Method for testing and analyzing trace elements in carbonate mineral sample by using ICP-OES instrument

Abstract

The invention discloses a method for testing and analyzing trace elements in a carbonate mineral sample by using an ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer) instrument. The method comprises the following steps: preparing a sample: collecting a carbonate rock powder sample and putting the carbonate rock powder sample into a pollution-free special centrifugal tube; digesting the sample: digesting the sample with a 5% dilute nitric acid solution; preliminarily preparing a mixed standard solution: preliminarily preparing a multi-element mixed standard solution according to the element types of the target test sample; correcting the standard curve and carrying out preliminary ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer) test; testing a sample by using an inductively coupled plasma emission spectrometer ICP-OES; through an FACT interference correction method and multiple curve views, eliminating the influence of interference elements, and obtaining the initial content of each element; the concentration of elements in the mixed standard solution is adjusted, and a new standard solution is prepared again according to the adjusted concentration; and 6, testing the sample: testing and analyzing by using the new mixed standard solution, and finally obtaining the concentrations of various elements in the carbonate rock sample. The invention provides a feasible method for flexible expansion of a multi-element detection system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of analytical testing technology, and relates to a method for atomic absorption spectrometry, in particular to a method for testing and analyzing trace elements in carbonate mineral samples by using an ICP-OES instrument. BACKGROUND

[0002] Inductively coupled plasma optical emission spectrometry (ICP-OES) is a commonly used chemical analysis technique. The principle is to atomize and introduce the sample into a high-temperature plasma, so that the elements in the sample are excited and emit characteristic spectra. According to the intensity of the emitted characteristic spectrum, the content of elements in the sample can be quantitatively analyzed. Carbonate rock samples are sedimentary rocks composed of calcite, dolomite and other authigenic carbonate minerals, and their formation involves complex geological and chemical processes. Among them, stalagmite, a natural mineral integrated in carbonate rock caves, is formed by the precipitation of CaCO3, and the ratio of trace elements such as Mg, Sr and Ba in stalagmite to Ca can indicate the dry and wet changes of the climate outside the cave when stalagmite is deposited.

[0003] At present, most of the methods for testing trace elements in carbonates by ICP-OES are for ppm-level concentration testing, and there is a lack of good testing methods for multi-element and trace element testing. In the existing process, a multi-element mixed standard solution needs to be prepared in advance before testing. When the analysis requirements change (for example, new elements need to be added for analysis, or the concentration gradient of the original standard solution does not meet the test range), the mixed standard sample containing all target elements can only be re-prepared. This not only causes waste of the prepared standard solution, but also reduces work efficiency. In addition, when testing trace elements by ICP-OES, when the concentration of a certain element in the sample to be tested exceeds the linear range of the existing standard calibration curve, the conventional dilution method may be limited by instrument conditions and cannot be effectively adjusted. At this time, the mixed standard sample can only be re-prepared as a whole, further increasing the experimental time and cost. At present, there is still a lack of effective methods to supplement the standard sample, so as to improve the flexibility and efficiency of testing.

[0004] For example, in the stalagmite test, the current main test elements are magnesium (Mg), strontium (Sr), barium (Ba) and calcium (Ca), and only the ratios of Mg / Ca, Sr / Ca and Ba / Ca can be used. However, if it is necessary to use trace elements in the stalagmite to study biological activity or external pollutants (Zn / Ca, Cu / Ca), industrial activities or natural events such as volcanic eruptions (Pb / Ca, S / Ca), wind-blown dust or external mineral deposition (Th / Ca, Fe / Ca, Si / Ca) during stalagmite deposition, biological activity or organic matter decomposition (P / Ca), the current method lacks mixed standard solutions of these related trace elements (Fe, P, Cu, Mn, Zn, Si, Al, Th, Pb, S, etc.), and it is necessary to prepare a separate standard solution for each element for testing, which increases the time and cost of the experiment process, cannot meet the experimental demand of rapid and accurate measurement, and has limitations in testing multiple trace elements. In the process of analyzing the trace elements of the stalagmite, when the concentration of a specific element in the sample analyzed exceeds the linear range of the standard calibration curve, the conventional dilution method may not be able to achieve effective concentration adjustment due to limitations such as instrument test tubes. In order to ensure the reliability of the data, the experimental personnel need to re-prepare the standard solution with an adaptive concentration gradient and rebuild the calibration curve, which will significantly increase the pretreatment time cost and also reduce the efficiency of the actual test sample.

[0005] In addition, in the analysis process of ICP-OES, the optimal detection wavelength of each element may be different, making it difficult to obtain the optimal signal of all elements at the same time. For example, in the test of multiple elements such as Fe, P, Cu, Mn, Zn, Si, Al, Th, Pb, S, etc. using ICP-OES, due to spectral interference, the emission spectrum of copper element will affect the characteristic spectrum of phosphorus element, causing the characteristic spectrum of phosphorus element to be disturbed and affecting the accuracy of measurement. The current ICP-OES test method does not correct these elements with overlapping characteristic spectra. After the initial preparation of the commonly used multi-element standard solution, if it is necessary to expand the detection element type (such as adding trace metal element analysis), the existing standard solution lacks compatibility for common testing of multiple elements, and it is difficult to achieve new element detection function through simple dilution or mixing. This limitation causes the experimental personnel to repeat the preparation process of the full-element standard solution, resulting in the following negative effects: (1) the utilization rate of the prepared standard solution decreases, causing unnecessary waste; (2) the complexity of the experimental pretreatment process increases, significantly prolonging the experimental period. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a method for testing and analyzing trace elements in carbonate mineral samples using an ICP-OES instrument, which overcomes the drawbacks of the prior art in which a complete set of standard solutions containing all target elements needs to be prepared when expanding the types of test elements; the present application can simultaneously meet the testing needs of high-concentration and high-signal-intensity elements (such as the main elements of calcium carbonate stone: Mg, Sr, Ba, Ca), and has flexible expansion capability, allowing optional simultaneous detection of other trace elements such as Fe, P, Cu, and Mn, and can add other element standard solutions for testing without re-preparing the standard solutions according to new testing requirements. Specifically, the method of the present application maintains the accuracy of the analysis of original high-concentration test elements, and by separately preparing standard solutions for new test elements and using multiple test preparation strategies, modular management of standard solutions is achieved. When new elements are tested, the present method does not require the preparation of comprehensive standard samples containing all elements, but only requires the preparation of standard solutions for new elements, avoiding repeated preparation and resource waste, thereby significantly reducing the complexity and cost of standard solution preparation. In addition, the present application also solves the problem of replacing the mixed standard sample as a whole due to the concentration of one or a few elements exceeding the range of the original standard sample. Through the method, only the standard solution with the corresponding concentration range needs to be prepared for the element that does not meet the test range, without adjusting the standard preparation of other elements that meet the requirements, thereby improving the flexibility and efficiency of the test.

[0007] To solve the above technical problems, the present application adopts the following technical solutions:

[0008] The method for testing and analyzing trace elements in carbonate mineral samples using an ICP-OES instrument comprises the following steps:

[0009] Step one, preparing the sample:

[0010] Select a carbonate rock sample, collect a powder sample, and place it in a non-polluted experimental special centrifuge tube;

[0011] Step two, digesting the sample:

[0012] Digest the sample with 5% dilute nitric acid solution, mix well, and ensure that there is no suspended matter during the digestion process. After digestion, place it for standby use;

[0013] Step three, preliminary preparation of mixed standard solution:

[0014] According to the types of target test sample elements, preliminarily prepare multiple sets of multi-element mixed standard solutions required for trace element testing ；

[0015] Step four, correcting the standard curve and preliminarily testing by ICP-OES:

[0016] The sample is tested by using an inductively coupled plasma emission spectrometer ICP-OES; the influence of interfering elements on target elements is excluded by a FACT interference correction method and a multiple curve view, so as to obtain the preliminary content of each element;

[0017] Step five, adjusting the standard solution:

[0018] After obtaining the preliminary content of each element in the carbonate rock sample, the concentration of each element in the mixed standard solution is adjusted, and a new standard solution is prepared according to the adjusted concentration;

[0019] Step six, testing the sample:

[0020] The new mixed standard solution is used for testing and analysis, and finally the concentration of various elements in the carbonate rock sample is obtained.

[0021] The present application also comprises the following technical features:

[0022] Specifically, in step five, the concentration of each element in the mixed standard solution is adjusted, including:

[0023] The standard solution 2 of each element is set to be close to the element concentration of the carbonate rock sample; the standard solution 1 is set to be close to 50% of the element concentration of the carbonate rock sample; and the standard solution 3 is set to be close to twice the element concentration of the carbonate rock sample, so as to prepare a new mixed standard solution with such concentration.

[0024] Specifically, the concentration of each element in the standard solution is set as follows:

[0025] The standard solution 1 is: calcium: 50ppm; magnesium: 0.5ppm; strontium: 0.05ppm; barium: 0.05ppm; iron: 0.2ppm; phosphorus: 0.2ppm; copper: 0.2ppm; manganese: 0.2ppm; zinc: 0.2ppm; silicon: 0.2ppm; aluminum: 0.2ppm; thorium: 0.2ppm; lead: 0.2ppm;

[0026] The standard solution 2 is: calcium: 100ppm; magnesium: 1ppm; strontium: 0.1ppm; barium: 0.1ppm; iron: 0.5ppm; phosphorus: 0.5ppm; copper: 0.5ppm; manganese: 0.5ppm; zinc: 0.5ppm; silicon: 0.5ppm; aluminum: 0.5ppm; thorium: 0.5ppm; lead: 0.5ppm;

[0027] The standard solution 3 is: calcium: 200ppm; magnesium: 2ppm; strontium: 0.2ppm; barium: 0.2ppm; iron: 1ppm; phosphorus: 1ppm; copper: 1ppm; manganese: 1ppm; zinc: 1ppm; silicon: 1ppm; aluminum: 1ppm; thorium: 1ppm; lead: 1ppm.

[0028] Specifically, if the concentration of a specific element in the sample to be tested exceeds the coverage range of the existing standard calibration curve, a high concentration gradient standard solution is added separately to expand the calibration curve.

[0029] Specifically, if a new element to be tested needs to be added, the gradient standard solution of the new element is independently prepared under the premise of retaining the original element concentration gradient, and the digital mixing of the new and old standard solutions is realized by increasing the number of standard samples, without re-preparing the complete mixed standard sample.

[0030] Specifically, during the test, the following parameters are controlled: digestion time: 0.2-1 hour; digestion temperature: room temperature; test pressure: under standard atmospheric pressure.

[0031] Specifically, during the test, an ICP-OES spectrometer is used, and a special reagent 5% CMOS dilute nitric acid solution and a centrifuge tube with high purity requirements are provided.

[0032] Compared with the prior art, the present application has the following technical effects:

[0033] The test method of the present application standardizes the process of testing low-concentration elements by ICP-OES instrument, reduces the cost of testing trace elements of carbonate rock samples, and improves the accuracy of testing carbonate rock samples by ICP-OES. When testing trace elements by ICP-OES, multiple trace elements with a concentration of ppb level can be accurately tested at the same time, reducing the test time and cost, improving the breadth of testing trace elements in carbonate rock samples by ICP-OES at ppb concentration, and expanding the application range of ICP-OES in carbonate rock research. In addition, the test method also provides a scheme for testing the detection limit of each trace element by ICP-OES. This standard solution optimization adjustment method improves the efficiency of updating the standard solution, reduces the waste of the standard solution, and provides a feasible method for flexible expansion of the multi-element detection system.

[0034] The present application solves the problem of updating elements or adjusting concentrations by using the modular preparation and expansion strategy of the mixed standard solution and the adjusted standard solution. Only the standard solution of the required element needs to be prepared separately without re-preparing the complete mixed standard sample, thereby saving time and resources. That is, the modular standard solution preparation method is used to prepare the standard solution of the new element or the over-limit element on the basis of retaining the original element gradient, without re-preparing the complete mixed standard sample, thereby reducing the pretreatment time and cost and improving the test efficiency.

[0035] In the present application, the standard curve is corrected and ICP-OES testing is performed, that is, the FACT interference correction method and multiple curve views are combined to effectively eliminate or weaken the influence of spectral overlap on target elements during analysis, thereby improving the accuracy and reliability of measurement.

[0036] The multiple test analysis method of the application not only realizes efficient and cooperative detection of multiple trace elements in the carbonate rock, expands the application breadth of ICP-OES in the geochemistry field, but also effectively avoids the test error caused by spectral interference, improves the accuracy of the standard curve and the reliability of the analysis result, and has high practical value and popularization prospect. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a specific flowchart of the method of the application.

[0038] Figure 2 is a multiple standard test analysis method interface.

[0039] Figure 3 is a multiple standard test analysis method interface.

[0040] Figure 4 is an interface and method for adding a new prepared standard solution (sulfur standard sample).

[0041] Figure 5 is a repeatability comparison chart of each element in the carbonate rock sample.

[0042] Figure 6 is a test result chart of each element in the carbonate rock sample.

[0043] Figure 7 is a test result chart of each element in the carbonate rock sample. DETAILED DESCRIPTION

[0044] The application provides a test analysis method for trace elements in a carbonate mineral sample by using an ICP-OES instrument, multiple correction methods (FACT interference correction method, multiple curve view) are used to accurately test the content of trace elements in a carbonate mineral (for example, stalagmite) by using ICP-OES, such as Figure 1 , comprising the following steps:

[0045] Step 1, sample preparation:

[0046] Select a carbonate rock sample, use a hand drill or Micromill to collect a 500 microgram to 1 milligram powder sample; place the sample in a non-polluted experimental special centrifuge tube to ensure that the collected sample is easy to be digested;

[0047] Step 2, sample digestion:

[0048] Digest the sample with 5% dilute nitric acid solution, mix uniformly, ensure that there is no suspended matter in the digestion process, and place it after digestion for standby;

[0049] Step 3, preliminary preparation of mixed standard solution:

[0050] According to the target test sample element species, a multi-element mixed standard solution required for trace element testing is prepared, and the standard solution of each element can be set to the same concentration gradient;

[0051] The concentration of each element in the standard solution is set as follows:

[0052] Standard solution 1: calcium (Ca): 50 ppm; magnesium (Mg): 0.5 ppm; strontium (Sr): 0.05 ppm; barium (Ba): 0.05 ppm; iron (Fe): 0.2 ppm; phosphorus (P): 0.2 ppm; copper (Cu): 0.2 ppm; manganese (Mn): 0.2 ppm; zinc (Zn): 0.2 ppm; silicon (Si): 0.2 ppm; aluminum (Al): 0.2 ppm; thorium (Th): 0.2 ppm; lead (Pb): 0.2 ppm;

[0053] Standard solution 2: calcium (Ca): 100 ppm; magnesium (Mg): 1 ppm; strontium (Sr): 0.1 ppm; barium (Ba): 0.1 ppm; iron (Fe): 0.5 ppm; phosphorus (P): 0.5 ppm; copper (Cu): 0.5 ppm; manganese (Mn): 0.5 ppm; zinc (Zn): 0.5 ppm; silicon (Si): 0.5 ppm; aluminum (Al): 0.5 ppm; thorium (Th): 0.5 ppm; lead (Pb): 0.5 ppm;

[0054] Standard solution 3: calcium (Ca): 200 ppm; magnesium (Mg): 2 ppm; strontium (Sr): 0.2 ppm; barium (Ba): 0.2 ppm; iron (Fe): 1 ppm; phosphorus (P): 1 ppm; copper (Cu): 1 ppm; manganese (Mn): 1 ppm; zinc (Zn): 1 ppm; silicon (Si): 1 ppm; aluminum (Al): 1 ppm; thorium (Th): 1 ppm; lead (Pb): 1 ppm;

[0055] Step four, correct the standard curve and initially test ICP-OES:

[0056] The sample is tested using an inductively coupled plasma emission spectrometer (ICP-OES); by using appropriate correction methods (FACT interference correction method, multiple curve view) such as Figure 2, excluding the influence of interfering elements (such as Cu, P, Mn) on the target element, to obtain the preliminary content of each element. The emission spectrum lines of different elements overlap in the similar wavelength range. Due to the limited resolution of the instrument, when the characteristic spectrum line emitted by the analyzed element is close to the spectrum line emitted by other elements, especially in the case that the concentration of the analyzed element is low, it may cause errors in the measurement results. The FACT interference correction method provided by the instrument is used for correction, which effectively reduces the experimental steps and reduces the analysis cost. After the multi-element standard solution is determined, if it is found that the concentration of a certain element in the sample to be tested changes greatly, an additional low-activity high-sensitivity detection wavelength can be selected for the element during testing, and the multi-curve view module is used for analysis, so as to ensure the detection accuracy of high and low concentration samples.

[0057] Table 1 preliminary results of sample testing

[0058]

[0059] Step five, adjust the standard solution:

[0060] After obtaining the preliminary content of each element in the carbonate rock sample, according to the preliminary test results of the sample, the concentration of each element in the mixed standard solution is adjusted according to the specific sample, and a new standard solution is prepared according to the adjusted concentration.

[0061] Firstly, as shown in Table 1, the preliminary concentration content of the sample is obtained by testing, and the test results include elements such as aluminum, barium, calcium, copper, etc. The content of aluminum and lead is very low, and the specific concentration is not detected, and the other elements normally get the results.

[0062] After obtaining the preliminary content of each element in the carbonate rock sample, the concentration of each element in the mixed standard sample is adjusted accordingly. The standard solution can be appropriately increased for elements with lower concentration and elements not detected, and the concentration of elements with higher concentration can be appropriately reduced. The specific method is to set the standard solution 2 of each element to be approximately the concentration of the elements in the carbonate rock sample, set the standard solution 1 to be approximately 50% of the concentration of the elements in the carbonate rock sample, and set the standard solution 3 to be approximately twice the concentration of the elements in the carbonate rock sample. A new mixed standard solution is prepared according to the concentration; if the concentration of a specific element in the sample to be tested is significantly higher than the existing standard calibration curve coverage range (such as Ca concentration exceeding the upper limit of 200ppm), a high concentration gradient standard solution (such as 500ppm) can be added separately to expand the calibration curve Figure 3 ); if a new element to be tested needs to be added (such as temporarily adding S element analysis), the gradient standard solution of the new element (for example, blank 0ppm, standard 4:1ppm, standard 5:2ppm, standard 6:3ppm) is independently prepared on the premise of retaining the concentration gradient of the original elements, and the digital mixing of the new and old standard solutions is realized by increasing the number of standard samples, without the need to reconfigure the complete mixed standard sample Figure 4 ).

[0063] Step 6: Test samples:

[0064] The new mixed standard solution was used for testing and analysis, and the concentrations of multiple elements in the carbonate rock samples were finally obtained. The measured data were then processed ( Figure 5 ,6,7).

[0065] In the above test and analysis steps, process parameters and control: During the test process, the following parameters are controlled:

[0066] Digestion time: 0.2 to 1 hour;

[0067] Digestion temperature: room temperature;

[0068] Test pressure: carried out under standard atmospheric pressure;

[0069] ICP-OES operating conditions: temperature, frequency, and power are controlled according to instrument requirements.

[0070] Specialized equipment and reagents are required for the above-mentioned test and analysis steps: This method requires an ICP-OES spectrometer and specialized reagents, such as a 5% CMOS dilute nitric acid solution and high-purity centrifuge tubes. Furthermore, standard solution mixing equipment, such as a high-precision titrator and automatic mixer, is required.

[0071] Implementation Effect and Feasibility of the Invention: This method addresses the matrix effects and isotope interference issues present in existing technologies, effectively improving the accuracy of trace element testing in carbonate rock samples. Furthermore, because this method optimizes the preparation and digestion processes of standard solutions, testing time is significantly shortened, facilitating rapid analysis of large-scale samples. Furthermore, when existing standard solutions are insufficient for test samples, this method optimizes the preparation steps of standard solutions, reducing unnecessary waste and saving experimental costs.

[0072] The core of this invention is to improve existing trace element analysis methods for carbonate rock samples. Without changing the test sample, it increases the instrument's detection limit. This is particularly true when using an ICP-OES instrument for simultaneous multi-element analysis. Matrix effects and spectral interference are reduced, improving detection accuracy and efficiency. The method also allows for flexible addition of desired standard solution concentrations without changing the existing standard sample. By optimizing the preparation of standard solutions and combining precise sample pretreatment procedures, the repeatability and accuracy of the test process are ensured.

[0073] In theory, the basic principle of inductively coupled plasma optical emission spectrometry (ICP-OES) relies on atomizing and introducing the sample into a high-temperature plasma, so that the elements in the sample are excited and emit characteristic spectra. According to the intensity of the emission spectrum, the content of elements in the sample can be quantitatively analyzed. However, carbonate rock samples are usually complex geological samples containing multiple matrix elements, which can easily cause the following problems: matrix effect: some matrix elements may affect the spectral emission of other trace elements, causing errors in quantitative analysis. By using optimized multi-element standard solutions for calibration, the invention can effectively reduce this matrix effect. Spectral interference: due to the complexity of elements in carbonate rock samples, spectral overlap may occur when analyzing multiple elements simultaneously. By refining the sample pretreatment and introducing multiple correction methods, these spectral interferences can be effectively excluded.

[0074] In the present invention, standard solution optimization: by preparing standard solutions with different concentration gradients, the invention can ensure accurate detection of trace elements in a wide concentration range. The concentration of each element in the standard solution is set to multiple gradients, so that both high-concentration elements and low-concentration elements can be accurately detected during testing.

[0075] In the present invention, sample pretreatment improvement: fine sample collection and digestion steps are used to completely release trace elements in carbonate rock samples. This not only avoids testing errors caused by sample residues, but also ensures the integrity of the sample during digestion.

[0076] In the present invention, ICP-OES test optimization: by adjusting the operating parameters of ICP-OES and introducing special correction methods, the influence of spectral overlap and matrix effect on experimental results is avoided, and the reliability of the results is improved.

[0077] In the present invention, high efficiency and low cost: compared with ICPMS and other instruments, the method of the present invention has significant advantages in cost control and analysis speed. ICP-OES testing time is shorter and operation is simpler, combined with optimized pretreatment steps and standard solution calibration, it can show good economic benefits in large-scale sample testing.

[0078] The method of the present invention can be applied to the analysis of various carbonate rock samples, and has important practical significance in the tracking and analysis of trace elements in environmental and climate change research.

[0079] The trace element content in the stalagmite can be quickly analyzed by the ICP-OES test method, and the past climate and local hydrological change history can be reconstructed according to the test result. Taking the stalagmite as an example, the method for testing the trace element content in the carbonate by the ICP-OES high-precision test is explored. The specific embodiments of the present application are given below, and it should be noted that the present application is not limited to the following specific embodiments, and any equivalent transformation made on the basis of the technical solutions of the present application falls within the protection scope of the present application.

[0080] Embodiment:

[0081] The embodiment provides a test and analysis method for trace elements in carbonate mineral samples by using an ICP-OES instrument, which tests calcium and various trace elements (Al, Ba, Fe, Mg, P, Pb, Si, Sr, Th, Zn, and S) in the carbonate rock sample. Since the tested sample is a stalagmite, the main component of the stalagmite is CaCO3, and Ca is tested as a major element. Because the concentration of Ca is very different from that of the remaining elements, a multiple curve view is used. The specific operation of the multiple curve view in the method includes setting the Ca test wavelength to 315.887 nm and 317.933 nm, wherein 315.887 nm is a high-energy wavelength, mainly testing samples with Ca of 200 ppm; 317.933 nm is a low-energy wavelength, mainly testing samples with Ca greater than 200 ppm. The same operation is applied to the Mg element (selected wavelength: 280.27 nm / 285.213 nm). The remaining elements are tested as trace elements, and the concentration gradient of the standard solution is 0.2 / 0.5 / 1 ppm. Among them, Ba and Sr are important test elements, and after testing a large number of stalagmite samples, the concentration of the standard solution of the two elements is set to 0.05 / 0.1 / 0.2, and the FACT interference correction method is used in the test process.

[0082] A specific wavelength is selected for each element (tested according to the wavelength with less interference wavelength near the wavelength), and the wavelengths selected for each element are as follows: Al (396.152 nm), Ba (455.403 nm), Ca (315.887 nm / 317.933 nm), Cu (327.395 nm), Fe (238.204 nm), Mg (280.270 nm / 285.213 nm), Mn (257.610 nm), P (213.610 nm), Pb (220.353 nm), Si (251.432 nm), Sr (421.552 nm), Th (283.730 nm), Zn (213.857 nm), and S (180.669 nm).

[0083] The test results show that, by using multiple curve view and FACT correction, Cu and Pb elements are still not detected, the main reason is that the sample amount is not enough, the sample amount can be continuously added, the concentration of Ca standard solution is increased, and the detection limit of the remaining elements is improved by using multiple curve view. Figure 4

[0084] The test results show that Figure 5 , Figure 6 The Mg / Ca, Sr / Ca and Ba / Ca ratios mainly used for paleoclimate analysis show a significant positive correlation, which is consistent with the variation law of trace elements in the growth process of stalagmites. The results verify the effectiveness of the method in the quantitative analysis of trace elements in stalagmites and carbonates, and provide reliable numerical basis for paleoclimate research. Further analysis shows that the S / Ca ratio shows a sudden increase and then a slow decrease, which may reflect the signal of volcanic eruption. This change trend is consistent with the sharp change of the environment after volcanic eruption, and provides an indication of the influence of volcanic activity on carbonate deposition. At the same time, the Th / Ca ratio shows a phased change, which may indicate the input of aeolian sediments. The results show that the method can effectively track the influence of wind-blown, wind-blown dust and other external sediments, and further reveal the details of environmental change in the deposition process. In the analysis of precipitation intensity and vegetation coverage, the P / Ca, Si / Ca and Zn / Ca ratios show a consistent change trend. The synchronous change of these element ratios may be closely related to the change of precipitation pattern and vegetation coverage, thereby providing important geochemical evidence for the study of hydrological cycle and ecological environment change in paleoclimate. In addition, the Fe / Ca, Mn / Ca and Al / Ca ratios also show a consistent change trend, which indicates the change of carbonate deposition environment. The relative enrichment or dilution of these elements can provide effective indication of the change of redox conditions and sediment source in the deposition environment.

[0085] In summary, the test results prove that the test method adopted by the present application can comprehensively and accurately analyze a variety of trace elements in carbonates, and is effectively applied to the study of paleoclimate change. The method not only has wide applicability in the study of carbonates, but also provides effective technical support for in-depth study of paleoclimatology problems such as environmental change and climate fluctuation.​

Claims

1. A method for testing and analyzing trace elements in carbonate mineral samples using an ICP-OES instrument, characterized in that: The following steps are involved: Step 1: Prepare the sample: Select carbonate rock samples, collect powder samples, and place them in non-polluting experimental centrifuge tubes; Step 2: Digest the sample: Digest the sample with 5% dilute nitric acid solution, mix well, and ensure there is no suspended matter during the digestion process. Set aside after digestion; Step 3: Preliminary preparation of mixed standard solution: According to the element types of the target test samples, preliminarily prepare multiple sets of multi-element mixed standard solutions required for trace element testing ； Step 4: Calibrate the standard curve and perform preliminary ICP-OES testing: The samples were tested using an inductively coupled plasma optical emission spectrometer (ICP-OES). The FACT interference correction method and multiple curve views were used to eliminate the effects of interfering elements on the target elements to obtain the preliminary content of each element. Step 5: Adjust the standard solution: After obtaining the preliminary content of each element in the carbonate rock sample, adjust the concentration of the elements in the mixed standard solution and re-prepare a new standard solution based on the adjusted concentration; Step 6: Test samples: The new mixed standard solution was used for testing and analysis, and the concentrations of multiple elements in the carbonate rock samples were finally obtained.

2. The method for testing and analyzing trace elements in carbonate mineral samples using an ICP-OES instrument as claimed in claim 1, wherein: In the step 5, adjusting the concentration of the elements in the mixed standard solution comprises: The standard solution 2 of each element is set to be close to the element concentration of the carbonate rock sample; the standard solution 1 is set to be close to 50% of the element concentration of the carbonate rock sample; the standard solution 3 is set to be close to 2 times the element concentration of the carbonate rock sample, and new mixed standard solutions are prepared at this concentration.

3. The method for testing and analyzing trace elements in carbonate mineral samples using an ICP-OES instrument as claimed in claim 2, wherein: The concentration of each element in the standard solution is set as follows: Standard solution 1: calcium: 50 ppm; Magnesium: 0.5ppm; Strontium: 0.05ppm; Barium: 0.05ppm; Iron: 0.2ppm; Phosphorus: 0.2ppm; Copper: 0.2ppm; Manganese: 0.2ppm; Zinc: 0.2ppm; Silicon: 0.2ppm; Aluminum: 0.2ppm; Thorium: 0.2ppm; Lead: 0.2ppm; Standard solution 2: Calcium: 100ppm; Magnesium: 1ppm; Strontium: 0.1ppm; Barium: 0.1ppm; Iron: 0.5ppm; Phosphorus: 0.5ppm; Copper: 0.5ppm; Manganese: 0.5ppm; Zinc: 0.5ppm; Silicon: 0.5ppm; Aluminum: 0.5ppm; Thorium: 0.5ppm; Lead: 0.5ppm; Standard solution 3: calcium: 200 ppm; magnesium: 2 ppm; strontium: 0.2 ppm; barium: 0.2 ppm; iron: 1 ppm; phosphorus: 1 ppm; copper: 1 ppm; manganese: 1 ppm; zinc: 1 ppm; silicon: 1 ppm; aluminum: 1 ppm; thorium: 1 ppm; lead: 1 ppm.

4. The method for testing and analyzing trace elements in carbonate mineral samples using an ICP-OES instrument as claimed in claim 1, wherein: If the concentration of a specific element in the sample to be tested exceeds the coverage range of the existing standard calibration curve, a high concentration gradient standard solution is separately added to expand the calibration curve.

5. The method for testing and analyzing trace elements in carbonate mineral samples using an ICP-OES instrument as claimed in claim 1, wherein: If a new element needs to be added, the gradient standard solution of the newly added element is prepared independently while retaining the original element concentration gradient. By increasing the number of standard samples, the new and old standard solutions can be digitally mixed, without the need to re-prepare the entire set of mixed standards.

6. The method for testing and analyzing trace elements in carbonate mineral samples using an ICP-OES instrument as claimed in claim 1, wherein: During the test, the following parameters were controlled: digestion time: 0.2 to 1 hour; digestion temperature: room temperature; test pressure: standard atmospheric pressure.

7. The method for testing and analyzing trace elements in carbonate mineral samples using an ICP-OES instrument as claimed in claim 1, wherein: During the test, an ICP-OES spectrometer was used, equipped with a special reagent, 5% CMOS dilute nitric acid solution, and centrifuge tubes with high purity requirements.

Images