tested is ≥the second highest point concentration of the standard curve, the dilution operation is preferably carried out according to the detection sample requirement, at this time the dilution is detection dilution, the concentration C1 after detection dilution satisfies: 3 times the lower limit of determination ≤C1 <the second highest point concentration of the standard curve, and the temperature program is preferably optimized according to the concentration after detection dilution.

[0117] In the present application, the combination of dilution enrichment procedure and optimized temperature program preferably further comprises:

[0118] If the total time of the optimized drying stage and the optimized ashing stage temperature program increases more than 90s, and the absorbance of the sample to be tested corresponds to a concentration < the concentration of the second highest point on the standard curve, the optimized temperature program is preferably combined with the dilution procedure (temperature dilution, N 升温稀释 When the corresponding concentration after temperature dilution is < the detection limit, temperature dilution is preferably performed with an enrichment procedure, and the enrichment multiple is ≤ the temperature dilution multiple; preferably N 升温稀释 ≤ 10 times, but the best is not diluted, if diluted, the dilution in this stage is preferably not more than 10 times, and in special cases not more than 20 times.

[0119] In the present application, the conditions of ideal signal and non-ideal signal are consistent with the above technical solutions, and will not be repeated here.

[0120] In the present application, the method for optimizing the drying stage preferably comprises:

[0121] In the drying stage of the preset temperature program, one step of drying is added, two-step drying is performed, and the absorbance-time real-time signal is checked. If the absorbance-time real-time signal is not ideal, optimization is continued, the position of the abnormal peak of the absorbance-time real-time signal is checked, if the temperature corresponding to the abnormal peak position is < 120℃, then one step of drying is continuously added, three-step drying is performed, the absorbance-time real-time signal is checked, if the absorbance-time real-time signal is still not ideal, optimization is continued, the position of the abnormal peak of the absorbance-time real-time signal is checked, if the temperature corresponding to the abnormal peak position is < 120℃, then the temperature time corresponding to the abnormal peak in the three-step drying is increased, the temperature of the three-step drying is not changed, and the temperature of the corresponding drying stage is increased.

[0122] In the present application, the temperature difference of the two-step drying is preferably 15-25℃, more preferably 20℃, for example, the temperature of the two-step drying can be set to 95℃, 110℃, the temperature increasing time is 5s, and the holding time is 10s. In the present application, the temperature difference of the three-step drying is preferably 15-20℃, for example, the temperature of the three-step drying can be set to 80℃, 95℃, 110℃, the temperature increasing time is 5s, and the holding time is 10s. In the present application, the temperature of the preferred drying stage is preferably 75-120℃, more preferably 80-110℃, and most preferably 90-100℃.

[0123] In the present application, the temperature rising time is preferably increased by 4-6s, more preferably by 5s, and the holding time is preferably increased by 8-12s, more preferably by 10s, during the increasing of the temperature rising time and the holding time of the corresponding drying stage. In the present application, the temperature rising time of the optimized drying stage is preferably up to 15s, starting from 5s, and increased by 5s each time; the holding time is preferably up to 50s, starting from 10s, and increased by 10-20s each time.

[0124] In the present application, the temperature rising procedure of the two-step drying preferably comprises:

[0125] Drying 1 (80-95℃: 5s+10s) + Drying 2 (100-110℃: 5s+10s).

[0126] In the present application, the temperature rising procedure of the three-step drying preferably comprises:

[0127] Drying 1 (75-80℃: 5s+10s) + Drying 2 (95℃: 5s+10s) + Drying 3 (110-120℃: 5s+10s).

[0128] In the present application, the temperature rising procedure of the three-step drying more preferably comprises:

[0129] Drying 1 (75-80℃: 5s / 10s / 15s......+10s / 20s / 30s / 40s / 50s.....) + Drying 2 (95℃: 5s / 10s / 15s......+10s / 20s / 30s / 40s / 50s.....) + Drying 3 (110-120℃: 5s / 10s / 15s......+10s / 20s / 30s / 40s / 50s.....).

[0130] In the present application, the method for optimizing the ashing stage preferably comprises:

[0131] In the ashing stage of the preset temperature rising procedure, one step of ashing is added to perform two-step ashing, and the absorbance-time real-time signal is checked; if the absorbance-time real-time signal is not ideal, optimization is continued, and the position of the abnormal peak is checked; if the temperature corresponding to the abnormal peak position is ≥120℃ and <atomization temperature, one step of ashing is continuously added to perform three-step ashing, and the absorbance-time real-time signal is checked; if the absorbance-time real-time signal is still not ideal, optimization is continued, and the position of the abnormal peak is checked; if the temperature corresponding to the abnormal peak position is ≥120℃ and <atomization temperature, the temperature time corresponding to the abnormal peak in the three-step ashing is increased without changing the temperature of the three-step ashing, and the temperature rising time and the holding time of the corresponding ashing stage are increased.

[0132] In the present application, the final ashing temperature of the two-step ashing is preferably the second-stage ashing temperature, the ashing temperature of the first stage is preferably 480-520°C, more preferably 500°C; the temperature rising time is preferably 4-6s, more preferably 5s, and the holding time is preferably 8-12s, more preferably 10s.

[0133] In the present application, the temperature rising procedure of the two-step ashing preferably comprises:

[0134] Ashing 1 (500°C: 5s+10s) + Ashing 2 (Ashing maximum temperature: 5s+10s).

[0135] In the present application, the temperature rising procedure of the three-step ashing preferably comprises:

[0136] Ashing 1 (500°C: 5s+10s) + Ashing 2 (0.5×(500°C+maximum ashing temperature)±100°C: 5s+10s) + Ashing 3 (Ashing maximum temperature: 5s+10s).

[0137] In the present application, the temperature rising procedure of the three-step ashing more preferably comprises:

[0138] Ashing 1 (500°C: 5s / 10s / 15s......+10s / 20s / 30s.....) + Ashing 2 (0.5×(500°C+maximum ashing temperature)±100°C: 5s / 10s / 15s......+10s / 20s / 30s.....) + Ashing 3 (Ashing maximum temperature: 5s / 10s / 15s......+10s / 20s / 30s.....).

[0139] In the present application, the abnormal peak preferably further comprises:

[0140] Abnormal atomization peak shape;

[0141] The abnormal atomization peak shape preferably comprises:

[0142] The atomization peak is not a sharp single peak, the atomization peak has a tailing phenomenon and / or the peak tail of the atomization peak is higher than the blank value level.

[0143] In the present application, the atomization peak shape is preferably a sharp single peak, if it is not a single peak such as a doublet, M peak, a first optimized atomization temperature rising procedure is preferably performed.

[0144] In the present application, the method of the first optimized atomization temperature rising procedure preferably comprises:

[0145] Lowering the atomization temperature.

[0146] In the present application, the atomization temperature is lowered by 50-100°C, more preferably 60-90°C, most preferably 70-80°C.

[0147] In the present application, the first optimized atomization temperature program preferably comprises:

[0148] atomization (T 原子化 / T 原子化 -50℃ / T 原子化 -100℃: atomization time unchanged).

[0149] In the present application, if the atomization peak type has a "tail" phenomenon, the second optimized atomization temperature program is preferably performed, which preferably comprises:

[0150] Increasing the atomization holding time and increasing the atomization temperature.

[0151] In the present application, the increase in the atomization holding time is preferably an increase of 1 s in holding time, and the atomization holding time is preferably not more than 5 s. In the present application, the increase in the atomization temperature is preferably an increase of not more than 500℃ in temperature, and preferably an increase of 100℃ each time.

[0152] In the present application, the second optimized atomization temperature program preferably comprises:

[0153] atomization (T 原子化 / T 原子化 +100℃ / T 原子化 +200℃ / T 原子化 +300℃ / T 原子化 +400℃ / T 原子化 +500℃: 0s+2s / 3s / 4s / 5s).

[0154] In the present application, if the atomization peak tail is higher than the blanking value level, an optimized blanking temperature program is preferably performed, and the method of the optimized blanking temperature program preferably comprises:

[0155] Increasing the blanking temperature and increasing the blanking holding time.

[0156] In the present application, for the "memory" elements, in order to avoid the invalid extension of the detection time caused by the whole blanking, the optimized blanking temperature program is performed. The "memory" elements generally have two characteristics: first, the atomization temperature is relatively high, generally greater than or equal to 2200℃, for example, Al, Be, and Ba; second, the peak type after atomization is prone to tailing, and multiple blanking is required to complete the cleaning.

[0157] In the present application, the increase in the blanking temperature is preferably an increase of 80-120℃ in temperature each time, and more preferably 100℃; the increase in the blanking holding time is preferably an increase of 1-2 s in holding time each time, and more preferably 1 s; the blanking time is preferably not more than 5 s; and the increase in the blanking temperature is preferably not more than 300℃.

[0158] In the present application, the optimized purge temperature program preferably comprises:

[0159] purge (T 清除 purge (T 清除 +100℃ / T 清除 +200℃ / T 清除 +300℃:0s+1s / 2s / 3s / 4s / 5s).

[0160] In the present application, the optimized purge temperature program is preferably followed by a return of the atomization peak tail to the original emptying graphite tube value, and more preferably comprises:

[0161] The absorbance of the graphite tube after the optimized purge and re-emptying is not more than 0.005 different from the maximum emptying absorbance of the original emptying graphite tube 11 times.

[0162] In the present application, if the total length of the optimized temperature program is too long and the interference has not been eliminated, it is preferred to dilute the sample to be tested appropriately in order to shorten the total time of the optimized temperature program, and the dilution factor is N 升温稀释 , preferably N 升温稀释 ≤20 times, more preferably N 升温稀释 ≤10 times, and most preferably without dilution.

[0163] In the present application, the concentration solution of the prepared standard curve is used to perform detection according to the optimized temperature program, so as to ensure that the temperature program of the standard curve and the sample to be tested are completely consistent.

[0164] In the present application, the method for obtaining the standard curve preferably comprises:

[0165] According to the concentration of the sample to be tested and the determination linear range, 6-10 standard curve concentration points are taken to obtain a linear regression equation, thereby obtaining a standard curve.

[0166] In the present application, when the number of regression points of the standard curve is ≤7, the regression coefficient of the graphite furnace method is not less than 0.997; and when the number of regression points of the standard curve is 8≤ the number of regression points≤10, the regression coefficient of the graphite furnace method is not less than 0.995.

[0167] In the present application, the standard curve concentration points are preferably set according to the following table:

[0168]

[0169] In the present application, the highest concentration point of the standard curve is preferably not more than 25 times the lower limit of determination; preferably ST2 and ST3 are combined into one point, taking the middle of the two, and the concentration points are evenly spaced, preferably more than 2 times the lower limit of determination.

[0170] In the present application, the absorbance value of the highest concentration point of the standard curve is preferably set to be <0.6, and if the absorbance value of the highest concentration point of the standard curve is greater than 0.6, the highest concentration point can be reduced or the width of the slit of the target element hollow cathode lamp light source is re-set under the condition that there is no spectral interference, thereby reducing the signal-to-noise ratio.

[0171] In the present application, the injection RSD of the standard curve is preferably required to include:

[0172] The concentration points on the standard curve are preferably measured twice or more, and the average value is taken, and the RSD of the points near the zero point and the detection limit is as low as possible; and / or;

[0173] When the blank solution is determined 7-21 times, the maximum drift amount under the current state of the instrument is obtained, and the RSD of the lower limit point is required to be <10%; and / or;

[0174] When the absorbance value is <0.050, the SD of the two measurement values is <3 times the blank solution drift amount, and the RSD is <10%; and / or;

[0175] When the absorbance value is 0.050-0.100, the SD of the two measurement values is <5 times the blank solution drift amount, and the RSD is <10%; and / or

[0176] When the absorbance value is 0.100, the SD of the two measurement values is <10 times the blank solution drift amount, and the RSD is <5%.

[0177] In the present application, the blank solution drift amount is the determination value of the blank solution determined 7-21 times, and the 1 times drift amount = the maximum value of the blank solution determination - the minimum value of the blank solution determination.

[0178] In the present application, the inspection of the standard curve preferably includes:

[0179] The slope, intercept, regression standard deviation, and residual of the standard curve are detected.

[0180] In the present application, the method for inspecting the standard curve preferably includes:

[0181] Each point on the standard curve is removed one by one, if the curve has N points, a new one-dimensional linear regression curve is obtained by re-doing the least square method on the remaining points, and the new curve slope b0... b n-1 , intercept v0... v n-1 , regression standard deviation S A / C0... S A / Cn-1 , the removed points in the new regression curve residual d0... d n-1 , if the following conditions are met, the test is qualified:

[0182] New slope b0... b n-1 ∈[b 平均 -STDEV(b0... b n-1 )×t 双侧(n-2，0.05) , b 平均 +STDEV(b0... b n-1 )×t 双侧(n-2，0.05) ]; and / or;

[0183] Intercept v0... v n-1 ∈[v 平均 -STDEV(v0... v n-1 )×t 双侧(n-2，0.05) , v 平均 +STDEV(v0... v n-1 )×t 双侧(n-2，0.05) ]; and / or;

[0184] Regression standard deviation S A / C0 ... S A / Cn-1 ∈[S A / C平均 -STDEV(S A / C0 ... S A / Cn-1 )×t 双侧(n -2, 0.05) , S A / C平均 +STDEV(S A / C0 ... S A / Cn-1 )×t 双侧(n-2，0.05) ]; and / or;

[0185] The removed points in the new regression curve residual d0... d n-1 ∈[d 平均 -STDEV(d0... d n-1 )×t 双侧(n -2, 0.05) , d 平均 +STDEV(d0... d n-1 )×t 双侧(n-2，0.05) ].

[0186] In the present application, the test preferably further comprises:

[0187] Calculate t0, if t0 单侧(n-2，0.05) , the test is qualified.

[0188] In the present application, the calculation method of t0 preferably comprises:

[0189]

[0190] wherein,

[0191] In the present application, after removing the zero concentration point, the regression equation of the remaining points is recalculated, and the regression standard deviation S of the dependent variable is calculated A / c , the dependent variable residual d0 at c = 0 in the new regression equation is calculated, and t0 on the standard curve is calculated; A0 is the absorbance value (average of two or more times) measured by the removed zero point, and C0 = 0, C0 = 0 estimated value in the new regression equation of the remaining points after removing the zero point.

[0192] In the present application, the test preferably further comprises:

[0193] After testing the sample to be tested, the nearest standard curve concentration point at both ends of the sample to be tested is back tested, and if the following conditions are met, the test is qualified:

[0194] If the concentration point of the sample to be tested is between 1 times and 2 times the lower limit of determination, the back test error is <10%;

[0195] If the concentration point of the sample to be tested is between 3 times and 5 times the lower limit of determination, the back test error is <7%;

[0196] If the concentration point of the sample to be tested is between 6 times and 10 times the lower limit of determination, the back test error is <5%;

[0197] If the concentration point of the sample to be tested is higher than 10 times the lower limit of determination, the back test error is <3%.

[0198] In the present application, the sample to be tested is detected by using different range parallel samples for detection, testing and correcting the interference of the sample to be tested. In the present application, the method for testing and correcting whether there is matrix effect interference by using parallel samples is preferably:

[0199] According to the optimized temperature rising program, the concentration of the sample to be tested is C1 (if the sample to be tested is not diluted during optimization of the temperature rising program, it is the original sample to be tested, and if dilution is performed during optimization of the temperature rising program, it is the sample to be tested after dilution by the temperature rising program):

[0200] If the lower limit of determination ≤ C1 < the second highest point of the standard curve:

[0201] If 1 times the lower limit of determination ≤ C1 < 2 times the lower limit of determination, the parallel sample is added with a standard treatment to obtain a C2 solution, the addition standard multiple shall not be less than 1.25 times, and shall not exceed 3 times, and the addition standard multiple is J 加标 ; if C1 = (85-115%) (1 / J 加标 ) × C2, it is considered that there is no interference during atomization; at this time, C试样最终测定结果 = N 升温稀释 × C1 = N 升温稀释 × (1 / J 加标 ) × C2, where J 加标 ∈ [1.25, 3], N 升温稀释 = 1 if no dilution is used when optimizing the temperature program;

[0202] If 2xLCL < C1 < 3xLCL, the C2 solution is obtained by spiking or diluting the parallel sample, the spiking factor is J 加标 , and the dilution factor is N 检测稀释 , the spiked or diluted C2 solution simultaneously satisfies: 2xLCL < C2 < 4xLCL; if C1 = (90-110%) (N 检测稀释 or 1 / J 加标 ) × C2, it is considered that there is no interference during atomization; C 试样最终测定结果 = N 升温稀释 × C1 = N 升温稀释 × (N 检测稀释 or 1 / J 加标 ) × C2, N 升温稀释 = 1 if no dilution is used when optimizing the temperature program;

[0203] If 3xLCL < C1 < the second highest point concentration of the standard curve, the C2 solution is obtained by diluting the parallel sample, the dilution factor is N 检测稀释 , and 2xLCL < C2; if C1 = (95-105%) N 检测稀释 × C2, it is considered that there is no interference during atomization; C 试样最终测定结果 = N 升温稀释 × C1 = N 升温稀释 × N 检测稀释 × C2, N 升温稀释 = 1 if no dilution is used when optimizing the temperature program;

[0204] If the second highest point concentration of the standard curve < C1, the solutions CC1 and CC2 (CC1 concentration > CC2 concentration) are obtained by twice diluting the parallel sample, the dilution factors are N 检测稀释1 and N 检测稀释2 , respectively; simultaneously satisfy: 3xLCL < CC1 < the second highest point concentration of the standard curve, 3xLCL < CC2 < the second highest point concentration of the standard curve; if N 检测稀释1 CC1 = (95-105%) N 检测稀释2 × CC2, it is considered that there is no interference during atomization; C 试样最终测定结果 = N 升温稀释 × N 检测稀释1 × CC1 = N 升温稀释 × N 检测稀释2 × CC2, N升温稀释 = 1;

[0205] If the detection limit ≤ C1 < the lower limit of determination, the parallel sample is added with a standard or diluted to obtain a C2 solution, the addition multiple should not be less than 1.25 times and should not exceed 3 times, and the addition multiple is J 加标 ; the dilution multiple should not be less than 1.25 times and should not exceed 2 times, and the dilution multiple is N 检测稀释 ; the concentration of the C2 solution obtained by dilution should not be less than the detection limit; if C1 = (75-125%) (1 / J 加标 ) x C2, it is considered that there is no interference during atomization; at this time, C 试样最终测定结果 = N 升温稀释 x C1 = N 升温稀释 x (1 / J 加标 ) x C2, wherein J 加标 ∈ [1.25, 3], if there is no dilution when optimizing the temperature program, N 升温稀释 = 1;

[0206] If C1 < the detection limit and there is no dilution when optimizing the temperature program, i.e. N 升温稀释 = 1, at this time, the enrichment program does not have to be performed, and it is judged whether there is interference during atomization: if the C1 solution is determined for 7 times, t 单侧检验(7次 , 0.95) x S 7次C1溶液测定浓度值 ≤ MDL, the detection limit, it is considered that there is no interference; the determination result is not detected;

[0207] If C1 < the detection limit and dilution is performed when optimizing the temperature program, i.e. 1 < N 升温稀释 ≤ 10, at this time, the enrichment program must be performed until the concentration after enrichment is greater than the detection limit, the enrichment multiple is recorded as F 富集 , 1 < F 富集 ≤ 10, and C 试样最终测定结果 = N 升温稀释 x (1 / F 富集 ) x C1; if the enrichment multiple exceeds 10 times and is still not greater than the detection limit, the enrichment is stopped, and the sample detection result is not detected; it is judged whether there is interference during atomization: if the C1 solution before enrichment is determined for 7 times, t 单侧检验(7次，0.95) x S 7次未富集前C1溶液测定浓度值 ≤ MDL, the detection limit; at the same time, the enrichment is performed twice, i.e. CC1 and CC2, if CC1 = (70-130%) CC2; if the above two conditions are met, it is considered that there is no interference during atomization.

[0208] In the present application, if the optimized drying, ashing and temperature rising program time is too long, and the absorbance of the sample to be tested is relatively high (corresponding to high concentration), dilution is suitable or the absorbance of the sample to be tested is already higher than the highest concentration range of the standard curve, the sample to be tested must be diluted according to the detection requirements during the detection process, at this time, the temperature rising program of the diluted sample to be tested can be optimized, and the temperature rising program time can be appropriately reduced. If the concentration of the sample to be tested is high, dilution is carried out according to the normal detection requirements, for detection dilution, N 检测稀释 represents that detection dilution does not require enrichment program; but if the concentration of the sample to be tested does not exceed the highest concentration range of the standard curve, and the dilution is simply for reducing the optimized temperature rising program time, for temperature rising dilution, N 升温稀释 represents that N 升温稀释 ≤10 times, but the best is not diluted, if diluted, the dilution should not be more than 10 times, and special cases should not be more than 20 times; then after the standard curve is drawn, when the concentration of the sample to be tested is less than the detection limit, the enrichment program is considered; the sample to be tested is determined according to the optimized temperature rising program, and is recorded as C1 (if the sample to be tested is not diluted during the optimization of the temperature rising program, it is the original sample to be tested, and if the sample to be tested is diluted during the optimization of the temperature rising program, it is the sample to be tested after the temperature rising dilution).

[0209] In the present application, the graphite furnace enrichment program is the enrichment times f, the total sampling times f+1, the enrichment multiple F=f+1, and the operation program is to perform drying and ashing in the graphite furnace temperature rising program after each sampling, and then continue to sample, and after all the samples are sampled, atomization and cleaning are performed together, which is theoretically equivalent to f+1 times enrichment.

[0210] In the present application, atomic absorption detection method refers to the detection of most metals and a few non-metallic elements, which is divided into flame method and graphite furnace method. First, a linear equation of concentration and absorbance is established through a standard solution with known concentration, and then the metal concentration value of the unknown sample is indirectly obtained on the standard curve by measuring the absorbance of the unknown sample.

[0211] The application is applied to the field of graphite furnace atomic absorption environment sample detection, corrects the interference of a matrix on atomic absorption determination in an environment sample, and in order to realize the precise correction method of the matrix effect, needs to test in the linear range of the standard curve of the linear regression of the least square method, ensures that the standard curve of the linear regression of the least square method is a straight line, so as to correct the matrix effect interference in the atomization process. If the molecular absorption interference and light scattering interference caused by the matrix effect occur in drying and ashing before the atomization signal, the interference can be eliminated by optimizing the graphite furnace temperature program alone or by combining the method of optimizing the graphite furnace temperature program + dilution enrichment program; if the molecular absorption interference and light scattering interference caused by the matrix effect occur in the atomization process, the matrix interference checking method can be used to correct the matrix effect interference in the atomization process through the dilution enrichment program.

[0212] Embodiment

[0213] The graphite furnace (TAS-990 atomic absorption spectrophotometer provided by Beijing Puzan General Instrument Co., Ltd.) is used to detect the chromium element, and the matrix effect interference is excluded.

[0214] In order to verify the implementation effect, the matrix effect interference solution is self-made, which is also a standard solution.

[0215] Preparation of a chromium-free matrix sample: 200 mL of ultrapure water + 1.5 g of sodium carbonate (solid) + 1.0 g of sodium hydroxide (solid) + 0.4 g of magnesium chloride (solid);

[0216] Preparation of a chromium-containing matrix sample: 200 mL of ultrapure water + 0.1 mL of chromium standard solution (1000 mg / L) + 1.5 g of sodium carbonate (solid) + 1.0 g of sodium hydroxide (solid) + 0.4 g of magnesium chloride (solid);

[0217] Preparation of a chromium-containing matrix sample: 200 mL of ultrapure water + 0.1 mL of chromium standard solution (1000 mg / L) + 1.5 g of sodium carbonate (solid) + 1.0 g of sodium hydroxide (solid) + 0.4 g of magnesium chloride (solid);

[0218] Adjust the graphite furnace instrument parameters:

[0219] Peak search of the chromium element, the characteristic peak is 357.87 nm, the peak search result is 357.88 nm, which meets the requirement of ±0.15 nm; the calibration energy is 100.9%, the graphite tube is placed, the energy is adjusted to 80%, and the energy is calibrated again to 100.5%.

[0220] Chromium element preset temperature rising procedure: drying 100℃ (5s+10s); ashing 1300℃ (5s+10s); atomization 2000℃ (0s+2s); cleaning 2100℃ (0s+1s).

[0221] Empty burning graphite tube 11 times: the absorbance value of 11 times of empty burning graphite tube is 0.000-0.008, the real-time signal is ideal, and meets the requirement of "2000℃≤T 原子化温度 <2200℃, A 空烧11次最大值 ≤0.010".

[0222] Determination of standard curve blank solution 7 times: the standard curve blank solution is ultrapure water, the absorbance value of 7 times of standard curve blank solution determination is 0.001-0.009, the real-time signal is ideal, and meets the requirement of "2000℃≤T 原子化温度 <2200℃, A 标准曲线空白溶液21次最大值 ≤0.012" and "A 单次标准曲线空白值 ∈A n次标准曲线空白平均值 ±t 双侧检验(n-1，0.99) ×S n次标准溶液空白值吸光度标准偏差 ".

[0223]

[0224] Optimization of temperature rising procedure to eliminate interference before atomization (drying / ashing):

[0225] Optimization of temperature rising procedure: three-step drying+three-step ashing+atomization+cleaning, the total time length in the temperature rising procedure is 140s, wherein 0s-45s is drying, 46s-135s is ashing, 136s-138s is atomization (peak rising), and 139s-140s is cleaning.

[0226] In order to shorten the temperature rising time, the un-chromium-added sample with interference is diluted by 10 times to 20 times in the optimization of temperature rising procedure, the real-time signal curve of absorbance-time of the undiluted sample is shown in Figure 3 , and the interference is serious; the real-time signal of absorbance-time of the diluted sample is shown in Figure 4 . (The purpose of the application is to correct matrix interference, the self-prepared reagent without chromium addition is equivalent to a separated matrix solution, and it can be seen that the matrix has serious interference, and it is proved that the method of the application is feasible, and the ABS-T real-time signal is not ideal, which is from the self-prepared interference solution, and the reagent with interference is analytical pure, and the chromium is not added in the reagent, which does not mean that the reagent does not contain chromium, and the detection limit of the graphite furnace is extremely low, so the chromium is detected in the chromium-free sample without chromium addition)

[0227] Optimization of temperature rising procedure: elimination of matrix interference of atomization peak type, in order to alleviate the tailing phenomenon of atomization peak, the cleaning temperature is set to be 200℃ higher than the atomization, and the optimized temperature rising procedure and parameters are as follows:

[0228] Serial number Temperature rising program function Execution temperature (°C) Temperature rising time (s) Hold time (s) Argon gas 1 Drying 1 80 5 10 On 2 Drying 2 100 5 10 On 3 Drying 3 120 5 10 On 4 Ashing 1 500 50 10 On 5 Ashing 2 1000 5 10 On 6 Ashing 3 1300 5 10 On 7 Atomization 2000 0 3 Off 8 Purging 2200 0 2 On

[0229] Prepare the standard curve solution, determine the standard curve solution and test the standard curve:

[0230] 0 2.5 10 20 30 40 50 60 70 80 0.002 0.026 0.101 0.201 0.274 0.359 0.466 0.555 0.672 0.735

[0231] Prepare the standard curve according to the data in the above table, and the obtained standard curve is shown in Figure 5 and Figure 6

[0232] C (ng / mL) = 107.97A - 0.361, A = 0.0092C (ng / mL) + 0.0039, R = 0.99919

[0233] Calculate the detection limit and the determination lower limit:

[0234]

[0235] Detection limit determination method:

[0236] According to all the steps of sample analysis, repeat n (n≥7) times of blank test, convert each determination result to the concentration or content in the sample, calculate the standard deviation of n times of parallel determination, and the detection limit = t (n-1，0.99) ×S n次标准溶液空白值吸光度对应浓度标准偏差 ; The t value table is:

[0237] Parallel determination times (n) Degrees of freedom (n-1) [CAT (n-1，0.99) ]]> 7 6 3.143 8 7 2.998 9 8 2.896 10 9 2.821 11 10 2.764 16 15 2.602 21 20 2.528

[0238] Test the standard curve:

[0239]

[0240]

[0241] Further test C = 0, i.e. the intercept v of the standard curve:

[0242] t0= 0.259 < t 单侧(7,0.95) = 1.895, qualified.

[0243] Test the sample to be tested and determine the atomization interference:

[0244] Preparation of sample without chromium matrix: 200 mL ultrapure water + 1.5 g sodium carbonate (solid) + 1.0 g sodium hydroxide (solid) + 0.4 g magnesium chloride (solid);

[0245] Preparation of sample with chromium matrix 500 μg / L: 200 mL ultrapure water + 0.1 mL chromium standard solution (1000 mg / L) + 1.5 g sodium carbonate (solid) + 1.0 g sodium hydroxide (solid) + 0.4 g magnesium chloride (solid);​

[0246] Chromium-added matrix sample preparation 250 μg / L: 200 mL ultrapure water + 0.05 mL chromium standard solution (1000 mg / L) + 1.5 g sodium carbonate (solid) + 1.0 g sodium hydroxide (solid) + 0.4 g magnesium chloride (solid).

[0247] Assuming that the true concentration of the above sample is not clear, the following results verify the method of the application (each sample is diluted 10 times, and the dilution multiple is set for optimizing the temperature program):

[0248]

[0249]

[0250] Because the matrix samples in this embodiment are self-designed, the recovery rate is calculated based on the final detection results of the calculated matrix-free samples, and the accuracy is further verified:

[0251]

[0252] Because the chromium element has been detected in the matrix sample without adding chromium, in order to further illustrate the accuracy of the detection results of the 500 μg / L chromium-added matrix sample and the 250 μg / L chromium-added matrix sample, the corresponding multiple of the matrix sample can be removed from the chromium-added matrix sample.

[0253]

[0254]

[0255] The application is applied in the field of graphite furnace atomic absorption detection, corrects the interference of the matrix in the environmental sample on the atomic absorption determination, in order to realize the precise correction method of the matrix effect, first, the linear range test of the monadic linear regression standard curve based on the least square method in the detection is proposed, it is necessary to ensure that the monadic linear regression standard curve based on the least square method is a straight line, so as to correct the matrix effect interference in the atomization process; if the molecular absorption interference and light scattering interference caused by the matrix effect occur before the drying and ashing of the atomization signal, it can be displayed in the real-time signal of the graphite furnace atomic absorption spectrometer, and it can be eliminated by optimizing the graphite furnace temperature program alone or combining the graphite furnace temperature program + dilution enrichment program; if the molecular absorption interference and light scattering interference caused by the matrix effect occur in the atomization process, the matrix interference checking method can be used to correct the matrix effect interference in the atomization process through the dilution enrichment program.

[0256] While the application has been described and illustrated with reference to specific embodiments thereof, those skilled in the art will appreciate that various adaptations, changes, modifications, substitutions, developments, improvements, and permutations can be made in the specific embodiments described without departing from the true spirit and scope of the application as defined by the appended claims. All such modifications are intended to be within the scope of the claims. Although methods disclosed herein have been described with reference to particular operations performed in a particular order, it will be understood that these operations can be combined, sub-divided, or re-ordered to form equivalent methods without departing from the teachings of the present application. Accordingly, unless specifically indicated herein, the order and grouping of operations are not a limitation of this application.

Claims

1. A method for correcting matrix effects in graphite furnace atomic absorption spectrometry, comprising: Check the real-time absorbance-time signal of the highest concentration value of the standard curve according to the preset heating program; If the absorbance-real-time signal is not ideal, the heating program is optimized using the absorbance-time real-time signal of the sample to be tested, and an optimized heating program is obtained. The absorbance corresponding to the concentration point on the standard curve was measured according to the optimized heating program to obtain the standard curve. The standard curve was tested. The standard curve method was used to test the sample, and parallel samples were used to correct for and check whether there was any interference from matrix effects. Methods for correcting for and verifying the presence of matrix effect interference using parallel samples include: The concentration of the sample to be tested was determined as C1 according to the optimized heating program: If 1 times the lower limit of quantification ≤ C1 < 2 times the lower limit of quantification, the parallel samples are spiked to obtain solution C2, with a spiking factor not less than 1.25 times and not more than 3 times, and the spiking factor is J. 加标 If C1 = (85-115%) (1 / J) 加标 If C2 is calculated as C, then it is considered that there was no interference during atomization; If 2 times the lower limit of quantification ≤ C1 < 3 times the lower limit of quantification, and parallel samples are spiked or diluted to obtain solution C2, the spiking factor is J. 加标 The dilution factor is N. 检测稀释 The spiked or diluted C2 solution must simultaneously satisfy: 2 times the lower limit of detection ≤ C2 < 4 times the lower limit of detection; if C1 = (90-110%) (N 检测稀释 or 1 / J 加标 If C2 is calculated as C, then it is considered that there was no interference during atomization; If the limit of determination (3 times) is ≤ C1 < the concentration at the second highest point of the standard curve, then C2 is obtained by diluting parallel samples, and the dilution factor is N. 检测稀释 If the lower limit of determination is 2 times ≤ C2; if C1 = (95-105%)N 检测稀释 ×C2 is considered to be without interference during atomization; If the concentration at the second highest point of the standard curve is ≤ C1, and parallel samples are diluted twice to obtain solutions CC1 and CC2, where CC1 concentration > CC2 concentration, the dilution factors are N. 检测稀释1 and N 检测稀释2 Simultaneously satisfying: 3 times the lower limit of quantification ≤ CC1 < the second highest concentration of the standard curve, and 3 times the lower limit of quantification ≤ CC2 < the second highest concentration of the standard curve; if N 检测稀释1 CC1 = (95-105%)N 检测稀释2 ×CC2 is considered to be without interference during atomization; If the detection limit ≤ C1 < the quantitation limit, the parallel samples should be spiked or diluted to obtain a C2 solution, with a spiking factor of not less than 1.25 times and not more than 3 times, and the spiking factor is J. 加标 The dilution factor should be no less than 1.25 times and no more than 2 times, with a dilution factor of N. 检测稀释 The concentration of the C2 solution obtained by dilution should not be less than the detection limit; if C1 = (75-125%) (1 / J) 加标 If C2 is calculated as C, then it is considered that there was no interference during atomization; If C1 < detection limit, and dilution was not performed during temperature optimization, determine if atomization interference exists: If the C1 solution is measured 7 times, t 单侧检验(7次，0.95) ×S 7次C1溶液测定浓度值 If the detection limit is ≤MDL, it is considered to be free of atomized interference; If C1 < detection limit, and dilution is performed during temperature calibration, then 1 < N. 升温稀释 For concentrations ≤10, perform the enrichment procedure until the enriched concentration is greater than the detection limit. The enrichment factor is recorded as F. 富集 ,1<F 富集 ≤10, C 试样最终测定结果 =N 升温稀释 ×(1 / F 富集 If the enrichment factor exceeds 10 times but the detection limit is still not exceeded, enrichment is stopped, and the sample test result is not detected; to determine if there is interference from atomization: if the C1 solution before enrichment is measured 7 times, t 单侧检验(7次，0.95) ×S 7次未富集前C1溶液测定浓度值 ≤MDL detection limit; enriched twice, as CC1 and CC2, if CC1 = (70~130%)CC2; if the above two conditions are met, it is considered to be free of atomization interference.

2. The method according to claim 1, characterized in that, Before checking the absorbance-time real-time signal of the highest concentration value of the standard curve according to the preset heating program, the following steps are also included: Peak finding, wherein the energy of the peak finding is 98-102%; Verification energy, wherein the verification energy includes: Adjust the optical path to the optimal level, verify the energy at 100%, and after placing the graphite tube, ensure the energy is not lower than 75%.

3. The method according to claim 1, characterized in that, The preset heating program includes: One-step drying, one-step ashing, atomization, and cleaning; The heating time for the first-step drying is 4-6 seconds, the drying temperature is 90-110°C, and the holding time is 8-12 seconds. The heating time for the one-step ashing is 4-6 seconds, the ashing temperature is the highest temperature at which the element to be measured is not lost, and the holding time is 8-12 seconds. The atomization temperature is the lowest temperature corresponding to the maximum value of the absorbance signal of the element to be measured, and the holding time is 2 to 4 seconds. The removal temperature is 90–110°C higher than the atomization temperature, and the holding time is 1–2 seconds.

4. The method according to claim 1, characterized in that, Before checking the absorbance-time real-time signal of the highest concentration value of the standard curve according to the preset heating program, the following steps are also included: Check the absorbance-time real-time signal of the zero-point concentration value of the standard curve according to the preset heating program; and / or; Check the real-time absorbance-time signal of the dry-burning graphite tube according to the preset heating program.

5. The method according to claim 1, characterized in that, The method for optimizing the heating program using the real-time absorbance-time signal of the sample to be tested includes: The absorbance-time real-time signal obtained by the test sample is detected according to the preset heating program. If the absorbance-time signal is not ideal, the abnormal peak position in the absorbance-time signal is checked. If the temperature corresponding to the abnormal peak position is <120℃, the drying stage is optimized. If the temperature corresponding to the abnormal peak position is ≥120℃ and <atomization temperature, the ashing stage is optimized. The method for optimizing the heating program using the real-time absorbance-time signal of the sample to be tested also includes: If the concentration corresponding to the absorbance of the sample to be tested is greater than or equal to the concentration at the second highest point of the standard curve, then the sample to be tested should be diluted before optimizing the temperature program. The concentration C1 after dilution should satisfy: 3 times the lower limit of determination ≤ C1 < the concentration at the second highest point of the standard curve.

6. The method according to claim 5, characterized in that, The method for optimizing the drying stage includes: Add a drying step to the preset heating program's drying stage, performing two drying steps. Check the absorbance-time real-time signal. If the absorbance-time real-time signal is not ideal, continue optimization. Check the position of abnormal peaks in the absorbance-time real-time signal. If the temperature corresponding to the abnormal peak position is <120℃, add another drying step, performing three drying steps. Check the absorbance-time real-time signal. If the absorbance-time signal is still not ideal, continue optimization. Check the position of abnormal peaks in the absorbance-time real-time signal. If the temperature corresponding to the abnormal peak position is <120℃, increase the heating time and holding time of the corresponding drying stage without changing the three-step drying temperature. The method for optimizing the ashing stage includes: Add an ashing step to the preset heating program's ashing stage, performing two ashing steps. Check the absorbance-time real-time signal. If the absorbance-time real-time signal is not ideal, continue optimization. Check the position of abnormal peaks in the absorbance-time real-time signal. If the temperature corresponding to the abnormal peak position is ≥120℃ and <atomization temperature, add another ashing step, performing three ashing steps. Check the absorbance-time real-time signal. If the absorbance-time real-time signal is still not ideal, continue optimization. Check the position of abnormal peaks in the absorbance-time real-time signal. If the temperature corresponding to the abnormal peak position is ≥120℃ and <atomization temperature, then for the abnormal peak temperature and time in the three ashing steps, without changing the three ashing temperatures, increase the heating time and holding time of the corresponding ashing stage.

7. The method according to claim 6, characterized in that, The method for optimizing the heating program using the real-time absorbance-time signal of the sample to be tested also includes: If the total increase time of the optimized drying stage and the optimized ashing stage is >90s, then the sample to be tested should be diluted before the optimized heating program is performed, and the dilution factor is ≤20 times.

8. The method according to claim 5, wherein the abnormal peak further comprises: Atomization peak shape anomaly, the atomization peak shape anomaly including: The atomization peak is not a sharp single peak; the atomization peak has a tailing phenomenon and / or the peak tail is higher than the air burn value level.

9. The method according to claim 1, characterized in that, The verification of the standard curve includes: The slope, intercept, regression standard deviation, and residuals of the test standard curve are measured.

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