Application of AA-1800 atomic absorption spectrometry in the field of environmental analysis - Database & Sql Blog Articles

Application of AA-1800 Atomic Absorption Spectrometry in the Field of Environmental Analysis

Key words: atomic absorption spectrometry; environmental analysis; analysis instrument ; AA-1800 atomic absorption spectrometry basic principle, combined with examples to introduce its application in the field of environmental analysis, and a simple analysis of the current stage The insufficiency and development trend of atomic absorption spectrophotometry, atomic absorption spectrometry, also known as atomic absorption spectrophotometry, referred to as atomic absorption method, is an effective method for the determination of trace and ultra-trace metal elements. Atomized metal elements and a small amount of non-metallic elements. The paper published in 1955 by Australian physicist Walsh "Atomic Absorption Spectroscopy in Analytical Chemistry" laid the foundation for the rapid development of atomic absorption spectrometry. At present, it can measure more than 70 kinds of elements, and the measurement is accurate, fast, sensitive, selective, strong anti-interference ability, simple instrument and equipment, easy to operate, and has wide application in chemical, biological, environmental and other fields. Fundamental Principles of Absorption Spectroscopy Atomic absorption spectroscopy is based on the ground state of the element to be tested in the vapor phase of the sample. The absorption of the characteristic line of the atom is used for quantitative analysis of the element. The basis of quantitative analysis is in accordance with Beer's law A=k'c), that is, under certain experimental conditions, the absorbance is proportional to the concentration. 2 Atomic absorption Quantitative methods for spectral analysis commonly used quantitative analysis methods are: standard curve method, standard addition method. 2.1 standard curve method using a standard substance to prepare a suitable set of standard solutions, from low to high concentration once the standard solution absorbance Ai i = 1 , 2,3,4,5...) is the ordinate, the concentration of the element to be tested Cj j=1, 2, 3, 4, 5 ...) is the abscissa, and the AC standard curve is drawn. Under the same measurement conditions, the measurement is to be performed. The absorbance value Ax of the test sample solution is obtained from the standard curve to obtain the concentration cx of the measured element in the solution to be tested. From the viewpoint of the photometric error, the photometric error is small between 0.1 and 0.5. The concentration range of the standard curve should be selected such that the absorbance is between 0.1 and 0.5. In order to ensure the accuracy of the measurement results, the composition of the standard solution should be as close as possible to the composition of the sample solution. 2.2 Standard addition method The measured elements in the element are very The matrix composition is complex. When it is difficult to prepare a standard solution with similar sample composition, the standard addition method can be used, which can automatically perform matrix matching, compensate the physical and chemical interference of the sample, and improve the accuracy of the measurement. First measure a certain volume of test solution ( C) absorbance A? Then add a certain amount of standard solution similar to the unknown test solution concentration in the test solution, the absorbance measured by Cs is A, then Ax=k'cx; A=k' (cx+ Cs). Take a number of test solutions cx) of the same volume, and sequentially add different amounts of the standard solution (Co.) of the test substance. The concentration after constant volume is: X, CX+C0, CX+2C0, CX +3C0, Cx+4C0..., respectively, the absorbance is measured as: AX, A1, A2, A3, A4.... A is plotted against the concentration C. The Cx point in the figure is the concentration of the solution to be tested. 3 Atomic absorption spectroscopy The application of environmental analysis in environmental analysis is based on the chemical substances in the environment, which are complex in composition, various in variety, low in content and poor in stability. Atomic absorption spectroscopy is a relatively mature analytical method, mainly used to determine each Micro-trace metal elements in the sample. 3.1 Water quality analysis for sewage There are many inorganic and organic substances in mineral water, such as mineral water, and the situation is complicated. Generally, separation methods such as extraction method and ion exchange method are used together with the calibration addition method to mainly measure metals such as lead, copper, chromium, cadmium and mercury in water. Ma Xiaoguo Determination of trace cadmium in environmental water samples by liquid-liquid microextraction-graphite furnace atomic absorption spectrometry. The experiment shows that the method is sensitive, accurate, rapid and environmentally friendly. It is a method for analyzing trace cadmium in water samples. Better method. The atomic absorption method can also analyze the morphology and valence state of the element. For example, the organic mercury and inorganic mercury in the river water can be separately determined by the cold atomic absorption method; the ambient water can be separately determined by the atomic absorption method using the generator system. Valence arsenic in the sample, etc. 3.2 Soil and sediments Determination of molybdenum in soil by flame atomic absorption spectrometry. Determination of chromium and lead in soil and offshore sediment standards by microwave digestion-atomic absorption spectrophotometry Heavy metals such as cadmium. Determination of Cu, Zn, Pb, Cd, Cr and NI in soil by microwave digestion-atomic absorption spectrophotometry. The experimental results show that the method is used to analyze soil. In the above six elements of the standard sample, except for the individual elements in the individual samples, the measurement results are basically consistent with the guaranteed values, and the repeatability is good, which is suitable for the routine analysis and research of metal elements in the soil. The heavy metal pollution in soil was studied by microwave digestion and flame atomic absorption spectrophotometry. The contents of four heavy metals in Cu, Zn, Pb and Cr were determined. Jing Lijie et al. pretreated the soil to be tested by microwave digestion. Flame atomic absorption spectrophotometry was used to determine five heavy metals such as zinc, copper, lead, cadmium and chromium in contaminated soil digestion solution. Experiments show that the method is simple, sensitive and accurate, and is suitable for the determination of heavy metals in contaminated soil. When the particulate matter is determined by atomic absorption method to determine trace elements in the atmosphere or fly ash, an atmospheric sampler is needed, and then the digestion system and the basic improver are selected according to the specific elements. At present, the atomic absorption method has been used to analyze ambient air and industrial waste gas. And heavy metal elements such as mercury, copper and cadmium in atmospheric particulates, and the results are highly accurate and accurate. Atomic absorption such as Tao Tao Spectrophotometric determination of heavy metals in atmospheric particulates showed that the HNO3-HC 104 digestion system was easy to operate and the sample digestion was complete. The accuracy and precision of the results were high. Ye Qianhui et al. used transmission electron microscopy and flame atomic absorption spectrometry. The total suspended solids in the atmosphere were determined by flame atomic absorption spectrometry for the water-soluble conventional elements K, Na, Ca and Mg. The relative standard deviation of the determination results was 0.6% -2.1% n=6). Spectrophotometric determination of cadmium in atmospheric particulates, the relative standard deviation of the determination results is 2.1% -7.5%, the detection limit is 0.366 μg / L, the method is suitable for the determination of cadmium in the atmosphere and stationary pollution source exhaust. 4 At present, atomic absorption spectroscopy has become a relatively mature instrumental analysis method, but there are still some shortcomings at this stage, mainly as follows: (1) Simultaneous analysis of multiple elements cannot be performed. Different elements must be replaced. 2) It is not possible to measure the elements of the resonance line in the vacuum ultraviolet region, such as phosphorus, sulfur, etc.; 3) the linear range of the standard working curve is narrow, in the determination of high background and low content samples, Density decline. There are problems. In recent years, many experts at home and abroad are also working on new technologies to improve the sensitivity of the measurement. For example, the application of laser in atomic absorption analysis, using a tunable laser instead of a hollow cathode lamp source, Sample atomization. The application of this method will provide new methods for micro-area and thin film analysis, and provide a new method for atomization of refractory elements. The application of Zeeman effect enables smooth implementation in a high background. Determination. The establishment and application of new methods will allow atomic absorption spectroscopy to achieve faster development and wider application.