WDXRF testing method based on polyester film pretreatment and application of WDXRF testing method

Abstract

The invention belongs to the technical field of X-ray fluorescence spectrum analysis, and provides a WDXRF testing method based on polyester film pretreatment and application thereof.The method comprises the steps that a sample to be tested is placed in a sample cup, covered with a polyester film and pressed into a tablet through a hydraulic machine, the tablet is placed in a mold, and a WDXRF test is conducted; the parameters of the hydraulic machine comprise that the target pressure is 300-400 kn, and the pressure maintaining time is 5-20 s; the pressing time is 3-5 s; the sampling time is 5-7 s; the sample adding depth is 7-9 s. The method disclosed by the invention is simple, convenient and feasible, is low in cost, can be widely applied to WDXRF tests of various special samples, and has extremely high practical value. According to the method, the polyester film is used for treating the special sample, so that the test of the special sample which cannot be tested originally is realized, the change of sample components is avoided, the side effect is small, the accuracy is high, and the test method has an important application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of X-ray fluorescence spectrometry analysis, and specifically relates to a wavelength dispersive X-ray fluorescence (WDXRF) testing method based on polyester film pretreatment and its application in the detection of special sample elements. The method is particularly suitable for the non-destructive analysis of samples that are difficult to press, easily absorb water, or are heat-sensitive. Background Art

[0002] X-ray fluorescence (XRF) is a technique that enables rapid quantitative analysis of multiple elements by emitting characteristic X-rays from the sample. Wavelength dispersive X-ray fluorescence (WDXRF) has become the mainstream method for elemental analysis in solid samples due to its high resolution and excellent sensitivity. However, WDXRF technology places stringent demands on sample preparation, requiring a uniform, dense surface with low hygroscopicity. For specialized samples such as soil and carbon powder, traditional tableting methods often lead to tablet breakage and rough surfaces due to loose sample particles, poor adhesion, or hygroscopic expansion. This can cause vacuum leaks or contamination in the instrument, seriously compromising test stability.

[0003] Existing methods typically address these challenges, such as drying, incineration, or the addition of adhesives. However, these pretreatments can alter the sample's original composition (e.g., loss of volatile elements and carbonization of the organic matrix), are cumbersome, and costly. For example, while incineration can improve sample compression yield, it can also lead to the loss of light elements such as Cl and S, significantly impacting the accuracy of semi-quantitative results. Therefore, there is an urgent need for novel pretreatment methods that do not require high temperatures or chemical treatments, maintain sample integrity, and meet the requirements of WDXRF analysis. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the core purpose of the present invention is to provide a WDXRF testing method based on polyester film pretreatment and its application. By optimizing the sample pressing process and instrument parameter configuration, the testing range of WDXRF technology is expanded, and the testing difficulties caused by special samples that are difficult to press, easy to absorb moisture or heat-sensitive are solved. At the same time, changes in sample composition are avoided, and the test accuracy and instrument stability are improved.

[0005] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a WDXRF testing method for a sample processed using a film, the method comprising: placing a sample to be tested in a sample cup, covering it with a polyester film, pressing it into a tablet using a hydraulic press, placing the tablet into a mold, and performing a WDXRF test;

[0007] The parameters of the hydraulic press include: target pressure of 300-400 kN, holding time of 5-20 s; pressing time: 3-5 s; sampling time: 5-7 s; and sampling depth: 7-9 s.

[0008] Among them, the target pressure is 300-400 kN, for example, it can be 300 kN, 320 kN, 340 kN, 360 kN, 380 kN or 400 kN; the holding time is 5-20 s, for example, it can be 5 s, 10 s, 15 s or 20 s; the pressing time: 3-5 s, for example, it can be 3 s, 4 s or 5 s; the sampling time: 5-7 s, for example, it can be 5 s, 6 s or 7 s; the sampling depth: 7-9 s, for example, it can be 7 s, 8 s or 9 s.

[0009] This invention provides a WDXRF testing method for special samples. Due to issues such as uneven particle size, excessive impurities, and insufficient adhesion, these samples are difficult to compress into disc-shaped samples that meet testing requirements. These samples also tend to absorb water, leading to test failure. Therefore, this invention utilizes polyester film to treat these special samples. The film is then applied hydraulically to the sample, resulting in a compact, flat, and smooth disc. This disc produces stable fluorescence during subsequent testing and is unaffected by the vacuum pressure.

[0010] The method of the present invention can prevent special samples from contaminating instruments, reduce the influence of polyester film pretreatment on the linear intensity of special sample analysis, and reduce operating costs.

[0011] The method of the present invention is simple, easy to implement, low-cost, can be widely applied to WDXRF testing of various special samples, and has extremely high practical value.

[0012] In the present invention, the polyester film is made of polyethylene terephthalate (PET), a thermoplastic polyester. Polyester films include PET film, BOPET film, BOPI film, CPET (uniaxially oriented polyester film), or PET high-gloss film.

[0013] In one embodiment of the invention, the polyester film used is BOPET (biaxially oriented polyester film). BOPET film is made from polyethylene terephthalate (PET) through processes such as drying, extrusion, and biaxial stretching. Biaxial stretching involves stretching a thick PET sheet by a certain multiple in both the longitudinal and transverse directions within an appropriate temperature range (above the glass transition temperature and below the melting point) to align the molecular chains or crystal planes parallel to the film plane. The film is then heat-set to stabilize the oriented structure, and finally cooled to set the film.

[0014] In the present invention, the use of polyester film has the following advantages: it has similar light transmittance among different types of films of similar thickness, but polyester film has significant advantages in ductility, firmness, flexibility, etc., and is more suitable for practical use. Other film materials (such as PP film) cannot be used in some scenarios.

[0015] Preferably, the polyester film has a thickness of 2.5-10 μm, for example, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10 μm, etc.

[0016] In the present invention, as the film thickness decreases, the higher the net light intensity, the better the light transmittance, and the closer the semi-quantitative result is to the true value, the better the test result. After comprehensive analysis, it is determined that the test results of 2.5-10 μm film are better.

[0017] In the present invention, the WDXRF testing method is particularly suitable for processing samples that are difficult to tablet (such as high carbon content samples, etc.), samples that easily absorb water, and samples that will change under the influence of high temperature (such as nickel concentrate, etc.).

[0018] In the present invention, the method can successfully test special samples such as soil and carbon powder, which originally failed to be tested due to being difficult to press into tablets or easily absorbing water.

[0019] In the present invention, the equipment used for the WDXRF test is selected from: Rigaku ZSX Primus III+ instrument or other instruments of the same type and capability.

[0020] In the present invention, the target material for the WDXRF test is Rh.

[0021] Preferably, the voltage of the WDXRF test is 20-60 kV, for example, 20 kV, 25 kV, 30 kV, 35 kV, 40 kV, 45 kV, 50 kV, 55 kV or 60 kV.

[0022] Preferably, the current of the WDXRF test is 2-100 mA, for example, it can be 2 mA, 10 mA, 30 mA, 40 mA, 50 mA, 60 mA, 70 mA, 80 mA, 90 mA or 100 mA.

[0023] Preferably, the power of the WDXRF test is 3-4 kw, for example, 3 kw, 3.5 kw or 4 kw.

[0024] Preferably, the optical path atmosphere of the WDXRF test is vacuum.

[0025] Preferably, the parameters of the WDXRF test further include: sample spin-on; adjusting the pha range to be 100-300, for example, 100, 150, 200, 250 or 300.

[0026] In the present invention, the influence of the polyester film on the characteristic X-ray light intensity is reduced by adjusting the appropriate mold and instrument test parameters. Finally, the spectrum and light intensity are analyzed and calculated using SQX software to obtain qualitative results and semi-quantitative analysis values.

[0027] The present invention utilizes common and simple materials and obtains an optimal combination through multiple attempts at pre-treatment, test process, and test parameters, thereby enhancing the test range and capability of the instrument. It has the advantages of being fast, economical, and stable, and has practical application value. It can play a role in production practice and promote technological progress and social development.

[0028] Preferably, the pretreatment of the sample to be tested is carried out at a temperature of 10-30°C, for example, 10°C, 15°C, 20°C, 25°C or 30°C, and a humidity of 35-80%, for example, 35%, 40%, 50%, 60%, 70% or 80%.

[0029] The method of the present invention requires a 1-5 minute process to treat the sample. If the temperature or humidity exceeds the specified range, there is no guarantee that the sample will not be affected before being protected by this method, and there is no guarantee of stable operation of the instrument, which will affect the stability and accuracy of the test results.

[0030] In a second aspect, the present invention provides an application of the WDXRF testing method for treating samples using polyester film as described in the first aspect in analysis and detection.

[0031] In the present invention, the analysis and detection include: inorganic material analysis, polymer material analysis, metal material analysis, environmental monitoring and new energy detection, etc.

[0032] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The method of the present invention enables the testing of special samples that were originally difficult to test and achieves good test results. The method of the present invention can successfully test special samples that were originally difficult to press into tablets or easily absorb water, such as soil, carbon powder, etc. This not only expands the test range of WDXRF technology, but also reduces the failure rate of the instrument. The schematic diagram of the sample that is difficult to press into tablets is as follows Figure 1 , the schematic diagram of the sample that easily absorbs water is as follows Figure 2 and 3 , fragile samples after tableting such as Figure 4 As shown, if the above sample is tested directly, it will cause instrument failure. The most common reason is that the vacuum degree becomes poor, and the second is because of contamination of the instrument. After the tablet is pressed by the method of the present invention, Figure 5 As shown, the surface is not broken and is more suitable for testing.

[0035] (2) The method of the present invention can avoid changes in sample composition. Compared with traditional pretreatment methods, the present invention avoids the influence of drying, burning and other treatment processes on sample composition, thereby ensuring the accuracy of the test results.

[0036] (3) The method of the present invention has few side effects and high precision. When testing standard samples (such as copper and aluminum) using the method of the present invention, it was found that the deviation range was small (about 1%), indicating that the method has minimal impact on the sample and has high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the loose structure of difficult-to-tablet samples.

[0038] Figure 2 is a schematic diagram of an aqueous sample.

[0039] Figure 3 Schematic diagram of water absorption of hygroscopic samples in traditional tableting.

[0040] Figure 4 It is the fracture state of unpackaged tablets in a vacuum environment.

[0041] Figure 5 This is a diagram of the tableting process after polyester film packaging. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0043] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0044] Comparative Example 1

[0045] This comparative example was tested using the loss on ignition method.

[0046] 1. Use a 1 / 1000th balance to weigh approximately 1 g ± 0.001 g of sample (organosilicon compound) and record the reading.

[0047] 2. Weigh the ceramic crucible.

[0048] 3. Place the sample in a ceramic crucible, burn it at 850℃ for 4 hours, and then cool it to room temperature.

[0049] 4. Remove one sample and place it in a laboratory at 25°C and 50% humidity. Weigh 1 g of the sample and place it in a PE cup. Adjust the hydraulic press parameters to: target pressure: 400 kN; hold time: 5 s; press time: 3 s; sampling time: 6 s; and sample depth: 8 s. Form the sample into a pancake shape and place it in a mold with a 20 mm diameter window.

[0050] 5. Place the mold in the test area of ​​the Rigaku ZSX Primus III+ instrument, set and calibrate the instrument parameters. The test conditions are: target material: Rh, voltage 30 kV, current 100 mA, power 4 kW, optical path atmosphere: vacuum, sample spin on, calibrate the detector, and adjust the pha (pulse height analyzer) between 100-300.

[0051] 6. Start sample testing and set the parameters as follows: element test range Na-U, peak detection sensitivity: 1, smoothing points: 11 points.

[0052] 7. After the test is completed, open the SQX software for calculation, and obtain qualitative results and semi-quantitative analysis values ​​based on the spectrum and the corresponding characteristic X-ray light intensity.

[0053] The test results are shown in Table 1.

[0054] Table 1

[0055]

[0056] The sample's unique properties make direct tableting difficult. Traditionally, it requires burnout treatment before tableting. As can be seen in the table, this sample is within the Na-U test range, exhibiting high concentrations of Zn, Si, Mo, and W. The Cl content is very low, almost absent. It is speculated that the Cl content was converted to Cl₂ during the burnout process, resulting in its absence. The same applies to S and P.

[0057] Example 1

[0058] This embodiment provides a WDXRF testing method for treating a sample using polyester film, using a film sealing method for testing, the method comprising:

[0059] 1. Use a 1 / 1000th balance to weigh approximately 1 g ± 0.001 g of sample (organosilicon compound) and record the reading.

[0060] 2. In a laboratory at 25°C and 50% humidity, weigh approximately 1 g of sample and place it in a PE cup. Cover with 2.5 μm thick polyester film (Chemplex Cat. No. 100). Adjust the hydraulic press parameters to: target pressure: 400 kN; hold time: 5 s; press time: 3 s; sampling time: 6 s; and sample depth: 8 s. Form the sample into a pancake shape and place it into a mold with a 20 mm diameter window.

[0061] 3. Place the mold in the test area of ​​the Rigaku ZSX Primus III+ instrument, set and calibrate the instrument parameters. The test conditions are: target material: Rh, voltage 30 kV, current 100 mA, power 4 kW, optical path atmosphere: vacuum, sample spin on, calibrate the detector, and adjust the pha (pulse height analyzer) between 100-300.

[0062] 4. Start sample testing and set the parameters as follows: element test range: Na-U, peak detection sensitivity: 1, smoothing points: 11 points.

[0063] 5. After the test is completed, open the SQX software for calculation. Based on the spectrum and the corresponding characteristic X-ray light intensity, the qualitative results and semi-quantitative analysis values ​​are obtained. The test results are shown in Table 2.

[0064] Table 2

[0065]

[0066] The subsequent improved method uses the membrane sealing method. It can be seen from the table that the sample has more Zn, Cl, Si, P, S, Mo, and W elements within the test range of Na-U, which corresponds to the content pattern of the sample after burn-out. However, the pre-treatment before burn-out obviously changes the composition of the sample, resulting in a reduction in Cl, S, and P elements. The detection rate of Cl element is 34.93%, which is highly consistent with the actual composition of the sample. The content of the main element Zn is also exaggerated, with an error of 34.9%, which ultimately leads to inaccurate test results and cannot reflect the actual situation of the sample, which may cause waste in the production process and safety hazards during use.

[0067] Example 2

[0068] This embodiment provides a WDXRF testing method for treating a sample with polyester film, using a film sealing method (the film completely encapsulates the sample) for testing. The method includes:

[0069] 1. Use a 1 / 1000 balance to weigh approximately 1 g ± 0.001 g of sample (nickel concentrate composition analysis standard material (GNI-5)) and record the reading.

[0070] 2. In a laboratory at 25°C and 50% humidity, weigh approximately 1 g of sample and place it in a PE cup. Cover with 2.5 μm thick polyester film (Chemplex Cat. No. 100). Adjust the hydraulic press parameters to: target pressure: 400 kN; hold time: 5 s; press time: 3 s; sampling time: 6 s; and sample depth: 8 s. Form the sample into a pancake shape and place it into a mold with a 20 mm diameter window.

[0071] 3. Place the mold in the test area of ​​the Rigaku ZSX Primus III+ instrument, set and calibrate the instrument parameters. The test conditions are: target material: Rh, voltage 30 kV, current 100 mA, power 4 kW, optical path atmosphere: vacuum, sample spin on, calibrate the detector, and adjust the pha (pulse height analyzer) between 100-300.

[0072] 4. Start sample testing and set the parameters as follows: element test range: Na-U, peak detection sensitivity: 1, smoothing points: 11 points.

[0073] 5. After the test is completed, open the SQX software for calculation, and obtain qualitative results and semi-quantitative analysis values ​​based on the spectrum and the corresponding characteristic X-ray light intensity.

[0074] Comparative Example 2

[0075] This comparative example provides a WDXRF testing method, which adopts a film covering method (a film only covers the surface) for detection, and the method comprises:

[0076] 1. Use a 1 / 1000 balance to weigh approximately 1 g ± 0.001 g of sample (nickel concentrate composition analysis standard material (GNI-5)) and record the reading.

[0077] 2. In a laboratory at 25°C and 50% humidity, weigh approximately 1 g of sample and place it in a PE cup. Adjust the hydraulic press parameters to: target pressure: 400 kN; hold time: 5 s; press time: 3 s; sampling time: 6 s; and sample depth: 8 s. Form the sample into a pancake shape. Cover with 2.5 μm thick polyester film (Chemplex cat. no. 100). Keeping the surface as flat as possible, place the sample into a mold with a 20 mm diameter window.

[0078] 3. Place the mold in the test area of ​​the Rigaku ZSX Primus III+ instrument, set and calibrate the instrument parameters. The test conditions are: target material: Rh, voltage 30 kV, current 100 mA, power 4 kW, optical path atmosphere: vacuum, sample spin on, calibrate the detector, and adjust the pha (pulse height analyzer) between 100-300.

[0079] 4. Start sample testing and set the parameters as follows: element test range: Na-U, peak detection sensitivity: 1, smoothing points: 11 points.

[0080] 5. After the test is completed, open the SQX software for calculation, and obtain qualitative results and semi-quantitative analysis values ​​based on the spectrum and the corresponding characteristic X-ray light intensity.

[0081] Example 2 and Comparative Example 2 above compared several recent XRF testing methods. For membrane treatment, the membrane treatment simply covered the sample, referred to as the membrane covering method. Example 2 innovatively sealed the membrane onto the sample, referred to as the membrane sealing method. To compare the advantages and disadvantages of these methods, a nickel concentrate component analysis standard (GNI-5) was tested using 2.5 μm polyester film and compared with different membrane treatment methods (membrane covering method and membrane sealing method), and the data were analyzed.

[0082] The results of the investigation of Example 2 and Comparative Example 2 are as follows:

[0083] (1) From the naked eye analysis, the surface of the membrane sealing method is smooth, while the surface of the membrane covering method is rough and has protrusions, which does not meet the principle of smooth sample surface.

[0084] (2) Analyzing the test results, the standard sample included 23 substances, 20 of which were detected in the three types of samples. The three substances that were not detected were trace amounts of V and Ti, and OH, which was not within the test range. Comparing the test results with the standard values, the order was membrane sealing method > membrane capping method. In addition, the stability of the membrane sealing method was greater than that of the membrane capping method after multiple tests. It was also found that the membrane treatment avoided the influence of high temperature on the sample, making the test results closer to the true value. Table 3 lists the test results.

[0085] Table 3

[0086]

[0087] The above results show that relative deviations are calculated by comparing test values ​​with reference values. Smaller absolute deviations indicate closer approximation to the true result, indicating better performance. Five components were selected to represent five dimensions for evaluation: Ni (reference value 8.88%) represents the main element, Fe₂O₃ (reference value 47.99%) represents high-content elements, MgO (reference value 6.2%) represents medium-content elements, K₂O (reference value 0.05%) represents trace elements, and CaO (reference value 1.12%) represents low-content elements. For all five dimensions, the absolute relative deviations for the membrane-sealed method were lower than those for the membrane-capped method, indicating a closer approximation to the true value. Based on the available information, it is reasonable to speculate that surface roughness causes light intensity fluctuations. The more unstable the light intensity, the greater the deviation from the reference value. The more stable the light intensity, the closer the test result is to the reference value. The experiments show that the membrane-sealed method performs better than the membrane-capped method.

[0088] Example 3

[0089] This example provides a WDXRF testing method for a sample treated with polyester film (boric acid standard: Aladdin Product No. B111592-500g). This method differs from Example 1 in that the hydraulic press parameters are set to a target pressure of 200 kN and a holding time of 5 s, 10 s, 15 s, or 20 s.

[0090] Example 4

[0091] This example provides a WDXRF testing method for a sample treated with polyester film (boric acid standard: Aladdin Product No. B111592-500g). This method differs from Example 1 in that the hydraulic press parameters are set to a target pressure of 300 kN and the holding time is set to 5 s, 10 s, 15 s, or 20 s.

[0092] Example 5

[0093] This example provides a WDXRF testing method for a sample treated with polyester film (boric acid standard: Aladdin Product No. B111592-500g). This method differs from Example 1 in that the hydraulic press parameters are set to a target pressure of 400 kN and the holding time is set to 5 s, 10 s, 15 s, or 20 s.

[0094] Example 6

[0095] This example provides a WDXRF testing method for a sample treated with polyester film (boric acid standard: Aladdin Product No. B111592-500g). This method differs from Example 1 in that the hydraulic press parameters are set to a target pressure of 600 kN and the holding time is set to 5 s, 10 s, 15 s, or 20 s.

[0096] The results of Examples 3-6 are shown in Table 4.

[0097] Table 4

[0098]

[0099] Based on the above experimental results, holding pressure at 300-400 kN for 5-20 s is beneficial for daily use. Holding pressure at 400 kN for 5 s is preferred because it has higher pressure and saves time.

[0100] Example 7

[0101] This example provides a WDXRF testing method for a sample (aluminum hydroxide standard, CAS: 21645-51-2) processed using polyester film. This method differs from Example 1 in that the polyester film is a 6 μm thick Mylar film (Chemplex cat. no. 100). When a hydraulic press is used for pressing, the target pressure is set to 400 kN and the holding time is set to 5 s for sample preparation. Analysis is performed based on light intensity using SQX analysis software.

[0102] Example 8

[0103] This example provides a WDXRF testing method for a sample (aluminum hydroxide standard, CAS: 21645-51-2) processed using a polyester film. This method differs from Example 1 in that the polyester film is a 10 μm thick Mylar film (Chemplex cat. no. 100). When a hydraulic press is used for pressing, the target pressure is set to 400 kN and the holding time is set to 5 s for sample preparation. Analysis is performed based on light intensity using SQX analysis software.

[0104] Example 9

[0105] This example provides a WDXRF testing method for a sample (aluminum hydroxide standard, CAS: 21645-51-2) processed using polyester film. This method differs from Example 1 in that the polyester film is a 40 μm thick Mylar film (Chemplex cat. no. 100). When a hydraulic press is used for pressing, the target pressure is set to 400 kN and the holding time is set to 5 s for sample preparation. Analysis is performed based on light intensity using SQX analysis software.

[0106] Example 10

[0107] This example provides a WDXRF testing method for a sample (aluminum hydroxide standard, CAS: 21645-51-2) processed using polyester film. This method differs from Example 1 in that the polyester film is a 100 μm thick Mylar film (Chemplex cat. no. 100). When a hydraulic press is used for pressing, the target pressure is set to 400 kN and the holding time is set to 5 s for sample preparation. Analysis is performed based on light intensity using SQX analysis software.

[0108] The analysis results of Example 1 and Examples 7-10 are shown in Table 5.

[0109] Table 5

[0110]

[0111] The purity of the aluminum hydroxide standard is 99.99%. Given the ease of sample preparation and the lack of temperature effects, the test results without a membrane are theoretically optimal, as light intensity loss is minimized. Using a membrane can affect light transmission, resulting in light loss and ultimately distorting the analysis results. As shown in the table, the order of light intensity from highest to lowest is 2.5 μm > 6 μm > 10 μm > 40 μm > 100 μm. The order of error between the analytical results and the standard values ​​is 2.5 μm > 10 μm > 6 μm > 40 μm > 100 μm. This indicates that as the membrane thickness decreases, the loss of light intensity decreases, and the test results are closer to the standard values. The errors for 40 μm and 100 μm are excessively large, exceeding 5%. The errors for 2.5 μm, 6 μm, and 10 μm are relatively small, all within 5%, with no significant difference between them. Therefore, membranes between 2.5 and 10 μm exhibit good detection performance and can be used for testing.

[0112] The data shows that as film thickness decreases, the net light intensity increases, indicating better transmittance. Semi-quantitative results that are closer to the true value indicate better test results. Comprehensive analysis shows that films with thicknesses between 2.5 and 10 μm exhibit good test results, with 2.5 μm films performing best.

[0113] Example 11

[0114] This example provides a WDXRF testing method for treating a sample using polyester film. The sample to be tested is a copper standard (cat. 3590). The processing steps of the testing method are similar to those in Example 1.

[0115] Comparative Example 3

[0116] This comparative example provides a WDXRF testing method for treating a sample using a thin film. The sample to be tested is a copper standard (cat. 3590). The processing steps of the testing method are similar to those of Example 1, except that the thin film used is a 4 μm PP film.

[0117] The results of Example 11 and Comparative Example 3 are as follows:

[0118] 1. Visually analyze the sample using the film-sealing method. The polyester film (Chemplex cat. no. 100) adhered perfectly to the copper standard, while the PP film had a small amount of gaps. After the test, the PP film showed signs of damage after two hours of storage. However, the polyester film showed no noticeable changes over the two weeks, ensuring the long-term storage of the sample.

[0119] 2. Analyze the light intensity from the test results, as shown in Table 6. For copper labels, polyester film > PP film.

[0120] Table 6

[0121]

[0122] In WDXRF (Wavelength Dispersive X-ray Fluorescence) testing, net light intensity is a key metric for measuring the detector's ability to capture X-ray fluorescence and is directly related to the target element concentration in the sample. Typically, net light intensity is positively correlated with the target element concentration; higher concentrations produce higher net light intensity. However, in this experiment, given the use of a copper standard of consistent purity (99.99%), the difference in net light intensity is primarily due to the physical effects of different film materials on X-rays, including absorption, scattering, and transmission properties. Specifically, polyester film exhibits higher net light intensity, reflecting its improved transmission properties, allowing more X-ray fluorescence to penetrate and reach the detector. From a performance perspective, higher net light intensity not only improves the signal-to-noise ratio but also enhances measurement accuracy. In summary, polyester film demonstrates superior performance compared to PP film in this example.

[0123] In general, different types of films of similar thickness have similar light transmittance, but polyester film has significant advantages in ductility, strength, flexibility, etc., and is more suitable for practical use. At the same time, PP film cannot be used in some scenarios.

[0124] In summary, the present invention proposes a novel method for treating special samples using polyester film. This method is innovative and can solve the special sample testing problems in the prior art. The method of the present invention is simple, easy to implement, low-cost, and can be widely applied to WDXRF testing of various special samples, with extremely high practical value. By treating special samples with polyester film, the present invention enables the testing of special samples that were originally untestable, avoids changes in sample composition, and has minimal side effects and high accuracy. Therefore, the present invention has significant technical advantages and application prospects.

[0125] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and disclosure scope of the present invention.

Claims

1. A WDXRF testing method based on polyester film pretreatment, characterized in that: The WDXRF testing method comprises: placing a sample to be tested in a sample cup, covering it with a polyester film, pressing it into a tablet using a hydraulic press, placing the tablet into a mold, and performing a WDXRF test; The parameters of the hydraulic press include: target pressure of 300-400 kN, holding time of 5-20 s; pressing time: 3-5 s; sampling time: 5-7 s; and sampling depth: 7-9 s.

2. The WDXRF testing method based on polyester film pretreatment according to claim 1, characterized in that: The polyester film has a thickness of 2.5-10 μm.

3. The WDXRF testing method based on polyester film pretreatment according to claim 1, characterized in that: The voltage of the WDXRF test is 20-60 kV.

4. The WDXRF testing method based on polyester film pretreatment according to claim 1, characterized in that: The current of the WDXRF test is 2-100 mA.

5. The WDXRF testing method based on polyester film pretreatment according to claim 1, characterized in that: The power of the WDXRF test is 3-4 kw.

6. The WDXRF testing method based on polyester film pretreatment according to claim 1, characterized in that: The optical path atmosphere of the WDXRF test is vacuum.

7. The WDXRF testing method based on polyester film pretreatment according to claim 1, characterized in that: The parameters of the WDXRF test also include: sample spin-on; and adjusting the pha range to 100-300.

8. The WDXRF testing method based on polyester film pretreatment according to claim 1, characterized in that: The pretreatment of the sample to be tested is carried out at a temperature of 10-30° C. and a humidity of 35-80%.

9. Application of the WDXRF testing method based on polyester film pretreatment according to any one of claims 1 to 8 in trace element detection.

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