A method for cleaning an ICP-MS nebulizer

Abstract

The application provides an ICP-MS atomizer cleaning method, which combines step-by-step chemical cleaning with online atomization verification, adopts two kinds of customized cleaning solutions (A and B) to clean different impurities: the cleaning solution A is used for cleaning metal impurities such as Cu, Ag, Pb, Fe, Co and Ni; the cleaning solution B is used for cleaning the internal microchannels of the atomizer, used for removing W deposition in the deep part of the Pt capillary, and in the cleaning process, the atomization cleaning solution is diagnosed by the instrument diagnosis mode, so that the stubborn deposits in the internal microchannels of the atomizer are completely removed; finally, the internal standard recovery rate and the standard curve linearity are used as indexes to ensure that the cleaning effect can be quantitatively verified. The results show that after the atomizer is cleaned by the method, the recovery rate of Rh (103) is between 91% and 95%, and the linear correlation coefficient R2 of W is greater than 0.9995, so that the problems of incomplete cleaning and device damage in the traditional cleaning method are solved.

Description

Technical Field

[0001] This invention belongs to the field of precision instrument maintenance technology, and relates to a systematic cleaning method for the nebulizer in a precision analytical instrument called inductively coupled plasma mass spectrometry (ICP-MS). Background Technology

[0002] Inductively coupled plasma mass spectrometry (ICP-MS) is a highly sensitive analytical instrument widely used in environmental monitoring, food safety, geological exploration, and materials science. In the analytical process of ICP-MS, the nebulizer is a key component responsible for converting liquid samples into aerosols and introducing them into the plasma for testing. However, over long-term use, the nebulizer is prone to clogging or contamination due to sample residue. This contamination and clogging problem is particularly pronounced when analyzing metal samples (such as high-purity metals and alloys) using ICP-MS. Metal samples typically contain high concentrations of matrix elements (such as Fe, Al, Cu, Ni) or insoluble oxides / carbides (such as Ti, W, Zr). These substances tend to deposit inside the nebulizer during nebulization, leading to decreased instrument sensitivity, abnormal internal standard recovery, memory effect, and deterioration of the standard curve's linearity.

[0003] Currently common atomizer cleaning methods include: 1. Rinsing with pure water / dilute acid, which can only remove some soluble residues and is ineffective against stubborn deposits; 2. Simple ultrasonic cleaning, which is ineffective against refractory metals and may damage the platinum capillary tubes of concentric atomizers; 3. Immersion in aqua regia, which cannot simulate the actual atomization effect, makes it difficult to evaluate the cleaning effect, and requires repeated disassembly and reassembly, increasing the risk of human error. Therefore, there is an urgent need for an efficient and quantifiable atomizer cleaning method to solve the above problems. Summary of the Invention

[0004] This invention addresses the shortcomings of existing ICP-MS atomizer cleaning methods by providing an improved method. It combines step-by-step chemical cleaning with online atomization verification, employing two customized cleaning solutions (A and B) to target residues of different properties, ensuring comprehensive cleaning. The cleaning solution is atomized in instrument diagnostic mode to thoroughly remove stubborn deposits from the microchannels inside the atomizer. Finally, the cleaning effect is quantified and verifiable using internal standard recovery rate and standard curve linearity as indicators. This method solves the problems of incomplete cleaning and potential damage to components inherent in traditional cleaning methods.

[0005] Based on the above ideas, the specific technical solution of the present invention is as follows:

[0006] The ICP-MS atomizer cleaning method provided by this invention includes the following steps:

[0007] A. Ultrasonic cleaning

[0008] Completely immerse the disassembled atomizer in cleaning solution A, which consists of HNO3, HCl, and H2O2, ensuring that all channels are filled with liquid. Use an ultrasonic power of 300W and sonicate at room temperature for 2-5 hours (preferably 3 hours). After sonication, rinse the atomizer with ultrapure water and dry the internal microchannels of the atomizer with high-purity nitrogen.

[0009] Preferably, the concentration ratio of HNO3, HCl, and H2O2 in cleaning solution A is 23:5:1. Nitric acid (23%) is used to oxidize metals such as Cu, Ag, and Pb to prevent reduced residues; hydrochloric acid (5%) can dissolve transition metal deposits such as Fe, Co, and Ni; hydrogen peroxide (1%) enhances the reducing power and decomposes organic complexing agents.

[0010] The preparation method of cleaning solution A is as follows: Mix 69% HNO3, 37% HCl and 30% H2O2 in a mass ratio of 2.47 : 1 : 2.47, and then make up to the predetermined volume with ultrapure water.

[0011] When performing ultrasonic cleaning, the ultrasonic temperature is at room temperature, which can avoid acid evaporation or atomizer deformation caused by high temperature.

[0012] B. Online dynamic atomization cleaning

[0013] Prepare cleaning solution B, connect the cleaned and dried atomizer to the atomization chamber, and force atomize the acid cleaning solution through the instrument diagnostic mode to ensure that the cleaning solution flows fully through the microchannels inside the atomizer and removes dead volume residue.

[0014] Preferably, the cleaning solution B consists of HNO3, H2O2, and HF, with a concentration ratio of 5:1:1. Hydrofluoric acid (1%) is specifically designed for insoluble silicides and aluminum oxides; the low concentration of HF avoids corrosion of the atomizer while ensuring that refractory metal residues are dissolved.

[0015] The preparation method of cleaning solution B is as follows: Mix 69% HNO3, 30% H2O2 and 49% HF in a mass ratio of 3.55 : 1.63 : 1, and then make up to the predetermined volume with ultrapure water.

[0016] Further, the operating method is as follows: Connect the cleaned and dried nebulizer to the nebulization chamber. Place the injection needle into cleaning solution B and enter the diagnostic mode on the software interface. In diagnostic mode, the nebulizer will start working. By observing the nebulization status, determine if the nebulizer is clogged: Normally, it should produce a uniform and fine aerosol. If the nebulization is unstable, check if the nebulizer is clogged. Maintain this state overnight to remove W deposits deep within the Pt capillary.

[0017] C. Cleanliness Verification

[0018] The cleanliness of the atomizer was judged by the internal standard recovery rate and the linearity of the standard curve.

[0019] Preferably, when determining the recovery rate of the internal standard, Rh(103) is used as the internal standard, and the recovery rate is required to be between 80-120%; when determining the linearity of the standard curve, a metal mixed standard solution of 1-10 ppb is tested, and R2 is required to be >0.9995.

[0020] The beneficial protections and effects of this invention are as follows:

[0021] This invention combines step-by-step chemical cleaning with online atomization verification, using two customized cleaning solutions (A and B) to clean different impurities: Cleaning solution A targets metallic impurities such as Cu, Ag, Pb, Fe, Co, and Ni; Cleaning solution B targets the microchannels inside the atomizer, used to remove W deposits deep within the Pt capillary. During the cleaning process, the cleaning solution is atomized in instrument diagnostic mode to thoroughly remove stubborn deposits in the microchannels inside the atomizer. Finally, the internal standard recovery rate and the linearity of the standard curve are used as indicators to ensure that the cleaning effect can be quantitatively verified. The results show that after cleaning the atomizer using the method of this invention, the recovery rate of Rh(103) is between 91% and 95%, and the linear correlation coefficient of W is R 2 >0.9995, which solves the problems of incomplete cleaning and easy damage to components that exist in traditional cleaning methods. Attached Figure Description

[0022] The present disclosure will be further described below with reference to the accompanying drawings, which are shown only for illustrating the embodiments of the present disclosure and are not intended to limit the scope of the present disclosure.

[0023] Figure 1 The results show a linear comparison before and after atomizer cleaning and maintenance. Detailed Implementation

[0024] The following embodiments and experimental examples further illustrate the present invention and should not be construed as limiting the invention. The embodiments do not include a detailed description of conventional methods, which are well known to those skilled in the art and described in numerous publications.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention, and the preferred embodiments and materials described herein are for illustrative purposes only.

[0026] I. Preparation of Cleaning Solution

[0027] Cleaning solution A: Take 333.3333g of 69% HNO3 + 135.1351g of 37% HCl + 33.3333g of 30% H2O2, and use ultrapure water (18.2... Bring the volume to 1000 mL;

[0028] Cleaning solution B: Take 72.4638g of 69% HNO3 + 33.3333g of 30% H2O2 + 20.4082g of 49% HF, and use ultrapure water (18.2... Bring the volume to 1000 mL;

[0029] Use PFA containers to avoid acid corrosion; prepare solutions in a fume hood, and operators should wear acid and alkali resistant gloves and special protective masks.

[0030] II. Ultrasonic Cleaning

[0031] (1) Ultrasonic treatment: Immerse the disassembled atomizer completely in cleaning solution A, ensuring that all channels are filled with liquid. Ultrasonic power 300W, ultrasonic temperature room temperature (avoid high temperature causing acid evaporation or atomizer deformation), ultrasonic treatment for three hours.

[0032] (2) Rinse the atomizer: After the ultrasonic treatment, rinse the atomizer with ultrapure water to ensure that there is no acid residue. Use high-purity nitrogen (99.999%) to dry the microchannels inside the atomizer.

[0033] III. Online Dynamic Atomization Cleaning

[0034] After cleaning and drying, connect the nebulizer to the nebulization chamber. Place the injection needle into cleaning solution B. In the "Syngistix" software interface, click System Tools → Nebulizer and Torch Gas → Diagnostics. The nebulizer will then start working. Observe the nebulization status. Normally, it should produce a uniform and fine aerosol (if the nebulization is unstable, check if the nebulizer is clogged). Maintain this state overnight. During the cleaning process, monitor the waste liquid level in the waste container to prevent overflow.

[0035] IV. Performance Verification Phase

[0036] 4.1 Ignite the plasma by clicking the power button before "Plasma" in the "control" interface of the "Syngistix" software.

[0037] 4.2 After igniting the plasma, use a nitric acid solution within its shelf life (with the same acidity as the sample) and inject the sample using a peristaltic pump for 5-10 minutes.

[0038] 4.3 Tuning: Click “SmartTune” to open the instrument tuning interface, and click “[STD] performanceCheck” to perform a performance test.

[0039] 4.4 Opening method: Insert the sample tube into the standard blank solution and wait for it to stabilize before establishing the standard curve.

[0040] V. Results

[0041] Table 1 shows the internal standard recovery rate after atomizer maintenance. The results show that the internal standard recovery rate is between 80-120%, which meets the requirements.

[0042] Table 1 Summary of Internal Standard Recovery Rates After Atomizer Maintenance

[0043]

[0044] Figure 1 A linear comparison graph showing the atomizer's performance before and after maintenance is displayed. (Example) Figure 1 Before cleaning the atomizer, the linear correlation coefficient R² of W is <0.9995. Figure 1 A); After cleaning the atomizer, the linear correlation coefficient R² > 0.9995 ( Figure 1 B).

[0045] pass Figure 1 The data in Table 1 demonstrate that this method can effectively clean the atomizer and restore the instrument to normal operation.

[0046] The undescribed parts of this invention are the same as or implemented using existing technology. The applicant declares that this invention is illustrated through the above specific embodiments, but the invention is not limited to the above detailed methods, i.e., it does not mean that the invention must rely on the above detailed methods to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A method for cleaning an ICP-MS atomizer, characterized in that, Includes the following steps: A. Ultrasonic cleaning The disassembled atomizer to be cleaned is completely immersed in cleaning solution A, which consists of HNO3, HCl, and H2O2. Ensure all channels are filled with liquid and sonicate at room temperature for 2-5 hours; after sonication, rinse the nebulizer with ultrapure water and dry the internal microchannels of the nebulizer with high-purity nitrogen; the concentration ratio of HNO3, HCl and H2O2 in cleaning solution A is 23:5:

1. B. Online dynamic atomization cleaning Prepare cleaning solution B, connect the cleaned and dried nebulizer to the nebulization chamber, and force it through the instrument diagnostic mode. The atomized pickling solution is allowed to flow fully through the microchannels inside the atomizer to remove dead volume residue; the cleaning solution B is composed of HNO3, H2O2 and HF, with a concentration ratio of 5:1:

1. C. Cleanliness Verification The cleanliness of the atomizer was judged by the internal standard recovery rate and the linearity of the standard curve.

2. The ICP-MS atomizer cleaning method according to claim 1, characterized in that: in, In step A, the preparation method of cleaning solution A is as follows: 69% HNO3, 37% HCl and 30% H2O2 are mixed in a mass ratio of 2.47:1:2.47, and then diluted to a predetermined volume with ultrapure water; In step B, the cleaning solution B is prepared as follows: 69% HNO3, 30% H2O2 and 49% HF are mixed in a mass ratio of 3.55 : 1.63 : 1, and then diluted to a predetermined volume with ultrapure water.

3. The ICP-MS atomizer cleaning method according to claim 1, characterized in that, Its features are: In step A, the ultrasonic power is 300W and the ultrasonic time is 3 hours.

4. The ICP-MS atomizer cleaning method according to claim 1, characterized in that: in, In step B, the atomizer starts working in diagnostic mode. By observing the atomization status, it is determined whether the atomizer is blocked: Normally, it should produce a uniform and fine aerosol. If the atomization is unstable, it is necessary to check whether the atomizer is blocked. Keep it in this state overnight to remove the W deposits deep in the Pt capillary.

5. The ICP-MS atomizer cleaning method according to claim 4, characterized in that: in, After cleaning and drying, connect the nebulizer to the nebulization chamber, place the injection needle into cleaning solution B, and click on the software interface to enter diagnostic mode.

6. The ICP-MS atomizer cleaning method according to claim 4, characterized in that: in, In step C, when determining the recovery rate of the internal standard, Rh(103) is selected as the internal standard, and the recovery rate is required to be between 80-120%. When determining the linearity of the standard curve, a metal mixed standard solution of 1-10 ppb is tested, and R2 is required to be >0.9995.

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