This paper systematically investigated the differences among the standard curve method,the certified reference material(CRM) curve method,and the standard addition method in inductively coupled plasma atomic emission spectrometry(ICP-AES) analysis,as well as their requirements for blank solutions.By deconstructing the spectral intensity composition of the calibration,sample,and blank solutions,the following conclusions were drawn:1)For the calibration curve based on the concentration of the added standard solution versus the spectral intensity,its intercept comprised the blank value,the content of matrix elements,and the fitting error.The measurement results required compensation for the over-deducted analyte content in the matrix metal.For the calibration curve based on the sum of the standard solution concentration and the matrix element content versus the spectral intensity,its intercept reflected only the blank value and fitting error,and the measurement results were final.No dedicated blank solution preparation was necessary in both cases.2)In the CRM curve method,the intercept encompassed the blank,CRM uncertainty,and fitting error.The test results were final,blank solution preparation was unnecessary,and abnormalities could not be judged solely by the blank value.3)The standard addition method required a blank solution and had the limitation of being unable to eliminate spectral interference from coexisting elements completely.4)When the calibration and sample solutions were prepared in separate batches,deducting their respective reagent blanks before calibration effectively eliminated blank variations caused by reagent batch differences.This approach solved the problem of reusing calibration solutions and yielded accurate test results.The study also showed that a full-process blank should be used when the matrix effect is minor,whereas a matrix metal blank solution should be employed when the matrix effect is strong (with results compensation).Moreover,the content of the analyte in the blank solution must be strictly controlled below half of the quantification limit to ensure accurate determination of elements at that level.

The gold ore is one of the scarce strategic ores in China.The sample processing and preparation process and the representativeness of samples are the main factors affecting the gold measurement results.In this paper,the research reports on domestic gold ore sample preparation since 2000 were retrieved and summarized.The paper publication overview,the source of gold samples,the occurrence state and particle size of gold in ore samples,the number of gold ore samples and gold grade characteristics,the coarse,middle and fine crushing of ore samples,the sample reduction and the processing research on difficult-to-break samples such as coarse gold were systematically sorted in order to provide support and reference for the processing,preparation,application and in-depth research of gold ore samples.

As an advanced analytical tool, the cathodoluminescence(CL) microscope is playing an increasingly important role in the field of clean steel.By detecting the inclusions in steel, analyzing the nozzle clogging, and evaluating the refractory erosion, it can provide strong support for the optimization of clean steel production processes and quality control. In this study,the combination of rapid remelting of samples and CL microscope enabled the rapid detection of inclusions during steel production.This method promoted the flotation of inclusions to the top of the sample through rapid remelting,followed by rapid detection of inclusion composition on the sample surface using the CL microscope,significantly enhancing the detection speed.Moreover,the color difference in CL images for inclusions with different compositions was also summarized to establish the quantitative relationship among inclusion composition,CL color,and spectral peaks.Despite some challenges,the application prospects of CL microscope in the field of clean steel are expected to broaden with continuous improvements in instrument performance and innovative analytical methods.In the future,this technology is likely to be more widely applied in steel production,contributing significantly to the improvement of steel purity and product quality.

The artificial sapphire has been widely used in light-emitting diode(LED) manufacturing and smartphone industries.During the quantitative analysis of impurity elements in artificial sapphire by glow discharge mass spectrometry(GD-MS),the electrical conductivity of artificial sapphire is insufficient when it is directly used as the cathode material.In response to this technical bottleneck,the composite auxiliary cathode was innovatively constructed using high-purity tantalum and high-purity graphite powder,and the test sample of sapphire containing auxiliary cathode was prepared through mechanical tableting.The pulse mode of GD-MS was adopted,and the optimal instrumental operation parameters were obtained as follows:the discharge current was 20 mA,the discharge gas flow rate was 700 mL/min and the discharge voltage was 1 000 V.The limits of detection of 15 impurity elements including Li,Na,Mg,Si,Ca,Ti,V,Cr,Fe,Co,Nb,Cu,Ga,Mo and W were less than 0.03 μg/g under the optimized experimental conditions.It was verified that the determination results of total impurity contents in artificial sapphire crystal bar by this method could completely meet the limit of less than 100 mg/kg specified in GB/T 30858-2014 and GB/T 31092-2022.This study provided a precise analysis method for the quality control of semiconductor grade sapphire materials.

The accurately determination of impurity elements content in high-purity cesium is crucial for guiding the production impurity removal,improving the material performance,and ensuring the stable operation of national defense,military industry,satellite navigation and other fields.Due to the high chemical reactivity of cesium(it can be rapidly oxidized upon contact with air and it is explosive when exposed to liquid solvents),its sampling and decomposition pose severe challenges.In this study,the sampling was conducted in an argon atmosphere within an oxygen-isolated glove box.Based on the characteristic of cesium that its melting point (28.5 ℃) is slightly higher than room temperature but lower than hand temperature,the solid samples were melted into liquid using hand warmth as a heat source.A pipette was used for quantitative liquid transfer,overcoming the difficulty of sampling high-viscosity solids.The wall-hung samples were placed in open air for over 10 h.Utilizing the properties of easy oxidation for cesium,susceptibility to hydration for cesium oxides and deliquescence for cesium hydroxides,a three-stage gas-solid reaction chain of "oxidation→hydration→deliquescence" was constructed with oxygen and water vapor as reactants to achieve gradual passivation and mild decomposition.Based on this,a method for determination of 9 impurity elements in high-purity cesium,including lithium,sodium,potassium,calcium,magnesium,iron,aluminum,lead and rubidium,by inductively coupled plasma atomic emission spectrometry(ICP-AES) was established.To address the coupled ionization and physical interference effects caused by cesium matrix,a strategy was adopted that primarily used the matrix matching method(for correcting lithium,sodium,potassium,calcium,magnesium,iron,aluminum,lead) and supplemented by the standard addition method(for correcting rubidium).The calibration curves had good linear relationships,and the correlation coefficients (r) were all not less than 0.999 6.The limit of detection ranged from 0.000 001% to 0.000 042%,and the limit of quantification ranged from 0.000 01% to 0.000 42%.The content of 9 impurity elements in actual and synthetic high-purity cesium samples were determined according to the experimental method.The relative standard deviations(RSD,n=5) of the determination results were between 0.86% and 9.5%,and the recoveries ranged from 94.9% to 103% (except rubidium).The content of rubidium in sample was determined by inductively coupled plasma mass spectrometry(ICP-MS) and compared with the experimental method.It was found that the measurement results of two methods were basically consistent.

Angola possesses favorable geological conditions with high-purity quartz deposits.However,there is no report on the analysis method for impurity elements and silicon dioxide purity in Angolan quartz ore to date.In this study,1 g of sample was calcined at 960 ℃ for 1 h,and the loss on ignition(LOI) was calculated by measuring the mass difference before and after calcination.Then 0.25 g of sample was completely digested with 5 mL of HF,0.5 mL of HNO₃,and 0.1 mL of HClO₄.After evaporation,the residue was redissolved with 5 mL of aqua regia.The contents of 16 impurity elements(potassium,calcium,sodium,magnesium,aluminum,iron,titanium,manganese,barium,zinc,nickel,copper,cobalt,chromium,lithium,and vanadium) were determined by inductively coupled plasma atomic emission spectrometry(ICP-AES).The linear correlation coefficients of calibration curves for all elements were not less than 0.999 8.The limit of detection for each element ranged from 0.02 to 2.78 μg/g.The content of impurity elements in Angolan quartz ore samples was determined according to the experimental method,and the relative standard deviations(RSD,n=6)was all less than 11%.The proposed method was applied for the determination of impurity elements in certified reference material quartz rock GBW07837,and the absolute value of relative errors(RE) of results was all below 5.8%.The LOI and impurity elements of 10 Angolan quartz ore samples were analyzed according to the experimental method.By converting the impurity contents into oxides and summing them with the LOI,the silicon dioxide purity(in mass fraction) was calculated through subtraction method.The results indicated that the silicon dioxide purity in samples all exceeded 99%.

The composition design of certified reference material of cerium oxide is required for practical application based on cerium oxide product standard.In this study,the high-purity cerium oxide was used as the main matrix,then total components including 15 rare earth impurities and 23 non-rare earth impurities were added according to the properties of impurities.The methods of physical mixing,low-temperature drying and high-temperature burning were adopted.The dry-basis,pale yellow and powdery certified reference material candidates of cerium oxide for chemical composition analysis were prepared through grinding,sieving and mechanical mixing.The homogeneity and stability test results indicated the prepared certified reference material could meet the requirements.The content of 38 chemical components in certified reference material of cerium oxide for chemical composition analysis were characterized by various method with different principles in at least 9 laboratories with a high level of testing capability.The measured values were accurate and reliable,and the uncertainty evaluation was reasonable.The developed certified reference material could meet the traceability needs in actual production and scientific research.It gradually filled the gap of reference materials in the field of rare earths,and also provided a reference for the development of other types of reference materials.

The content of indium in indium electrolyte is an important control index in the refining process of refined indium by electrolytic refining. At present, the analysis methods of indium in indium electrolyte mainly include EDTA titration and electrochemical pulse voltammetry. These methods have some shortcomings such as long analysis process, complicated operation and use of many reagent materials. In this paper, an analytical method for the determination of indium in indium electrolyte by inductively coupled plasma atomic emission spectrometry (ICP-OES) with vertical observation was established. Hydrochloric acid solution with concentration of 3% (V/V) was selected as the medium and the pretreatment of sample was not required. In 303.936 nm was used as the analytical line of indium. The influence of matrix effect was reduced by controlling the dilution factor of sample to make sure the concentration of indium was within the linear detection range of instrument. The linear correlation coefficient of calibration curve of indium was 0.999 9. The detection limit of the method was 0.14 mg/L. The content of indium in indium electrolyte was determined according to the experimental method, and the relative standard deviations (RSD, n=11) were between 0.33% and 0.47%. The spiked recoveries ranged from 96.78% to 102.87%. The determination results had no significant difference with those obtained by EDTA complex titration.

Too high content of calcium in rare earth concentrate will affect the mass transfer efficiency in subsequent extraction,thus influencing the yield of rare earths.Therefore,the accurate determination of calcium in rare earth concentrate is of great significance.At present,the determination of calcium content in rare earth concentrate mainly adopts flame atomic absorption spectrometry(FAAS) or EDTA titration in national standard GB/T 18114.3-2010 Chemical analysis methods of rare earth concentrates-Part 3:Determination of calcium oxide content.But the operation requirements are strict in EDTA titration and the endpoint of titration is hardly controlled,and the determination range of calcium content(the determination range of calcium oxide was 0.50%-3.00%) is limited in FAAS method.In experiments,the sample was melted at high temperature with the mixed flux of anhydrous sodium carbonate and boric acid followed by dissolution with hydrochloric acid.The calibration curve was plotted by matrix matching method.Ca 393.366 nm was selected as the analytical line of calcium.The content of calcium in rare earth concentrate was determined by inductively coupled plasma atomic emission spectrometry(ICP-AES).The experiments showed that the mass concentration of calcium in range of 1.0-10.0 μg/mL had a good linear relationship with the emission spectral intensity,and the linear correlation coefficient(r) was 0.999 94.The limit of detection was 0.008 7%.It was found that the coexisting elements almost had no influence on the determination results.The content of calcium in 3 rare earth concentrate samples was determined according to the experimental method,and the relative standard deviation(RSD,n=7) was between 0.25% and 0.53%.The content of calcium in certified reference materials of Bayan Obo rare earth concentrate(GSB04-3309-2016,GSB04-3310-2016 and GSB04-3311-2016) were determined by the proposed method and EDTA titration in GB/T 18114.3-2010,respectively.The determination results of two methods were consistent and in good agreement with the standard values.

At present,the hydrochloric acid-calcium acetate centrifugal exchange method is the mainstream method for the determination of cation exchange capacity in calcareous soils.However,the operation of each link in this determination method is complex,and it requires a high level of skill from the operator.It is difficult to precisely control the actual operation,and the precision of the experimental results can hardly meet the quality requirements of relevant specifications.Based on the industrial standard NY/T 1121.5-2006 Soil testing-Part 5: Determination of cation exchange capacity in calcareous soils,the experimental conditions were optimized through experiments in this paper,which specifically included the following items:the appropriate concentration of hydrochloric acid was selected to effectively destroy and decompose the carbonates and gypsum in the soil,so that the soil solution reached a hydrogen-saturated state;during the process of using 40% ethanol (volume fraction) to remove the excess hydrochloric acid,a high-speed centrifuge was selected and the number of washing was determined,which significantly reduced the risk of soil colloid loss and destruction.The potentiometric titration method was used for the determination to ensure the stability and accuracy of the data.The cation exchange capacity(CEC) in 5 reference material for available nutrients of soil was determined according to the experimental method.The relative standard deviation(RSD,n=5) of determination results was between 1.4% and 3.7%,and the absolute value of relative error(RE) was between 0.5% and 2.4%.The determination results were compared with those obtained by traditional titration method,and the results of two methods were consistent with each other,and both could meet the quality control requirements of the technical specifications for the third national soil survey.The proposed method was applied for the determination of CEC in actual calcareous soil samples,and the RSD(n=12) of measured results ranged from 3.8% to 9.3%,which could meet the quality control requirements of the technical specifications for the third national soil survey.

Sulfur in tungsten tailings will cause environmental pollution and affect the product performance.Therefore,the accurate determination of sulfur content in tungsten tailings is essential to monitoring the environmental impact and support the development and utilization of tungsten tailings.In experiments,300 mg of copper sheet was used as flux agent to cover 150 mg of sample. The air was selected as the carrier gas.The sample was heated and burned at 1 250 ℃ for 4 min to convert the sulfur into sulfur dioxide.The potassium iodate standard solution was used to titrate the generated sulfurous acid with starch-potassium iodide as indicator.A method for the determination of sulfur in tungsten tailings by combustion-iodometry was established.The determination range of sulfur was 0.032%-26.58%.The content of sulfur in tungsten tailings sample was determined according to the experimental method.The relative standard deviations(RSD,n=11) of the results were between 0.13% and 2.2%,and the recoveries were between 93.4% and 101.4%.

Carbon dots with yellow green fluorescence emission and high fluorescence quantum yield were synthesized through one step solvothermal treatment using biomass resources as the carbon source.The infrared spectrometry and fluorescence spectrometry were employed for the structural characterization and analysis of carbon dots.The results showed that the synthesized carbon dots were formed by codoping N and S,which had strong fluorescence characteristic at long wavelength.The effects of solvothermal reaction temperature,reaction time,reactant ratio and solution pH on the fluorescence intensity of carbon dots were investigated.The results showed that the synthesized carbon dots exhibited good stability under the following experimental conditions:at solvothermal reaction temperature of 180 ℃ for 3 h and pH 7.0.The prepared carbon dots had high fluorescence quantum yield at long wavelength.The further study indicated that Cu²⁺ had obvious quenching effect on the fluorescence intensity of carbon dots prepared according to the experimental method.On the basis of this,a new method for the detection of Cu²⁺ was established.The experimental results showed that the concentration of Cu²⁺ in range of 0.5×10^-6-5.0×10^-6 mol/L had a good linear relationship with the fluorescence quenching response of carbon dots.The limit of detection was 1.7×10^-7 mol/L.The proposed method was applied for the determination of Cu²⁺ in domestic wastewater.The determination results were basically consistent with those obtained by atomic absorption spectrometry(AAS).The relative standard deviations(RSD,n=6) was in range of 2.1%-3.5%.