What Is Trace Theory?

Trace analysis An analysis method in which the content of the component to be measured in the sample is less than one part per million.

The common methods of trace analysis are described as follows:

Trace analysis is mainly used in the fields of geochemistry, materials science, biomedicine, environmental science, surface science, and evidence analysis.

Trace analysis Trace analysis of lead

Lead is an accumulative poison that is harmful to the human body. It has been recognized that even low doses of lead can cause varying degrees of chronic damage to the body, especially children's nervous system, hematopoietic system, growth and development, etc. due to its accumulation in the body. Therefore, the harm of trace lead is attracting more and more attention, and its analysis technology has been continuously developed, and its methods have become increasingly mature. The analysis of trace lead has been paid more and more attention, the traditional analysis technology has been continuously improved and developed, and new analysis technology has also appeared. Flame atomic absorption spectrometry (FAAS) continues to be the most commonly used position in trace lead analysis. Although anodic stripping voltammetry is simple to use, it has high sensitivity and selectivity for the determination of trace lead, and has been widely used. Attention and research; the online separation and enrichment of samples and the combined technology have greatly improved the selectivity and sensitivity of trace lead analysis, and simplifying the analysis process is still the main direction and hot topic of research. ^[2]

Trace analysis of trace amounts of arsenic

The determination of arsenic includes the determination of various forms of arsenic. In the early days, it was often determined by spectrophotometry. The most common method is the silver salt method and the new silver salt method. The former uses AgDDC-CH3-pyridine as an absorption method; the latter uses NaBH4 to convert arsenic to arsenic hydride, develops color in a nitric acid-polyvinyl alcohol-ethanol system, and determines the difference in absorption wavelength of complexes formed by different arsenic hydrides. content. Measured by general photometry and combined techniques, such as HPLC-ICP-MS. There are many methods for analyzing arsenic species and trace arsenic, but these methods are mostly valence analysis, and there are not many morphological analysis. As far as the analysis objects are concerned, it has involved biochemical samples such as the atmosphere, soil, ore, and blood, and environmental water analysis. At most, from the measurement method, there is no method that can identify various forms at the same time. The ICP-MS method has high sensitivity, but it is expensive and not available in general laboratories. The future tasks of the analysts are to further study the efficient separation techniques that can achieve various arsenic species and the analytical methods for the determination of ultra-trace arsenic species with high sensitivity and high selectivity. ^[3]

Trace analysis Trace analysis of vanadium

Vanadium is widely distributed in nature, and the total content in the earth's crust ranks 22nd in the metal, about 0.02%-0.03%. Vanadium is mainly found in rock minerals, and trace amounts of vanadium are found in steel, silt, wastewater, food and even human hair. With the continuous development of society, people's understanding of vanadium is getting deeper and deeper. First, vanadium is biologically active and is one of the trace elements necessary for the human body. However, excessive vanadium in the body can stimulate the respiratory, digestive, and nervous systems, and can also damage the skin, heart, and kidneys. It can also inhibit the activity of adenosine triphosphate and phosphatase, causing skin inflammation and causing allergic diseases. The vanadium content in natural water is very low, about 1-10 g / L, and it does not cause toxic effects on humans, animals and plants. Secondly, vanadium can be used to make a variety of alloys. Adding a very small amount of vanadium to the alloy can significantly change its properties. It is called the "vitamin" in the alloy. Vanadium is often used as an additive for alloy steel and as a catalyst in the chemical industry. Therefore, industrial wastewater such as steel, petroleum, chemical, dyes, textiles, ceramics, photography, electronics and other industrial waste water contains a large amount of vanadium and often causes pollution. With the continuous improvement of people's living standards, more and more attention is paid to the impact of trace vanadium on human physical and mental health. The biological activity and toxicity of vanadium are determined by its concentration and the chemical form in which it exists, while its nutritional value and toxicity differ only by a small concentration range. Therefore, the determination of vanadium content and chemical form plays an important role in vanadium chemistry. Therefore, it is of great significance to accurately determine trace vanadium in water, food, pharmaceuticals, living organisms and other samples.

In recent years, with the synthesis of new analytical reagents, the establishment of new analytical systems, and the development of new analytical testing techniques, vanadium determination methods have their own characteristics. Spectrophotometry, fluorescence, chemiluminescence, polarography, stripping voltammetry, high performance liquid chromatography, atomic spectroscopy, and mass spectrometry. Nevertheless, most methods for the determination of vanadium remain in laboratory research and rarely applied as practical methods in specific fields. From the development of life sciences, environmental sciences and materials sciences, it is of theoretical and practical significance to establish a new method for the determination of vanadium with high sensitivity, selectivity and reproducibility. The development trend of measurement methods mainly has the following aspects:

(1) Development of combined technology for the determination of vanadium. However, this method is expensive in terms of equipment and equipment, and has high analysis costs, and there are few reports in China.

(2) Develop efficient and fast on-line separation technology to determine vanadium.

(3) Automation of the detection reaction process. The combination of flow injection analysis, catalytic kinetics, and chemiluminescence analysis can not only improve the analysis speed, but also improve the measurement sensitivity, which may bring new vitality to the determination of vanadium. This method has been reported in many countries. ^[4]