analytical chemistry

Analytical chemistry is the science of researching the composition, state, structure, and methods and principles for determining the content of constituents. It is an important branch of the chemistry discipline. Analytical chemistry plays an important role not only in the development of the chemical discipline itself, but also in all fields related to chemistry. It can be said that any human practice involving chemical phenomena is inseparable from analytical chemistry. Nowadays, many different analytical methods have been developed, which can be classified according to analysis tasks, analysis objects, analysis basis, analysis requirements and sample dosage. According to the analysis tasks, it can be divided into qualitative analysis, quantitative analysis and structural analysis. The task of qualitative analysis is to identify which elements, groups of atoms, functional groups or compounds are composed of substances; the task of quantitative analysis is to determine the content of the relevant components in the substance; the task of structural analysis is to study the molecular structure or crystal structure of the substance. (1) According to the analysis object, it can be divided into inorganic analysis and organic analysis; the object of inorganic analysis is inorganic matter, and the object of organic analysis is organic matter. In inorganic analysis, it is usually required to identify which elements, ions, atomic groups or compounds are composed. The percentage of each component is determined, and sometimes the crystal structure is determined. In organic analysis, not only the constituent elements are required to be identified, More importantly, analysis and structural analysis of functional groups are required. (2) According to the physical or chemical properties of the material, it can be divided into instrumental analysis and chemical analysis. According to the specific requirements, it can be divided into routine analysis, rapid analysis and arbitration analysis. Routine analysis refers to the analysis in the daily production of general laboratories, also known as routine analysis; rapid analysis is a kind of routine analysis, mainly used for the control of production processes, requiring the results to be reported in the shortest possible time, analysis error Generally, the arbitral analysis is that when different units have arguments about the analysis results, the relevant units are required to perform accurate analysis using the specified method to judge the accuracy of the original analysis results. (3) According to the dosage of the sample, it can be generally divided into constant (>0.1g), semi-micro (0.01～0.1g) and trace (1～10mg). (4) In the inorganic qualitative chemical analysis, the semi-micro method is generally used, and in the quantitative chemical analysis, the constant analysis method is often used. The relative amounts of the components analyzed in the sample were roughly divided into a constant component analysis (>1%), a trace component analysis (0.01 to 1%), and a trace component analysis (<0.01%). The analysis of many complex mixtures and trace or trace components in some materials requires separation and enrichment. This has resulted in a range of separation techniques such as extraction, distillation, ion exchange, chromatography, precipitation and flotation separation, which are integral parts of analytical chemistry. [Environmental Analytical Chemistry] Environmental Analytical Chemistry, referred to as environmental analysis, is a discipline that studies the types and components of pollutants in the environment and how to conduct qualitative and quantitative analysis of chemical pollutants in the environment. It is a branch of environmental chemistry. Environmental analytical chemistry is produced, developed, and refined when solving environmental problems. In the 1950s, the public plagues in Japan had alarmed the world. In order to find the cause of pain, it has been 11 years. Later, environmental analysis chemists used spectroscopy to check that the river water in the ward contained harmful elements such as lead, cadmium, and arsenic, and then used elemental tracking to analyze the soil and food in the ward, and found that the content of lead and cadmium was high. . Later, the quantitative analysis of the bones of patients with pain and pain was carried out, and the contents of zinc, lead and cadmium in the ashes were surprisingly high. In order to determine the causative factors, zinc, lead and cadmium were separately fed into the feed to feed the animals, and elemental tracking analysis was carried out on the animals to confirm the serious harm of cadmium to bones, and the cause of pain and pain was uncovered. The development of modern science, especially the development of modern chemistry, physics, mathematics, electronics, biology, as well as the emergence of accurate, reliable, sensitive, selective, fast, and simple environmental pollution analysis techniques and automated instruments, leading to environmental analytical chemistry The sun is ripe. Environmental analytical chemistry has now penetrated into all areas of environmental science and is the most effective means of obtaining environmental quality information. The objects of environmental analytical chemistry research are quite complex, including the atmosphere, water, soil, sediment, minerals, waste, animals, plants, food, human tissue and so on. The content of the contaminating element or compound determined by the Environmental Analytical Chemistry is very low, and the absolute content thereof is often at a level of 10-6 to 10-12 g. Analytical techniques for environmental analytical chemistry are moving toward continuous automation, computerization, and the combined use of multiple methods and instruments. The automatic analysis methods currently used include colorimetric analysis, ion selective electrode, x-ray fluorescence spectroscopy, atomic absorption spectroscopy, polarography, gas chromatography, liquid chromatography, and flow injection analysis. Laser has been applied as a light source technology for analytical chemistry. Laser technology plays a key role in the development of environmental analytical chemistry due to its high resolution, high sensitivity, long distance and short time. With the development of environmental science research in depth, environmental analytical chemistry often requires detection and analysis of trace and ultra-trace levels. Therefore, research on high sensitivity, selectivity, and rapid trace and ultra-trace analysis methods. It is the main direction for the future development of environmental analytical chemistry. [Qualitative Analytical Chemistry] Qualitative analytical chemistry is the science of determining the elements or constituents of a sample. A branch of analytical chemistry. The purpose of the study is to determine the chemical composition of the subject (sample). The main contents of qualitative analytical chemistry research are: 1 Separate samples for analysis. That is, take a part of the sample and use the exclusive reaction to detect any one of the components to be detected. 2 Perform a systematic analysis of the sample. That is, several selective reactions are sequentially applied to gradually separate the ions, and then each group is separated until it is separated into only one substance, and finally a confirmatory reaction is taken to confirm the substance. The most famous cation system analysis is the H2S system method. In recent years, due to the use of selected instruments, qualitative analysis has developed as rapidly as variable analysis, and has become an important direction of analytical chemistry.