Pretreatment method for detection of polyether-ether-ketone plastic, trace element content detection method of polyether-ether-ketone plastic, application and digestion container

Abstract

The invention provides a detection pretreatment method of polyether-ether-ketone plastic, a trace element content detection method of polyether-ether-ketone plastic, application and a digestion container, and relates to the technical field of analysis and detection.The method comprises the steps that a sample to be detected and a digestion agent are mixed, then digestion and constant volume are conducted in sequence, and a sample solution to be detected is obtained; wherein the digesting agent comprises nitric acid and hydrogen peroxide, the digesting agent only uses nitric acid and hydrogen peroxide reagents, sulfuric acid, perchloric acid, hydrofluoric acid and other reagents are not needed, the analysis cost is remarkably reduced, the background value is reduced, meanwhile, after volume metering, the solution is clear, transparent and free of turbidity, and the requirement for daily detection of the polyether-ether-ketone plastic is met.

Description

Technical Field

[0001] The invention relates to the technical field of analysis and detection, in particular to a detection pretreatment method for polyetheretherketone plastics, a detection method for trace element content of polyetheretherketone plastics, an application thereof and a digestion container. Background Art

[0002] Polyetheretherketone (PEEK) is a high-performance thermoplastic with high strength, rigidity and high temperature resistance (can be used for a long time at 260°C). It has excellent resistance to most chemicals and solvents, including strong acids, strong alkalis and organic solvents. It is often used to make precision mechanical parts, aerospace components, medical devices and automotive parts. Pure polyetheretherketone plastic has excellent mechanical properties and chemical stability. However, the presence of impurities may affect its performance, such as reducing strength, heat resistance or dimensional stability, and some impurities may cause potential harm to users. For example, excessive heavy metal ions such as lead and cadmium may cause biological toxicity and do not meet the safety standards for medical or food contact materials. Many industries have strict regulatory requirements. For example, medical devices need to comply with the strict regulations of ISO 13485 or FDA, which have clear restrictions on the purity of polyetheretherketone plastics. Therefore, regular testing and control of the content of impurity elements in polyetheretherketone plastics is an important step to ensure product quality, safety and reliability.

[0003] However, current detection technology still faces many challenges and limitations. For example, Fu Luoling, Hu Xiaopeng, Tao Wenbin, et al. Determination of the content of 24 elements in special engineering plastics by super microwave digestion-inductively coupled plasma atomic emission spectrometry [J]. Physical and Chemical Testing-Chemical Volume, 2023, 59(03): 326-331. This scheme uses a super microwave digestion method of nitric acid-perchloric acid-hydrofluoric acid system, supplemented by inductively coupled plasma atomic emission spectrometry (ICP-OES) to determine the content of 24 elements in PEEK. However, the acid system of this scheme is complex, perchloric acid is flammable and explosive, and the reaction will generate a lot of pressure. The use of perchloric acid is generally prohibited or restricted in microwave digestion instruments, and high-purity reagents of perchloric acid are difficult to obtain, and often contain impurity elements such as sodium, calcium, and titanium, resulting in The detection limit is relatively high. In addition, hydrofluoric acid is highly toxic to the human body and needs to be driven out before entering most analytical instruments, otherwise it will corrode the sampling system and is not recommended for use. PerkinElmer's solution uses a nitric acid-sulfuric acid system for digestion. This solution essentially uses sulfuric acid to sulfonate the polyetheretherketone plastic material, introduces the sulfonic acid group into the organic molecule, obtains a sulfonic acid compound, and then uses nitric acid to digest the sulfonated polyetheretherketone plastic. However, when sulfuric acid is used as the digestion reagent, the sample solution will need to match the standard solution with the sample solution because of the inconsistent viscosity of the sulfuric acid, which increases the complexity of the operation. In addition, due to the addition of sulfuric acid, the sulfur content in the polyetheretherketone plastic cannot be measured, affecting the overall detection effect.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for pre-treatment of polyetheretherketone plastics to solve at least one of the technical problems in the prior art. The digestion agent in the method for pre-treatment of polyetheretherketone plastics only uses nitric acid and hydrogen peroxide reagents, and does not require reagents such as sulfuric acid, perchloric acid and hydrofluoric acid, which significantly reduces the analysis cost and background value.

[0006] The second purpose of the present invention is to provide an application of the above-mentioned pre-treatment method for detecting polyetheretherketone plastic in detecting the trace element content of polyetheretherketone plastic.

[0007] The third object of the present invention is to provide a method for detecting the trace element content of polyetheretherketone plastics. The method for detecting the trace element content of polyetheretherketone plastics uses the sample solution obtained after the pretreatment method for detection, and uses a nitric acid-hydrogen peroxide system as a digester, which is safer to operate and can reduce analysis costs.

[0008] A fourth object of the present invention is to provide a digestion container, wherein a hole is provided on the container cover of the digestion container to maintain pressure balance inside and outside the digestion container.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0010] In a first aspect, the present invention provides a method for pre-detection treatment of polyetheretherketone plastics, comprising the following steps:

[0011] The sample to be tested and the digestion agent are mixed, and then digestion and volume adjustment are performed in sequence to obtain a solution of the sample to be tested;

[0012] Wherein, the components of the digester include nitric acid and hydrogen peroxide.

[0013] Further, the volume ratio of the nitric acid to the hydrogen peroxide is (1-5):1;

[0014] Preferably, the concentration of the nitric acid is 65-68% w / w, and the concentration of the hydrogen peroxide is 30% w / w.

[0015] Further, the digestion pressure is greater than standard atmospheric pressure;

[0016] Preferably, the digestion pressure is increased to be greater than the standard atmospheric pressure by increasing the pressure in the digestion container;

[0017] Preferably, the method of increasing the pressure in the digestion container includes introducing an inert gas;

[0018] Preferably, the pressure of the inert gas is 1.0-4.0 MPa;

[0019] Preferably, the inert gas includes at least one of nitrogen, argon and helium.

[0020] Further, the digestion includes microwave digestion;

[0021] Preferably, the microwave digestion procedure includes: first heating to 180-200°C, keeping warm for 0-3 min, then heating to 240-260°C, keeping warm for 0-3 min, then heating to 280-295°C, keeping warm for 20-40 min;

[0022] Preferably, the microwave digestion is performed using a microwave chemical workstation.

[0023] In a second aspect, the present invention provides an application of the above-mentioned pre-treatment method for detecting polyetheretherketone plastic in detecting the trace element content of polyetheretherketone plastic.

[0024] In a third aspect, the present invention provides a method for detecting the trace element content of polyetheretherketone plastics, comprising the following steps:

[0025] The standard series solutions of trace elements and the sample solution to be tested prepared by the polyetheretherketone plastic pre-test treatment method are tested to obtain the content of the element to be tested in the sample solution to be tested.

[0026] Further, the concentration of the standard series solution is 0.00-1.00 mg / L;

[0027] Preferably, the trace elements include at least one of sulfur, phosphorus, arsenic, potassium, sodium, calcium, magnesium, cadmium, chromium and copper.

[0028] Further, preparing the standard series solutions includes: adding nitric acid solution to the trace element standard metal element solution;

[0029] Preferably, the concentration of the dilute nitric acid is 1-5% w / w;

[0030] Preferably, inductively coupled plasma emission spectroscopy is used to detect the standard series solutions and the sample solutions to be tested.

[0031] In a fourth aspect, the present invention provides a digestion container, the digestion container comprising a container body and a container cover;

[0032] The container body is provided with a cavity, and the cavity is used to contain the sample to be tested and the digestion agent in the pre-treatment method for detecting polyetheretherketone plastic;

[0033] The container cover is arranged at the opening of the container body, and a hole for balancing the air pressure inside and outside the container body is opened on the container cover.

[0034] Furthermore, the material of the container body is quartz and the material of the container cover is modified polytetrafluoroethylene.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The polyetheretherketone plastic detection pretreatment method provided by the present invention adopts a nitric acid-hydrogen peroxide system as a digester, and provides strong oxidizing property through nitric acid to accelerate the decomposition of the sample to be tested. Hydrogen peroxide, as a synergistic oxidant, can not only further enhance the oxidation effect and completely digest the polyetheretherketone plastic, but also effectively reduce the generation of harmful substances and reduce the impact on the environment. The decomposition product of hydrogen peroxide is mainly water, which has a very low impact on analytical instruments, and can ensure the clarity and transparency of the digestion solution. After the volume is fixed with ultrapure water, no precipitation or suspended matter is generated, thereby ensuring the purity of the solution.

[0037] The method for detecting the trace element content of polyetheretherketone plastic provided by the present invention uses only nitric acid and hydrogen peroxide reagents, and does not require reagents such as sulfuric acid, perchloric acid and hydrofluoric acid, thereby significantly reducing analysis costs and background values. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic structural diagram of a digestion container provided in an embodiment of the present invention.

[0040] Icon: 100 - container body; 200 - container cover; 210 - hole. DETAILED DESCRIPTION

[0041] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0042] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] A first aspect of the present invention provides a method for pre-detection treatment of polyetheretherketone plastics, the method for pre-detection treatment of polyetheretherketone plastics comprising the following steps:

[0044] The sample to be tested and the digestion agent are mixed, and then digestion and volume adjustment are performed in sequence to obtain a solution of the sample to be tested;

[0045] Wherein, the components of the digester include nitric acid and hydrogen peroxide.

[0046] The detection pretreatment method of polyetheretherketone plastic provided by the present invention does not use complex reagents such as perchloric acid, sulfuric acid and hydrofluoric acid. The reasons are as follows: perchloric acid is flammable and explosive at high temperature, and is generally limited to use in a microwave digestion instrument, and it is difficult to obtain a high-purity reagent, resulting in a high detection limit; sulfuric acid has a large viscosity, and the same volume fraction of sulfuric acid needs to be added to the standard series solution to match the test liquid matrix, and after using sulfuric acid, the sulfur content in the polyetheretherketone plastic cannot be tested; hydrofluoric acid will corrode the sampling system of most analytical instruments, so it takes a lot of time to drive out the acid, and hydrofluoric acid is highly toxic to the human body. The present invention adopts a nitric acid-hydrogen peroxide system as a digester, and provides strong oxidizing property through nitric acid to accelerate the decomposition of a sample to be tested. Hydrogen peroxide, as a synergistic oxidant, can not only further enhance the oxidizing effect and completely digest the polyetheretherketone plastic, but also effectively reduce the generation of harmful substances and reduce the impact on the environment. The decomposition product of hydrogen peroxide is mainly water, which has a very low impact on analytical instruments, and can ensure the clarity and transparency of the digestion solution. After being fixed to volume with ultrapure water, the solution is clear and transparent without turbidity, and does not generate any precipitation or suspended matter, thereby ensuring the purity of the solution.

[0047] Furthermore, the sample to be tested includes polyetheretherketone plastic, and the polyetheretherketone plastic is preferably cylindrical polyetheretherketone plastic particles with a diameter of 4 mm and a height of 5 mm.

[0048] Furthermore, the volume determination step includes: after the digestion treatment, transferring the digestion solution in the digestion container to a volumetric flask, cleaning the digestion container cover and the inner wall of the digestion container with ultrapure water for multiple times, combining the cleaning solution into the previous volumetric flask, and determining the volume to the scale with ultrapure water to obtain the sample solution to be tested.

[0049] In some preferred embodiments, the volume ratio of the nitric acid to the hydrogen peroxide is (1-5):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, etc.;

[0050] Preferably, the concentration of the nitric acid is 65-68% w / w, for example, 65% w / w, 66% w / w, 67% w / w, 68% w / w, etc., and the concentration of the hydrogen peroxide is 30% w / w.

[0051] In some preferred embodiments, the digestion pressure is greater than standard atmospheric pressure;

[0052] Preferably, the digestion pressure is increased to be greater than the standard atmospheric pressure by increasing the pressure in the digestion container;

[0053] Preferably, the method of increasing the pressure in the digestion container includes introducing an inert gas;

[0054] Preferably, the pressure of the inert gas is 1.0-4.0 MPa, for example, 1.0 MPa, 2.0 MPa, 3.0 MPa, 4.0 MPa, etc.;

[0055] In the present invention, by introducing inert gas, the pressure in the digestion container is increased to increase the boiling point of the digester, and the digester can reach a high temperature of 300°C. The oxidizing property of the digester increases with the increase of temperature, thereby promoting the breaking of chemical bonds of the polymer chain, the degree of element ionization is higher, and the digestion efficiency is improved.

[0056] Preferably, the inert gas comprises at least one of nitrogen, argon and helium;

[0057] Preferably, the digestion comprises microwave digestion;

[0058] Preferably, the microwave digestion procedure includes: first heating to 180-200°C, for example, 180°C, 185°C, 190°C, 195°C, 200°C, etc., keeping warm for 0-3min, for example, 0min, 1min, 2min, 3min, etc., then heating to 240-260°C, for example, 240°C, 245°C, 250°C, 255°C, 260°C, etc., keeping warm for 0-3min, for example, 0min, 1min, 2min, 3min, etc., then heating to 280-295°C, for example, 280°C, 285°C, 290°C, 295°C, etc., keeping warm for 20-40min, for example, 20min, 25min, 30min, 35min, 40min, etc.;

[0059] In the present invention, during the digestion process, a gradient temperature increase method is adopted, starting from a relatively low temperature and gradually increasing the temperature, and finally achieving complete decomposition of the polyetheretherketone plastic at a high temperature, ensuring the ionization of all trace elements, thereby improving the accuracy of the analysis. The gradient temperature increase can prevent local overheating of the sample to be tested, avoid partial carbonization of the sample or formation of insoluble compounds, and affect the release of elements. The gradient temperature increase can make the sample to be tested evenly heated and reduce the generation of by-products.

[0060] Preferably, the microwave digestion is performed using a microwave chemical workstation.

[0061] In the present invention, the microwave chemical workstation is preferably an EXPEC 790S super microwave chemical workstation, with a microwave transmission power of 150-1200W, PID temperature control, equipped with high-pressure nitrogen, and having a pre-pressurization function. The present invention adopts high temperature, high pressure and closed conditions to enable nitric acid and hydrogen peroxide to fully perform a digestion reaction, and also to make the digestion reaction more thorough.

[0062] Further explanation: the specific process of the sample to be tested entering the microwave chemical workstation is: weigh the polyetheretherketone plastic into the digestion container, add the digestion agent, cover the container lid, and shake to mix; transfer the digestion tube to the liner barrel, which is pre-filled with the load solution, wherein the components of the load solution include 150mL ultrapure water and 5mL hydrogen peroxide, and then transfer the liner barrel to the pre-treatment equipment (i.e., the microwave chemical workstation). Then, 1.0-4.0MPa nitrogen is filled into the cavity of the pre-treatment equipment, and the above-mentioned gradient heating method is used for digestion treatment.

[0063] In some preferred embodiments, before the volume is fixed, the digested mixed solution of the sample to be tested and the digestion agent is cooled, and the cooling temperature is preferably 60° C.;

[0064] The second aspect of the present invention provides an application of the pre-treatment method for detecting polyetheretherketone plastic in detecting the trace element content of polyetheretherketone plastic.

[0065] The third aspect of the present invention provides a method for detecting the content of trace elements in polyetheretherketone plastics, the method comprising the following steps:

[0066] The standard series solutions of trace elements and the sample solution to be tested prepared by the polyetheretherketone plastic pre-test treatment method are tested to obtain the content of the element to be tested in the sample solution to be tested.

[0067] In some preferred embodiments, the concentration of the standard series solution is 0.00-1.00 mg / L;

[0068] Preferably, the trace elements include at least one of sulfur, phosphorus, arsenic, potassium, sodium, calcium, magnesium, cadmium, chromium and copper.

[0069] In some preferred embodiments, preparing the standard series solutions includes: adding nitric acid solution to the trace element standard metal element solution;

[0070] Specifically, the preparation process of the standard series solution is: take a certain amount of sulfur, phosphorus, arsenic, potassium, sodium, calcium, magnesium, cadmium, chromium, and copper standard metal element solutions, and dilute them with dilute nitric acid to form a standard series solution.

[0071] Preferably, the concentration of the dilute nitric acid is 1-5% w / w, for example, 1% w / w, 2% w / w, 3% w / w, 4% w / w, 5% w / w, etc.;

[0072] Preferably, inductively coupled plasma emission spectroscopy is used to detect the standard series solutions and the sample solutions to be tested.

[0073] In the present invention, the sample solution and the standard series solution are detected by an inductively coupled plasma optical emission spectrometer (ICP-OES), and the content of each element to be detected in the polyetheretherketone test solution is calculated by an external standard method. In addition, the ICP-OES detection does not require matrix matching, has a low detection limit, and can measure sulfur. The inductively coupled plasma optical emission spectrometer is preferably EXPEC 6100D, and the observation direction is axial observation.

[0074] It is further explained that the present invention adopts inductively coupled plasma optical emission spectrometry (ICP-OES) to achieve the simultaneous determination of 10 elements including sulfur by optimizing microwave digestion conditions and various ICP-OES instrument parameters, with a precision of 0.9%-4.4% and a spiked recovery rate ranging from 95.3% to 102%, which meets the needs of daily detection of polyetheretherketone plastics.

[0075] A fourth aspect of the present invention provides a digestion container, the digestion container comprising a container body 100 and a container cover 200;

[0076] The container body 100 is provided with a cavity, and the cavity is used to contain the sample to be tested and the digestion agent in the pre-treatment method for detecting polyetheretherketone plastic;

[0077] The container cover 200 is disposed on the opening of the container body 100 , and a hole 210 for balancing the air pressure inside and outside the container body 100 is opened on the container cover 200 .

[0078] Specifically, if Figure 1As shown, the container body 100 is a tubular structure, and the container body 100 is preferably a digestion tube. A microhole with a diameter of 1-5 mm is opened on the top side of the container cover 200. During microwave operation, 1-4 MPa nitrogen is pre-pressurized into the digestion tube through the microhole. The pre-pressurization can increase the boiling point of the digester. During microwave operation, the pressure generated by sample digestion can be discharged through the microhole to keep the internal and external pressures consistent, so that the container cover 200 will not be opened by the gas generated by the reaction.

[0079] Preferably, the container body 100 is a cylindrical container with a diameter of 1-2 cm and a height of 10-12 cm, and is equipped with a tube cover.

[0080] In some preferred embodiments, the material of the container body is quartz and the material of the container cover is modified polytetrafluoroethylene.

[0081] Specifically, at a temperature above 260° C., the container body 100 made of quartz material will not soften, thereby ensuring the stability of the structure and thus ensuring the digestion result.

[0082] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0083] In the embodiments and comparative examples of the present invention, the instruments and reagents used are as follows:

[0084] 1. Instrument model and configuration:

[0085] The pretreatment equipment model used in the pretreatment method for the detection of polyetheretherketone plastics is EXPEC 790S super microwave digester, which is equipped with: 15mL quartz digestion tube;

[0086] The detection and analysis equipment model in the method for detecting the trace element content of polyetheretherketone plastic is EXPEC 6100D ICP-OES, which is equipped with: a quartz injection system.

[0087] Among them, the detection parameters of the inductively coupled plasma atomic emission spectrometer are shown in Table 1 below.

[0088] Table 1

[0089] Instrument parameters Settings RF power (W) 1150 Atomizing gas flow rate (L / min) 0.60 Auxiliary gas flow (L / min) 1.00 Cooling air flow (L / min) 12.0 Rinse / analysis pump speed (rpm) 30 Observation method Axial Repetitions 3

[0090] 2. Reagents and samples

[0091] Reagents: nitric acid, 30% hydrogen peroxide, both of high-grade purity;

[0092] Pure water: 18.2MΩ·cm deionized water;

[0093] Samples to be tested: 3 types of PEEK plastic particles (sample 1, sample 2 and sample 3);

[0094] Standard solution: sulfur, phosphorus, arsenic, potassium, sodium, calcium, magnesium, cadmium, chromium, copper element standard solution, 1000μg / mL, National Research Institute of Nonferrous Metals.

[0095] Example 1

[0096] This embodiment provides a method for pre-treatment of polyetheretherketone plastics, comprising the following steps:

[0097] Accurately weigh 0.1 g (accurate to 0.001 g) of the sample 1 to be tested into a digestion tube, add 4 mL of nitric acid and 1 mL of hydrogen peroxide in sequence, shake well, transfer to the super microwave platform, and digest according to the program in Table 2 (super microwave digestion heating program). Among them, the concentration of nitric acid is 67% w / w, and the concentration of hydrogen peroxide is 30% w / w.

[0098] After cooling to 60°C, dilute to 50 mL with deionized water. At this point, the sample is completely digested and the digestion solution is colorless and transparent.

[0099] At the same time, a blank solution is prepared, wherein the preparation of the blank solution includes: replacing the sample with deionized water, and preparing according to the above steps in sequence to obtain a blank solution.

[0100] Table 2

[0101]

[0102] Example 2

[0103] This embodiment provides a method for pre-treatment of polyetheretherketone plastics, which is different from Embodiment 1 in that the sample to be tested in Embodiment 2 adopts the sample to be tested 2, and the remaining steps are consistent with Embodiment 1.

[0104] Example 3

[0105] This embodiment provides a method for pre-treatment of polyetheretherketone plastics, which is different from Embodiment 1 in that the sample to be tested in Embodiment 3 adopts the sample to be tested 3, and the remaining steps are consistent with Embodiment 1.

[0106] Example 4

[0107] This embodiment provides a method for pre-treatment of polyetheretherketone plastics, comprising the following steps:

[0108] Accurately weigh 0.1 g (accurate to 0.001 g) of the sample 1 to be tested into a digestion tube, add 3 mL of nitric acid and 1 mL of hydrogen peroxide in sequence, shake well, transfer to the super microwave platform, and digest according to the program in Table 3 (super microwave digestion heating program). Among them, the concentration of nitric acid is 65% w / w, and the concentration of hydrogen peroxide is 30% w / w.

[0109] After cooling to 60°C, dilute to 50 mL with deionized water. At this point, the sample is completely digested and the digestion solution is colorless and transparent.

[0110] At the same time, a blank solution is prepared, wherein the preparation of the blank solution includes: replacing the sample with deionized water, and preparing according to the above steps in sequence to obtain a blank solution.

[0111] Table 3

[0112]

[0113] Example 5

[0114] This embodiment provides a method for pre-treatment of polyetheretherketone plastics, comprising the following steps:

[0115] Accurately weigh 0.1 g (accurate to 0.001 g) of the sample 1 to be tested into a digestion tube, add 5 mL of nitric acid and 1 mL of hydrogen peroxide in sequence, shake well, transfer to the super microwave platform, and digest according to the program in Table 4 (super microwave digestion heating program). Among them, the concentration of nitric acid is 68% w / w, and the concentration of hydrogen peroxide is 30% w / w.

[0116] After cooling to 60°C, dilute to 50 mL with deionized water. At this point, the sample is completely digested and the digestion solution is colorless and transparent.

[0117] At the same time, a blank solution is prepared, wherein the preparation of the blank solution includes: replacing the sample with deionized water, and preparing according to the above steps in sequence to obtain a blank solution.

[0118] Table 4

[0119]

[0120]

[0121] Embodiment 6-10

[0122] Embodiment 6-10 provides a method for detecting the trace element content of polyetheretherketone plastic, comprising the following steps:

[0123] (1) Prepare standard intermediate solutions of sulfur, phosphorus, arsenic, potassium, sodium, calcium, magnesium, cadmium, chromium and copper:

[0124] (2) Pipette 0.5 mL of each standard solution of sulfur, phosphorus, arsenic, potassium, sodium, calcium, magnesium, cadmium, chromium, and copper into the same 50 mL volumetric flask, dilute to scale with water, and shake well. The mass concentration of sulfur, phosphorus, arsenic, potassium, sodium, calcium, magnesium, cadmium, chromium, and copper in this solution is 10 mg / L.

[0125] (3) Preparation of calibration solution series: In a series of 50 mL volumetric flasks, take 0.00 mL, 0.10 mL, 0.50 mL, 2.50 mL, and 5.00 mL of sulfur, phosphorus, arsenic, potassium, sodium, calcium, magnesium, cadmium, chromium, and copper standard intermediate solutions, add nitric acid (wherein the concentration and amount of nitric acid in Examples 6-10 are respectively consistent with the concentration and volume of nitric acid in the digester of Examples 1-5), dilute to the scale with water, and shake well. The mass concentrations of this series of solutions are shown in Table 5 (Standard Solution Concentration Gradient).

[0126] Table 5

[0127]

[0128] (4) Calibration curve drawing:

[0129] Using an inductively coupled plasma atomic emission spectrometer, according to the detection parameters in Table 1, the emission intensity of each element spectral line in the calibration solution series and the sample solutions to be tested in Examples 5-10 and the blank solution was measured respectively.

[0130] (5) Calculation of results:

[0131] Each element compound is expressed in mass fraction ω, and the value is expressed in mg / kg, and is calculated according to formula (1):

[0132] Formula (1):

[0133] Where:

[0134] ρ——The mass concentration of the element in the sample solution, in micrograms per milliliter (μg / mL);

[0135] ρ0——The mass concentration of the element in the blank test solution, in micrograms per milliliter (μg / mL);

[0136] V——volume of the sample solution, in milliliters (mL);

[0137] m – the mass of the sample, in grams (g).

[0138] Comparative Example 1

[0139] This comparative example provides a method for pre-treatment of polyetheretherketone plastics, which is different from Example 1 in that the components of the digester only include nitric acid, and the remaining steps are consistent with Example 1.

[0140] Comparative Example 2

[0141] This comparative example provides a method for pre-treatment of polyetheretherketone plastics, which is different from Example 1 in that the components of the digester only include hydrogen peroxide, and the remaining steps are consistent with Example 1.

[0142] Comparative Example 3

[0143] This comparative example provides a pretreatment method for detecting polyetheretherketone plastics, which is different from Example 1 in that: before digestion, nitrogen is not filled into the cavity of the pretreatment equipment, that is, no pre-pressurization is performed, and the remaining steps are consistent with Example 1.

[0144] Comparative Examples 4-6

[0145] Comparative Examples 4-6 provide a method for detecting the trace element content of polyetheretherketone plastics. The difference from Example 6 is that the test sample solutions, blank solutions and measurement calibration solution series in Comparative Examples 1-3 are used for detection respectively, and the remaining steps are consistent with Example 6.

[0146] Test results:

[0147] It should be noted that Examples 6-10 sequentially use the sample solutions prepared in Examples 1-5. Comparative Examples 4-6 sequentially use the sample solutions prepared in Comparative Examples 1-3.

[0148] (1) Accuracy test results

[0149] Tables 6-8 are the element contents of the samples measured in Examples 6-8, in units of %. Table 9 is the element contents of the samples measured in Example 9, in units of %. Table 10 is the element contents of the samples measured in Example 10, in units of %. Tables 11-13 are the element contents of the samples measured in Comparative Examples 4-6, in units of %.

[0150] Table 6

[0151]

[0152] Table 7

[0153]

[0154] Table 8

[0155]

[0156] Table 9

[0157]

[0158]

[0159] Table 10

[0160]

[0161] Table 11

[0162]

[0163] Table 12

[0164]

[0165] Table 13

[0166]

[0167] As can be seen from the data in the table, according to Examples 6-8, the present method can completely digest the samples 1, 2, and 3 to be tested, the tested elements have been completely released, and the recovery rate of the elements is the highest. According to Example 9, the dosage of nitric acid is reduced, and the test results of each element are slightly reduced, indicating that there are still trace elements that have not been released. According to Example 10, the dosage of nitric acid is increased, and the test results of each element remain basically unchanged, indicating that the elements have been completely released. The samples obtained by Comparative Examples 4-6 were not digested and clarified. According to Comparative Example 4, when only nitric acid is used, the sample cannot be completely digested, not only because hydrogen peroxide has high oxidative activity, but also hydrogen peroxide will regenerate nitric acid with nitrogen oxides produced by decomposition of nitric acid, and the digestion effect is better. According to Comparative Example 5, when only hydrogen peroxide is used, the sample is basically not digested, because hydrogen peroxide does not have the ability to dissolve polymers. According to Comparative Example 6, when an inert gas is not flushed in, the sample is not completely digested, because when not pressurized, the boiling point of the digestion solution is lower than the boiling point when pressurized, and the temperature of the digestion solution does not reach 280°C, so the oxidative activity is insufficient and the sample cannot be completely digested.

[0168] (2) Spike recovery and precision test results

[0169] Weigh 12 portions of the polyetheretherketone plastic sample 1 to be tested, divide them into two groups, one group as background, and one group with a standard solution added, and test them according to the method of Example 6 under the same conditions. The results are shown in Table 14 (element content in the sample, unit: mg / kg).

[0170] Table 14

[0171]

[0172] It can be seen from the data in the table that the spiked recovery rate of the embodiments of the present invention is between 96% and 104%, and the relative standard deviation between the results is between 0.9% and 4.4%, indicating that the test precision and accuracy of this method are good.

[0173] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for pre-treatment of polyetheretherketone plastics, characterized in that: The following steps are involved: The sample to be tested and the digestion agent are mixed, and then digestion and volume adjustment are performed in sequence to obtain a solution of the sample to be tested; Wherein, the components of the digester include nitric acid and hydrogen peroxide.

2. The method for pre-detection of polyetheretherketone plastic according to claim 1, characterized in that: The volume ratio of the nitric acid to the hydrogen peroxide is (1-5):1; Preferably, the concentration of the nitric acid is 65-68% w / w, and the concentration of the hydrogen peroxide is 30% w / w.

3. The method for pre-detection treatment of polyetheretherketone plastic according to claim 1, characterized in that: The pressure of the digestion is greater than the standard atmospheric pressure; Preferably, the digestion pressure is increased to be greater than the standard atmospheric pressure by increasing the pressure in the digestion container; Preferably, the method of increasing the pressure in the digestion container includes introducing an inert gas; Preferably, the pressure of the inert gas is 1.0-4.0 MPa; Preferably, the inert gas includes at least one of nitrogen, argon and helium.

4. The method for pre-detection treatment of polyetheretherketone plastic according to claim 1, characterized in that: The digestion comprises microwave digestion; Preferably, the microwave digestion procedure includes: first heating to 180-200°C, keeping warm for 0-3 min, then heating to 240-260°C, keeping warm for 0-3 min, then heating to 280-295°C, keeping warm for 20-40 min; Preferably, the microwave digestion is performed using a microwave chemical workstation.

5. Application of the pre-treatment method for polyetheretherketone plastics as described in any one of claims 1 to 4 in the detection of trace element content in polyetheretherketone plastics.

6. A method for detecting the trace element content of polyetheretherketone plastics, characterized in that: The following steps are involved: The standard series solutions of trace elements and the sample solution to be tested prepared by the polyetheretherketone plastic pre-treatment method according to any one of claims 1 to 4 are tested to obtain the content of the element to be tested in the sample solution to be tested.

7. The method for detecting the trace element content of polyetheretherketone plastic according to claim 6, characterized in that: The concentration of the standard series solution is 0.00-1.00 mg / L; Preferably, the trace elements include at least one of sulfur, phosphorus, arsenic, potassium, sodium, calcium, magnesium, cadmium, chromium and copper.

8. The method for detecting the trace element content of polyetheretherketone plastic according to claim 6, characterized in that: The preparation of the standard series solutions includes: adding nitric acid solution to the trace element standard metal element solution; Preferably, the concentration of the nitric acid solution is 1-5% w / w; Preferably, inductively coupled plasma emission spectroscopy is used to detect the standard series solutions and the sample solutions to be tested.

9. A digestion container, characterized in that: The digestion container comprises a container body and a container cover; The container body is provided with a cavity, and the cavity is used to accommodate the sample to be tested and the digestion agent in the pre-treatment method for detecting polyetheretherketone plastic according to any one of claims 1 to 4; The container cover is arranged at the opening of the container body, and a hole for balancing the air pressure inside and outside the container body is opened on the container cover.

10. The digestion container according to claim 9, characterized in that: The material of the container body is quartz and the material of the container cover is modified polytetrafluoroethylene.

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