Analysis of the Application Progress in Laser-induced Breakdown Spectroscopy : A Review (Invited)

Laser-Induced Breakdown Spectroscopy (LIBS) shows its application prospects in coal detection, metallurgical analysis, biomedicine detection, water quality detection, and other fields because of its advantages of simple sample preparation, fast, in situ, remote, and all-element synchronous analysis. Therefore, it is known as the"future superstar" of analytical chemistry. With the efforts of researchers around the world, LIBS has developed rapidly in various fields, and significant research results have been obtained, which accelerates its commercialization process. Therefore, we focus on the research progress of LIBS in the past five years in the four fields of coal detection, metallurgical analysis, biomedicine detection, and water quality detection. In terms of coal detection, coal is the cornerstone of the energy system. But pollutants such as soot, sulfur dioxide, and nitrogen oxide emitted by coal combustion have caused great harm to our ecological environment. Therefore, researchers have conducted a series of explorations on the coal's detection, greatly improving the quantitative accuracy and detection sensitivity of LIBS. However, the poor industrial environment can interfere with the accuracy of LIBS analysis results. Therefore, to accurately and stably detect the state of coal combustion and timely guide the process of coal combustion, the research and application of the LIBS online instrument will become the development focus in the field of coal detection. In the aspect of metallurgical analysis, metallurgical technology has improved the national economic development level. But the disadvantages of the traditional metallurgical industry are gradually revealed. Therefore, using LIBS technology to select the good quality of raw materials and realize real-time monitoring is of great significance to reduce environmental pollution. Therefore, we summarized the research status of LIBS metallurgy from these aspects. However, due to the influence of various factors, such as device performance and working conditions, the application of LIBS in the field of metallurgy still faces many challenges. With the development of LIBS and the improvement of optical instrument performances, it will play a huge role in energy saving and emission reduction in the metallurgical industry in the future. In the field of biomedicine detection, as a mature analytical technology, LIBS is playing an increasingly important role in biomedical research. Compared with traditional medical diagnostic technology, biomedical detection based on LIBS has unique advantages such as real-time, rapid, and low cost. But these research results lack the physiological and pathological explanation between the changes in elements and diseases. Therefore, it is necessary to combine LIBS with machine learning and pathology. Similarly, practical biological detection equipment will be the next stage of the future development of LIBS. In water quality testing, with the improvement of urbanization and industrialization, wastewater aggravates the heavy metal pollution in water bodies and even seriously harms human health. Therefore, effective and accurate detection of element content in water is the top priority of water pollution control. At present, researchers have proposed a variety of indirect water quality detection methods, which make it possible to detect water element content quickly, efficiently, and stably. However, the field of LIBS water quality detection is still in the laboratory research stage, and the application of LIBS equipment in direct field detection is rarely reported. Therefore, the establishment of a warning system for heavy metal pollution will become the research focus in the future. In summary, although LIBS has made rapid progress in the above four fields, there are still problems such as poor long- term repeatability, poor quantitative accuracy, and low sensitivity in instrumentalization. With the progress of technology, researchers have gradually shifted their research objectives from scientific problems to applications and promoted LIBS to online monitoring.