Online purification sampling system and method for ICP-MS (Inductively Coupled Plasma Mass Spectrometry) analysis

Abstract

The invention discloses an online purification sampling system and method for ICP-MS (Inductively Coupled Plasma Mass Spectrometry) analysis. The system comprises a sample conveying unit, a precipitator conveying unit, a mixed reaction unit, an online solid-liquid separation unit and a control unit, an inlet of the mixed reaction unit is respectively connected with an outlet of the sample conveying unit and an outlet of the precipitant conveying unit, and the mixed reaction unit is used for carrying out precipitation reaction on a sample and a precipitant solution; an inlet of the on-line solid-liquid separation unit is connected with an outlet of the mixed reaction unit, and the on-line solid-liquid separation unit is used for separating solid precipitates and clarifying purified liquid; a liquid outlet of the online solid-liquid separation unit is connected with a feeding end of the ICP-MS analysis system; and the control unit is electrically connected with all the units. According to the system and the method, the interference of chloride ions in a high-purity hydrochloric acid matrix can be effectively removed, the analysis background is greatly reduced, the analysis accuracy and sensitivity of elements such as As, V and Cr are remarkably improved, and the comprehensive performance of the system and the method is remarkably superior to that of the prior art.

Description

Technical Field

[0001] This invention relates to the field of analytical chemistry, and in particular to an online purification and injection system and method for ICP-MS analysis. Background Technology

[0002] Inductively coupled plasma mass spectrometry (ICP-MS) is a key technology for determining trace and ultra-trace metal impurities in high-purity electronic chemicals used in industries such as semiconductors and photovoltaics. However, ICP-MS faces significant technical bottlenecks when analyzing high-chlorine matrix samples such as high-purity hydrochloric acid (HCl).

[0003] The bottleneck primarily stems from matrix interference, particularly polyatomic ion interference. In argon (Ar) plasma, chlorine (Cl) in the sample matrix reacts with argon, oxygen, hydrogen, and other gases to form... 40 Ar 35 Cl + , 35 Cl 16 O + , 35 Cl 16 O 1 H + Various polyatomic ions, including those with mass-to-charge ratios (m / z) that are identical or very close to isotopes of some key monitored metallic elements, resulting in severe spectral peak overlap interference. For example: 40 Ar 35 Cl + (m / z=75) Severe interference with arsenic ( 75 As + The determination of ); 35 Cl 16 O + (m / z=51) Severe interference with vanadium ( 51 V + The determination of ); 37 Cl 16 O + (m / z=53) Severe interference with chromium ( 53 Cr + The determination of ).

[0004] To solve this problem, existing technologies typically employ the following methods: 1. High-dilution method: The sample is diluted tens or even hundreds of times with ultrapure water or dilute nitric acid to reduce the concentration of chloride ions. The main drawback of this method is that while diluting the matrix, the target analyte is also diluted by the same factor, resulting in a sharp decrease in analytical sensitivity. For electronic chemicals that require monitoring at the ppt or even ppq level, the concentration of many elements will be below the instrument's detection limit, failing to meet quality control requirements.

[0005] 2. Collision / Reaction Cell (CRC) Technology: A collision / reaction cell is set up in the ion transport path of ICP-MS, and a reaction gas (such as H2, He, NH3, etc.) is introduced. Interference is eliminated by utilizing the differences in reactivity or collision cross-section between polyatomic ions and target ions. However, CRC technology is not a panacea. For high concentrations of chloride matrices, the interference elimination efficiency is limited, and residual interference may exist. Furthermore, the introduction of the reaction gas may cause side reactions with the target analyte, resulting in signal loss or introducing new interference, making optimization conditions complex.

[0006] 3. Mathematical Formula Correction Method: This method measures the intensity of interfering ions formed by non-analyte isotopes and calculates and subtracts their contribution to the target analyte isotope signal using known isotope abundance ratios. The accuracy of this method is highly dependent on the uniqueness of the interference source and the stability of the isotope ratios. It exhibits significant errors and high uncertainty in complex plasma environments.

[0007] In summary, existing technologies suffer from problems such as sacrificing sensitivity, incomplete interference elimination, complex operation, or insufficient accuracy when processing samples with high chlorine matrices. There is an urgent need for a new solution that can eliminate chlorine matrix interference at its source without compromising analytical sensitivity. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides an online purification and sample introduction system and method for ICP-MS analysis, which can actively and efficiently remove chloride ions from the matrix before the sample enters the ICP-MS, thereby eliminating interference at the source and achieving accurate determination of trace metals in high-chlorine matrix samples.

[0009] To address the problems mentioned in the background section and achieve the aforementioned technical objectives, the present invention provides the following technical solution: The first aspect of this invention provides an online purification and injection system for ICP-MS analysis, comprising: The sample delivery unit is used to deliver the high-chlorine matrix sample to be tested. A precipitant delivery unit is used to deliver a precipitant solution that reacts with chloride ions to form a sparingly soluble precipitate. A mixing reaction unit, the inlet of which is connected to the outlet of the sample delivery unit and the outlet of the precipitant delivery unit, is used to uniformly mix the sample and the precipitant solution to induce a precipitation reaction. An online solid-liquid separation unit, the inlet of which is connected to the outlet of the mixing reaction unit, is used to separate the solid precipitate and the clarified and purified liquid generated by the precipitation reaction; the liquid outlet of the online solid-liquid separation unit is connected to the feed end of the ICP-MS analysis system; The control unit is electrically connected to each of the above-mentioned units.

[0010] Preferably, the high-chlorine matrix sample is high-purity hydrochloric acid.

[0011] Preferably, the precipitant solution is a silver salt solution, and more preferably a silver nitrate solution.

[0012] Preferably, the online solid-liquid separation unit is equipped with a microporous filter membrane with a pore size ≤1.0μm.

[0013] Preferably, the microporous filter membrane is made of polytetrafluoroethylene or perfluoroalkoxy polymer.

[0014] Preferably, the online purification and injection system for ICP-MS analysis further includes a cleaning unit for introducing cleaning fluid to remove solid precipitates within the online solid-liquid separation unit.

[0015] Preferably, the liquid outlet of the online solid-liquid separation unit is equipped with a multi-channel switching valve, and the outlet of the cleaning unit and the feed end of the ICP-MS analysis system are respectively connected to the multi-channel switching valve.

[0016] Preferably, the cleaning solution is ammonia.

[0017] A second aspect of the present invention provides an online purification injection method for ICP-MS analysis, applied to the aforementioned online purification injection system for ICP-MS analysis, comprising the following steps: The high-chlorine matrix sample is uniformly mixed with the precipitant solution online, so that the chloride ions in the high-chlorine matrix sample react with the precipitant solution to form a precipitation reaction, generating an insoluble solid precipitate; The mixture after precipitation reaction is subjected to solid-liquid separation online, and the solid precipitate is retained to obtain a clear and purified liquid; The clarified and purified solution was introduced into the ICP-MS analysis system.

[0018] Preferably, the method further includes removing the retained solid precipitate after the ICP-MS analysis is completed.

[0019] The beneficial effects of this invention are as follows: 1. Eliminates interference at its source with extremely high accuracy: Interference sources (Cl) are almost completely removed before the sample enters the plasma via chemical precipitation. - ), fundamentally avoiding 40 Ar 35 Cl + The formation of polyatomic ions eliminates matrix interference in the determination of elements such as As, V, and Cr, resulting in analytical results with accuracy and reliability far exceeding those of CRC technology or mathematical correction methods.

[0020] 2. No dilution required, ensuring sensitivity of ultra-trace analysis: Interference sources are actively removed rather than diluted, and the sample can be analyzed directly without high dilution. The concentration of the target metal element is maintained, fully meeting the stringent requirements for detection limits of PPT or even PPQ level ultra-trace analysis of electronic chemicals.

[0021] 3. Fully automated process to avoid secondary contamination: The entire purification and sample introduction process is completed automatically in a closed pipeline system, avoiding environmental pollution and human error introduced by traditional offline pretreatment (such as open heating, transfer, etc.), and ensuring the cleanliness of ultrapure analysis.

[0022] 4. Wide applicability and easy operation: The system has a simple structure and is easy to couple with any brand of ICP-MS on the market; after the method is established, the operator only needs to place the sample and reagents, and can start the analysis process with one click through the control unit, which greatly simplifies the analysis of high-chlorine matrix samples. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the online purification and injection system for ICP-MS analysis according to the present invention.

[0024] Figure 2 This is a flowchart of the online purification and injection method for ICP-MS analysis according to the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Example

[0026] Reference Figure 1 This embodiment describes the construction of an online purification and sample introduction system for ICP-MS analysis. (See [link to documentation]). Figure 1 The system mainly includes a sample delivery unit 1, a precipitant delivery unit 2, a mixing reaction unit 3, an online solid-liquid separation unit 4, a cleaning unit 5, and a control unit; the structure and parameter design of each unit in the system are as follows: The sample to be tested in sample delivery unit 1 is commercially available G4 grade high-purity hydrochloric acid (metal impurity content <1 ppb), which is used as the representative analytical object for high-chlorine matrix samples. The precipitant solution in precipitant delivery unit 2 is a silver salt solution, specifically a 0.05M high-purity silver nitrate (AgNO3) solution prepared with ultrapure water (18.2 MΩ•cm), and acidified with trace metal analytical grade nitric acid to pH≈2 to ensure the stability of the precipitant solution and avoid introducing additional impurities.

[0027] The inlet of the mixing reaction unit 3 is equipped with a mixing tee. The outlets of the sample delivery unit 1 and the precipitant delivery unit 2 are connected to the mixing tee via pipes. The mixing tee is made of PFA material, which is chemically inert and ensures that the sample and precipitant are initially mixed without leaching contamination. A sample pump (a multi-channel peristaltic pump) is also installed between the mixing reaction unit 3 and the sample delivery unit 1, with a flow rate set to 1.0 mL / min. A precipitant pump (a multi-channel peristaltic pump) is also installed between the mixing reaction unit 3 and the precipitant delivery unit 2, with a flow rate set to 0.2 mL / min. This flow rate ratio ensures that Ag... ⁺ Relative to Cl in the sample - The stoichiometry is in excess to ensure that the chloride ions react completely to form a precipitate.

[0028] Mixing reaction unit 3 employs a tubular reactor, internally equipped with a PFA coil with an inner diameter of 1.0 mm and a length of 150 cm. This structural design provides a reaction residence time of approximately 45 seconds, ensuring Cl... - With Ag + After uniform mixing and sufficient precipitation reaction, a stable AgCl solid precipitate is formed.

[0029] The inlet of the online solid-liquid separation unit 4 is connected to the outlet of the mixing reaction unit 3 via a pipeline. The outlet of the online solid-liquid separation unit 4 is equipped with a multi-channel switching valve 6. The outlet of the cleaning unit 5 and the feed end of the ICP-MS analysis system are also connected to the multi-channel switching valve 6 via pipelines. The multi-channel switching valve 6 allows for flexible switching between two flow paths: an analytical flow path (where the clarified and purified liquid directly enters the ICP-MS analysis system via the online solid-liquid separation unit 4) and a cleaning flow path (where the cleaning liquid flows in reverse into the online solid-liquid separation unit 4 to remove trapped precipitates).

[0030] The online solid-liquid separation unit 4 contains a hydrophilic microporous membrane with a pore size of 0.2 μm, made of polytetrafluoroethylene (PTFE) or perfluoroalkoxy polymer (PFA). This microporous membrane is resistant to chemical corrosion and can efficiently retain AgCl solid precipitates. At the same time, its hydrophilicity allows the clarified and purified liquid containing target metal ions (such as As, V, Cr, etc.) to pass smoothly through the microporous membrane and be transported to the ICP-MS analysis system (model ICPMS-2030).

[0031] Cleaning unit 5 uses a 5% ammonia solution as the cleaning fluid, which can react with AgCl precipitate to form a soluble silver ammonia complex ([Ag(NH3)2)). + This enables efficient regeneration of the filter membrane.

[0032] The control unit, using a computer connected to the pump and valve bodies, is electrically connected to the aforementioned units (sample delivery unit 1, precipitant delivery unit 2, online solid-liquid separation unit 4, etc.), the sample pump, the precipitant pump, and the multi-channel switching valve 6. Through a preset timing program, it controls the start / stop, flow rate adjustment, and flow path switching of each component, automating the sample injection, reaction, separation, and analysis process and reducing human error. Example

[0033] This embodiment utilizes the online purification and injection system for ICP-MS analysis built in Example 1 to implement an online purification and injection method for ICP-MS analysis. (See [link to example]). Figure 2 The specific steps are as follows: S1, System Preprocessing: Start the control unit and flush the entire system piping with ultrapure water or dilute nitric acid for 5 minutes via the sample pump and precipitant pump to remove any residual impurities and ensure a clean analytical environment. Introduce the commercially available G4 grade high-purity hydrochloric acid-perchloride matrix sample to be tested into the sample delivery unit, and introduce a silver salt solution, specifically a high-purity silver nitrate (AgNO3) precipitant solution, into the precipitant delivery unit.

[0034] S2, Online mixing and precipitation reaction: The control unit synchronously starts the sample pump of the sample delivery unit and the precipitant pump of the precipitant delivery unit, and pumps the sample and precipitant solution into the tubular reactor at a preset flow rate ratio (e.g., sample flow rate 1.0 mL / min, precipitant flow rate 0.2 mL / min, to ensure stoichiometric excess of precipitant). The high-purity hydrochloric acid sample and silver nitrate solution are combined through a mixing three-way valve and then enter the tubular reactor for thorough mixing and precipitation reaction to generate insoluble AgCl solid precipitate.

[0035] S3. Online purification and analysis: The mixed liquid containing solid precipitate flows into the online solid-liquid separation unit. The AgCl solid precipitate is retained by a 0.2μm microporous filter membrane, while the clarified and purified liquid containing the target metal ions passes through the filter membrane and enters the nebulizer of the ICP-MS analysis system for analysis via a multi-channel switching valve. Signals of 30 metal elements, including V, Cr, As, and Se, are acquired.

[0036] S4. Result Verification: When the clarified and purified solution from this method is introduced into the ICP-MS analysis system for analysis, 75The background equivalent concentration (BEC) of As was less than 0.5 ppt; the recovery rates of each element in high-purity hydrochloric acid samples with 10 ppt of As, V and Cr were between 95% and 105%, and the relative standard deviation (RSD) was less than 3%, indicating excellent analytical accuracy and precision.

[0037] S5, System Regeneration: After a single analysis, the control unit stops the sample pump and precipitant pump, and switches the flow path to cleaning mode via the multi-channel switching valve. The cleaning unit pumps cleaning solution (5% ammonia solution) into the online solid-liquid separation unit to backwash the online solid-liquid separation unit, dissolving and removing the trapped solid precipitate. The dissolved AgCl complex is discharged through the waste liquid outlet. Then, ultrapure water is pumped in for 5 minutes to rinse, and the system returns to standby mode, ready for the next analysis.

[0038] Comparative example:

[0039] The comparative sample used a traditional injection method, diluting the same sample 10-fold before direct injection. The ICP-MS analysis system was in CRC mode and H2 reaction gas was introduced. 75 The background equivalent concentration of As is as high as 50 ppt or more, the recovery rate of 10 ppt spiked sample is less than 60%, and the signal fluctuation is significant.

[0040] Experimental Analysis:

[0041] The experimental results of Example 2 and the comparative example show that the system and method of the present invention can effectively remove chloride ion interference in the high-purity hydrochloric acid matrix, greatly reduce the analytical background, and significantly improve the analytical accuracy and sensitivity of elements such as As, V, and Cr. Its comprehensive performance is significantly better than that of the prior art.

[0042] In summary, the present invention has at least the following advantages compared with the prior art: 1. Eliminates interference at its source with extremely high accuracy: Interference sources (Cl) are almost completely removed before the sample enters the plasma via chemical precipitation. - ), fundamentally avoiding 40 Ar 35 Cl + The formation of polyatomic ions eliminates matrix interference in the determination of elements such as As, V, and Cr, resulting in analytical results with accuracy and reliability far exceeding those of CRC technology or mathematical correction methods.

[0043] 2. No dilution required, ensuring sensitivity of ultra-trace analysis: Interference sources are actively removed rather than diluted, and the sample can be analyzed directly without high dilution. The concentration of the target metal element is maintained, fully meeting the stringent requirements for detection limits of PPT or even PPQ level ultra-trace analysis of electronic chemicals.

[0044] 3. Fully automated process to avoid secondary contamination: The entire purification and sample introduction process is completed automatically in a closed pipeline system, avoiding environmental pollution and human error introduced by traditional offline pretreatment (such as open heating, transfer, etc.), and ensuring the cleanliness of ultrapure analysis.

[0045] 4. Wide applicability and easy operation: The system has a simple structure and is easy to couple with any brand of ICP-MS on the market; after the method is established, the operator only needs to place the sample and reagents, and can start the analysis process with one click through the control unit, which greatly simplifies the analysis of high-chlorine matrix samples.

[0046] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. An online purification and injection system for ICP-MS analysis, characterized in that, include Sample delivery unit (1) is used to deliver the high-chlorine matrix sample to be tested; Precipitant delivery unit (2), which is used to deliver precipitant solution that reacts with chloride ions to generate sparingly soluble precipitates; The mixing reaction unit (3) has its inlet connected to the outlet of the sample delivery unit (1) and the outlet of the precipitant delivery unit (2), and is used to make the sample and the precipitant solution mix evenly to produce a precipitation reaction; The online solid-liquid separation unit (4) has its inlet connected to the outlet of the mixing reaction unit (3) and is used to separate the solid precipitate and the clarified and purified liquid generated by the precipitation reaction; the liquid outlet of the online solid-liquid separation unit (4) is connected to the feed end of the ICP-MS analysis system. The control unit is electrically connected to each of the above-mentioned units.

2. The online purification and injection system for ICP-MS analysis according to claim 1, characterized in that, The high-chlorine matrix sample was high-purity hydrochloric acid.

3. The online purification and injection system for ICP-MS analysis according to claim 1, characterized in that, The precipitant solution is a silver salt solution, preferably a silver nitrate solution.

4. The online purification and injection system for ICP-MS analysis according to claim 1, characterized in that, The online solid-liquid separation unit (4) is equipped with a microporous filter membrane with a pore size ≤1.0μm.

5. The online purification and injection system for ICP-MS analysis according to claim 4, characterized in that, The microporous filter membrane is made of polytetrafluoroethylene or perfluoroalkoxy polymer.

6. The online purification and injection system for ICP-MS analysis according to claim 1, characterized in that, The online purification and injection system for ICP-MS analysis also includes a cleaning unit (5), which is used to introduce cleaning fluid to remove solid precipitates in the online solid-liquid separation unit (4).

7. The online purification and injection system for ICP-MS analysis according to claim 6, characterized in that, The liquid outlet of the online solid-liquid separation unit (4) is equipped with a multi-channel switching valve (6), and the outlet of the cleaning unit (5) and the feed end of the ICP-MS analysis system are respectively connected to the multi-channel switching valve (6).

8. The online purification and injection system for ICP-MS analysis according to claim 6, characterized in that, The cleaning solution is ammonia.

9. An online purification injection method for ICP-MS analysis, applied to the online purification injection system for ICP-MS analysis as described in any one of claims 1 to 8, characterized in that, Includes the following steps: The high-chlorine matrix sample is uniformly mixed with the precipitant solution online, so that the chloride ions in the high-chlorine matrix sample react with the precipitant solution to form a precipitation reaction, generating an insoluble solid precipitate; The mixture after precipitation reaction is subjected to solid-liquid separation online, and the solid precipitate is retained to obtain a clear and purified liquid; The clarified and purified solution was introduced into the ICP-MS analysis system.

10. The method according to claim 9, characterized in that, The method also includes removing the retained solid precipitates after ICP-MS analysis.

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