A method for correcting interference in flame atomic absorption spectrometry

Abstract

The present invention provides a method for correcting interference in a flame atomic absorption spectrometry, comprising: using the flame atomic absorption spectrometry to detect whether the absorbance of a characteristic concentration value on a standard curve is within a preset range; if not, performing correction by adjusting the sensitivity until the absorbance reaches the preset range; drawing a standard curve to obtain a standard curve; detecting whether the ratio of the absorbance difference to the concentration difference in the highest section of the standard curve to the ratio of the absorbance difference to the concentration difference in the lowest section of the standard curve is within a preset range; if not, performing correction by adjusting the sensitivity to obtain a corrected standard curve; and using the corrected standard curve to detect an environmental sample and perform an anti-interference operation to determine whether interference exists. The present invention utilizes the standard curve in combination with reasonable sensitivity increase / decrease to correct interference in flame atomic absorption detection. After correcting the interference, the effect of eliminating the interference is further verified.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental detection methods, and in particular relates to a method for correcting interference of a flame atomic absorption method. Background Art

[0002] Interferences in flame atomic absorption spectrometry include chemical interference, ionization interference, spectral interference, physical interference, and background absorption interference. Regardless of the source or type of interference, they all interfere with atomization efficiency, ultimately leading to changes in the sensitivity of one or more standard curve points. A certain level of interference can affect the accuracy of flame atomic absorption spectrometry.

[0003] The current methods for correcting interference include: spectral-based interference correction, such as the deuterium lamp method: the deuterium lamp is a continuous light source. If there is strong absorption of coexisting elements within the instrument's spectral passband, it will be mistakenly regarded as "background" and deducted from the total absorbance. The Zeeman effect method for correcting background: the equipment is relatively complex and cannot be applied to all atomic absorption spectrometers. The hollow cathode lamp self-absorption method for correcting background: the emission line of the hollow cathode lamp becomes broadened when a large current is applied to produce self-absorption, thereby measuring the background absorption; however, some elemental spectral lines are prone to self-absorption, which has little effect on sensitivity; while the spectral lines of other elements in the hollow cathode lamp are less likely to self-absorb, and after background correction, the sensitivity loss is relatively large. The method of correcting interference based on the spectrum is complex to operate and places high demands on the atomic absorption spectrometer. In terms of instrument management, the background correction capability needs to be tested and can only be used if it passes.

[0004] Correction of interference by standard addition method: Take four equal amounts of the same test sample and prepare four identical solutions. No standard solution is added to the first solution. Standard solutions of different concentrations are added to the second, third and fourth solutions in proportion, respectively: 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, that is, C x ≈0.5C0; Under the same test conditions, measure the absorbance of four solutions; Use the mass concentration of the added standard solution as the horizontal axis and the corresponding absorbance as the vertical axis to establish a calibration curve. The intersection of the curve with the concentration axis when it is extended in the opposite direction is the mass concentration of the test sample; Notes on the standard addition method: The volume error caused by the addition of the standard solution should not exceed 0.5%; The standard addition method can only offset the influence of the matrix effect, but cannot eliminate the influence of background absorption; This method is only applicable to the area where the mass concentration and absorbance are linear.

[0005] In existing atomic absorption technology testing, the standard addition method is generally used to eliminate matrix interference when a large amount of matrix is ​​present in the sample and the matrix content is unknown. However, the scope of application of the standard addition method is more stringent: the calibration curve must not only be strictly within the linear range, but the absorbance value should also preferably be within the range of 0.100 to 0.200. The standard addition method is also labor-intensive and is particularly unsuitable for large-scale sample analysis. Because the standard addition method involves adding standard solutions of varying concentrations to the sample, each calibration curve can only measure one sample. If the concentration of the test sample is very high or very low and is not suitable for the standard addition method, the matrix must be separated in advance. The matrix separation process is cumbersome and difficult to separate when the matrix is ​​unknown.

[0006] The use of chemical agents such as release agents, protective agents, buffers, matrix effect modifiers, and deionizers is selective and may not eliminate all interferences. The effect of eliminating interferences also needs to be verified. Summary of the Invention

[0007] In view of this, the object of the present invention is to provide a method for correcting interferences in flame atomic absorption spectrometry. The method provided by the present invention is used to detect and correct various interferences of environmental samples by obtaining an accurate standard curve.

[0008] The present invention provides a method for correcting interference in flame atomic absorption spectrometry, comprising:

[0009] Flame atomic absorption spectrometry is used to detect whether the absorbance of the characteristic concentration value on the standard curve is within the preset range. If it is not within the preset range, correction is performed by sensitivity adjustment until the absorbance reaches the preset range;

[0010] Draw a standard curve to obtain a standard curve;

[0011] detecting whether the ratio of the absorbance difference and concentration difference in the highest section of the standard curve to the ratio of the absorbance difference and concentration difference in the lowest section is within a preset range; if not, performing correction by adjusting the sensitivity until the range is reached; and obtaining a corrected standard curve;

[0012] Use the calibrated standard curve to detect environmental samples and perform anti-interference operations to determine whether there is interference.

[0013] Preferably, the preset range of absorbance of the characteristic concentration value includes:

[0014] The concentration points between the detection limit and 5 times the lower limit of determination, the preset range of absorbance of the concentration points between the detection limit and 5 times the lower limit of determination is 0 to 0.050;

[0015] The concentration points between 5 times and 10 times the lower limit of determination, wherein the preset absorbance range of the concentration points between 5 times and 10 times the lower limit of determination is 0.050 to 0.100;

[0016] The concentration points between 10 times and 50 times the lower limit of determination are preset in a range of absorbance from 0.100 to 0.500.

[0017] Preferably, the concentration points between 10 times the lower limit of determination and 50 times the lower limit of determination include the second highest concentration point; the preset range of absorbance of the second highest concentration point includes:

[0018] If 0.300 ≥ the absorbance of the highest point of the standard curve > 0.200, the preset range of the absorbance of the second highest concentration point is 0.100 to 0.200;

[0019] If 0.400 ≥ the absorbance of the highest point of the standard curve > 0.300, the preset range of the absorbance of the second highest concentration point is 0.200 to 0.300;

[0020] If 0.500 ≥ the absorbance of the highest point of the standard curve > 0.400, the preset range of the absorbance of the second highest concentration point is 0.300 to 0.400;

[0021] If 0.600 ≥ the absorbance of the highest point of the standard curve > 0.500, the preset range of the absorbance of the second highest concentration point is 0.400 to 0.500.

[0022] Preferably, if the absorbance of the characteristic concentration value is less than a preset range, the sensitivity is increased; if the absorbance of the characteristic concentration value is greater than the preset range, the sensitivity is decreased;

[0023] If the ratio of the highest absorbance difference and concentration difference to the lowest absorbance difference and concentration difference is less than the preset range, the sensitivity is increased; if the ratio of the highest absorbance difference and concentration difference to the lowest absorbance difference and concentration difference is greater than the preset range, the sensitivity is reduced.

[0024] Preferably, the method for reducing sensitivity includes:

[0025] When the detection light path passes through the basic hole, rotate the burner head angle clockwise by 5 to 10 degrees each time until it reaches the preset range.

[0026] Preferably, the method for improving sensitivity includes:

[0027] On the basis of detecting the light path passing through the standard hole, adjust the height of the combustion head, increasing it by 1.0 to 2.0 nm each time until it reaches the preset range.

[0028] Preferably, after obtaining the calibrated standard curve, the method further comprises:

[0029] Test the calibrated standard curve;

[0030] The inspection includes:

[0031] Detect the RSD value of the absorbance of 2 to 3 concentration points on the calibrated standard curve;

[0032] The linearity of the standard curve after calibration was tested;

[0033] Detect the slope, intercept, standard deviation and residual of the calibrated standard curve;

[0034] The ratio of the standard deviation to the mean absorbance of the concentration points on the calibrated standard curve was detected.

[0035] Preferably, the anti-interference operation method includes:

[0036] The parallel samples of the environmental samples are spiked or diluted according to the concentration of the detected environmental samples, including: the concentration of the detected environmental samples is C 原始 :

[0037] If 1 times the lower limit of determination ≤ C 原始 <4 times the lower limit of determination, the parallel samples were spiked to obtain C 加标 For solutions, the spike multiple should be no less than 1.25 times and no more than 4 times;

[0038] If 4 times the lower limit of determination ≤ C 原始 If the value is less than 10 times the lower limit of determination, the parallel samples should be spiked or diluted to obtain C 加标 / 稀释 Solution, spiked or diluted C 加标 / 稀释 The solution also meets the following requirements: 4 times the lower limit of determination ≤ C 加标 / 稀释 <10 times the lower limit of determination;

[0039] If 10 times the lower limit of determination ≤ C 原始 If the concentration is less than the second highest point of the standard curve, the parallel samples are diluted to obtain C 稀释 , 10 times the lower limit of determination ≤ C 稀释 ;

[0040] If the concentration of the second highest point of the standard curve is ≤ C 原始 , then the parallel samples are diluted twice to obtain solutions CC1 and CC2, CC1 concentration>CC2 concentration, and at the same time meet the following conditions: 10 times the lower limit of determination ≤ CC1 < the concentration of the second highest point of the standard curve, 10 times the lower limit of determination ≤ CC2 < the concentration of the second highest point of the standard curve;

[0041] If the detection limit ≤ C 原始 < determination limit, then spike the parallel samples to obtain C 加标Solution, 10 times the lower limit of determination ≤ C 加标 / 稀释 <The second highest point of the standard curve;

[0042] If C 原始 If the value is less than the detection limit, the parallel samples were measured 7 times.

[0043] Preferably, the method for determining whether interference exists includes:

[0044] If 1 times the lower limit of determination ≤ C 原始 <4 times the lower limit of determination, then C 原始 =(85~115%)(1 / J 加标 )×C 加标 , it is considered that there is no interference in the detection;

[0045] If 4 times the lower limit of determination ≤ C 原始 <10 times the lower limit of determination, then C 原始 =(90~110%)(N 稀释 or 1 / J 加标 )×C 加标 / 稀释 , it is considered that there is no interference in the detection;

[0046] If 10 times the lower limit of determination ≤ C 原始 < the concentration of the second highest point of the standard curve, then C 原始 =(95~105%)N 稀释 ×C 稀释 , it is considered that there is no interference in the detection;

[0047] If the concentration of the second highest point of the standard curve is ≤ C 原始 , then N 稀释1 CC1=(95~105%)N 稀释2 ×CC2, considered as no interference in the detection;

[0048] If the detection limit ≤ C 原始 <determination limit, then C 原始 =(75~125%)(1 / J 加标 )×C 加标 , it is considered that there is no interference in the detection.

[0049] The present invention utilizes a standard curve combined with reasonable sensitivity increase / decrease to correct for interference in flame atomic absorption detection. In flame atomic absorption detection, due to continuous liquid sampling, the atomization efficiency is low and unstable, typically only 1% to 10% of atoms are ultimately atomized and detected by the detector. The sensitivity improvement method involves: first, peak detection. The characteristic spectral line peak detection result must not exceed ±0.3nm of the characteristic value. The detection light path is elevated at the flame height through a base aperture. The closer to the flame center, the higher the atomization temperature, but the linearity of the correlation curve deteriorates. The sensitivity reduction method, primarily targeting potassium and sodium, focuses on more active elements. First, peak detection. The characteristic spectral line peak detection result must not exceed ±0.3nm of the characteristic value. After the detection light path passes through the base aperture, the angle of the burner is appropriately rotated. The principle is that the shorter the length of the detection light path through the flame, the lower the sensitivity. The present invention utilizes a standard curve combined with reasonable sensitivity increase / decrease to correct for interference in flame atomic absorption detection. Parameters such as the sensitivity of the standard curve are checked for discrepancies, and then the presence of interference is checked. If interference is present, the interference is corrected and the effectiveness of interference elimination is further verified.

[0050] The method provided by the present invention first obtains an accurate standard curve, then verifies the standard curve, and finally uses the verified standard curve to correct various interferences of environmental samples, thereby accurately detecting environmental samples. The standard curve is basically configured with pure substances to be tested, and the interference is caused by the environmental test samples. The best standard curve is to verify and correct the interference in sample detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a standard curve diagram obtained in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0053] The present invention provides a method for correcting interference in flame atomic absorption spectrometry, comprising:

[0054] Flame atomic absorption spectrometry is used to detect whether the absorbance of the characteristic concentration value on the standard curve is within the preset range. If it is not within the preset range, correction is performed by sensitivity adjustment until the absorbance reaches the preset range;

[0055] Draw a standard curve to obtain a standard curve;

[0056] detecting whether the ratio of the absorbance difference and concentration difference in the highest section of the standard curve to the ratio of the absorbance difference and concentration difference in the lowest section is within a preset range; if not, performing correction by adjusting the sensitivity until the range is reached; and obtaining a corrected standard curve;

[0057] Use the calibrated standard curve to detect environmental samples and perform anti-interference operations to determine whether there is interference.

[0058] In the present invention, the characteristic concentration value preferably includes:

[0059] The concentration values ​​of the concentration points between the detection limit and 5 times the lower limit of determination, the concentration values ​​of the concentration points between 5 times the lower limit of determination and 10 times the lower limit of determination, and the concentration values ​​of the concentration points between 10 times the lower limit of determination and 50 times the lower limit of determination.

[0060] In the present invention, the concentration values ​​of the concentration points between 10 times and 50 times the lower limit of determination preferably include:

[0061] The concentration value of the second highest concentration point.

[0062] In the present invention, the concentration value of the second highest concentration point preferably includes:

[0063] The concentration value of the concentration point between 10 times and 15 times the lower limit of measurement, the concentration value of the concentration point between 15 times and 20 times the lower limit of measurement, the concentration value of the concentration point between 20 times and 25 times the lower limit of measurement, the concentration value of the concentration point between 25 times and 30 times the lower limit of measurement, the concentration value of the concentration point between 30 times and 35 times the lower limit of measurement, the concentration value of the concentration point between 35 times and 40 times the lower limit of measurement, the concentration value of the concentration point between 40 times and 45 times the lower limit of measurement, and the concentration value of the concentration point between 45 times and 50 times the lower limit of measurement are one or more, and more preferably 3.

[0064] In the present invention, the preset range of the absorbance of the concentration values ​​at the concentration points between the detection limit and 5 times the lower limit of determination is preferably 0 to 0.050; the preset range of the absorbance of the concentration values ​​at the concentration points between 5 times the lower limit of determination and 10 times the lower limit of determination is preferably 0.050 to 0.100; the preset range of the absorbance of the concentration values ​​at the concentration points between 10 times the lower limit of determination and 50 times the lower limit of determination is preferably 0.100 to 0.500.

[0065] In the present invention, the preset absorbance range of the concentration value of the second highest concentration point preferably includes:

[0066] If 0.300 ≥ the absorbance of the highest point of the standard curve > 0.200, the preset range of the absorbance of the concentration value of the second highest concentration point is 0.100 to 0.200;

[0067] If 0.400 ≥ the absorbance of the highest point of the standard curve > 0.300, the preset range of the absorbance of the concentration value of the second highest concentration point is 0.200 to 0.300;

[0068] If 0.500 ≥ the absorbance of the highest point of the standard curve > 0.400, the preset range of the absorbance of the concentration value of the second highest concentration point is 0.300 to 0.400;

[0069] If 0.600 ≥ the absorbance of the highest point of the standard curve > 0.500, the preset range of the absorbance of the concentration value of the second highest concentration point is 0.400 to 0.500.

[0070] In the present invention, the preset range of absorbance of the characteristic concentration value on the standard curve is preferably as shown in the following table:

[0071]

[0072] In the present invention, the absorbance of the characteristic concentration value on the detection standard curve preferably also includes:

[0073] Peak search is performed according to the wavelength of the characteristic spectral line.

[0074] In the present invention, the peak search result is preferably not more than ±0.3 nm of the characteristic value; if the above conditions are not met during the peak search process, the peak search is preferably repeated.

[0075] In the present invention, the absorbance of the characteristic concentration value on the detection standard curve preferably also includes:

[0076] Adjust the detection light path to pass through the standard hole.

[0077] In the present invention, the adjustment of the detection light path to pass through the standard hole is preferably based on visually observing that the detection light path just passes through the standard hole.

[0078] In the present invention, it is preferred that if the absorbance of the characteristic concentration value is less than a preset range, the sensitivity is increased; if the absorbance of the characteristic concentration value is greater than the preset range, the sensitivity is decreased.

[0079] In the present invention, if the absorbance of the characteristic concentration value on the standard curve is too low when the detection light path passes through the standard hole, and is less than the preset range, then the sensitivity is too low, and the concentration at the highest point of the standard curve can be reasonably increased. In the present invention, the method for improving sensitivity preferably includes:

[0080] Increase the height of the detection light path in the flame.

[0081] In the present invention, it is preferred to adjust the height of the combustion head based on the detection light path passing through the standard hole, and increase the height of the detection light path in the flame by 1 to 2 nm each time, most preferably 1 nm; until satisfactory sensitivity is obtained and the absorbance of the characteristic concentration value reaches within the preset range.

[0082] In the present invention, after adjusting the detection light path to pass through the basic hole, the height of the detection light path in the flame is increased by adjusting the height of the combustion head, so that the detection light path is close to the flame core. The closer to the flame core, the higher the flame temperature, and the atoms to be measured obtain higher flame temperature and energy, thereby improving the atomization efficiency of the atoms to be measured and improving the sensitivity at the same time.

[0083] In the present invention, if the absorbance of the characteristic concentration value on the standard curve is too large when the detection light path passes through the standard hole, exceeding the preset range, it means that the sensitivity is too high. At this time, the detection result is unstable and the linearity of the standard curve is poor. This is generally the case with potassium and sodium elements. In the present invention, the method of reducing sensitivity preferably includes:

[0084] Rotate the burner head by 5 to 10° clockwise each time until the absorbance of the characteristic concentration value on the obtained standard curve reaches the preset range.

[0085] In the present invention, after adjusting the detection light path through the basic hole, the angle of the burner head is rotated to shorten the length of the detection light path through the combustion flame, reduce the energy of the atoms to be measured to obtain the flame, thereby reducing the atomization efficiency of the atoms to be measured and reducing the sensitivity.

[0086] In the present invention, the method for drawing the standard curve preferably includes:

[0087] Set the concentration points on the standard curve, use flame atomic absorption spectrometry to detect the absorbance corresponding to each concentration point, and use the least squares method to make a linear regression line for each curve point and the corresponding absorbance to obtain the standard curve.

[0088] In the present invention, the standard curve can be directly obtained by the software of the flame atomic absorption detection equipment, or can be drawn by EXCEL software by first making a scatter plot and then adding a trend line.

[0089] In the present invention, the correlation coefficient of the standard curve is preferably ≥0.999, otherwise the standard curve is redrawn.

[0090] In the present invention, the setting of concentration points on the standard curve preferably includes:

[0091] Zero concentration point, concentration points between 1 and 5 times the lower limit of determination, concentration points between 5 and 10 times the lower limit of determination, and concentration points between 10 and 50 times the lower limit of determination.

[0092] In the present invention, the concentration points between 10 times and 50 times the lower limit of determination preferably include 3 concentration points between 10 times and 50 times the lower limit of determination; the 3 concentration points are preferably selected from 3 of the concentration points between 10 times and 15 times the lower limit of concentration determination, the concentration points between 15 times and 20 times the lower limit of concentration determination, the concentration points between 20 times and 25 times the lower limit of concentration determination, the concentration points between 25 times and 30 times the lower limit of concentration determination, the concentration points between 30 times and 35 times the lower limit of concentration determination, the concentration points between 35 times and 40 times the lower limit of concentration determination, the concentration points between 40 times and 45 times the lower limit of concentration determination, and the concentration points between 45 times and 50 times the lower limit of concentration determination.

[0093] In the present invention, the setting of concentration points on the standard curve preferably further comprises:

[0094] One or both of the detection limit concentration point and the determination lower limit concentration point.

[0095] In the present invention, the detection limit concentration point and the determination lower limit concentration point are preferably combined into one concentration point, and the middle value between the two is preferably taken as one concentration point.

[0096] In the present invention, the highest concentration point among the concentration points on the standard curve is preferably no more than 25 times the lower limit of determination; and the concentration points above 2 times the lower limit of determination are preferably evenly spaced.

[0097] In the present invention, the concentration points on the standard curve are preferably set as shown in the following table:

[0098]

[0099] In the present invention, the ratio of the absorbance difference and concentration difference in the highest section of the standard curve to the ratio of the absorbance difference and concentration difference in the lowest section is detected to see whether it is within a preset range. If it is not within the preset range, correction is performed by sensitivity adjustment until it reaches the preset range; and a corrected standard curve is obtained.

[0100] In the present invention, the preset range of the ratio of the absorbance difference and concentration difference in the highest section of the standard curve to the ratio of the absorbance difference and concentration difference in the lowest section preferably includes:

[0101] Divide the standard curve into 5 segments and measure the absorbance difference / concentration difference of each segment:

[0102] If the absorbance at the highest point of the standard curve is greater than 0.050, the ratio of the absorbance difference / concentration difference in the highest section to the absorbance difference / concentration difference in the lowest section should be greater than or equal to 0.9;

[0103] If the absorbance at the highest point of the standard curve is greater than 0.100, the ratio of the absorbance difference / concentration difference in the highest section to the absorbance difference / concentration difference in the lowest section should be greater than or equal to 0.85;

[0104] If the absorbance at the highest point of the standard curve is greater than 0.200, the ratio of the absorbance difference / concentration difference in the highest section to the absorbance difference / concentration difference in the lowest section should be ≥ 0.8;

[0105] If the absorbance at the highest point of the standard curve is greater than 0.300, the ratio of the absorbance difference / concentration difference in the highest section to the absorbance difference / concentration difference in the lowest section should be greater than or equal to 0.75;

[0106] If the absorbance at the highest point of the standard curve is greater than 0.400, the ratio of the absorbance difference / concentration difference in the highest segment to the absorbance difference / concentration difference in the lowest segment should be ≥ 0.7.

[0107] In the present invention, if the concentration values ​​of the standard curve are not uniform, the estimated values ​​of the standard curve can be used to check whether the above requirements are met.

[0108] In the present invention, preferably, if the ratio of the highest absorbance difference to the lowest absorbance difference to the lowest concentration difference is less than a preset range, the sensitivity is increased; and if the ratio of the highest absorbance difference to the lowest absorbance difference to the highest concentration difference is greater than the preset range, the sensitivity is decreased. In the present invention, the methods for increasing and decreasing sensitivity are consistent with those described in the above technical solution and are not further described here.

[0109] In the present invention, after obtaining the calibrated standard curve, it is preferred to further include:

[0110] Check the corrected calibration curve.

[0111] In the present invention, the inspection preferably includes:

[0112] The RSD values ​​of the absorbance at 2 to 3 concentration points on the calibrated standard curve were measured.

[0113] In the present invention, it is preferred that if the RSD values ​​of the absorbances at 2 to 3 concentration points on the standard curve meet the following conditions, the calibrated standard curve is qualified, otherwise the standard curve is redrawn:

[0114] 0.020≤A 曲线点吸光度平均值 <0.030, RSD <12.5%; and / or;

[0115] 0.030≤A 曲线点吸光度平均值 <0.040, RSD <10.0%; and / or;

[0116] 0.040≤A 曲线点吸光度平均值 <0.050, RSD <7.5%; and / or;

[0117] 0.050≤A 曲线点吸光度平均值 <0.100, RSD <2.5%; and / or;

[0118] 0.100≤A 曲线点吸光度平均值 <0.200, RSD <2.0%; and / or;

[0119] 0.200≤A 曲线点吸光度平均值 <0.250, RSD <1.25%; and / or;

[0120] 0.250≤A 曲线点吸光度平均值 <0.600, RSD<1.0%.

[0121] In the present invention, the RSD calculation method preferably includes:

[0122] Relative standard deviation (RSD) = standard deviation (SD) / arithmetic mean of absorbance (A) × 100%;

[0123] Standard deviation (SD) = Ai - A 吸光度平均值 .

[0124] In the present invention, the RSD calculation process preferably does not include detection points with an absorbance arithmetic mean (A) less than 0.020.

[0125] In the present invention, the inspection preferably further comprises:

[0126] The linearity of the calibration standard curve was checked.

[0127] In the present invention, the linearity detection method preferably includes:

[0128] The correlation coefficient of the standard curve is ≥0.999. Under the selected significance level, the concentration points on the standard curve are removed in sequence as the test points (excluding the zero concentration point of the standard curve). The residual of the dependent variable (absorbance) of the test point (removed point) is subjected to t-test. After removing the tested 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 , calculate the residual d of the dependent variable of the tested point (removed point) in the new regression equation, and calculate ti for each concentration point on the standard curve respectively, N is the number of experimental points after removal, and the degree of freedom in the t-test is N-2; at the significance level of a=0.05, check the one-sided column t(a, N-2) in the t-test critical table. When ti>t(a, N-2), the test fails, and the standard curve should be redrawn and re-measured; when ti<t(a, N-2), the test passes.

[0129] In the present invention, the calculation method of ti preferably includes:

[0130]

[0131] in,

[0132] i is the inspected point (removed point), Ai is the absorbance value (average of two or more times) measured at the inspected point (removed point), Ci is the concentration value of the inspected point (removed point), After point i is removed, Ci is estimated in the new regression equation for the remaining points.

[0133] In the present invention, the inspection preferably further comprises:

[0134] The ratio of the standard deviation to the mean absorbance of the concentration points on the calibrated standard curve was detected.

[0135] In the present invention, the ratio of the standard deviation to the average value of the absorbance of the concentration points on the detection standard curve refers to the ratio of the standard deviation to the average value of the absorbance of the concentration points on the detection standard curve after a batch of environmental samples (samples to be tested) are detected; preferably, the ratio of the standard deviation to the average value of the absorbance of the concentration points on the detection standard curve is measured after every 8 to 12 environmental samples are detected, and more preferably, the ratio of the standard deviation to the average value of the absorbance of the concentration points on the detection standard curve is measured after every 10 environmental samples are detected.

[0136] In the present invention, the concentration points on the standard curve preferably include:

[0137] The highest concentration point and the concentration point between 0.8 times the detection limit and the lower limit of determination.

[0138] In the present invention, the measured value of the absorbance is preferably retained to three decimal places; preferably, after every 8 to 12 environmental samples are detected, the absorbance value of the highest concentration point and the absorbance value of the concentration point between 0.8 times the detection limit and the lower limit of determination are detected, preferably 10 to 12 times, more preferably 11 times.

[0139] In the present invention, it is preferred that if the ratio of the standard deviation to the mean value of the absorbance at the highest concentration point meets the following conditions, the test is qualified, otherwise the standard curve is redrawn:

[0140] If 0.050≤A 最高点平均值 <0.100, then the standard deviation / average absorbance at the highest concentration point ≤3%;

[0141] If 0.100≤A 最高点平均值 <0.200, then the standard deviation / average absorbance at the highest concentration point ≤2.5%;

[0142] If 0.200≤A 最高点平均值 <0.250, then the standard deviation / average absorbance at the highest concentration point ≤1.75%;

[0143] If 0.250≤A 最高点平均值 <0.600, then the standard deviation / average absorbance at the highest concentration point ≤1.5%.

[0144] In the present invention, it is preferred that if the ratio of the standard deviation and the average value of the absorbance at the concentration points between 0.8 times the detection limit and the lower limit of determination meets the following conditions, the test is qualified, otherwise the standard curve is redrawn:

[0145] If 0.02≤A 低浓度点平均值 <0.03, then the standard deviation / average absorbance of low concentration point ≤15%;

[0146] If 0.03≤A 低浓度点平均值 <0.04, then the standard deviation / average absorbance of low concentration point ≤12.5%;

[0147] If 0.04≤A 低浓度点平均值 <0.05, then the standard deviation / average absorbance of low concentration point ≤10%.

[0148] In the present invention, the inspection preferably further comprises:

[0149] Backtest the concentration points on the standard curve at both ends of the environmental sample concentration value.

[0150] In the present invention, the backtest refers to backtesting the concentration points on both sides of the standard curve interval where the environmental sample concentration value is located after the environmental sample is detected. Backtesting each environmental sample requires detecting the concentration points on two standard curves. Preferably, backtesting is performed after each measurement of the environmental sample to detect the concentration points at both ends, and preferably one test is performed.

[0151] In the present invention, it is preferred that if the ratio of the standard deviation and the average value of the absorbance of the concentration points on the standard curve at both ends of the back-tested environmental sample concentration value meets the following conditions, the test is qualified, otherwise the standard curve is redrawn:

[0152] If 0.03≤A 回测点平均值 <0.04, then the standard deviation / average absorbance of the back-test point ≤5%;

[0153] If 0.04≤A 回测点平均值 <0.05, then the standard deviation / average absorbance of the back-test point is ≤4%;

[0154] If 0.05≤A 回测点平均值 <0.1, then the standard deviation / average absorbance of the back-test point is ≤1.2%;

[0155] If 0.1≤A 回测点平均值 <0.2, then the standard deviation / average absorbance of the back-test point is ≤1.0%;

[0156] If 0.2≤A 回测点平均值 <0.25, then the standard deviation / average absorbance of the back-test point is ≤0.6%;

[0157] If 0.25≤A 回测点平均值 <0.6, then the standard deviation / average absorbance of the back-test point is ≤0.5%.

[0158] In the present invention, the inspection preferably further comprises:

[0159] Detect the slope, intercept, standard deviation, and residual of the calibrated standard curve.

[0160] In the present invention, it is preferred that if the slope, intercept, standard deviation, and residual of the standard curve meet the following conditions, the test is qualified; otherwise, the standard curve is redrawn:

[0161] Remove each concentration point on the standard curve one by one. If the curve has N points, re-do the least squares linear regression curve for the remaining points to obtain the new curve slopes b0.....b n-1 、Intercept v0......v n-1 , regression standard deviation S A / C0 ......S A / Cn-1 , the residual d0......d in the new regression curve of the removed point n-1 :

[0162] 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;

[0163] 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;

[0164] 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;

[0165] The residual d0...d in the new regression curve of the removed point 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) ].

[0166] In the present invention, the method for determining whether interference exists preferably includes:

[0167] According to the concentration of the detected environmental sample, the parallel samples of the environmental sample are spiked or diluted. According to the relationship between the concentration of the parallel samples after treatment and the original detection concentration of the environmental sample, it is judged whether there is interference in the detection of the environmental sample.

[0168] In the present invention, the spike addition or dilution process is an anti-interference operation, preferably including:

[0169] C 原始 The concentrations obtained from environmental sample testing;

[0170] If the lower limit of determination ≤ C 原始 <Second highest point of standard curve:

[0171] If 1 times the lower limit of determination ≤ C 原始 <4 times the lower limit of determination, for C 原始 The solution (parallel sample) was spiked to obtain C 加标 Solution, the spike multiple shall not be less than 1.25 times and shall not exceed 4 times. The spike multiple is J 加标 If the calibrated standard curve is used to detect C 加标 solution, and obtain C 原始 =(85~115%)(1 / J 加标 )×C 加标 , it is considered that there is no interference in the detection. At this time, C 原始 =(1 / J 加标 )×C 加标 , where J 加标 ∈[1.25,4]; at the same time C 加标 The measured absorbance A of the solution 加标 ≥0.04;

[0172] If 4 times the lower limit of determination ≤ C 原始 <10 times the lower limit of determination, for C 原始 The solution (parallel sample) was spiked or diluted to obtain C 加标 / 稀释 Solution, spiked at J 加标, the dilution factor is N 稀释 , spiked or diluted C 加标 / 稀释 The solution also meets the following requirements: 4 times the lower limit of determination ≤ C 加标 / 稀释 <10 times the lower limit of determination, if the calibrated standard curve is used to test C 加标 / 稀释 solution, and obtain C 原始 =(90~110%)(N 稀释 or 1 / J 加标 )×C 加标 / 稀释 , it is considered that there is no interference in the detection, C 原始 =(N 稀释 or 1 / J 加标 )×C 加标 / 稀释 ; At the same time C 加标 / 稀释 The measured absorbance A of the solution 加标 / 稀释 ≥0.04;

[0173] If 10 times the lower limit of determination ≤ C 原始 <The concentration of the second highest point of the standard curve, for C 原始 The solution (parallel sample) was diluted to obtain C 稀释 , the dilution factor is N 稀释 , 10 times the lower limit of determination ≤ C 稀释 If the calibrated standard curve is used to detect C 稀释 solution, and obtain C 原始 =(95~105%)N 稀释 ×C 稀释 ; If 4 times the lower limit of determination ≤ C 稀释 <10 times the lower limit of determination, if the calibrated standard curve is used to detect C 稀释 solution, and obtain C 原始 =(90~110%)N 稀释 ×C 稀释 , it is considered that there is no interference in the detection, C 原始 =N 稀释 ×C 稀释 ;

[0174] If the concentration of the second highest point of the standard curve is ≤ C 原始 , for C 原始 The solution (parallel sample) was diluted twice to obtain solutions CC1 and CC2 (CC1 concentration > CC2 concentration), and the dilution multiples were: N 稀释1 and N 稀释2 ; At the same time, the following conditions must be met: 10 times the lower limit of determination ≤ CC1 < the second highest point concentration of the standard curve, 10 times the lower limit of determination ≤ CC2 < the second highest point concentration of the standard curve. If the calibrated standard curve is used to detect CC1 and CC2 solutions, N 稀释1 CC1=(95~105%)N 稀释2 ×CC2, it is considered that there is no interference in the detection, C 原始=N 稀释1 ×CC1=N 稀释2 ×CC2;

[0175] If the detection limit ≤ C 原始 <Determination limit, for C 原始 The solution (parallel sample) was spiked to obtain C 加标 Solution, 10 times the lower limit of determination ≤ C 加标 / 稀释 <The second highest point of the standard curve, the spike multiple is J 加标 If the calibrated standard curve is used to detect C 加标 solution, and obtain C 原始 =(75~125%)(1 / J 加标 )×C 加标 , it is considered that there is no interference in the detection. At this time, C 原始 =(1 / J 加标 )×C 加标 ;

[0176] If C 原始 <Detection limit, if the determination of C 原始 Solution (parallel sample) 7 times, t 单侧检验(7次，0.95) ×S 7次C原始溶液测定浓度值 If the detection limit is less than or equal to the MDL, it is considered that there is no interference in the test; the measurement result is not detected.

[0177] In the present invention, after the above dilution or addition, it is preferred to be as close as possible to the concentration point with the smallest ti value range within a certain concentration range. According to the degree of accuracy, ti is preferably divided into the following ranges: 0≤ti<0.500; 0.500≤ti<1.000; 1.000≤ti<1.500; 1.500≤ti<critical value t (a=0.05); the lower the ti value, the more accurate the detection result.

[0178] In the present invention, atomic absorption detection 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 regression equation between concentration and absorbance is established by using a standard solution of known concentration. Then, by measuring the absorbance of the unknown sample, the metal concentration value of the unknown sample is indirectly obtained on the standard curve.

[0179] The present invention utilizes a standard curve in combination with reasonable increase / decrease in sensitivity to correct interference in flame atomic absorption detection. The method for increasing sensitivity is as follows: the detection side light path is raised at the flame height by the basic hole. The closer to the center of the flame, the higher the atomization temperature, but at the same time the linearity of the relevant curve will deteriorate. The method for reducing sensitivity is as follows: mainly for potassium and sodium, which are more active elements, the detection light path passes through the basic hole, and the angle of the burner head is appropriately rotated. The principle is that the length of the detection light path through the flame is shortened and the sensitivity is reduced. The present invention utilizes a standard curve in combination with reasonable increase / decrease in sensitivity to correct interference in flame atomic absorption detection, checks whether there are differences in parameters such as the sensitivity of the standard curve, and then checks whether there is interference. If interference exists, after correcting the interference, the effect of eliminating the interference is further verified.

[0180] Example

[0181] The TAS-990 atomic absorption spectrophotometer provided by Beijing Puxi General Instrument Co., Ltd. was used to detect 1000 mg / L standard substance solution of iron in water (commercially available standard substance). (1+99) hydrochloric acid (1 volume of hydrochloric acid + 99 volumes of ultrapure water) was used for stepwise dilution to obtain the required detection concentration point. Peak search adjustment was first performed, and the optical path just passed through the standard hole. The peak search result did not exceed ±0.3nm of the characteristic value. The energy during peak search should not be less than 98%. If the conditions were not met, the peak search was repeated. The detection optical path was adjusted to pass through the standard hole and visually passed. The following table tests whether the concentration point is within the preset range. If the absorbance of the concentration point exceeds the preset range when the detection light path passes through the standard hole, it means that the sensitivity is too high. You can rotate the burner head angle until the absorbance of the concentration point reaches the preset value range. If the absorbance of the concentration point is lower than the preset value range when the detection light path passes through the standard hole, it means that the sensitivity is too low. You can increase the height of the detection light path in the flame. On the basis of the detection light path passing through the standard hole, increase it by 1nm each time until the absorbance of the concentration point reaches the preset value range. The final concentration point and absorbance detection values ​​are as follows:

[0182]

[0183] Note: C is the concentration, is the average of two measurements, Estimated values ​​for the standard curve.

[0184] For (1+99) high-grade pure hydrochloric acid, 11 measurements were performed and the detection limit was calculated. The results are as follows:

[0185]

[0186] Detection limit determination method:

[0187] According to all the steps of sample analysis, repeat the blank test n times (n≥7), convert each measurement result into the concentration or content in the sample, calculate the standard deviation of n parallel measurements, 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:

[0188] Number of parallel determinations (n) degrees of freedom (n-1) <![CDATA[t (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

[0189] Based on the above concentration points and the detected absorbance values, a standard curve was drawn using EXCEL (the absorbance was measured twice and the average value was taken). The obtained standard curve was (as shown in Figure 1 shown):

[0190] A=0.0828C+0.0023;

[0191] Test the above labeled curve:

[0192] The correlation coefficient R obtained by detection is 0.99974.

[0193] Requirements for the absorbance difference / concentration difference of the standard curve:

[0194] In the 0-2.5 mg / L curve, the measured difference in the 0-0.5 mg / L segment is 0.046, and the measured difference in the 2-2.5 mg / L segment is 0.039. The ratio is 0.85, which meets the requirements.

[0195] RSD requirements for the absorbance of 2 to 3 times the standard curve point:

[0196]

[0197] Standard curve T test, slope, intercept, standard deviation, residual test:

[0198] Taking the 2.5 mg / L concentration point as an example, first remove the 2.5 mg / L concentration point, and then use the least squares method to perform a linear regression on the remaining experimental points of 0, 0.5, 1.0, 1.5, and 2.0 mg / L. The standard curve equation is: A 0、0.5、1.0、1.5、2.0mg / L =0.0836C+0.0018, N=5, N-2=3, S A / c =(1.08E-05 / 3) 1 / 2 =0.0019, [(N+1) / N] 1 / 2 =1.095, substitute 2.5mg / L into the new equation, d A / c2.5 =0.208-0.2108=0.0028, t 2.5 =0.0028 / (0.0019×1.095)=1.35, check the sidebar of the t-test form, t(0.05,3)=2.353. 2.5<t(0.05,3), so the 2.5 mg / L point is a point within the 0-2.5 mg / L straight line. The test results are:

[0199]

[0200] Note: d A / c : The residual of the test point in the new regression equation.

[0201]

[0202] Backtest the low concentration point / highest concentration point of the standard curve:

[0203] The test results of the highest concentration point are as follows:

[0204]

[0205] The low concentration point detection results are as follows:

[0206]

[0207] The test results of the back-tested environmental sample concentration values ​​at the two ends of the standard curve are as follows:

[0208]

[0209] Note: The absorbance of the test sample is 0.157, and the back-test points are points 3 and 4 in the table above. Parallel samples of the environmental samples (diluted 2 times) are set, and the absorbance is 0.080. The back-test points are points 1 and 2. The back-test is performed once, which meets the RSD requirements of the back-test points.

[0210] Requirements for measuring parallel samples of environmental samples:

[0211] The original test result of the quality control sample was 1.87 mg / L, and the 10-fold lower limit of determination was ≤C 原始 <The concentration of the second highest point of the standard curve, diluted 2 times, the test result after dilution is 1.88 mg / L, (1.88 / 1.87)×100%=1.005%, there is no interference, the test result is 1.87 mg / L; the original solution and the 2-fold diluted solution are both within the expanded uncertainty of the quality control sample.

[0212] The values ​​of the B2005111 (1.86 ± 0.09 mg / L) quality control sample at the 0-2.5 mg / L standard curve are as follows:

[0213]

[0214] (Choose a 2-fold dilution because the concentration of a 2-fold dilution corresponds to a standard curve ti < 0.5, which can be accurately detected)

[0215] The present invention utilizes a standard curve in combination with reasonable increase / decrease in sensitivity to correct interference in flame atomic absorption detection. The method for increasing sensitivity is as follows: the detection side light path is raised at the flame height by the basic hole. The closer to the center of the flame, the higher the atomization temperature, but at the same time the linearity of the relevant curve will deteriorate. The method for reducing sensitivity is as follows: mainly for potassium and sodium, which are more active elements, the detection light path passes through the basic hole, and the angle of the burner head is appropriately rotated. The principle is that the length of the detection light path through the flame is shortened and the sensitivity is reduced. The present invention utilizes a standard curve in combination with reasonable increase / decrease in sensitivity to correct interference in flame atomic absorption detection, checks whether there are differences in parameters such as the sensitivity of the standard curve, and then checks whether there is interference. If interference exists, after correcting the interference, the effect of eliminating the interference is further verified.

[0216] Although the present invention has been described and illustrated with reference to specific embodiments of the present invention, these descriptions and illustrations do not limit the present invention. It will be clearly understood by those skilled in the art that, without departing from the true spirit and scope of the present invention as defined by the appended claims, various changes may be made to make specific circumstances, materials, compositions of matter, substances, methods or processes suitable for the object, spirit and scope of the present application. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a specific order, it will be understood that these operations may be combined, subdivided or reordered to form equivalent methods without departing from the teachings of the present invention. Therefore, unless otherwise indicated herein, the order and grouping of operations are not limitations of the present application.

Claims

1. A method for correcting interference in flame atomic absorption spectrometry, comprising: Flame atomic absorption spectrometry is used to detect whether the absorbance of the characteristic concentration value on the standard curve is within the preset range. If it is not within the preset range, correction is performed by sensitivity adjustment until the absorbance reaches the preset range; The preset range of absorbance of the characteristic concentration value includes: The concentration point between the detection limit and 5 times the lower limit of determination, the preset range of absorbance of the concentration point between the detection limit and 5 times the lower limit of determination is 0-0.050; The concentration points between 5 times and 10 times the lower limit of determination, wherein the preset absorbance range of the concentration points between 5 times and 10 times the lower limit of determination is 0.050 to 0.100; The concentration points between 10 times and 50 times the lower limit of determination are preset in the range of absorbance between 0.100 and 0.

500. Draw a standard curve to obtain a standard curve; detecting whether the ratio of the absorbance difference and concentration difference in the highest section of the standard curve to the ratio of the absorbance difference and concentration difference in the lowest section is within a preset range; if not, performing correction by adjusting the sensitivity until the range is reached; and obtaining a corrected standard curve; The preset range of the ratio of the absorbance difference and concentration difference of the highest segment of the standard curve to the ratio of the absorbance difference and concentration difference of the lowest segment includes: dividing the standard curve into 5 segments on average, and measuring the absorbance difference / concentration difference of each segment: if the absorbance of the highest point of the standard curve is greater than 0.050, then the ratio of the absorbance difference / concentration difference of the highest segment to the absorbance difference / concentration difference of the lowest segment is greater than or equal to 0.9; If the absorbance at the highest point of the standard curve is greater than 0.100, the ratio of the absorbance difference / concentration difference in the highest section to the absorbance difference / concentration difference in the lowest section should be greater than or equal to 0.85; If the absorbance at the highest point of the standard curve is greater than 0.200, the ratio of the absorbance difference / concentration difference in the highest section to the absorbance difference / concentration difference in the lowest section should be ≥ 0.8; If the absorbance at the highest point of the standard curve is greater than 0.300, the ratio of the absorbance difference / concentration difference in the highest section to the absorbance difference / concentration difference in the lowest section should be greater than or equal to 0.75; If the absorbance at the highest point of the standard curve is greater than 0.400, the ratio of the absorbance difference / concentration difference in the highest section to the absorbance difference / concentration difference in the lowest section should be ≥ 0.7; If the ratio of the highest absorbance difference and concentration difference to the lowest absorbance difference and concentration difference is less than a preset range, the sensitivity is increased; if the ratio of the highest absorbance difference and concentration difference to the lowest absorbance difference and concentration difference is greater than a preset range, the sensitivity is reduced. The method for reducing the sensitivity includes: when the detection light path passes through the standard hole, rotating the burner head angle clockwise by 5 to 10 degrees each time until the preset range is reached; The method for improving sensitivity includes: adjusting the height of the combustion head based on the detection light path passing through the standard hole, increasing it by 1.0 to 2.0 nm each time until it reaches the preset range; Use the calibrated standard curve to detect environmental samples and perform anti-interference operations to determine whether there is interference; The anti-interference operation method includes: The parallel samples of the environmental samples are spiked or diluted according to the concentration of the detected environmental samples, including: the concentration of the detected environmental samples is C 原始 : If 1 times the lower limit of determination ≤ C 原始 <4 times the lower limit of determination, the parallel samples were spiked to obtain C 加标 For solutions, the spike multiple should be no less than 1.25 times and no more than 4 times; If 4 times the lower limit of determination ≤ C 原始 If the value is less than 10 times the lower limit of determination, the parallel samples should be spiked or diluted to obtain C 加标 / 稀释 Solution, spiked or diluted C 加标 / 稀释 The solution also meets the following requirements: 4 times the lower limit of determination ≤ C 加标 / 稀释 <10 times the lower limit of determination; If 10 times the lower limit of determination ≤ C 原始 If the concentration is less than the second highest point of the standard curve, the parallel samples are diluted to obtain C 稀释 , 10 times the lower limit of determination ≤ C 稀释 ; If the concentration of the second highest point of the standard curve is ≤ C 原始 , then the parallel samples are diluted twice to obtain solutions CC1 and CC2, CC1 concentration>CC2 concentration, and at the same time meet the following conditions: 10 times the lower limit of determination ≤ CC1 < the concentration of the second highest point of the standard curve, 10 times the lower limit of determination ≤ CC2 < the concentration of the second highest point of the standard curve; If the detection limit ≤ C 原始 < determination limit, then spike the parallel samples to obtain C 加标 Solution, 10 times the lower limit of determination ≤ C 加标 / 稀释 <The second highest point of the standard curve; If C 原始 < detection limit, the parallel samples were measured 7 times; The method for determining whether interference exists includes: If 1 times the lower limit of determination ≤ C 原始 <4 times the lower limit of determination, then C 原始 =(85~115%)(1 / J 加标 ) × C 加标 , it is considered that there is no interference in the detection; If 4 times the lower limit of determination ≤ C 原始 <10 times the lower limit of determination, then C 原始 =(90~110%)(N 稀释 or 1 / J 加标 ) × C 加标 / 稀释 , it is considered that there is no interference in the detection; If 10 times the lower limit of determination ≤ C 原始 < the concentration of the second highest point of the standard curve, then C 原始 =(95~105%)N 稀释 ×C 稀释 , it is considered that there is no interference in the detection; If the concentration of the second highest point of the standard curve is ≤ C 原始 , then N 稀释1 CC1=(95~105%)N 稀释2 ×CC2, considered as no interference in the detection; If the detection limit ≤ C 原始 <determination limit, then C 原始 = (75~125%) (1 / J 加标 ) × C 加标 , it is considered that there is no interference in the detection.

2. The method according to claim 1, characterized in that The concentration points between 10 times the lower limit of determination and 50 times the lower limit of determination include the second highest concentration point; the preset absorbance range of the second highest concentration point includes: If 0.300 ≥ the absorbance of the highest point of the standard curve > 0.200, the preset range of the absorbance of the second highest concentration point is 0.100~0.200; If 0.400 ≥ the absorbance of the highest point of the standard curve > 0.300, the preset range of the absorbance of the second highest concentration point is 0.200~0.300; If 0.500 ≥ the absorbance of the highest point of the standard curve > 0.400, the preset range of the absorbance of the second highest concentration point is 0.300~0.400; If 0.600 ≥ the absorbance of the highest point of the standard curve > 0.500, the preset range of the absorbance of the second highest concentration point is 0.400~0.

500.

3. The method according to claim 1, characterized in that If the absorbance of the characteristic concentration value is less than the preset range, the sensitivity is increased; if the absorbance of the characteristic concentration value is greater than the preset range, the sensitivity is decreased.

4. The method according to claim 1, wherein After obtaining the calibrated standard curve, the following steps are also included: Test the calibrated standard curve; The inspection includes: Detect the RSD value of the absorbance of 2~3 concentration points on the calibrated standard curve; The linearity of the standard curve after calibration was tested; Detect the slope, intercept, standard deviation and residual of the calibrated standard curve; The ratio of the standard deviation to the mean absorbance of the concentration points on the calibrated standard curve was detected.

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