The so-called atomic absorption spectrometry (Atomic Absorption Spectroscopy) is also called atomic absorption spectrophotometry, usually referred to as atomic absorption spectrometry (AAS). The founder of atomic absorption analysis methods and instruments is Australian scientist Walsh. In 1955, he proposed the physical basis and chemical practice of chemical analysis of elements using atomic absorption phenomena and creatively used hollow cathode lamps as practical sharp-line light sources, overcoming technical difficulties and laying a solid foundation for the development of atomic absorption instruments. The analytical method he advocated at that time was mainly flame atomic absorption technology. The basic principle is: a beam of incident light of a specific wavelength is emitted from a hollow cathode lamp or light source, and the ground state atomic vapor of the element to be measured in the atomizer absorbs it, and the unabsorbed part is transmitted. By measuring the amount of light absorbed at a specific wavelength, the content of the element to be measured is determined.
The quantitative relationship of atomic absorption spectrometry can be expressed by Lambert-Beer's law A=abc. In the formula, A is the absorbance, a is the absorption coefficient, b is the optical path length of the absorption cell, and c is the concentration of the measured sample. This method has the characteristics of high sensitivity and precision; good selectivity and less interference; fast speed and easy automation; many measurable elements and wide range; simple structure and low cost. Because of this, the development of this method has also been considerable. fast. The instrument used in atomic absorption spectrometry (AAS) is an atomic absorption spectrometer or an atomic absorption spectrophotometer. The atomic absorption spectrometers currently seen in China can be roughly divided into two generations according to the level of technological development:
The first generation: single flame atomic absorption spectrometer (Hitachi Z500, Shen Branch Factory WYX-9004 , Huayang's AA2610, Bohui's BH5100 series, Beijing East-West Analytical Instrument Co., Ltd.'s early single flame type, etc.)
Second generation: flame atomic absorption spectrometer with external graphite furnace (Hitachi's Z180-80 , Rayleigh's WFX120A, Bohui's BH2100 series, Puji's TAS990, etc.). Its design purpose is to make up for the shortcomings of insufficient sensitivity of flame absorption spectrometers and to cater to the upgrading and transformation needs of early domestic customers. The measurement of blood lead is an old topic in epidemic prevention departments and a new topic in hospitals and maternal and child health departments. Blood lead testing in children is a hot topic. If you take more blood, digest it in the usual way and use an instrument to measure it, it is not troublesome. But if you only take a trace amount of 20-40ul blood for measurement, it will be a problem. For some groups, such as children's blood lead census, it is difficult to take more blood. , when there are many samples, conventional digestion methods are needed to process the samples, which is troublesome and easy to contaminate the samples. Therefore, a fast, simple, sensitive and accurate analysis method is needed.
There are sensitive and accurate methods for measuring blood lead, such as plasma mass spectrometry, but this instrument is too expensive and cannot be equipped in general laboratories.
Then there is the commonly used atomic absorption method. Its characteristics of less blood collection, high precision, simple operation and fast speed have been recognized by the market and have become the mainstream product for lead detection. It is recognized that graphite furnace atomic absorption has Zeeman effect background correction, and the manufacturers include (Hitachi's Z180-80, Rayleigh's WFX120A, Bohui's BH2100 series, Puxi's TAS990, etc.).
The second is the electrochemical method. As a mid-to-low-end product, the electrochemical method was widely used in the 1990s. Due to problems with the technical means, the results of electrochemical instruments using hair samples to detect blood lead were Inaccurate use banned in many areas. Newer models of instruments have also begun to use peripheral blood as test specimens, but they have not been recognized by the mainstream market because the results are too biased and unstable. It is only used as a low-cost blood lead determination method in remote areas and basic health centers. Electrochemical trace elements and analyzers are positioned in the mid- to low-end market. In the medical industry, it is mainly positioned at medical institutions below the county level, such as hospitals, disease control, maternal and child health hospitals, traditional Chinese medicine hospitals, etc.
The majority of rural hospitals are still the main force in the application of trace element analysis instruments, and more avant-garde private individual hospitals are also joining the ranks.
The geological and mining departments are traditional users of electrochemical polarographs.
Agrichemicals have certain market demand because some methods for detecting trace elements in soil are listed as national standards.
Enterprise physical and chemical inspections are potential customers of electrochemical trace element analysis instruments.
University scientific research departments, school teaching and scientific research departments all have certain quantitative needs, but the overall demand is not large.
Health care products and drug dealers are an emerging user group. Before 2002, the main market for trace element analyzers was physical and chemical testing at epidemic prevention stations. The entire market capacity is very limited, with only individual users in hospitals and sporadic users in universities. Since SARS in 2002, driven by the sales of lead-removing health products and zinc, iron, and calcium supplements, trace element testing in hospitals has begun, and instrument sales have rapidly heated up. Due to the huge number of hospital units, sales increased dramatically once it was launched. The number of instruments sold in the national market has quickly reached 4,000-5,000 from less than 200 units. and continue to develop.
The pediatric health care departments of county-level hospitals have begun to popularize trace element testing. In particular, county-level maternal and child health hospitals have become high-quality users of trace element testing instruments. And in some areas with good economic development, trace element testing has been listed as a routine physical examination item for children aged 0-6 years old, which has great development potential. (1) First, the medical system reform is launched, and the government will increase investment in basic public health networks.
(2) In 2007, the coverage of the "New Rural Cooperative Medical Care" pilot program will be expanded to 60% of the total counties (cities, districts) in the country. It will be basically implemented nationwide in 2008 and will basically cover rural residents in 2010. Target.
(3) "Medical reform" has enhanced the potential of the mid- to low-end market. According to an authoritative survey report, about 15% of the medical instruments and equipment owned by 175,000 medical and health institutions across the country were produced around the 1970s. Of the products, 60 were produced before the mid-1980s. This also indicates that they need to be updated, and in this process, the rapid growth of China's medical device market will be guaranteed in the next 10 years or even longer.