A sample preparation method for glow discharge mass spectrometry

Abstract

The present application relates to the technical field of sample preparation methods for mass spectrometry, and particularly relates to a sample preparation method for glow discharge mass spectrometry. The method comprises the following steps: placing a plurality of metal strips on the surface of a mold, placing adjacent metal strips alternately, pouring sample particles into the area enclosed by the plurality of metal strips, then pouring graphite powder on the surface of the mold, the graphite powder completely covering the metal strips and the area enclosed by the metal strips, moving the mold to a tablet press, pressing to obtain a shaped sample, and finally taking out the shaped sample, taking the bottom surface of the shaped sample as a sputtering area, and performing glow discharge mass spectrometry. The sample preparation method uses metal strips to constrain the movement of sample particles during pressing, and uses the conductivity of the metal strips to maximize the signal during sputtering, thereby solving the problems of difficulty in sample preparation of large-particle-size powder, small-size particle samples, and non-conductor samples that cannot be normally tested by glow discharge.

Description

Technical Field

[0001] This invention relates to the technical field of sample preparation methods for mass spectrometry, and more particularly to a sample preparation method for glow discharge mass spectrometry. Background Technology

[0002] Glow discharge mass spectrometry (GDMS) is one of the most effective methods for analyzing trace and ultra-trace elements in metal and semiconductor materials. GDMS uses direct solid-state injection, which simplifies sample preparation. It also has advantages such as low matrix effect, high sensitivity, low detection limit (sub-ppb level), high resolution, and wide dynamic range (12 orders of magnitude). Among the mainstream GDMS models on the market, Astrum, Element GD, and VG9000 are all DC-GDMS (direct current glow discharge mass spectrometry), which requires the sample to be a conductive material. In existing technologies, such as the method disclosed in Chinese patent document CN113514534A for analyzing small-sized conductive and non-conductive materials using glow discharge mass spectrometry, the method involves first placing graphite powder in an aluminum cup and gently agitating the cup to smooth the surface of the graphite powder; then placing a small-sized conductive or non-conductive material on top of the graphite powder; covering it with several layers of tracing paper; pressing it with a tablet press to form a test sample; and performing DC glow discharge mass spectrometry analysis. This method can test some small-sized conductive and non-conductive materials, but it has some problems: 1. Multiple small, irregularly sized samples may disperse during the pressing process and may not be sputtered simultaneously, resulting in a low test signal intensity. 1. Decreased data accuracy; 2. Graphite generally has poor conductivity. If the conductivity of the sample to be tested is extremely poor, the overall conductivity of the sample after embedding graphite powder will be poor, which will lead to the inability to perform normal glow discharge, i.e., the inability to test. For example, a glow discharge mass spectrometer device for measuring non-conductive powders disclosed in Chinese patent document CN209416974U presses the non-conductive powder into the cavity of a mold made of high-purity tantalum. Using high-purity tantalum as the second cathode of the glow discharge ion source, it effectively solves the problem that non-conductive powders cannot be detected by GDMS due to their non-conductivity. This method can test some powder samples, but it cannot effectively prepare samples such as large-diameter powders and small-sized particles. Summary of the Invention

[0003] In view of this, the purpose of this invention is to propose a sample preparation method for glow discharge mass spectrometry testing, so as to solve the problems of difficulty in preparing large-diameter powder and small-sized particle samples, and the inability to perform normal glow discharge testing on non-conductive samples.

[0004] To achieve the above objectives, the present invention provides a sample preparation method for glow discharge mass spectrometry testing, comprising the following steps:

[0005] Multiple metal strips are placed on the surface of the mold, with adjacent metal strips placed alternately;

[0006] Pour the sample particles into the area enclosed by multiple metal strips;

[0007] Pour graphite powder onto the surface of the mold, completely covering the metal strip and the area enclosed by the metal strip;

[0008] The mold is moved into the tablet press and pressed to obtain the shaped sample;

[0009] Remove the molded sample and use the bottom surface of the molded sample as the sputtering area to perform glow discharge mass spectrometry testing.

[0010] Preferably, the metal strip has a length of 5-25mm, a width of 2-5mm, and a thickness of 0.8-2mm.

[0011] Preferably, four metal strips are placed on the surface of the mold, and the four metal strips together form a rectangular area.

[0012] Preferably, three metal strips are placed on the surface of the mold, and the three metal strips together form a triangular area.

[0013] Preferably, the inner diameter of the area enclosed by the metal strip is 2-10 mm.

[0014] Preferably, the inner diameter of the area enclosed by the metal strip is 3-5 mm.

[0015] Preferably, the mold includes a base and a mold sleeve;

[0016] First, place the pressure head on the base platform, place multiple metal strips on the pressure head, pour sample particles into the area enclosed by the multiple metal strips, attach the mold sleeve to the base platform, and then sprinkle graphite powder on the pressure head.

[0017] An upper pressure head is placed on the mold sleeve, with the bottom end of the upper pressure head pressing against the top end of the lower pressure head to apply pressure to the upper pressure head and press the sample to obtain a shaped sample.

[0018] Preferably, the graphite powder is sprinkled in multiple passes, and after each pass of graphite powder is sprinkled, the upper and lower pressure heads are pressed down for pre-pressing.

[0019] The beneficial effects of this invention are as follows: By placing multiple metal strips on the surface of a mold, with adjacent metal strips placed alternately, sample particles are poured into the area enclosed by the multiple metal strips, and then graphite powder is poured onto the surface of the mold, completely covering the metal strips and the area enclosed by the metal strips. The mold is then moved into a tablet press to press and obtain a shaped sample. Finally, the shaped sample is removed, and the bottom surface of the shaped sample is used as the sputtering area for glow discharge mass spectrometry testing. This sample preparation method uses metal strips to constrain the movement of sample particles during the pressing process, and at the same time utilizes the conductivity of the metal strips to maximize the signal during sputtering. This solves the problems of difficulty in preparing large-diameter powder and small-sized particle samples, as well as the inability to perform normal glow discharge testing on non-conductive samples. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the sample particle compression preparation structure in the existing technology;

[0022] Figures 2 to 5 This is a schematic diagram of the sample particle compression preparation structure in this invention;

[0023] Figure 6 This is a schematic diagram of the mold structure in this invention.

[0024] The diagram is marked as follows:

[0025] 1. Base; 2. Mold; 3. Lower pressure head; 4. Upper pressure head; 5. Sample particles; 6. Graphite powder; 7. Sputtering area. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0027] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0028] A sample preparation method for glow discharge mass spectrometry includes the following steps:

[0029] Multiple metal strips are placed on the surface of the mold, with adjacent metal strips placed alternately;

[0030] Pour sample particles 5 into the area enclosed by multiple metal strips;

[0031] Pour graphite powder 6 onto the surface of the mold, so that the graphite powder 6 completely covers the metal strip and the area enclosed by the metal strip;

[0032] The mold is moved into the tablet press and pressed to obtain the shaped sample;

[0033] Remove the molded sample and use the bottom surface of the molded sample as sputtering area 7 for glow discharge mass spectrometry testing.

[0034] This invention is based on existing methods for glow discharge mass spectrometry (GFMS) analysis of conductive and non-conductive materials. While pressing non-conductive powder into the cavity of a mold made of high-purity tantalum, using high-purity tantalum as the second cathode of the glow discharge ion source, effectively solves the problem of GDMS detection of non-conductive powder due to its non-conductivity, it still presents challenges for large-particle-size powders and small-sized particle samples. Because the sample particles (5) cannot be crushed, they are difficult to adhere to the mold cavity, making sample preparation difficult. While pressing the sample particles (5) onto graphite powder (6) allows for sample preparation, the particles easily disperse during the pressing process. Figure 1 As shown, during testing, the sample particles cannot be sputtered simultaneously, resulting in low test signal strength. Furthermore, even when non-conductive sample particles 5 are embedded in graphite powder 6, their conductivity remains extremely poor, preventing normal glow discharge testing. To address this, this invention places multiple metal strips on the mold surface, with adjacent strips staggered. Sample particles 5 are poured into the area enclosed by the metal strips, followed by graphite powder 6, completely covering the metal strips and the enclosed area. The mold is then moved to a tablet press to obtain a shaped sample. Finally, the shaped sample is removed, and its bottom surface is used as the sputtering area 7 for glow discharge mass spectrometry testing. This sample preparation method utilizes metal strips to constrain the movement of sample particles 5 during the pressing process, while simultaneously leveraging the conductivity of the metal strips to maximize the signal strength during sputtering. This solves the problems of difficulty in preparing large-diameter powder and small-sized particle samples, as well as the inability to perform normal glow discharge testing on non-conductive samples.

[0035] The metal strip has a length of 5-25mm, a width of 2-5mm, and a thickness of 0.8-2mm. The inner diameter of the area enclosed by the metal strip is 2-10mm, preferably 3-5mm. Specifically, for example... Figures 2 to 5Four metal strips are placed on the mold surface, forming a rectangular area, or three metal strips are placed on the mold surface, forming a triangular area, or any polygonal shape. The sample particles are actually non-conductive oxides such as indium oxide, tin oxide, zirconium oxide, gallium oxide, or ceramic materials such as SiO2. The corresponding metal strips are preferably tantalum strips with a purity of 99.999% or higher. The selection of metal strips can also refer to specific metal elements that are not of interest in the sample to be tested. For example, if the sample to be tested does not have Cu, then copper strips can be used in practice.

[0036] The following detailed description uses specific examples:

[0037] Example 1:

[0038] like Figures 1 to 6 As shown, the mold includes a base 1 and a mold sleeve 2. First, the lower pressure head 3 is placed on the base 1, and then... Figure 2 The scheme involves placing four tantalum strips (3mm wide, 20mm long, and 1mm thick), with adjacent tantalum strips staggered to expose an area of ​​approximately 4mm*4mm. Large-particle indium oxide powder is poured into the area enclosed by the multiple metal strips. The mold sleeve 2 is then fitted onto the base platform 1, and graphite powder 6 is sprinkled onto the lower pressure head 3.

[0039] An upper pressure head 4 is placed on the mold sleeve 2, with its bottom end pressing against the top end of the lower pressure head 3. Pressure is applied to the upper pressure head 4 to press the sample and obtain a molded sample 5. The bottom surface of the molded sample 5 is as follows: Figure 2 As shown.

[0040] Finally, it was tested using GDMS, and the splashed area 7 is enclosed by the red dashed line.

[0041] Preferably, the graphite powder 6 is sprinkled in multiple passes. After each pass of graphite powder 6 is sprinkled, the upper press head 4 is pressed down first for pre-pressing. Before pre-pressing, the sprinkled graphite powder 6 is spread out evenly.

[0042] Example 2:

[0043] like Figures 1 to 6 As shown, the mold includes a base 1 and a mold sleeve 2. First, the lower pressure head 3 is placed on the base 1, and then... Figure 3 The scheme involves placing four tantalum strips (3mm wide, 7mm long, and 1.5mm thick), with adjacent tantalum strips staggered to expose an area of ​​approximately 4mm*4mm. Silicon particles are poured into the area enclosed by multiple metal strips, and the mold sleeve 2 is fitted onto the base 1. Graphite powder 6 is then sprinkled onto the lower pressure head 3.

[0044] An upper pressure head 4 is placed on the mold sleeve 2, with its bottom end pressing against the top end of the lower pressure head 3. Pressure is applied to the upper pressure head 4 to press the sample and obtain a molded sample. The bottom surface of the molded sample is as follows: Figure 3 As shown.

[0045] Finally, it was tested using GDMS, and the splashed area 7 is enclosed by the red dashed line.

[0046] Based on the above methods, effective sample preparation can be achieved for large-diameter powders, small-sized particles, and non-conductive material samples, resulting in samples with good mechanical stability and good conductivity, allowing for normal glow discharge.

[0047] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0048] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A sample preparation method for glow discharge mass spectrometry, characterized in that, Includes the following steps: Multiple metal strips are placed on the surface of the mold, with adjacent metal strips placed alternately; Pour the sample particles into the area enclosed by the multiple metal strips; Graphite powder is poured onto the surface of the mold, completely covering the metal strip and the area enclosed by the metal strip; The mold is moved into the tablet press and pressed to obtain the shaped sample; Remove the molded sample and use the bottom surface of the molded sample as the sputtering area to perform glow discharge mass spectrometry testing.

2. The sample preparation method for glow discharge mass spectrometry testing according to claim 1, characterized in that, The metal strip has a length of 5-25mm, a width of 2-5mm, and a thickness of 0.8-2mm.

3. The sample preparation method for glow discharge mass spectrometry testing according to claim 1, characterized in that, Four metal strips are placed on the surface of the mold, and the four metal strips together form a rectangular area.

4. The sample preparation method for glow discharge mass spectrometry testing according to claim 1, characterized in that, Three metal strips are placed on the surface of the mold, and the three metal strips together form a triangular area.

5. The sample preparation method for glow discharge mass spectrometry according to claim 1, characterized in that, The inner diameter of the area enclosed by the metal strip is 2-10 mm.

6. The sample preparation method for glow discharge mass spectrometry according to claim 1, characterized in that, The inner diameter of the area enclosed by the metal strip is 3-5 mm.

7. The sample preparation method for glow discharge mass spectrometry according to claim 1, characterized in that, The mold includes a base and a mold sleeve; First, place the pressure head on the base platform, place multiple metal strips on the pressure head, pour sample particles into the area enclosed by the multiple metal strips, attach the mold sleeve to the base platform, and then sprinkle graphite powder on the pressure head. An upper pressure head is placed on the mold sleeve, with the bottom end of the upper pressure head pressing against the top end of the lower pressure head to apply pressure to the upper pressure head and press the sample to obtain a shaped sample.

8. The sample preparation method for glow discharge mass spectrometry testing according to claim 7, characterized in that, Graphite powder is added in multiple passes. After each pass of graphite powder is added, the upper pressure head is pressed down for pre-pressing.

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