The addition of a high content niobium (Nb) in IN718 alloy leads to the precipitation of a large number of niobium-containing phases. The morphology, area fraction, quantity and shape of these niobium-containing phases are main factors affecting the properties of IN718 alloy. Therefore, the quantitative characterization of niobium-containing phases is of great significance for the study of the structure-activity relationship of the alloy. In this paper, the images of niobium-containing phases in the large field of view of IN718 alloy were efficiently acquired using high-throughput field emission scanning electron microscope based on its characteristics such as high imaging flux, fast automatic scanning speed and strong data processing ability. The image segmentation, recognition and statistical analysis module of niobium-containing phases were established by MIPAR image processing software, realizing the high efficiency extraction and quantitative statistical distribution characterization of niobium-containing phases in large size range of alloys. 1 225 backscattered electron (BSE) images were collected for each sample. These images were rapidly processed in batch using the established image processing module of niobium-containing phases. The information such as morphology and area fraction of niobium-containing phases in different regions of the cross section of IN718 alloy forged bar was obtained. It was found that the niobium phases in the core mostly had the shape of needles and long strips, and the area fraction was relatively high. However, there were more short-rod and round granular precipitated phases at the edge of the forgings. These data would provide guidance for the improvement of forging process and performance.

Platinum and palladium are precious metal elements with high price. The contents of platinum and palladium in crude selenium is an important indicator for trade settlement, so it is of great significance to accurately determine the contents of platinum and palladium in crude selenium. In this study, a method for the determination of platinum and palladium in crude selenium by inductively coupled plasma atomic emission spectrometry (ICP-AES) after selenium volatilization with perchloric acid was established. The samples were dissolved in aqua regia. The interference of selenium matrix was eliminated by perchloric acid smoke to volatilize the selenium. Pt 265.945 nm and Pd 360.955 nm were used as the analytical lines for the determination in the medium of 10% aqua regia. The results showed that 1.0 g of sample could be completely dissolved by adding 15 mL of aqua regia. Most of the selenium matrix could be removed by adding 10 mL of perchloric acid for volatilization at high temperature. A small amount of residual selenium matrix and other coexisting elements had no interference with the measurement. The weighing method was adopted during whole test to reduce the personal error and measurement instrument error caused by volume calculation method. The content of platinum and palladium in range of 0.02-15.0 μg/g was linear to the corresponding intensity. The correlation coefficients were 0.999 93 and 0.999 98, respectively. The limits of detection for platinum and palladium were 0.000 094% and 0.000 11%, and the limits of quantification were 0.000 31% and 0.000 33%, respectively. The experimental method was used to determine platinum and palladium in crude selenium, the relative standard deviations (RSD, n=7) were less than 5%. The measured results were consistent with those obtained by oxidizing roasting-lead fire assay-ICP-AES. The precision and trueness were superior to the conventional volume calculation method. The recoveries of platinum and palladium in crude selenium sample were 98%-105% and 99%-104%, respectively.

A method for analysing and characterizing the three-dimensional morphology and three-dimensional structural characteristic parameters of inclusions in steel was developed based on X-ray microscopy. Three different types of steels were selected to analyse the three-dimensional structural characteristic parameters and three-dimensional spatial distribution of inclusions, including the volume fraction, equivalent diameter, shape factor, diameter and volume distribution, sphericity and orientation. The results showed that the X-ray microscope could accurately characterize the inclusions with size of 1-500 μm in steel. It could also distinguish the high-density phase, non-metallic inclusions and micro-porosity based on the difference of contrast or grey. When the deformation of stainless steel reached 50%, the three-dimensional morphology of plastic inclusions evolved from spherical to flat, and the shape factor decreased from 0.67 to 0.57, and the spatial orientation angle (Phi) increased from 63.48° to 77.40°. For the steel treated with Te, the element of Te was wrapped outside the MnS to form a composite inclusion, which improved the corrosion resistance of the steel. According to the three-dimensional structural characteristic parameters of MnS inclusions, the three-dimensional grain boundaries of sulphur-containing steel were divided, and the relationship between the precipitation process of grain boundary inclusions and solidification selective crystallization was explained. A new method for characterizing the three-dimensional morphology and structural of inclusions in steels was established instead of synchrotron radiation, which was to promote the research of controlling the inclusions modification evolution of characterizing inclusions using X-ray microscopy. The proposed method provided more accurate and reliable analytical and testing approaches for the control of inclusions.

Selenium (Se) is an amphoteric non-metallic element. As one of the essential trace elements for human body, the insufficient or excessive intake of Se will be harmful to human health. As the material basis for human survival, soil is the most fundamental source for people to obtain Se from the outside world. Therefore, it is of great practical significance to establish a highly sensitive and accurate method for the detection of Se in soil and stream sediments. Due to the characteristics of simple analysis operation, high sensitivity, fast analysis speed and low operating cost, the hydride generation-atomic fluorescence spectrometry (HG-AFS) is widely used for the determination of Se. However, the pretreatment method, light source and coexisting elements may interfere with the determination of Se, affecting the test results. In this paper, the sources and causes of the interference of Se in soil and stream sediments by atomic fluorescence spectrometry were focused on. The research and application progress of Se interference elimination were summarized and discussed. Moreover, the future development direction of hydride generation-atomic fluorescence spectrometry in the determination of Se in soil and stream sediments were prospected.

A special zinc sulfate solution has appeared in the raw material procurement market for wet zinc smelting. Such zinc sulfate solution contains high contents of manganese and aluminum, which will cause interference with the determination of zinc content, seriously affecting the determination results. In this study, the zinc sulfate solution containing high content of manganese and aluminum were treated for precipitation separation of manganese in solution. Then, excessive EDTA was added to complex zinc and aluminum in acetate-sodium acetate buffer solution. The excess EDTA was titrated with zinc standard solution to obtain the total amount of EDTA that was used to complex zinc and aluminum. The Al-EDTA complex was then decomposed with ammonium fluoride, and the released EDTA was titrated with zinc standard solution. The content of zinc in zinc sulfate solution could be indirectly measured by subtracting the amount of Al-EDTA complex released EDTA from the total amount of EDTA. The contents of zinc in three high-manganese and high-aluminum zinc sulfate solution samples were determined according to the experimental method. The relative standard deviations (RSD,n=11) of measurement results were between 0.27% and 0.29%, which was less than the 0.30% required in general titration operations. The recoveries were between 95% and 101%.

Q690D steel has excellent properties in strength and toughness. The inclusion in the steel is an important factor affecting the strength and toughness. The modification of inclusions is an important measure to improve the product performance. In order to investigate the modification effect of magnesium on inclusions in Q690D steel for construction machinery, the distribution pattern and size of inclusions in the steel before and after magnesium treatment were compared and analyzed using metallurgical microscopy, scanning electron microscopy, inclusion three-dimensional etcher and FactSage thermodynamic software. The results showed that the inclusions in Q690D steel after calcium treatment were mainly composed of CaO-Al₂O₃, and some of them were wrapped by CaS. The inclusions in magnesium treated steel were mainly composed of MgO·Al₂O₃ or MgO, and some of them were wrapped by MgS. Magnesium could make Al₂O₃ finer and more uniformly distributed, and the average equivalent diameter of inclusions was reduced. The number density and area fraction of inclusions in the magnesium treated rolling stock were 65 mm² and 0.031%, respectively, which were lower than those after treatment by calcium, i.e., 96 mm² and 0.050%, respectively. Magnesium treatment showed better effect to purity the molten steel and improve the size and distribution of inclusions.

The accurate determination of iron content in lanthanum cerium carbonate is of great significance for quality control and subsequent application of its products. The content of iron in lanthanum cerium carbonate is commonly measured by spectrophotometry. However, when the iron content was low (below 0.3%), the color change was not obvious in the determination. Moreover, the coloring process is very easily affected by other impurity ions. In this study, the sample was dissolved with hydrochloric acid, and its acidity in solution was controlled at 2%. Fe 259.939 nm was selected as the analytical line for iron. The calibration curve was prepared by standard addition method to eliminate the influence of factors such as lanthanum cerium carbonate matrix on the determination results. The content of iron in lanthanum cerium carbonate was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The linear correlation coefficient of calibration curve was 0.999 9. The limit of detection of the method was 0.001%. The content of iron in lanthanum cerium carbonate was determined according to the experimental method. The relative standard deviations (RSD, n=11) of the measurement results were between 1.3% and 3.3%, and the spiked recoveries were between 98% and 103%.

The presence of oxygen and nitrogen impurities will seriously affect the performance of high purity copper. In this study, the sample surface was treated with lathe finishing followed by acid corrosion. Under the condition without flux, a method for the determination of trace oxygen and nitrogen in high purity copper by inert gas fusion-infrared absorption/thermal conductivity was established. The analytical power was 4 500 W. The effect of three surface treatment methods, including acid corrosion, lathe finishing, and lathe finishing followed by acid corrosion, on the determination of oxygen and nitrogen was investigated. The results showed that the influence of three surface treatment methods on the determination of nitrogen could be ignored. However, for the determination of oxygen, the determination results of lathe finishing followed by acid corrosion were much lower than those obtained by other two methods, indicating that the method of lathe finishing followed by acid corrosion could effectively remove the oxygen on sample surface. The certified reference materials of copper with low mass fraction as possible were selected to calibrate the analyzer for the determination of oxygen and nitrogen. The limits of quantification were 0.17 μg/g and 0.31μg/g for oxygen and nitrogen, respectively. The contents of oxygen and nitrogen in high purity copper sample were determined for seven times according to the experimental method. The results showed that the standard deviation (SD, n=7) of oxygen measurement values was 0.13-0.19 μg/g, and the SD (n=7) of nitrogen measurement values was 0.062-0.070 μg/g. The content of oxygen was also determined by glow discharge mass spectrometry (GD-MS) for method comparison. The measurement results of two methods were basically consistent. The high purity copper sample was selected and determined according to the experimental method. In addition, the certified reference material of copper was added for the spiked recovery test. The results showed that the recoveries of oxygen and nitrogen were between 80% and 120%.

The content of CaF₂ in cassiterite and lead zinc sulfide co/associated fluorite is in range of 1%-50% (mass fraction, the same below). However, the current industry standard method is applicable for fluorite samples with CaF₂ content higher than 3%. There is an empirical correction coefficient of 0.30% in industry standard methods, so the accuracy of CaF₂ determination results below 10% is not high. In this study, acetic acid (1+9) was used to separate and remove calcium containing impurities such as CaCO₃ and CaSO₄ that are easily soluble in acetic acid. Then the content of F^- which was slightly soluble in the filtrate was determined by ion selective electrode method. The residue was extracted using AlCl₃, and In was selected as the internal standard element. The content of Ca in the extraction solution was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The results of two methods were converted into CaF₂ and then added together to obtain the CaF₂ content in fluorite. Therefore, a method for the determination of calcium fluoride in cassiterite and lead zinc sulfide co/associated fluorite by ion selective electrode combined with ICP-AES was established. The effects of AlCl₃ solution mass concentration, AlCl₃ solution extraction time, and the selection of Ca and its internal standard element spectral lines on the determination of Ca were investigated. The limit of detection of CaF₂ in the method was 0.010%, and the limit of quantification was 0.040%. The contents of CaF₂ in actual samples of cassiterite, lead zinc sulfide, and fluorite certified reference material were determined according to the experimental method. The relative deviations (RSD, n=6) of the measurement results were between 0.22% and 0.90%, and the relative errors (RE) were between 0.08% and 0.63%. The method solved the problem of empirical correction coefficient in the CaF₂ determination process. The internal standard method was employed in ICP-AES to eliminate the impact of instrument drift caused by environmental temperature fluctuations and changes in electronic component performance on the analysis results. The measurement range of the proposed method was effectively improved, and it could be used for the determination of CaF₂ in cassiterite and lead zinc sulfide co/associated fluorite.

The accurate determination of iron in copper concentrate will affect the pricing and transaction of copper concentrate, the regulation of slag pattern in melting process, and the heat effect of smelting furnace. In this study, the sample was decomposed by hydrochloric acid, nitric acid, bromine, and sulfuric acid. Matrix copper in sample was converted into copper (Ⅱ), which was used as the reduction end-point indicator of iron (Ⅲ) as well as the catalyst of iron (Ⅲ) reduction. Iron (Ⅲ) was reduced to iron (Ⅱ) with potassium borohydride in sulfuric acid medium. Then the method for determination of iron content in copper concentrate by potassium dichromate titration was established using sodium diphenylamine sulfonate as the indicator. In experiments, 0.20 g of sample was dissolved with 0.1 g of ammonium bifluoride, 10 mL of hydrochloric acid, 5 mL of nitric acid, 0.5 mL of bromine, and 10 mL of sulfuric acid (1+1). After sulfuric acid smoke until the volume of solution was 1 mL, the acidity of potassium borohydride reduction process could be ensured. Copper (Ⅱ) in test solution had a catalytic effect on the reduction of iron (Ⅲ) by potassium borohydride, and it had no interference with the determination of iron. When the concentration of potassium borohydride was 20 g/L, iron (Ⅲ) could be effectively reduced to iron (Ⅱ), and meanwhile, it did not affect the determination of iron. The titration endpoint was clear when the amount of sulfuric acid and phosphoric acid mixture was 15 mL. The interference tests indicated that the interference of coexisting elements in sample with the determination of iron could be ignored. The copper concentrate reference materials and actual samples with different contents of copper were selected, and the content of iron was determined according to the experimental method. The relative standard deviations (RSD, n=7) of the determination results were between 0.20% and 0.55%. The national standard method GB/T 3884.15-2014 was used for method comparison,the t-test was conducted on the measurement results of the two methods, and the results showed that there was no significant difference between the two methods.The proposed method could be used for the rapid analysis and determination of iron content in copper concentrate in large quantities in smelting enterprises.

The solid waste resource regeneration is crucial for achieving the goals of "carbon peaking and carbon neutrality" and "zero-waste city construction", and it is also a key link in comprehensively promoting the achievement of a beautiful China. Zinc oxide concentrate (ZnO-C) is a mixture mainly containing ZnO obtained by pyrometallurgical volatilization and enrichment of Zn-containing solid waste. The impurities include metallic elements (such as iron, aluminum and calcium) and nonmetallic elements (such as fluorine, chlorine, silicon and sulfur). ZnO-C is powder-like with color of grey and black, and it is a typical waste resource utilization product. The quality of ZnO enrichment by pyrometallurgical method is different due to the difference of raw material components and technology level. In this study, the typical regeneration ZnO-C enriched material was focused on. The raw material components, enrichment process and technical parameters of pyrometallurgical enrichment were investigated. The production process and main physicochemical characteristics of ZnO-C were systematically discussed. Given that the composition of ZnO-C was crucial for subsequent processing and utilization, the content of ZnO phase as well as the composition and content of other phases in typical ZnO-C were also paid attention to. The accurately analysis and identification of ZnO-C was the key to port supervision of imported renewable resources and a prerequisite for achieving resource utilization.

As an advanced means of micro and nano processing, the focused ion beam technology has a wide application prospect in the steel industry. In this paper, 82A cord steel billets and 55SiCr spring steel billets were selected as the test materials. A series of slicing and three-dimensional (3D) reconstruction of the composite inclusions were performed using the focused ion beam(FIB). It was found that there were some factors having adverse effects on the results in the 3D reconstruction process, such as method calibration and phase contrast differences. The results showed that the problems of distortion of reconstructed morphology and large deviation of size determination could be solved by introducing the offset calculation formula. Moreover, the reconstruction possibility of phases with insignificant differences in phase contrasts was realized by introducing energy dispersive spectroscopy mapping analysis in the series slicing process, which effectively solved the difficulties encountered in the current 3D reconstruction process and made the reconstruction results better support the project of research and development.

The test of alkaline value can be used to evaluate the content of alkaline additives in engine oil, and it is one of important indicators for evaluating the performance of engine oil. In this study, the dissociation constants of 20 types of engine oils were introduced into the Henderson-Hasselbalch equation. By combining with the Nernst equation, the theoretical endpoint pH values of different engine oils were calculated. The statistical analysis was conducted using the robust statistical algorithm A in statistics, and it was found that the endpoint pH value applicable for all engine oils was -4.5. A method for determining the alkaline value of engine oil by pH potentiometric titration was established using the mixture of acetic acid and chlorobenzene as the solvent and using the mixture of perchloric acid and acetic acid as the titrant. The limit of detection of this method was 0.004 1 mg KOH/g. The standard substance of alkaline engine oil was diluted with base oil that contained no alkaline substances. After well mixing, the blank spiked samples with alkaline content of 2, 5, and 20 mg KOH/g were prepared and determined according to the experimental method. The relative standard deviations (RSD, n=6) of the measurement results were between 0.60% and 1.2%, and the recoveries of blank spiked samples were between 99% and 102%. Various engine oil Petroleum Product Alkalinity Determination Method (Perchlorate Potentiometric Titration Method) was used for method comparison. The results showed that the difference between the two methods was within the repeatability limit required by the industry standard SH/T 0251-1993. Four standard substances of engine oil with different alkaline levels were selected and determined according to the experimental method. The test results were within the range of standard deviation, and the RSDs (n=6) were between 0.37% and 0.81%. The proposed method was applied for the determination of five types of engine oil samples, and the RSDs (n=10) of measurement results were less than 1%.

Silicon carbide deoxidizer is a kind of high-performance complex deoxidizer. The determination of titanium content can trace the elemental introduction and loss in smelting process, thus more effectively improving the properties of steel. The composition of silicon carbide deoxidizer is complicated. In this study, the sample was treated by melting at high temperature. Sodium carbonate and sodium peroxide were used as mixed flux. The nickel crucible containing sample and mixed flux was heated in high-temperature furnace at 400 ℃. Then the temperature was increased to 900 ℃ and kept for 30 min to melt the sample. After complete fusion, the sample was leached with hot water and acidified with hydrochloric acid. After dilution to the mark, the solution was filtered. Ti 334.941 nm was selected as the analytical line for titanium. The calibration curve was plotted by matrix matching method. The content of titanium in filtrate was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Consequently, the determination of titanium in silicon carbide deoxidizer was established. The linear correlation coefficient of calibration curve for titanium was above 0.999 9. The limit of detection was 0.000 5% (mass fraction). The content of titanium in silicon carbide deoxidizer sample was determined according to the experimental method, and the relative standard deviation (RSD, n=7) of measurement results was 2.0%. The spiked recoveries were between 98% and 102%. The contents of titanium in seven silicon carbide deoxidizer samples were determined according to the experimental method and spectrophotometry in national standard GB/T 16555-2017. The results were consistent.

In recent years,the integration of modern spectroscopic analysis technologies with development characteristics of the times (such as artificial intelligence,big data,cloud computing and the internet of things) is closer and closer,and it has been widely used in various fields including agriculture,food,petrochemicals,petrochemical engineering,metallurgy and geology.Some large-scale application achievements have been obtained in several fields,which makes a contribution to the development of technology and economy.This paper mainly introduces the constitution and characteristics of modern spectroscopic analysis technologies integrated with chemometrics,and summarizes the chemometric methodologies and advancements employed for quantitative and qualitative analysis in spectroscopy.Based on some representative instances,the application status of modern spectroscopic analysis technologies in various fields were introduced according to the application scenarios,for example,the laboratory high-throughput analysis scenarios such as rapid crude oil evaluation,grain sorting and port iron ore classification;on-site rapid analysis scenarios such as soil detection,mineral exploration,fruit picking assessment,and forensic identification;the industrial on-line analysis scenarios such as gasoline blending,smelting process material analysis,on-line coal quality analysis,and waste plastic classification.In the future,grounded in the miniaturization of spectrometers,in-depth exploration of new spectroscopic theories,and the profound amalgamation of deep learning algorithms with spectroscopic technology,the rapid developments in precision agriculture,smart factories,precision medicine,and intelligent environmental protection will offer robust impetus for the progressive evolution of modern spectroscopic analysis technologies,thus heralding further innovations and advancements.

To enhance the development and utilization of metal materials, the precise control of physical properties and mechanical performance of metal materials is crucial, wherein the hydrogen plays a particularly key role in influencing these aspects. In this paper, the impact and hazards of hydrogen on the performance of metal materials were summarized. The methods for determining hydrogen content in metal materials in recent years were introduced, mainly including physicochemical method, tube furnace heating-thermal conductivity/infrared method, inert gas protection pulse furnace heating-thermal conductivity/infrared method, inert gas protection pulse furnace heating-mass spectrometry method, thermal desorption-mass spectrometry method, etc. The corresponding analysis principles, instrument structures, and technical characteristics were summarized. The review of applicable detection objects, analysis range, detection limits, and other specifications could enable the technicians in relevant fields to have a comprehensive understanding of hydrogen content detection in metal materials.

In standard method of GB/T 14840-2010, the silicate minerals in limestone are dissolved with hot phosphoric acid to separate free silica, then the content of free silica is determined by gravimetry. However, the operations are cumbersome and time-consuming. In this paper, free silica in limestone was separated from limestone by means of the property that hot phosphoric acid could dissolve silicate minerals but hardly dissolve free silica. Then, the dissolved silicic acid was depolymerized with fluoroboric acid. After filtration with dense filter paper, free silica could be fully separated from other minerals. Then the precipitates were washed with hot water for three times followed by ashing in silver crucible. After fusion with 1.5 g of sodium hydroxide and leaching with hydrochloric acid, the content of silica in sample solution was determined by inductively coupled plasma atomic emission spectrometry(ICP-AES) with Si 251.611 nm as analytical line. Consequently, a method for determination of free silica in limestone was established. The linear correlation coefficient of silica calibration curve was 0.999 9, and the linear range was 0.024%-10.0%. The limit of detection and the limit of quantification were 0.008% and 0.024%, respectively. The contents of free silica in 4 certified reference materials of limestone were determined according to the proposed method, and the relative errors between the determination results and certified values were in range of -0.18%-0.48%. The relative standard deviations (RSD, n=12) were between 1.2% and 1.9%. The proposed method and the gravimetric method in standard method of GB/T 14840-2010 were applied in determination of 4 limestone samples for method comparison, and the determination results of the two methods were basically consistent.

Accurate and rapid determination of boron and impurities in ferroboron is of great importance for the scientific guidance of ironmaking and steelmaking production as well as ensuring the quality of high value-added steel. In this study, the sample was prepared by powder pressed pellet. The calibration sample series, which had a certain gradient and a certain content span covering the content ranges of elements in the sample, were prepared with 2 ferroboron certified reference materials and ferroboron samples determined by national standard method to overcome the matrix effect. Thus, the determination of B, Al, Si, P, S, Ti and Mn in ferroboron was realized by X-ray fluorescence spectrometry(XRF). The sample preparation conditions were optimized: 1.50 g of sample with particle size of 53 μm (screened with 280 mesh) was edged with boric acid and then pressed at 44 MPa for 40 s. The matrix effect of boron was corrected by concentration correction with empirical coefficient method. The limits of detection were listed as below: 0.085% for B, 0.000 99% for Al, 0.001 9% for Si, 0.000 72% for P, 0.000 41% for S, 0.003 4% for Ti, and 0.003 9% for Mn. The proposed method was applied for the determination of 6 different pellets which were parallelly prepared with ferroboron samples. The relative standard deviations (RSD) of determination results of elements were all less than 2.0%. The ferroboron samples were determined according to the proposed method, and the results were basically consistent with those obtained by other methods: B was determined by alkalimetry in GB/T 3653.1-1988; Al was determined by EDTA titration method in GB/T 3653.4-1988; Si was determined by perchloric acid dehydration gravimetry in GB/T 3653.3-1988; P was determined by antimony phosphomolybdenum blue spectrophotometry in GB/T 3653.6-1988; S was determined by infrared absorption method in GB/T 3653.7-2020; Ti and Mn were determined by inductively coupled plasma-atomic emission spectrometry in GB/T 6730.63-2006.

MFI molecular sieve is an important catalyst for catalytic cracking of heavy oil and methanol-to-gasoline, and the silicon-aluminum ratio is a major index influencing its catalytic performance.The sample was treated by super microwave digestion with hydrochloric acid, nitric acid and hydrofluoric acid, which overcame the problem of difficult digestion of high silicon samples. The oxygen mass transfer mode of tandem mass spectrometry(MS/MS) was adopted to determine Si with the mass-to-charge ratio of the first mass filter(Q1) of 28 and the second mass filter(Q2) of 60, and the flow rate of oxygen was controlled at 0.40 L/min. The helium collision cell mode of unipolar rod was adopted to determine Al with the flow rate of helium as 3.0 L/min. Sc and Ge were selected as the internal standard element for the correction of Si and Al, respectively. The determination of Si and Al in molecular sieve was realized by inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) with super microwave digestion. Therefore, the silicon-aluminum ratio could be calculated. In order to avoid the volatilization loss of Si, the time for addition of hydrofluoric acid was investigated. It was indicated that the determination result of Si was higher when the hydrofluoric acid was added after microwave digestion than that obtained before microwave digestion. Moreover, its corresponding relative standard deviation was lower. Therefore, the addition of hydrofluoric acid after microwave digestion could effectively avoid the loss of Si. Under the optimized experimental conditions, the linear ranges of calibration curve for Si and Al were 50-1 000 μg/L and 5-400 μg/L, respectively. The correlation coefficients were both 1.000 0. The limits of detection were 0.003 1 μg/g and 0.001 4 μg/g, and the limits of quantification were 0.010 2 μg/g and 0.004 5 μg/g, respectively. MFI molecular samples were determined according to the proposed method, and the determination results of Si and Al were basically consistent with those obtained by inductively coupled plasma atomic emission spectrometry (ICP-AES). The relative standard deviations (RSD, n=7) were 2.5% and 3.1% for Si and Al, respectively. The recoveries were 95%-110% and 90%-110%, respectively.

There is a great variety of manganese-containing minerals in manganese ore,and the classification is complex.However,the current methods for phase analysis of manganese ores have some disadvantages such as tedious operations,inconsistent procedures,and lack of detail description.In experiments,the manganese ores with different types and contents from various mining areas were selected.The monomineral test was conducted to select the leaching agent.Manganese carbonate was leached with 50 g/L aluminum nitrate in boiling water bath for 60 min.Manganese oxide was leached with 30 g/L hydroxylamine sulfate-1% (V/V) sulfuric acid in boiling water bath for 60 min.The residue was decomposed with acid to obtain manganese silicate.The content of manganese in treated solution was determined by inductively coupled plasma atomic emission spectrometry(ICP-AES).The method for the chemical phase analysis of manganese ore was established.The limits of detection were (in manganese):0.000 3% for manganese carbonate phase,0.000 5% for manganese oxide phase,and 0.000 3% for manganese silicate phase.One manganese carbonate raw ore and one manganese oxide raw ore were determined according to the experimental method.The relative standard deviations(RSDs,n=12) of determination results were less than 5.0%,which could meet the quality management requirements in DZ/T 0130.3-2006 The specification of testing quality management for geological laboratories.The proposed method was applied for the determination of certified reference materials of manganese ore for chemical phase analysis,i.e.,GBW(E)070256(manganese carbonate ore) and GBW(E)070258(manganese oxide ore).The relative errors(REs) of determination results of main phases were less than 1%.For other phases,the REs were less than 10%,which also could meet the requirements in DZ/T 0130.3-2006.

In this paper, the classification system of Chinese reference materials was briefly introduced, and the classification of geological reference materials, especially Chinese geological reference materials, was discussed.The 7th type of geological reference materials in the existing Chinese reference material classification and other types of geological material reference materials commonly used for geological analysis in China were mainly classified and evaluated, including the reference materials for bulk analysis, ultrafine geological reference materials, chemical phase and speciation analysis reference materials, micro-area in-situ analysis reference materials, isotope and geochronology analysis reference materials, organic pollutant analysis and environmental radioactivity measurement reference materials.As the most diverse and the largest number of reference materials for bulk analysis, they were classified and reviewed according to the fields of rocks, sediments, soils, ores, single minerals, precious metals, energy minerals, building materials, nuclear geological materials and environmental chemistry. The main contents included the number of reference materials, the number of samples and the number of property data. Finally, the classification of reference materials of complex geological materials and other existing problems in the development of geological reference materials in China were discussed,and relevant suggestions were put forward.Total 82 references were cited in this paper.

At present, the detection methods of zinc concentrate are mainly wet chemical methods. However, the sample preparation of these methods is complicated and the operation is cumbersome. Therefore, it is of great significance to find an accurate and rapid detection method for zinc concentrate to improve the detection efficiency. In this study, the handheld X-ray fluorescence spectrometer was employed for the rapid detection of five major and minor components in zinc concentrate, including Zn, S, Fe, Ca and Pb. The samples were prepared by grinding and tableting. Different drying periods were set to explore the effect of moisture content. It was found that the higher the moisture content, the greater the relative error (RE) of the determination results. The relative error of Pb with lower content in the sample was up to 39.02% when the moisture content was the largest. Different ball milling time was also set to explore the influence of particle size, and it was found that the change of particle size had the greatest impact on S and Fe. The relative error reached 10.43% and 19.68% when the ball milling time was 3 h, respectively. Moreover, more accurate measurement results could be obtained for the sample with smaller particle size, the ball milling time of 9 h was determined. Different compression time was also investigated to explore the effect of tablet thickness, and the holding time of 60 s was determined in experiments. Four zinc concentrate samples were detected according to the experimental method. The relative standard deviations (RSD, n=5) of Zn,S,Fe and Ca were all less than 1.5%, and the RSD of Pb with lower element content was also less than 3%. The measured values of inductively coupled plasma optical emission spectrometry (ICP-OES) were used as reference values, and the measured values of the experimental methods were compared with the reference values. It was found that the relative errors of the detection results of all five elements was less than 10%, which could meet the requirements of routine analysis and detection. The proposed method had important reference value for the rapid detection of minerals.

The influence of background noise on trace phase identification in X-ray diffraction (XRD) was focused in this study. The results showed that background noise could be divided into two parts: noise amplitude and noise fluctuation. The noise fluctuation could be further classified into three types:peaks,valleys,and platforms. According to the comparison of noise fluctuation, it was still possible to carry out match analysis using 3 strongest lines, 5 strongest lines, and so on of trace phase cards and confirm trace phase composition. On the basis of this, weak diffraction signals provided by trace CaCO₃ phase was qualitatively characterized. It was found that 3 strongest lines, 5 strongest lines, even 8 strongest lines in CaCO₃ phase card (PDF# 00-047-1743) were one-to-one matched with peaks or platforms of background noise, and the notable diffraction lines in other phase cards could not meet “one-to-one matched with the peaks or platforms”. The results well verified the role of background noise in trace phase identification and analysis.

The quantitative analysis of ultralight elements is always one of difficulties in the application field of electron probe microanalysis (EPMA). In this paper, carbon was selected as an example, and CrTiAlC magnetron sputtering material was used as a sample, then several key points for accurate measurement of K factor of ultralight element were analyzed according to the quantitative analysis process of ZAF. Proper methods for background deduction were discussed through the qualitative spectra of analytical element. Graphite and diamond were selected as certified reference materials of carbon. The quantitative analysis results were compared to discuss the importance of selection of certified reference materials. Moreover, how to properly use the pulse height analyzer (PHA) for peak filtering was also discussed in case of overlapping peak interference.

The spectral analysis technology has been widely used in food,medicine,petrochemical,metallurgy,and other fields due to its advantages of simplicity,rapidity,and nondestructive test.Therein,the chemometrics method is the key to spectral analysis technology.This paper summarizes the basic process and framework for quantitative analysis of complex matrix samples,including the data grouping,spectral pre-processing,variable selection,and multivariate calibration.Traditional methods in these four areas are briefly introduced,and recent advances in chemometric methods in the field of quantitative spectral analysis since 2018 are introdued in detail.It provides an important reference basis for the further promotion and application of chemometric methods in the field of spectral analysis.

In recent years,some intelligent sorting technologies for scrap metals based on algorithms and material composition have gradually emerged,including machine vision,X-ray fluorescence spectrometry(XRF),X-ray diffraction topography(XRT) and laser-induced breakdown spectroscopy(LIBS).The latest progress of these technologies in classification of scrap metals were reviewed.It indicated that the machine vision had achieved industrial application demonstration with a high level of automation,but further improvements were needed to address its sensitivity to the environmental conditions.The elemental identification capabilities of XRF/XRT were strong,but limited to specific metal types.Currently,the commercial instruments for sorting metals,plastics,and ores are quite mature in the market.LIBS technology,with its wide elemental detection range that theoretically covers the entire periodic table,suffers from low detection efficiency and is still under research and development.Each technology above has its advantages and disadvantages,requiring integration and innovation to optimize the sorting results.In the future,the combination use of multiple technologies should be explored to enhance sorting capabilities,customized to meet market demands,and independent research and development should be strengthened to enhance core competitiveness.Full-process automation will improve efficiency,and the integration of artificial intelligence(AI),blockchain,and cloud computing technologies will push the scrap metal intelligent sorting industry to a new level.

Similarity,as a quantitative and qualitative parameter in digital signal science,has been identified as an important evaluation index in the standard of traditional Chinese medicine fingerprint by Chinese Pharmacopoeia Commission.In this article,similarity evaluation is introduced into the research on rapid identification of solid waste properties of imported iron ore.First,X-ray diffraction(XRD) technology is used to establish XRD fingerprint for three groups of imported iron ores,each group consisting of 15 samples,with appearances of yellow(Y),red(R),and dark brown(B).The XRD average reference spectra are calculated and plotted for each group.After extracting the common characteristic peaks,the similarity evaluation is conducted using the correlation coefficient method and the cosine similarity method.The results show that the correlation coefficients between the XRD patterns of each group of 15 iron ore samples and their reference spectra are not less than 0.960 6,and the cosine of angle is not less than 0.980 0.The addition of iron-containing solid waste(such as iron oxide scale,slag,and precipitator dust) can lead to a decrease in similarity,with larger adulteration amounts resulting in greater differences between their XRD fingerprint patterns.This further helps to determine the threshold for solid waste identification,allowing for a direct discrimination of iron ores and iron-containing solid waste and their adulterants from quantitative data.The experimental results indicate that iron ore samples adulterated with 10% iron-containing solid waste can be effectively identified using this method,and it also demonstrates good rapid screening effects in the detection of actual samples.

The accurate determination of tin,phosphorus,lead,zinc and nickel in nickel-plated tin bronze strip substrate is the precondition to ensure the product quality.The nickel coating and tin bronze substrate on the surface of nickel-plated tin bronze strip sample were selectively separated with soak solution composed of 4.5 mol/L nitric acid and 1.25 g/L CM-911 nitric acid corrosion inhibitor in water bath at 40 ℃.After rinsing with clean water and anhydrous ethanol,the sample was pressed to block by cold-press method.The pressure was 70 t and the pressing time was 2 min.The working curve of bronze was selected.The standard sample of tin bronze was used as control sample for the calibration of working curve.The determination of tin,phosphorus,lead,zinc and nickel in nickel-plated tin bronze strip substrate by spark discharge atomic emission spectrometry was realized.Two rolls of tin bronze sample with different brands were selected.The electro-nickeling was conducted for both top and bottom sides to prepare the nickel-plated tin bronze sample.The contents of tin,phosphorus,lead,zinc and nickel in nickel-plated tin bronze strip substrate were determined according to the experimental method.The results showed that the relative standard deviations(RSDs,n=6) of determination results were less than 0.3% when the contents(mass fraction,the same below) of elements were in range of 1%-10%.When the contents of testing elements were in range of 0.01%-0.4%,the RSDs(n=6) were less than 4%.GB/T 5121 was used to analyze the elements in tin bronze strip for the comparison.The results showed that the found results of two methods were basically consistent.The proposed method was applicable for the chemical composition detection of multilayer materials by spark discharge atomic emission spectrometry,which solved the problem that the breakdown of sample easily occurred during spark discharge atomic emission spectrometric determination when its wall thickness was less than 1 mm.

The non-metallic inclusion in steel is one of defects that have the greatest hazard to steel structures and properties.The detection of inclusions in steel is critical to the production of high-quality steels.In this paper,the new detection methods for inclusions developed in recent years were briefly summarized.Then several advanced technologies were screened for the deep discussion,including ASPEX scanning electron microscope automatic analysis,micro-computed tomography(Micro-CT),continuous slice scanning electron micropy analysis(SBFSEM), transmission electron microscope(TEM) analysis,focused ion beam three-dimensional atom probe-atom probe tomography(FIB-3DAP-APT),laser-induced breakdown spectroscopy(LIBS),original position statistical distribution-spark mapping analysis for large samples(OPA-SMALS),and suspension steelmaking inclusion observation.The latest application progress of these technologies was analyzed,and the advantages and disadvantages were summarized via mutual comparison.Moreover,the influence of electron beam energy selection on the detection results during the inclusion composition analysis by scanning electron microscope was also introduced.Finally,the direction for further improvement and development of various detection technologies in future was pointed out.

The main components of nickel ore are nickel, copper, iron and sulfur. Where in the content of sulfur is in range of 20%-37%, and such a relatively high content has great influence on the lead fire assay separation and enrichment results. In order to obtain the proper lead button, the appropriate ratio of fire assay ingredients was selected in experiments. Silver nitrate was used as protective agent to reduce the loss of gold, platinum and palladium during cupellation. The obtained composite particle was dissolved, and the contents of gold, platinum and palladium were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The contents of gold, platinum and palladium in nickel ore were determined according to the experimental method, and the relative standard deviations (RSD, n=11) of measurement results were 4.1%-10.6%, 2.7%-6.5% and 1.9%-8.0%, respectively. The spiked recoveries of gold, platinum and palladium were 97%-100%,99%-103%, and 98%-103%, respectively. The proposed method effectively solved the lead fire assay ingredient for nickel ore with various sulfur contents. The contents of gold, platinum and palladium could be directly determined after dissolving the obtained composite particle.

The impurity elements in pure magnesium mainly include Si,Fe,Cu,Al,Mn,Zn and Pb with low contents.The wet chemical method has some shortcomings such as complicated determination procedures and long test period.Although the spark discharge atomic emission spectrometry can be used for rapid determination,there is a risk of contamination when a variety of metals are cross-tested.In this study,the samples were prepared using milling machine followed by rapid determination.The analytical method for the determination of Si,Fe,Cu,Al,Mn,Zn and Pb in pure magnesium by X-ray fluorescence spectrometry(XRF) was established.The standard sample analysis results showed that the measured values of each element were consistent with the certified values.This method effectively solved the problem of long test period of wet chemical method as well as cross contamination in the determination of various metals by spark discharge atomic emission spectrometry. The actual sample analysis and inter-laboratory comparison results indicated that the relative standard deviation(RSD) of the determination results for elements with content above 0.001 0% was less than 7%. The proposed method had good reproducibility and wide applicability.

The safe and efficient cycle of nuclear fuel is the foundation for the sustainable development of nuclear energy. In the nuclear fuel cycle process, it is necessary to conduct fast, online and non-contact detection of the key elements to meet the needs of nuclear material accounting, monitoring of operating conditions of nuclear facilities and safety assurance. Laser-induced plasma spectroscopy(LIPS) is an emerging atomic spectrum analysis technology with the advantages of simple operation and fast detection speed. It can realize the on-line and non-contact detection as well as the simultaneous determination of multi-elements. Therefore, LIPS has been widely concerned by researchers in the field of elemental analysis in nuclear fuel cycle. In this paper, the application of LIPS in the nuclear fuel cycle was reviewed focusing on three aspects: uranium ore detection, nuclear fuel processing, and radioactive contaminant treatment. The application of LIPS technology in whole process of nuclear fuel cycle was introduced, and its development prospect was discussed.

Inductively coupled plasma mass spectrometry is one of the powerful analytical methods for trace elements due to its high sensitivity and low detection limit. However, the simultaneous determination of major elements and trace elements is performed in many applications, which requires a wide linear dynamic range. Based on the dual-mode detector for inductively coupled plasma mass spectrometer (ICP-MS), a correction method for detection mode of this type of detector, namely Pulse Analog (PA) correction method, was investigated. Firstly, according to the dynamic range desired, the negative high voltage and positive high voltage of the detector was determined. The appropriate threshold voltage for this detector was obtained to ensure that the test signal was collected, and the noise signal was removed (the counting value at 220 u was less than 0.1 cps). Then the flow rate of helium (He) gas for collision reaction cell was determined, so that the counting value of test element at the concentration of 0.1 ng/L was less than 10 cps. Finally, the signal testing was conducted to determine the overlapping elements and their test data. The Pulse-Analog correction coefficient (abbreviated as PA coefficient) was calculated. Cubic polynomial fitting was performed to obtain the PA coefficients of elements in whole mass range. The fitting methods of spline interpolation and cubic polynomial were compared. The results showed that the fitting data by cubic polynomial were closer to the trend of original data within the whole mass range of 2-250 u. The proposed calibration method was validated using low, medium, and high mass number elements of Be, Cd, and U (0.1 ng/L-100 mg/L) with a linear dynamic range of 9 orders of magnitude. The results showed that the determination coefficients of calibration curves were all 1.000, and the determination coefficients of calibration curves were all higher than 0.999 5 under logarithmic coordinates of the test data. The superalloy certified reference material of GBW01636, which contained Cu, Ga, As, and Bi with content span in four orders of magnitude, was selected for verification, and the results showed that the test values were basically consistent with the certified values. The proposed correction method could achieve the simultaneous determination of major and trace elements with a linear dynamic range of up to 9 orders of magnitude, which could meet the test requirements of wide concentration range in certain applications.

In this paper, the literatures on iron ore analysis by X-ray fluorescence spectrometry(XRF) published in China since 2011 were reviewed. The preparation conditions of test portion piece, test portion for calibration curve used, the analysis conditions of instrument, the evaluation of calibration curve, the evaluation of analysis system, the evaluation of measurement uncertainty and related applications of pressed powder pellet and fusion sample preparation are summarized. The application prospect of XRF in component analysis of iron ores was prospected. It was suggested to conduct the research and application on test portion pieces for calibration curve and test portion pieces for standardization for primary and secondary components analysis of iron ore by XRF. Moreover, the application of high-pressure powder pelleting preparation technique in XRF analysis of iron ore was also proposed.

The accurate and rapid determination of molybdenum content in geological samples is of great significance for the development and utilization of molybdenum ore,geological scientific research,and many other fields.Since molybdenum is an element which is hardly ionized, the determination method by flame atomic absorption spectrometry(FAAS) usually has low sensitivity and high limit of detection.The sampling of redox system can increase the air-acetylene flame temperature,thus enhancing the absorbance sensitivity of molybdenum.On the basis of this principle,a method for the determination of molybdenum(0.002%) in geological samples by FAAS was established using perchloric acid as the oxidant and sucrose as the reducing agent.Under the optimized experimental conditions,the mass concentration of molybdenum in range of 2-20 μg/mL had a good linear relationship with the corresponding absorbance,with a correlation coefficient of 0.999 8.The sensitivity was 0.010 6 mL/μg,the limit of detection was 0.000 7%,and the limit of quantification was 0.002%.The content of molybdenum in certified reference materials of molybdenum ore for composition analysis was determined according to the experimental method.The maximum relative error between the found results and the certified values were all less than the relative error tolerance(Y_B) specified in DZ/T 0130-2006 The Specification of Testing Quality Management for Geological Laboratories.The relative standard deviations(RSD, n=9) of the determination results were between 1.5% and 8.2%.

The accurate determination of conventional components in limestone has important significance for guiding metallurgical production.To address the challenges posed by the complicated acid dissolution process and the challenges in determining the silicon content,as well as issues with the crucible adhesion of molten material and limitations in the determination of sodium and potassium content due to the use of molten reagents in the alkali fusion method,the borate fusion sample preparation method of X-ray fluorescence spectrometry (XRF) was referenced.0.2 g of sample,1.0 g of Li₂B₄O₇-LiBO₂(m∶m=67∶33) mixture flux,and 8-10 drops of 300 g/L ammonium iodide solution were mixed in a platinum-gold crucible.After fusion at high temperature(1 000 ℃) for 10 min,the fully detachable glass beads could be formed.The glass beads were then dissolved with 10% nitric acid(V/V) by heating.The contents of eight elements,including Al,Fe,Mg,Mn,Si,Ti,K and Na,were determined by inductively coupled plasma atomic emission spectrometry(ICP-AES).Based on the intensity and interference of spectral lines,the analytical lines with simple background and few interfering elements were selected.The matrix matching method was used to eliminate the influence of matrix effects caused by the flux and the main component matrix.Under the selected working conditions,the linear correlation coefficients of the calibration curves for each element were all greater than 0.999,and the limits of detection were in range of 0.001-0.03 μg/g.The precision tests were conducted using two limestone samples according to the experimental method.The relative standard deviations(RSD,n=6) of determination results of Al,Fe,Mg,Mn,Si,Ti,K and Na(in oxides) were between 0.53% and 4.8%.Two certified reference materials(GBW03106a,YSBC28707a-2013) were determined,and the found results were consistent with the certified value/standard value,which could meet the requirements of GB/T 27417-2017 Guidelines for Confirmation and Validation of Chemical Analysis Methods for Conformity Assessment.

The determination of rare earth elements in graphite ore is of great significance in evaluating resource value, protecting the environment, and scientific research. In experiments, the samples were treated by high-temperature microwave digestion in HNO₃-HF-HClO₄-H₂SO₄ system. The collision mode was used with helium (He) flow rate of 4-5 mL/min. ⁴⁵Sc, ⁸⁹Y, ¹³⁹La, ¹⁴⁰Ce, ¹⁴¹Pr, ¹⁴⁶Nd, ¹⁴⁷Sm, ¹⁵³Eu, ¹⁵⁷Gd, ¹⁵⁹Tb, ¹⁶³Dy, ¹⁶⁵Ho, ¹⁶⁶Er, ¹⁶⁹Tm, ¹⁷²Yb, and ¹⁷⁵Lu were selected as the isotopes to be measured. Sc, Y, La, Ce and Pr were corrected using Rh, and Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu were corrected using Re. The multi-atomic ion interference of ¹⁵⁷Gd, ¹⁵³Eu, ¹⁵⁹Tb and ¹⁶⁹Tm was corrected by the interference correction equation. The method for the determination of 16 rare earth elements in graphite ore by electrical coupled plasma mass spectrometry (ICP-MS) with microwave digestion was established. Under the optimized experimental conditions, the linear correlation coefficients of calibration curves of rare earth elements were between 0.999 7 and 1.000 0. The limits of detection were between 0.002 6 and 0.065 μg/g, and the limits of quantification were between 0.008 7 and 0.22 μg/g. The contents of 16 rare earth elements in graphite ore standard substances for composition analysis were determined according to the experimental method for 15 times in parallel. The relative standard deviations (RSD, n=15) of determination results were all less than 3.5%. The mixed standard working solution of rare earth elements were added based on 0.5-2 fold of element content for the spiked recovery tests, and the recoveries were between 90% and 105%. 16 rare earths in graphite ore sample were analyzed according to the experimental method, and the measurement results were basically consistent with those obtained by ashing-mixed acid dissolution-ICP-MS method.

Accurate determination and control of carbon content in praseodymium neodymium fluoride-lithium fluoride electrolytes is of great significance for the monitoring of praseodymium neodymium alloy production process and the quality of finished products. A method for the determination of carbon content in praseodymium neodymium fluoride-lithium fluoride electrolyte by high-frequency combustion infrared absorption was established. The analytical time was controlled at 35 s, and the sampling mass was 0.20-0.30 g. The standard sample of steel was used for the preparation of single-point calibration curve. Tungsten, tin, and iron were selected as the flux. An orthogonal experiment with four factors and three levels was designed, and the investigation factors includes the mass of tungsten, the mass of tin, the mass of iron, and the adding sequence of flux and sample. Through the experiments, the adding sequence of flux and sample was pure iron + sample + tungsten and tin. The dosage of flux was 0.60 g of iron, 1.20 g of tungsten, and 0.40 g of tin. The limit of detection of method was 0.000 255% (mass fraction, the same below), and the limit of quantification was 0.000 85%. Three different batches of praseodymium neodymium fluoride-lithium fluoride electrolyte samples were measured according to the experimental method, and the relative standard deviations (RSD, n=11) of determination results were between 2.8% and 3.3%. The Grubbs outlier judgment method was used to identify the outliers. The Grubbs G_Max of measurement results of three batches was 1.463, 1.503, and 1.335, and the G_Min was 1.704, 1.639, and 1.669, respectively. They were all less than the Grubbs critical value G_(0.05,11)=2.234 (significant level α=0.05), indicating that there were no abnormal values in the measurement results. The standard steel sample was used into the sample for spiked recovery tests, and the recoveries were between 96% and 105%.

Cerium-zirconium composite oxides are often used as rare earth co-catalysts. Lanthanum (La), praseodymium (Pr), yttrium (Y) and other rare earth elements contained in cerium-zirconium composite oxides can improve the catalytic performance and comprehensive performance. In experiments, the samples were decomposed with nitric acid, hydrogen peroxide and hydrofluoric acid followed by sulfuric acid smoke. La 333.749 nm, Pr 410.072 nm and Y 377.433 nm were selected as the analytical lines. The contents of La₂O₃, Pr₆O₁₁ and Y₂O₃ in cerium-zirconium composite oxides were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) in hydrochloric acid medium. The experimental results showed that Ce and Zr had no spectral interference with La, Pr and Y under the selected characteristic spectra. When the mass concentration of Ce and Zr in solution was less than 100 μg/mL, the matrix effect could be ignored. The coexisting elements in solution such as Fe, Ca, Zn, Al and Na had no influence on the determination. The mass concentration of La, Pr and Y in range of 1.00-20.00 μg/mL showed linear relationship with the corresponding emission intensity, and the linear correlation coefficients were not less than 0.999 9. The proposed method was applied for the determination of La₂O₃, Pr₆O₁₁ and Y₂O₃ in cerium-zirconium composite oxide, and the relative standard deviations (RSD, n=11) of the results were less than 2%. X-ray fluorescence spectrometry (XRF) was used to compare with the proposed method, and the results were consistent.

The content of platinum is usually determined by inductively coupled plasma mass spectrometry (ICP-MS) after enrichment by fire assay. The assay button should be dissolved for determination, so the operation is complicated and there is solution dilution effect. In this study, ¹⁹⁴Pt isotope diluent was added into the sample, and platinum was separated and enriched by antimony fire assay. The antimony composite granule was obtained after cupellation and then polished to antimony slice with smooth surface. The isotope ratio (¹⁹⁵Pt/¹⁹⁴Pt) was determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The content of platinum was quantified according to the formula of isotope dilution method. Thus, a determination method of trace platinum in geochemical samples was established with direct solid sampling after fire assay enrichment. The experiments showed that when self-purified antimony oxide was used as collector agent and high purity quartz crucible was used instead of traditional fire assay clay crucible, the blank value of platinum in antimony fire assay process could be reduced to 0.52 ng, which broke the bottleneck of high blank value for platinum in fire assay process. LA-ICP-MS planar imaging results showed that the distribution of ¹⁹⁴Pt and ¹⁹⁵Pt in antimony slice was not uniform, but the rules were similar for the trend of uneven distribution. LA-ICP-MS was used for the further multipoint ablation of ¹⁹⁴Pt and ¹⁹⁵Pt in antimony slice. The results showed that the relative standard deviations (RSDs,n=6) of mass spectral intensity of ¹⁹⁴Pt and ¹⁹⁵Pt were 14.7% and 14.1%,respectively. However, for the mass spectral intensity ratio of ¹⁹⁵Pt and ¹⁹⁴Pt, the RSD was 2.5%, indicating that platinum in isotope diluent had been fully exchanged with that in geochemical samples. The proposed method was applied for determination of platinum in geochemical certifeid reference materials, and the results were basically consistent with the certified values. The RSDs (n=6) of determination results were between 2.0% and 5.1%. The proposed method realized the determination of platinum in geochemical samples by solid-solid combined analysis technique (solid high temperature melting enrichment-laser ablation direct solid sampling) and isotope dilution.