Detection method of extractable aluminum content in paper products
Through a new aluminum content detection method in paper products, the absorbance is measured using cuvettes, which solves the problem of high cost and time-consuming existing detection methods, and achieves fast, accurate and low-cost aluminum content detection, which is suitable for internal quality control.
Patent Information
- Application Number
- CN202411753582.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-02
- Publication Date
- 2025-04-04
AI Technical Summary
The existing aluminum content detection methods in paper products have problems such as expensive instruments, high testing costs and long-term time, and it is difficult to meet the needs of internal quality control.
A method for detecting extractable aluminum content in paper products is provided. By soaking the paper product to be tested in distilled water, an aqueous solution is prepared, and p-nitrophenol ethanol solution, ammonia water, nitric acid, sodium acetate buffer solution, bromohexadecylpyridine-polyethylene glycol octylphenyl ether solution and chromium azure S solution are added in turn, and the absorbance is measured using a cuvette to calculate the aluminum content.
This method is cheap in testing and simple in operation. It can be completed in any laboratory. It has high practicality and can quickly and accurately detect aluminum content to meet the quality control needs of the production process.
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Figure CN119757249A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of aluminum content detection technology in paper products, and specifically to a method for detecting extractable aluminum content in paper products. Background Art
[0002] Aluminum and related compounds are widely used in chemical products and light industrial manufacturing due to their properties and low cost. However, if the human body ingests too much aluminum, it will affect the human nervous system, bones, and immune system. European Commission Regulation 1935 / 2004 (October 27, 2004), Chapters 30 and 31 of the German Food and Commodities Act (LFGB) (September 1, 2005) and its amendments, as well as BFR stipulate that the limit of extractable aluminum is 1000ug / L.
[0003] The chemical raw materials currently used in the papermaking technology industry, especially PAC, surface sizing agents and other products, all contain aluminum. These chemical raw materials have an important impact on the quality of paper. There are several methods for detecting aluminum content:
[0004] 1. Colorimetric method: In a slightly acidic medium, the sample is heated with aluminum reagent (rose red ammonium tricarboxylate) to form a stable red complex. The depth of color is proportional to the aluminum content. Based on this, the aluminum content is determined by colorimetry. The linear range of this method for determining aluminum content is 100-1000ug / L.
[0005] 2. Indirect photometry: Aluminum ions react to form a purple-red complex with a maximum absorption value at the corresponding wavelength, which can be used for colorimetric quantification. The linear range of this method for determining aluminum content is 100-800ug / L.
[0006] 3. X-ray fluorescence spectrometry (XRF): This is a non-destructive analysis method that determines the content of each element in the sample by irradiating the sample with X-rays to stimulate the atoms in the sample to emit characteristic X-rays. The XRF method can quickly and accurately detect the aluminum content and is suitable for the detection of most metal aluminum materials. The linear range of aluminum content determined by this method is 13.28% to 90.36%.
[0007] 4. Inductively coupled plasma emission spectrometry (ICP-MS): This is a highly sensitive, multi-element analysis method. The sample is first dissolved or pre-treated to obtain a solution, and then the solution is sprayed into a high-temperature plasma. The detector converts ions into electron pulses, and then uses the size of the electron pulses to analyze the content of each element in the sample. The linear range of this method for aluminum content is 100 to 25,000 ug / L.
[0008] 5. Graphite furnace atomic absorption spectrometry (GFAAS): This method is suitable for the analysis of low-concentration aluminum. After the sample is dissolved into a solution, it is heated and evaporated using a graphite furnace, and then a light source of a specific wavelength is used to irradiate the evaporated sample, and the absorption light intensity is measured to determine the aluminum concentration. The linear range of this method for determining aluminum content is 50-600ug / L.
[0009] Currently, the most commonly used, most accurate and most authoritative methods are X-ray fluorescence spectrometry (XRF), inductively coupled plasma emission spectrometry (ICP-MS) and graphite furnace atomic absorption spectrometry (GFAAS). However, the above methods have problems such as expensive instruments, high detection costs and long detection time (about 1.5 weeks at the fastest), which are not conducive to internal quality control. How to extract aluminum from paper, reduce detection costs and minimize time has become a major problem in the detection of extractable aluminum content in paper and paperboard today. Summary of the invention
[0010] The present application embodiment provides a method for detecting the extractable aluminum content in paper products, the detection method comprising:
[0011] preparing an aqueous solution of the paper product to be tested;
[0012] To the prepared aqueous solution of the paper product to be tested, add p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution in sequence and shake well;
[0013] The absorbance was measured using a cuvette;
[0014] The aluminum content in the paper product to be tested is calculated according to the measured absorbance.
[0015] In some optional embodiments, the step of sequentially adding p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution to the prepared aqueous solution of the paper product to be tested and shaking well comprises: taking 5 mL of the aqueous solution of the paper product to be tested, adding p-nitrophenol ethanol solution, adding ammonia water dropwise until it turns light yellow, then adjusting with 0.5 mol / L nitric acid until the yellow color disappears, adding 10.0 mL of acetic acid-sodium acetate buffer, 1.0 mL of cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution, 2.0 mL of chrome azuro blue S solution, diluting with distilled water and shaking well, and letting stand for a first preset time.
[0016] In some optional embodiments, the detection method further comprises: preparing a standard curve using an aluminum standard solution; and after the step of measuring the absorbance using a cuvette, comparing with the standard curve to verify the measured absorbance.
[0017] In some optional embodiments, the step of preparing a standard curve using an aluminum standard solution includes: taking multiple volumetric flasks and adding different amounts of aluminum standard solutions to each of them, adding p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution to each volumetric flask in turn and shaking well; using a cuvette to measure the absorbance of the solutions prepared in the multiple volumetric flasks and drawing a standard curve.
[0018] In some optional embodiments, the step of taking multiple volumetric flasks and adding different amounts of aluminum standard solution to each volumetric flask, adding acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution to each volumetric flask in sequence and shaking well includes: taking 8 50mL volumetric flasks, adding 0mL, 0.20mL, 0.50mL, 1.00mL, 3.00mL, 5.00mL, 7.00mL, and 10.00mL of aluminum standard solution, respectively, adding distilled water to 25±1mL, adding p-nitrophenol ethanol solution, adding ammonia water dropwise until it turns light yellow, and then adjusting with 0.5mol / L nitric acid until the yellow color disappears, adding acetic acid-sodium acetate buffer 10.0mL, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution 1.0mL, and chrome azuro blue S solution 2.0mL, diluting with distilled water and shaking well, and letting it stand for a second preset time.
[0019] In some optional embodiments, in the step of measuring the absorbance of the solutions prepared in multiple volumetric flasks using cuvettes respectively and drawing a standard curve: the absorbance is measured using a cuvette at a wavelength of 620 nm.
[0020] In some optional embodiments, the step of preparing the aqueous solution of the paper product to be tested includes:
[0021] Place the paper product to be tested in distilled water and soak for a preset time;
[0022] Take the aqueous solution after soaking the paper product to be tested.
[0023] In some optional embodiments, the preparation method of the cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution includes: weighing a certain amount of cetylpyridinium bromide, adding anhydrous ethanol to dissolve it, adding polyethylene glycol octylphenyl ether, adding distilled water and mixing.
[0024] In some optional embodiments, the preparation method of the acetic acid-sodium acetate buffer comprises: weighing a certain amount of anhydrous sodium acetate, adding distilled water to dissolve, adding glacial acetic acid, adding distilled water, and adjusting the pH to 6.5-7.0 using NaOH or glacial acetic acid.
[0025] In some optional embodiments, the chrome azure blue S solution is a chrome azure blue S ethanol solution.
[0026] The method for detecting the extractable aluminum content in paper products provided in the embodiments of the present application utilizes aluminum to react with chrome azuro blue S in the presence of cetylpyridinium bromide to generate blue-green quaternary micelles, and the absorbance value is measured at a wavelength of 620 nm and compared with a standard series for quantitative analysis. The method has low detection cost and simple test operation, and any laboratory can complete it, so it has high practicality. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
[0028] Figure 1 It is a flow chart of an embodiment of a method for detecting extractable aluminum content in paper products of the present application;
[0029] Figure 2 This is a schematic diagram of a process for preparing an aqueous solution of a paper product to be tested according to an embodiment of the present application;
[0030] Figure 3 It is a flow chart of another embodiment of the method for detecting the extractable aluminum content in paper products of the present application;
[0031] Figure 4 This is a schematic diagram of a process for preparing a standard curve using an aluminum standard solution in the present application;
[0032] Figure 5 It is a schematic diagram comparing the results of the detection method in the examples of the present application and the ICP-MS detection method. DETAILED DESCRIPTION
[0033] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.
[0034] The terms "first", "second", and "third" in the embodiments of the present application are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second", and "third" can expressly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the embodiments of the present application, all directional indications (such as up, down, left, right, front, back...) are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. The terms "including" and "having" in the embodiments of the present application and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or components inherent to these processes, methods, products, or devices.
[0035] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.
[0036] In the production process of paper and paperboard, the control of aluminum content is extremely important. Nowadays, international authoritative testing agencies (such as SGS) use inductively coupled plasma emission spectrometry (ICP-MS) for testing. Entrusting testing agencies to conduct testing not only has high testing costs, but also has long testing cycles, which is not conducive to production process control. In order to stabilize the quality and reduce the production of defective products, an accurate, low-cost, and short-time method is required to detect the aluminum content. In view of this, the embodiment of the present application provides a method for detecting the extractable aluminum content in paper products. Among them, the aluminum on white cardboard mainly comes from the surface coating, usually in the form of aluminum sulfate, aluminum chloride, polyaluminum chloride, etc., all of which are soluble in water. The method in the embodiment of the present application mainly extracts the aluminum on the white cardboard for detection.
[0037] See also Figure 1 , Figure 1 1 is a flow chart of an embodiment of a method for detecting extractable aluminum content in paper products of the present application, and the detection method includes but is not limited to the following steps.
[0038] Step S100, preparing an aqueous solution of paper products to be tested.
[0039] In this step, see Figure 2 , Figure 2 1 is a schematic diagram of a process for preparing an aqueous solution of a paper product to be tested according to an embodiment of the present invention. The method includes the following steps.
[0040] Step S110, placing the paper product to be tested in distilled water and soaking it for a preset time.
[0041] In this step, you can wear gloves to take a 10g paper sample and cut it into 1cm pieces with ceramic scissors. 2 Put the sample into a clean 500mL wide-mouth reagent bottle, add 200mL distilled water, and cover the bottle cap. Place it at a constant temperature (23±1℃) for 24 hours, and shake it every 4 hours.
[0042] Step S120, taking the aqueous solution after soaking the paper product to be tested.
[0043] In step S120, the mixture may be filtered using low-ash, aluminum-free quantitative filter paper to obtain a filtrate.
[0044] In addition, the detection method may further include setting up a blank group for control. In the step of preparing the aqueous solution of the paper product to be detected, 200 mL of distilled water may be specifically put into a 500 mL wide-mouth reagent bottle, covered with a bottle cap, left for 24 hours, filtered with low-ash, aluminum-free quantitative filter paper, and the filtrate may be taken.
[0045] Please continue reading Figure 1 The method for detecting the extractable aluminum content in paper products in the embodiment of the present application also includes step S200, adding p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution to the prepared aqueous solution of the paper product to be tested and shaking well.
[0046] In a specific embodiment of this step, it may include: taking 5 mL of the aqueous solution of the paper product to be tested and placing it in a 50 mL volumetric flask, adding distilled water to about 25 mL, adding 1 drop of p-nitrophenol ethanol solution, adding ammonia water until it turns light yellow, and then adjusting with 0.5 mol / L nitric acid until the yellow color disappears, adding 10.0 mL of acetic acid-sodium acetate buffer, 1.0 mL of cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution, and 2.0 mL of chrome azuro blue S solution, diluting with distilled water and shaking well, and standing for a first preset time, wherein the first preset time can be about 10 minutes.
[0047] Before this step, a step of preparing the above-mentioned medicine may also be included, as follows.
[0048] Soak the utensils used in 5% nitric acid 24 hours in advance, and rinse with distilled water for more than 3 times after soaking.
[0049] Experimental reagents:
[0050] 1. Ethanol solution (1+1): Measure 50 mL of distilled water and 50 mL of anhydrous ethanol, mix well, and you have the product.
[0051] 2. Chrome azure S solution (1 g / L): weigh 0.1 g of chrome azure S and dissolve it in 100 mL of ethanol solution (1+1) and mix well.
[0052] 3. Hexadecylpyridinium bromide-polyethylene glycol octylphenyl ether solution: weigh 0.5 g of hexadecylpyridinium bromide, add 30 mL of anhydrous ethanol to dissolve it, add 5 mL of polyethylene glycol octylphenyl ether, add distilled water to 200 mL, and mix well.
[0053] 4. Acetic acid-sodium acetate buffer solution (pH 6.5-7.0): Weigh 65 g of anhydrous sodium acetate, add 400 mL of distilled water to dissolve, add 2 mL of glacial acetic acid, and add distilled water to 500 mL. If the pH value is too high or too low, adjust the pH with 4% NaOH or glacial acetic acid.
[0054] 5. Nitric acid solution (5% aqueous solution).
[0055] 6. Ammonia water (1+6): Measure 10 mL of ammonia water and 60 mL of distilled water, mix well.
[0056] 7. p-Nitrophenol ethanol solution (1.0 g / L): Weigh 0.1 g of p-nitrophenol, dissolve it in 100 mL of ethanol, and mix well.
[0057] 8. Aluminum standard solution (Al=1 ug / mL).
[0058] Please continue reading Figure 1 The method for detecting the extractable aluminum content in paper products in the embodiment of the present application further includes step S300, measuring the absorbance using a cuvette.
[0059] The method for detecting the extractable aluminum content in paper products in the embodiments of the present application is based on the principle of extracting the aluminum content in the paper sample by cold water extraction, using acetic acid-sodium acetate solution as a buffer solution, and when the pH is 6.5-7.0, in the presence of cetylpyridinium bromide and polyethylene glycol octylphenyl ether, chrome azuro blue S reacts with aluminum to form blue-green quaternary micelles for colorimetric quantification.
[0060] In this step, the absorbance can be measured at a wavelength of 620 nm using a 2 cm cuvette. The aluminum content can be measured in the range of 200 to 10000 ug / L by this method.
[0061] Please continue reading Figure 1The method for detecting the extractable aluminum content in paper products in the embodiment of the present application further includes step S400, calculating the aluminum content in the paper product to be detected according to the measured absorbance.
[0062] The calculation formula is as follows:
[0063]
[0064] X: aluminum content in the sample ppm;
[0065] m: UV spectrophotometer reading
[0066] V: Sample volume mL
[0067] The method for detecting the extractable aluminum content in paper products provided in the embodiments of the present application utilizes aluminum to react with chrome azuro blue S in the presence of cetylpyridinium bromide to generate blue-green quaternary micelles, and the absorbance value is measured at a wavelength of 620 nm and compared with a standard series for quantitative analysis. The method has low detection cost and simple test operation, and any laboratory can complete it, so it has high practicality.
[0068] See also Figure 3 , Figure 3 1 is a flow chart of another embodiment of the method for detecting the extractable aluminum content in paper products of the present application, and the detection method includes but is not limited to the following steps.
[0069] Step S100, preparing an aqueous solution of paper products to be tested.
[0070] For the method of preparing the aqueous solution of the paper product to be tested, please refer to the aforementioned Figure 2 The detailed description of the embodiments will not be repeated here.
[0071] Step S500, preparing a standard curve using an aluminum standard solution.
[0072] See also Figure 4 , Figure 4 1 is a flow chart of an embodiment of the present application for preparing a standard curve using an aluminum standard solution, wherein the process includes the following steps.
[0073] Step S510, taking multiple volumetric flasks and adding different amounts of aluminum standard solution into each of them.
[0074] In a specific embodiment, eight 50 mL volumetric flasks are taken, and 0 mL, 0.20 mL, 0.50 mL, 1.00 mL, 3.00 mL, 5.00 mL, 7.00 mL, and 10.00 mL of the aluminum standard solution are added respectively, and distilled water is added to each of them to 25±1 mL.
[0075] Step S520, add p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution to each volumetric flask in sequence and shake well.
[0076] In step S520, in a specific embodiment, the following operations may be performed for each volumetric flask: add 1 drop of p-nitrophenol ethanol solution, add ammonia water until it turns light yellow, then adjust with 0.5 mol / L nitric acid until the yellow color disappears, add acetic acid-sodium acetate buffer 10.0 mL, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution 1.0 mL, chrome azuro blue S solution 2.0 mL, dilute with distilled water and shake well, and let stand for a second preset time, wherein the second preset time may be about 10 minutes.
[0077] Please continue reading Figure 4 The process further includes step S530, wherein the absorbance of the solutions prepared in the plurality of volumetric flasks is measured using cuvettes respectively and a standard curve is drawn.
[0078] In step S530, the solutions prepared in the multiple volumetric flasks are measured for absorbance at a wavelength of 620 nm using a 2 cm cuvette, 0 mL of the standard solution is added as a blank, the absorbance is measured, and a standard curve is drawn.
[0079] Please continue reading Figure 3 The method for detecting the extractable aluminum content in paper products in the embodiment of the present application also includes step S200, adding p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution to the prepared aqueous solution of the paper product to be tested and shaking well.
[0080] In a specific embodiment of this step, it can also include: taking 5mL of the aqueous solution of the paper product to be tested and placing it in a 50mL volumetric flask, adding distilled water to about 25mL, adding 1 drop of p-nitrophenol ethanol solution, adding ammonia water until light yellow, and then adjusting with 0.5mol / L nitric acid until the yellow disappears, adding acetic acid-sodium acetate buffer 10.0mL, bromocetylpyridinium-polyethylene glycol octylphenyl ether solution 1.0mL, chrome azuro blue S solution 2.0mL, adding distilled water to dilute and shake well, and standing for a first preset time, wherein the first preset time can be about 10min. For the preparation of each drug, please refer to the relevant description of the above embodiment.
[0081] Step S300, measuring absorbance using a cuvette.
[0082] In step S300, specifically, the absorbance is measured at a wavelength of 620 nm using a 2 cm cuvette. The aluminum content determined by this method ranges from 200 to 10000 ug / L.
[0083] Step S600, comparing with a standard curve to verify the measured absorbance.
[0084] Step S400, calculating the aluminum content in the paper product to be tested according to the measured absorbance.
[0085] The calculation formula is as follows:
[0086]
[0087] X: aluminum content in the sample ppm;
[0088] m: UV spectrophotometer reading
[0089] V: Sample volume mL
[0090] The comparison of the detection method and ICP-MS results in the examples of the present application is shown in the following table.
[0091]
[0092] Please also read Figure 5 , Figure 5 It is a schematic diagram comparing the results of the detection method in the embodiment of the present application and the ICP-MS detection method. The value line marked with A in the figure represents the value line of the detection method in the embodiment of the present application, and the value line marked with B in the figure represents the value line of the ICP-MS detection method. Among them, the difference between the detection method in the embodiment of the present application and the most authoritative ICP-MS detection method today is within 110ug / L, which is relatively small and can meet the process adjustment requirements of white cardboard during the production process.
[0093] The detection method in the embodiment of the present application is compared with the detection by ICP-MS, and the detection results are not much different. In addition, the detection cost is low, the inspection operation is simple, and any laboratory has the conditions to complete it, so it has high practicality.
[0094] The above descriptions are only some embodiments of the present application, and do not limit the protection scope of the present application. Any equivalent device or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.
Claims
1. A method for detecting extractable aluminum content in paper products, characterized in that: The detection method comprises: preparing an aqueous solution of the paper product to be tested; To the prepared aqueous solution of the paper product to be tested, add p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution in sequence and shake well; The absorbance was measured using a cuvette; The aluminum content in the paper product to be tested is calculated according to the measured absorbance.
2. The detection method according to claim 1, characterized in that: The step of sequentially adding p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution to the prepared aqueous solution of the paper product to be tested and shaking well comprises: taking 5 mL of the aqueous solution of the paper product to be tested, adding p-nitrophenol ethanol solution, dripping ammonia water until it turns light yellow, then adjusting with 0.5 mol / L nitric acid until the yellow disappears, adding acetic acid-sodium acetate buffer 10.0 mL, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution 1.0 mL, chrome azuro blue S solution 2.0 mL, adding distilled water to dilute and shake well, and standing for a first preset time.
3. The detection method according to claim 1, characterized in that: The detection method further comprises: preparing a standard curve using an aluminum standard solution; and after the step of measuring the absorbance using a cuvette, comparing with the standard curve to verify the measured absorbance.
4. The detection method according to claim 3, characterized in that: The step of using the aluminum standard solution to prepare a standard curve comprises: taking a plurality of volumetric flasks and adding different amounts of aluminum standard solutions respectively, adding p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution to each volumetric flask in sequence and shaking well; using a colorimetric dish to measure the absorbance of the solutions prepared in the plurality of volumetric flasks and drawing a standard curve.
5. The detection method according to claim 4, characterized in that: The step of taking a plurality of volumetric flasks and adding different amounts of aluminum standard solution respectively, and sequentially adding p-nitrophenol ethanol solution, ammonia water, nitric acid, acetic acid-sodium acetate buffer, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution and chrome azuro blue S solution to each volumetric flask and shaking well comprises: taking 8 50mL volumetric flasks, adding 0mL, 0.20mL, 0.50mL, 1.00mL, 3.00mL, 5.00mL, 7.00mL, 10.00mL of aluminum standard solution respectively, adding distilled water to 25±1mL respectively, adding p-nitrophenol ethanol solution, adding ammonia water dropwise until light yellow, adjusting with 0.5mol / L nitric acid until yellow disappears, adding acetic acid-sodium acetate buffer 10.0mL, cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution 1.0mL, chrome azuro blue S solution 2.0mL, adding distilled water to dilute and shake well, and standing for a second preset time.
6. The detection method according to claim 5, characterized in that: In the step of using a cuvette to measure the absorbance of the solutions prepared in the plurality of volumetric flasks and drawing a standard curve: the absorbance is measured at a wavelength of 620 nm using a cuvette.
7. The detection method according to claim 1, characterized in that: The step of preparing the aqueous solution of the paper product to be tested comprises: Place the paper product to be tested in distilled water and soak for a preset time; Take the aqueous solution after soaking the paper product to be tested.
8. The detection method according to any one of claims 1 to 7, characterized in that: The preparation method of the cetylpyridinium bromide-polyethylene glycol octylphenyl ether solution comprises: weighing a certain amount of cetylpyridinium bromide, adding anhydrous ethanol to dissolve it, adding polyethylene glycol octylphenyl ether, adding distilled water and mixing them evenly.
9. The detection method according to any one of claims 1 to 7, characterized in that: The preparation method of the acetic acid-sodium acetate buffer comprises: weighing a certain amount of anhydrous sodium acetate, adding distilled water to dissolve, adding glacial acetic acid, adding distilled water, and adjusting the pH to 6.5-7.0 using NaOH or glacial acetic acid.
10. The detection method according to any one of claims 1 to 7, characterized in that: The chrome azure S solution is a chrome azure S ethanol solution.