Progress in the application of ICP-MS in metallurgical analysis Hu Jingyu, Wang Haizhou (Institute of Iron and Steel Research, Beijing 100081) Methods, interference and correction methods, prospects for the application of ICP-MS in metallurgical analysis.
The new analytical techniques developed are considered to be the most powerful techniques for ultra-trace elemental analysis. The technology has simple spectrum, low detection limit, wide linear dynamic range, fast multi-element analysis, can use isotope ratio and isotope dilution method, multiple separation techniques and injection methods, and can adapt to complex systems. Trace element analysis. These features are very beneficial to the popularization and application of ICP-MS in metallurgical analysis, and more than 40 elements are required to be determined in this field. In order to predict the technical performance of materials, metallurgical scientists will have to discuss the content of more elements, and in the next few decades, chemists in steel laboratories will be required to determine some very low concentrations of atypical elements in steel samples. In order to meet the increasing demand for chemical analysis in the steel industry, it is necessary to research and establish new analytical methods, and ICP-MS technology with excellent analytical performance is becoming the focus of analytical chemists, such as the European Community Steel and Coal ( ECSC) organized research groups with different technical characteristics to jointly study the possibility and problems of ICP-MS technology application in the steel industry. 2'3.1 Decomposition of samples Despite the development of ICP-MS technology, There are more and more injection methods to choose from, but the decomposition process of steel samples is usually a necessary step. Due to the severe polyatomic ion mass spectrometry interference caused by sulfuric acid and phosphoric acid and the corrosiveness of the instrument sampling cone, it should be avoided in the analysis of ICP-MS. Nitric acid is considered to be the best acid medium for ICP-MS analysis. Most conventional decomposition processes involve placing samples and reagents in open containers and then placing them on a flame, hot plate or electric furnace, but microwave heating methods are gradually replacing these classic methods. Microwave technology produces much higher dissolution efficiencies than those that rely solely on heating the acid. The sealed container digestion method can avoid the contamination of the sample during the preparation process and shorten the reaction time. Coedo et al., Steel As, used hydrogen sulfide generation method, isotope dilution method and ICP-MS to determine trace sulfur in steel. The produced H2S was collected in an injection package and directly introduced into the ICP-MS. Determination of 2Mg / g ion exchange method in steel and ICP-MS 22 extraction separation extraction separation method as an effective method to remove the matrix, eliminate interference, despite the cumbersome operation, easy to contaminate samples and other shortcomings, in the ICP-MS It is used less in technology, but it still has important value in the ultra-trace analysis of metallurgical samples. When HirochitoNa-ka and Gregoe ICP-MS are used to determine the arsenic, antimony, antimony and lead in steel and alloy, in order to improve the test accuracy and more effectively eliminate the influence of the matrix on the determination, the content of the five elements below 0.0005% is extracted with ammonium iodide. The system extracts and separates the matrix, and the recovery rate (n=20) is 23 ion exchange separation method. The ion exchange pre-separation column with different fillers is used to selectively adsorb the matrix elements or the measured elements by ion exchange, thereby achieving the purpose of pre-separation. Since this method is easy to be online, it has recently been widely used in metallurgical analysis. Table 1 shows the application of ion exchange method combined with ICP-MS in metallurgical analysis.
Sample Pre-Separation Column Sample Pretreatment Method Analysis Results High-purity titanium cation exchange microcolumn was filled with 5 mL of Bio-RadAG50W-X12 resin (200400 mesh) HCl to wash the substrate alizarin titanium, and then rinsed with 4 mol/L HCl and 0.1 mol/L HF. The eluent was collected and evaporated in a PTFE beaker. The final recovery was 0.14 mol/L HNO3. The recovery was 92 士12%. The detection limit was 2.5 ng/g. High purity molybdenum and tungsten cation exchange separation column Dowex 50WX9 at 4% H2O2. The analyte was adsorbed on a cation exchange column in a medium of 4 mol/L HNO3, and then reverse-washed with 15 mL of 4 mol/L HNO3. When the separation coefficient was >104, 30 kinds of elements to be tested were removed, and 22 elements were detected. The NP/g grade strong basic anion exchange microcolumn (2mmIDX40mmL) is filled in the inclusion of 0. NbTaW, Zr, Hf spiked through the online microcolumn, the measured elements are quantitatively retained on the column, Fe rate is not The detection limit of more than 96% is reserved for high-purity iron, respectively, and then the RSD (n=6) at a concentration of 3 small detection limits is less than 3% high-purity zinc BIO-RADAG1-X8 anion exchange microcolumn (2. Hydrochloric acid Zinc in the medium is adsorbed on the on-line microcolumn, and Co, Cu in high purity metal zinc is determined by FI-ICP-MS. The detection limits of NiTh, L CoCu, NiTh, and L are respectively determined by measuring the metal molybdenum, tungsten, erbium, silver, strontium and titanium in MoW. The chelating agent, cation or anion chelating exchange resin adsorbed on cellulose is HPLC and ICP- Combined with MS, trace analytes are collected in a small volume of solution, and the matrix is ​​separated from the matrix. Determination of TaNb in the determination of 24 co-precipitation separation method Although the coprecipitation method is more complicated, but if the isotope dilution method is effective To compensate for the loss of analytes during the pre-separation process, the co-precipitation method is still a good separation and enrichment technique in 9999% pure copper. 2 Matrix effect Although the matrix effect is difficult to measure and quantify, high concentration of matrix elements will lead to irrational loss of signal caused by clogging of the sampling cone, which will deteriorate the analysis accuracy and usually inhibit the response of the analyte. Direct measurement. Kuss et al. studied the influence of iron base on the analysis signal. When the iron base concentration was 0~100mg/L, it had no significant effect on the response signal of 100%/L tested elements. When the iron base concentration reached 1g/L, it was found. There is a slight inhibitory effect; the matrix effect produced by the copper base is similar to that of the iron base. The effect of reducing the matrix effect can be diluted, but usually at the expense of the measurement limit; Tan and Horlick believe that the matrix effect is strongly dependent on the atomizing gas flow rate, while the plasma power and sampling depth have no serious effect on it. Therefore, the optimization of the instrument can reduce the matrix effect; for some substrates, the most ideal method is to separate the analyte and the substrate by ion exchange separation or other separation means, and at the same time enrich the analyte; A blank solution of the same matrix interference element as the sample solution, an internal standard method or a matrix-matched external standard correction is a commonly employed method. 3 Calibration method 43.1 Internal standard method: The internal standard method is used to monitor and correct the short-term and long-term drift of the signal and to calibrate the general matrix effect. In the solution analysis, the elements whose mass number and ionization degree are close to the measured elements are usually selected as internal standards. For example, In is used as the internal standard element in 12; when Coedo et al. determine Ca in steel, the maximum abunciation of Ca is disturbed by 40Ar. Degree isotope, using 44Ca isotope, the mass and ionization degree is similar to Ca, and Sc is the internal standard; FI-ICP-MS is used to determine the highest and lowest ionization energy of AsSbSnBi, Se and Te in the steel. Nearly 46 eV) is the double internal standard to correct the matrix effect. Coedo et al., but usually use polyatomic ions formed by matrix elements or matrix elements, such as the low abundance of iron isotope (58Fe) as an internal standard. 43.2 External standard calibration method: When ICP-MS analyzes steel, metal, alloy and other samples, because the matrix element suppresses the detection signal of trace analytes, it is necessary to determine the six kinds of steel labels by using the matrix matching standard and internal standard. In the sample (CRM), /b grade SbBi, Pb, Sn, a calibration curve was prepared by using the analytically certified pure iron sus-87 and the standard solution as the matrix-matched synthetic sample, and the measurement result was consistent with the standard value. Held et al. used a standard solution prepared from a highly pure compound for external standard calibration when determining trace ruthenium in metallic titanium. 43.3 Isotope dilution method: For the determination of an element having at least two isotopes and not being interfered by isobaric, an isotope dilution method may be employed. The isotope dilution method measures the ratio of the ratio of the added concentrated isotope to the signal intensity of another isotope. Therefore, the method has the characteristics of an ideal internal standard, and one isotope of each measured element is its internal standard, and the method is not The effects of various physical and chemical disturbances. Since the concentrated isotope diluent is usually added at the earliest stage of sample preparation, it can effectively compensate for the partial loss of 110 111516 of the tested component, so the accuracy and accuracy are extremely high. However, the shortcomings of this method are also very obvious and cannot be used for the determination of monoisotopic elements. At the same time, the source of concentrated stable isotopes is very limited and expensive, which makes the method limited in conventional analysis. 5 Application 1 Semi-quantitative analysis Semi-quantitative and direct analysis with sufficient accuracy. Pat-tberg et al. believe that LA-ICP-MS is a very useful fast and direct analytical method in the steel production control process. They use continuous wavelength, Q-switch, Nd-YAG laser as the laser for rapid analysis of steel samples by ICP-MS. Ablation system, analysis of most elements in steel samples, the results of RSD (n = 10) is 5% ~ 10% Hager in the absence of standard calibration, LA-ICP-MS on steel, copper, aluminum The semi-quantitative analysis is performed with a deviation from the standard value of less than 50%. Weijer et al. believe that since LA-ICP-MS requires expensive standard materials for accurate quantitative analysis, full quantitative analysis for a large number of samples , not the most appropriate method. However, as a semi-quantitative analysis method, it has the characteristics of rapid, no sample decomposition, and has higher sensitivity and faster analysis speed than DC arc emission spectrum. 52 Full Quantitative Analysis With the research of various combined techniques and calibration methods, ICP-MS technology has gradually shown its advantages in metallurgical analysis and has been rapidly developed. Multi-element simultaneous measurement is its most remarkable feature. GDMS, AES , AAS, ETV-ICP-MS methods, applications and problems in ultra-trace analysis, the determination of U, Th in SiO2, Cu, Co, Al; Matschat et al 48 using HR-ICP-MS to determine high purity 34 kinds of elements in metal Cd, Cu, GaZn, 29 of which are in the absence of matrix or matrix concentration of 2g / L, the detection limit is 6.53. Depth analysis depth analysis is the in-situ state analysis of materials One of the important contents, LA-ICP-MS can not only perform overall sampling, but also can trace specific micro-areas, so it has great application potential in depth analysis. 1992: 193. JarvisKE, Wait. Inductively Coupled Plasma Mass Spectrometry Manual. Beijing: Atomic Energy Press, 1997. Sun Jing, Zhang Hongdu, Zhang Gongyu. Journal of Chinese Mass Spectrometry, 199510 (10): 849.
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