Method for analyzing aluminum element in iodized peanut oil

Abstract

The invention relates to the technical field of analysis and detection, in particular to a method for analyzing an aluminum element in peanut iodized oil. The analysis method specifically comprises the following steps: sample pretreatment: fully reacting a to-be-detected sample with nitric acid, treating the to-be-detected sample in a water bath environment at 80-120 DEG C for 1-2 hours, and then carrying out microwave digestion; after the digestion is completed, treating in a water bath environment at 60-80 DEG C for 1-2 hours, and fixing the volume. Performing inductively coupled plasma mass spectrometry determination: respectively adding internal standard ISTD elements with the same concentration into the standard solution, the test solution and the blank solution, and performing determination; and preparing a standard curve by using the standard solution, and calculating the concentration of the aluminum element in the test solution by using the standard curve. Compared with the prior art, the analysis method provided by the invention not only has lower requirements on the sample dosage, but also has higher accuracy and lower detection limit.

Description

Technical Field

[0001] This application relates to the technical field of analytical testing, and in particular to an analytical method for aluminum in peanut iodized oil. Background Technology

[0002] Potassium iodide from peanuts, as a product with both nutritional and functional properties, is widely used in food additives and fortifiers. However, the aluminum content must be strictly controlled, as excessive aluminum intake can damage the nervous and skeletal systems, and long-term accumulation may lead to health problems such as cognitive impairment and osteoporosis. Therefore, accurate analysis of the aluminum content in potassium iodide from peanuts is crucial to ensuring product quality and safety and compliance with relevant national standards.

[0003] Currently, analytical methods for aluminum in food and related products mainly include spectrophotometry, atomic absorption spectrometry (AAS), and inductively coupled plasma mass spectrometry (ICP-MS). Among these, ICP-MS is used for the detection of aluminum in potassium iodide in peanuts due to its high sensitivity and ability to analyze multiple elements simultaneously. Its principle is to use inductively coupled plasma to convert aluminum into positively charged ions, which are then separated by a mass analyzer. The content is calculated based on the linear relationship between the ion signal intensity and concentration, using the mass-to-charge ratio. However, it still suffers from inaccurate results and insufficient stability.

[0004] With increasing consumer concern about food safety and stricter regulations, the market demands higher quality control standards for potassium iodide in peanuts. Simultaneously, manufacturers need reliable methods to monitor the production process, ensuring products meet quality standards and enhance market competitiveness. Therefore, to prevent substandard products from entering the market and endangering public health, it is necessary to further develop analytical methods suitable for aluminum content in potassium iodide from peanuts. Summary of the Invention

[0005] This application provides an analytical method for aluminum in peanut iodized oil. Compared with existing technologies, the analytical method provided in this application not only requires a smaller sample volume but also has higher accuracy and a lower detection limit.

[0006] This application provides a method for analyzing aluminum in peanut iodized oil, using the following technical solution:

[0007] A method for analyzing aluminum in peanut iodized oil, the method specifically includes the following steps:

[0008] Sample pretreatment: After the sample to be tested has fully reacted with nitric acid, it is placed in a water bath at 80-120℃ for 1-2 hours and then microwave digested; after digestion, it is placed in a water bath at 60-80℃ for 1-2 hours and then brought to a final volume.

[0009] The digestion process is as follows: Heating stage: room temperature - 220℃, heating time is 20-30 min; Holding stage: 220℃ - 220℃, holding time is 50-60 min; Cooling stage: 220℃ - room temperature, holding time is 20-30 min.

[0010] Inductively coupled plasma mass spectrometry (ICP-MS) determination: The same concentration of internal standard ISTD element was added to the standard solution, the test solution, and the blank solution, respectively, and the determination was performed; a standard curve was prepared using the standard solution, and the aluminum element concentration in the test solution was calculated using the standard curve.

[0011] Optionally, the amount of the sample to be tested is not less than 0.2g.

[0012] Optionally, the weight / volume ratio of the sample to be tested to the nitric acid is 1:(35-40).

[0013] Optionally, the measurement conditions for the inductively coupled plasma mass spectrometry are as follows: RF power: 1550W; nebulizing gas: 1.05L / min; nebulization chamber temperature: 2℃; peristaltic pump: 0.1r / s; dilution factor: 1.0725; scan type: single bar.

[0014] Optionally, the aluminum content is calculated as follows: Aluminum content (μg / g) = (C×V) / (1000×m); where C is the concentration of aluminum in the test solution, in ng / ml; V is the dilution factor, in ml; and m is the sample weight, in g.

[0015] In summary, this application includes at least one of the following beneficial technical effects:

[0016] This application uses inductively coupled plasma mass spectrometry (ICP-MS) to analyze and determine aluminum impurities in peanut iodized oil. A mixed internal standard containing Sc was selected as the internal standard solution. The radio frequency power was 1550W, the peristaltic pump speed was 0.1r / s, the nebulizer gas was 1.05L / min, and the nebulizer chamber temperature was 2℃.

[0017] The analytical method provided in this application has been validated for specificity, linearity, limit of quantitation, limit of detection and reporting, system precision, repeatability, intermediate precision, accuracy, and solution stability. All validation results meet acceptable standards. Key steps have been refined, making this method suitable for the analysis and determination of aluminum impurities in peanut iodized oil. This analytical method has been validated in the detection of aluminum impurities in peanut iodized oil. Detailed Implementation

[0018] Before describing the embodiments of this application in detail, it should be understood that the terminology used herein is for the purpose of describing a particular embodiment only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the term pertains.

[0019] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more.

[0020] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0021] In this application, the terms "comprising" or "including" are open-ended expressions, meaning they include the content specified in this application but do not exclude other aspects.

[0022] Peanut iodized oil is a non-sterile, oily liquid pharmaceutical raw material produced by our company. No other harmful metal elements (elemental impurities) are added during its production process. Due to the change in the inner packaging material to a pharmaceutical-grade screw-top aluminum bottle, according to relevant regulations, it is necessary to monitor and evaluate the aluminum content in the final product. Stability studies will be conducted periodically to determine the aluminum content in the product. Based on this test data, the impact of the inner packaging material change on the quality and shelf life (stability) of the peanut iodized oil will be further evaluated to ensure that the product complies with relevant regulations and quality standards.

[0023] Based on the above, aluminum is a material component of the pharmaceutical screw-top aluminum bottle used as the inner packaging of peanut iodized oil; however, aluminum is not used in the production process of peanut iodized oil. Given the practical situation, it is necessary to examine the aluminum residue in peanut iodized oil samples that have been stored for a period of time to confirm whether aluminum has migrated from the inner packaging material and the amount of migration. It is unnecessary to use freshly produced peanut iodized oil.

[0024] The subject of this test is a batch of peanut iodized oil products produced by our company for sample retention after the change of the inner packaging material of the peanut iodized oil. The products were manufactured by our company (Shanghai Wanxiang Pharmaceutical Co., Ltd.).

[0025] This application provides a method for analyzing aluminum in peanut iodized oil.

[0026] The analytical method specifically includes the following steps:

[0027] Sample pretreatment: After the sample to be tested is fully reacted with nitric acid, it is placed in a water bath at 80-120℃ for 1-2 hours and then microwave digested. After digestion, it is placed in a water bath at 60-80℃ for 1-2 hours and then brought to a final volume.

[0028] The amount of the sample to be tested shall not be less than 0.2 g. The weight / volume ratio of the sample to nitric acid shall be 1:(35-40).

[0029] The digestion process is as follows: Heating stage: room temperature - 220℃, heating time is 20-30 min; Holding stage: 220℃ - 220℃, holding time is 50-60 min; Cooling stage: 220℃ - room temperature, holding time is 20-30 min.

[0030] Inductively coupled plasma mass spectrometry (ICP-MS) determination: The same concentration of internal standard ISTD element was added to the standard solution, the test solution, and the blank solution, respectively, and the determination was performed; a standard curve was prepared using the standard solution, and the aluminum element concentration in the test solution was calculated using the standard curve.

[0031] The measurement conditions were as follows: RF power: 1550W; atomizing gas: 1.05L / min; atomization chamber temperature: 2℃; peristaltic pump: 0.1r / s; dilution factor: 1.0725; scan type: single bar.

[0032] The formula for calculating aluminum content is as follows: Aluminum content (μg / g) = (C×V) / (1000×m); where C is the concentration of aluminum in the test solution, in ng / ml; V is the dilution factor, in ml; and m is the sample weight, in g.

[0033] The principle of this application is as follows: After the sample is introduced into the atomization system by the carrier gas (argon) and atomized, it enters the plasma center region in the form of an aerosol. In the high temperature and inert gas, it is desolvated, vaporized, deionized and ionized, and converted into positively charged positive ions. The ions are then sent to the mass analyzer through the ion collection system. The mass analyzer separates the samples according to the mass-to-charge ratio and determines the aluminum content in the sample according to the peak intensity of the elemental mass spectrum.

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0035] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0036] In the following examples, unless otherwise stated, all reagents used were of analytical grade. The specific sources or preparation methods of some reagents are as follows:

[0037] (1) The water is Grade I water as specified in GB / T6682.

[0038] (2) The blank solution (5% nitric acid) is prepared by measuring 50 ml of nitric acid into a 1000 ml volumetric flask, diluting it with water to the mark, and mixing well.

[0039] (3) The aluminum standard solution had a concentration of 1000 μg / ml and was purchased from Anpu, with batch number 1063015-42.

[0040] The preparation method of aluminum standard stock solution 1 (concentration: 50 μg / ml) is as follows: transfer 2.5 ml of aluminum element standard solution into a 50 ml volumetric flask, and dilute to the mark with 5% nitric acid.

[0041] The preparation method of aluminum standard stock solution 2 (concentration: 5 μg / ml) is as follows: transfer 5 ml of aluminum standard stock solution 1 to a volumetric flask of 50 ml, and dilute to the mark with 5% nitric acid.

[0042] The method for preparing aluminum standard working solutions is as follows: transfer different volumes of aluminum standard stock solutions and dilute them with 5% nitric acid to prepare standard working solutions of different concentrations of 50 ng / ml, 100 ng / ml, 200 ng / ml, 400 ng / ml, 600 ng / ml, and 1000 ng / ml.

[0043] (4) The concentration of the internal standard mixture was 100 μg / ml. It was purchased from Agilent, batch number 56-139CRY2, and contained the internal standard Sc.

[0044] The preparation method of internal standard stock solution 1 (concentration: 5 μg / ml) is as follows: transfer 2.5 ml of internal standard mixed solution into a 50 ml volumetric flask, add 5% nitric acid to dilute to prepare a 5 μg / ml solution.

[0045] The internal standard solution (concentration: 50 ng / ml) is prepared by transferring 0.5 ml of internal standard stock solution into a volumetric flask containing 1 to 50 ml of the solution, adding 5% nitric acid to dilute it to prepare a 50 ng / ml solution.

[0046] In the following embodiments, the inductively coupled plasma mass spectrometer is an Agilent 7800, and the microwave digester is a PreeKemWX-8000.

[0047] The present application will be further described in detail below with reference to the embodiments and test results.

[0048] Example 1

[0049] This embodiment provides an analytical scheme for aluminum in potassium iodide from peanuts.

[0050] Specifically, the following steps are included:

[0051] (1) Sample pretreatment

[0052] Preparation of the test solution: Accurately weigh 0.2 g of the sample and place it in a microwave digestion vessel. Add a small amount of deionized water to moisten the sample, then add 7.5 ml of nitric acid to ensure full contact between the sample and the acid. After the chemical reaction stops, transfer the sample to a water bath and preheat at 100°C for 1 hour. Then, transfer the sample to a microwave digester and digest according to the microwave digestion program. After the program is complete, cool to room temperature, slowly release the pressure, open the digestion vessel, and transfer the sample to a water bath at 70°C for 1.5 hours. Cool to room temperature, transfer the solution to a 50 ml volumetric flask, and dilute to the mark with water.

[0053] The microwave digestion procedure is shown in Table 1.

[0054] Table 1 Microwave Digestion Procedure

[0055] stage Temperature range (°C) Heating / lowering / heating time (min) 1 (Heating Phase) Room temperature -220 25 2 (Maintenance Phase) 220-220 55 3 (Cooling-down phase) 220-room temperature 15

[0056] Preparation of blank solution: Except for not adding the sample, the other operations are the same as those in "Preparation of test solution".

[0057] (2) Instrument measurement conditions

[0058] RF power: 1550W; RF matching: 1.80; Atomizing gas: 1.05L / min; Atomization chamber temperature: 2℃;

[0059] Peristaltic pump: 0.1 r / s; Dilution factor: 1.0725; Scan type: single rod; Plasma mode: conventional;

[0060] (3) Inductively Coupled Plasma Mass Spectrometry

[0061] Inject the linear solution, blank solution, test solution, and internal standard solution simultaneously.

[0062] Calculation: Using the standard curve method with internal standard correction, the corresponding concentration of aluminum in the test sample solution, corrected by the internal standard solution, is obtained from the standard curve or regression equation, and the aluminum content in the sample is calculated.

[0063] (4) Calculation of results

[0064] The calculation formula is as follows: Aluminum content (μg / g) = (C×V) / (1000×m).

[0065] Where C is the concentration of aluminum in the test solution (ng / ml); V is the dilution factor (ml); and m is the sample weight (g).

[0066] Performance testing

[0067] I. Limits for Aluminum in Potassium Iodide from Peanuts

[0068] According to GB 2760-2014 National Food Safety Standard for the Use of Food Additives, the residual amount of aluminum...

[0069] ≤100mg / kg (100ppm). Therefore, the residual limit for aluminum in peanut iodized oil is not more than 100ppm.

[0070] II. Selection of Internal Standard Elements

[0071] 45 Scandium (Sc) has a mass number and ionization energy similar to those of aluminum, the element being measured; therefore, it was chosen as the element for this study. 45 Sc) is used as an internal standard element for the determination of aluminum by ICP-MS.

[0072] III. Verification Project

[0073] The following items were analyzed using the analysis method provided in Example 1.

[0074] (1) Exclusivity

[0075] Experimental method: Seven blank solutions were continuously measured, and the response values ​​of the aluminum blank solutions were recorded. The response values ​​of the aluminum blank solutions were compared with the response values ​​at the lowest concentration point of the linear solution. If the response value at the lowest concentration point of the linear solution was significantly higher than the response value of the blank solution, it indicates that the blank solution did not interfere with the determination, and that the specificity of the analytical method met the requirements.

[0076] The experimental results are shown in Table 2.

[0077] Table 2 Results of specificity test

[0078]

[0079] As shown in Table 2, the response values ​​at the lowest point of the linear aluminum solution concentration are significantly higher than those of the blank solution, indicating that the blank solution does not interfere with the determination and that the specificity is good.

[0080] (2) Linear

[0081] Experimental method: Inject the linear solution and the internal standard solution. Plot the standard curve of aluminum with aluminum concentration on the x-axis and the ratio of aluminum to internal standard response values ​​on the y-axis, and calculate the linear correlation coefficient (R). If the aluminum correlation coefficient is greater than 0.990, it indicates that the method has a good linear relationship and meets the validation requirements.

[0082] The experimental results are shown in Table 3.

[0083] Table 3 Results of the linear experiment

[0084]

[0085]

[0086] As shown in Table 3, the correlation coefficient of aluminum is greater than 0.990, which meets the verification requirements, indicating that the linear relationship of this method is good.

[0087] (3) Limit of quantitation, limit of detection and limit of reporting

[0088] Test method: After constructing the standard working curve, the blank solution was measured seven times consecutively. The concentration corresponding to three times the standard deviation (3SD) of the ratio of the seven blank solution response values ​​to the internal standard response value was taken as the limit of detection (LOD); the concentration corresponding to ten times the standard deviation (10SD) of the ratio of the seven blank solution response values ​​to the internal standard response value was taken as the limit of quantitation (LOQ). If both the limit of detection and the limit of quantitation are lower than the reporting limit, and the reporting limit is lower than the control threshold, the sensitivity requirements are met.

[0089] Calculation formula:

[0090] Where SD is the standard deviation of the response value or the ratio of response values; S is the slope of the working curve.

[0091] The experimental results are shown in Table 4.

[0092] Table 4. Results of tests for limit of quantitation and limit of detection (sensitivity)

[0093]

[0094] As shown in Table 4, both the detection limit and the quantitation limit are lower than the reporting limit, which meets the sensitivity requirements.

[0095] (4) System precision

[0096] Test method: The lowest concentration solution under the linear solution test (solution 1-2: 50 ng / ml) was used as the report limit solution; the solution under the linear test (solution 1-5: 400 ng / ml) was used as the standard solution. The report limit solution and standard solution for aluminum were measured six times consecutively. If the RSD of the ratio of the aluminum element response value to the internal standard element is ≤10%, it meets the validation requirements.

[0097] The experimental results are shown in Tables 5 and 6.

[0098] Table 5. System precision-report limit solution (50 ng / ml) test results

[0099]

[0100] Table 6. System Precision - Test Results of Standard Solution (400 ng / ml)

[0101]

[0102] As shown in Tables 5 and 6, the RSD of the ratio of aluminum element response value to internal standard element response value is ≤10%, indicating that the result meets the verification requirements.

[0103] (5) Repeatability

[0104] Test method:

[0105] Spiked test solution: Accurately weigh approximately 0.2 g of the sample (from the same batch used for stability testing after the inner packaging material change), place it in a microwave digestion vessel, add a small amount of deionized water to moisten, and add 7.5 ml of nitric acid. Ensure the sample is fully in contact with the acid, add 0.4 ml of stock solution 1 (50 μg / ml), and follow the same procedure as in Example 1 for the preparation of the test solution. Prepare 6 solutions using the same method.

[0106] Inject the internal standard solution and the repeatability solution simultaneously, and perform six consecutive measurements. Calculate the RSD of the aluminum content.

[0107] Calculation: Content (μg / g) = Measured amount (ng / ml) × 50ml / Sample weight (mg).

[0108] If the RSD of aluminum content in the 6 replicate solutions is ≤20%, it meets the verification requirements.

[0109] The experimental results are shown in Table 7.

[0110] Table 7 Results of Repeatability Tests

[0111]

[0112] As shown in Table 7, the RSD of aluminum content in the 6 repeatability solutions is less than 20%, indicating good repeatability and meeting the verification requirements.

[0113] (6) Intermediate precision

[0114] Test method: In accordance with the repeatability test requirements in (5), different personnel prepared and injected the solution on different dates, and each measurement was performed 6 times consecutively. The RSD of aluminum content was calculated for each person (n=6), and then the RSD of the two people was calculated (n=12). If different personnel injected the sample at different times, the RSD of aluminum content calculated for each person (n=6) should be ≤20%; the combined RSD of aluminum content in the 12 spiked solutions should be ≤25% (n=12), which meets the verification requirements.

[0115] The experimental results are shown in Table 8.

[0116] Table 8 Results of intermediate precision test

[0117]

[0118]

[0119] As shown in Table 8, when different personnel injected samples at different times, the RSD of aluminum content in 6 samples was <20%. The combined RSD of aluminum content in the 12 spiked solutions was <25%, which met the validation requirements and indicated that the intermediate precision of this method was good.

[0120] (7) Accuracy (spiking recovery rate)

[0121] Solution preparation:

[0122] Blank recovery solution: Add 7.5 ml of nitric acid to a microwave digestion vessel. Accurately add 0.4 ml of stock solution 1 (50 μg / ml). The subsequent method is the same as the preparation of the test solution in Example 1. Prepare 6 samples using the same method.

[0123] Report limit recovery solution: Accurately weigh approximately 0.2 g of sample and place it in a microwave digestion vessel. Add a small amount of deionized water to moisten the sample, then add 7.5 ml of nitric acid. Ensure the sample is fully in contact with the acid. Add 0.5 ml of stock solution 2 (5 μg / ml). The subsequent procedures are the same as for the preparation of the test solution in Example 1. Prepare three aliquots using the same method.

[0124] Recovery Solution 1 (50%): Accurately weigh approximately 0.2 g of sample and place it in a microwave digestion vessel. Add a small amount of deionized water to moisten the sample, then add 7.5 ml of nitric acid. Ensure the sample is fully in contact with the acid. Add 0.2 ml of Stock Solution 1 (50 μg / ml). The subsequent steps are the same as for the preparation of the test solution in Example 1. Prepare three solutions using the same method.

[0125] Recovery Solution 2 (100%): Accurately weigh approximately 0.2 g of sample and place it in a microwave digestion vessel. Add a small amount of deionized water to moisten the sample, then add 7.5 ml of nitric acid. Ensure the sample is fully in contact with the acid. Add 0.4 ml of Stock Solution 1 (50 μg / ml). The subsequent steps are the same as for the preparation of the test solution in Example 1. Prepare three solutions using the same method.

[0126] Recovery solution 3 (150%): Accurately weigh approximately 0.2 g of sample and place it in a microwave digestion vessel. Add a small amount of deionized water to moisten the sample, then add 7.5 ml of nitric acid. Ensure the sample is fully in contact with the acid. Add 0.6 ml of stock solution 1 (50 μg / ml). The subsequent steps are the same as for the preparation of the test solution in Example 1. Prepare 3 solutions using the same method.

[0127] Test method: Inject blank recovery solution, report limit recovery solution, and recovery solutions 1, 2, and 3 respectively, and calculate according to the following formula:

[0128]

[0129] Where: C 空 --Concentration of aluminum in the spiked blank solution, ng / ml;

[0130] C 样 --Concentration of aluminum in the spiked test solution, ng / ml;

[0131] C 加 --The concentration of aluminum added to the test solution, in ng / ml;

[0132] X -- The aluminum content in the sample, μg / g;

[0133] m - Sample weight, in g;

[0134] V -- Dilution factor, ml.

[0135] If the blank recovery rate of aluminum should be between 70% and 150% (n=6), with an RSD ≤ 20%; and the report limit recovery rate, recovery solutions 1, 2, and 3 are all between 70% and 150% (n=12), with an RSD ≤ 25% (n=12), then the validation requirements are met.

[0136] The experimental results are shown in Tables 9 and 10.

[0137] Table 9 Results of Recovery Rate-Blank Recovery Rate Tests

[0138]

[0139] Table 10 Recovery Rate - Results of Sample Spiking Recovery Test

[0140]

[0141] As shown in Tables 9 and 10, the blank recovery rate of aluminum is between 70% and 150%, with an RSD of <20%; the report limit recovery rate, recovery rate solutions 1, 2, and 3 are all between 70% and 150%, with an RSD of <25%, and the results all meet the validation requirements; in summary, the accuracy of this method is good.

[0142] (8) Sample background measurement and solution stability

[0143] 1. Sample background measurement

[0144] Test method: Take approximately 0.2 g of sample (from the same batch as the stability test after the inner packaging material change), and follow the same procedure as in Example 1 for the preparation of the test solution. Inject the test solution and internal standard solution simultaneously to determine the aluminum impurity content. The aluminum content in the actual sample should be ≤100 μg / g.

[0145] The experimental results are shown in Table 11.

[0146] Table 11 Sample Background Measurement Records

[0147]

[0148] As shown in 11, the aluminum content is below the reporting limit and below the limit requirement.

[0149] 2. Solution stability

[0150] Experimental Method: Linear solutions from the linearity test and repeatable solutions from the repeatability test were placed at room temperature for 8 hours, and the internal standard solution, linear solution, and repeatable solution were measured separately. Calculation: The relative percentage content was calculated using the two concentration measurements. If the relative percentage content of aluminum element solution concentration is between 80% and 120% after 8 hours of standing at room temperature, it indicates that the linear solution and repeatable solution are stable after 8 hours of standing at room temperature, meeting the verification requirements.

[0151] The experimental results are shown in Tables 12 and 13.

[0152] Table 12 Results of Solution Stability-Linear Solution Tests

[0153]

[0154] Table 13 Solution stability - Results of repeatable solution tests

[0155]

[0156] As shown in Tables 12 and 13, the relative percentage concentration of aluminum in both the linear and repeatable solutions remained within the range of 80%–120% after being placed at room temperature for 8 hours, meeting the verification requirements. In summary, both the linear and repeatable solutions were stable after being placed at room temperature for 8 hours.

[0157] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0158] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for analyzing aluminum in peanut iodized oil, characterized in that, The analytical method specifically includes the following steps: Sample pretreatment: After the sample to be tested has fully reacted with nitric acid, it is placed in a water bath at 80-120℃ for 1-2 hours and then microwave digested; after digestion, it is placed in a water bath at 60-80℃ for 1-2 hours and then brought to a final volume. The digestion process is as follows: Heating stage: room temperature - 220℃, heating time is 20-30 min; Holding stage: 220℃ - 220℃, holding time is 50-60 min; Cooling stage: 220℃ - room temperature, holding time is 20-30 min. Inductively coupled plasma mass spectrometry (ICP-MS) determination: The same concentration of internal standard ISTD element was added to the standard solution, the test solution, and the blank solution, respectively, and the determination was performed; a standard curve was prepared using the standard solution, and the aluminum element concentration in the test solution was calculated using the standard curve.

2. The analytical method according to claim 1, characterized in that, The amount of the sample to be tested is not less than 0.2g.

3. The analytical method according to claim 1, characterized in that, The weight / volume ratio of the sample to be tested to the nitric acid is 1:(35-40).

4. The analytical method according to claim 1, characterized in that, The inductively coupled plasma mass spectrometry (ICP-MS) measurement conditions are as follows: RF power: 1550W; nebulizing gas: 1.05L / min; nebulization chamber temperature: 2℃; peristaltic pump: 0.1r / s; Dilution factor: 1.0725; Scan type: single bar.

5. The analytical method according to claim 1, characterized in that, The formula for calculating aluminum content is as follows: Aluminum content (μg / g) = (C×V) / (1000×m); where C is the concentration of aluminum in the test solution, in ng / ml; V is the dilution factor, in ml; and m is the sample weight, in g.

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