At present, all levels of medical and health care units in China, especially maternal and child health care units, children's hospitals, general hospitals, etc., have taken the detection of human elements (lead, zinc, copper, calcium, magnesium, iron, etc.) as routine items. The methodology of trace element detection is introduced below.
1. Traditional methods for detecting trace elements.
At present, the methods that can be used to detect trace elements in human body include: radionuclide dilution mass spectrometry, molecular spectrometry, atomic emission spectrometry, atomic absorption spectrometry, X-ray fluorescence spectrometry, neutron activation analysis, biochemical analysis and electrochemical analysis. But the methods widely used in clinical medicine are mainly biochemical method, electrochemical analysis method and atomic absorption spectrometry. The following briefly introduces the main characteristics of biochemical method and electrochemical analysis method.
(1) The characteristics of biochemical method are: the blood consumption of samples is large, which requires pretreatment, complicated operation and takes a long time to clarify serum; The influence of recent diet on the detection of serum makes the data lack of objective accuracy; The cost of reagents is high, and the types of detection elements are limited.
(2) Characteristics of electrochemical analysis: it can be used for trace measurement, but the error is large; When determining various elements, the repeatability is poor; Serious pollution to the environment and laboratory personnel; Pretreatment is extremely complicated and time-consuming; Experiments are sometimes difficult to control and the results are often unstable.
2. Atomic absorption spectrometry.
the so-called atomic absorption spectrometry (AAS), also known as atomic absorption spectrometry, is usually referred to as atomic absorption spectrometry. Its basic principle is that a beam of incident light with a specific wavelength is emitted from a hollow cathode lamp or light source, which is absorbed by atomic vapor in the ground state of the element to be measured in an atomizer, and the unabsorbed part is transmitted. The content of the elements to be measured can be obtained by measuring the amount of light absorbed at a specific wavelength. The quantitative relationship of atomic absorption spectrometry can be expressed by Lambert-Beer law and A-abc. Where, a is absorbance, a is absorption coefficient, b is optical path length of absorption cell, and c is concentration of sample to be measured. This method has high sensitivity and accuracy. Good selectivity and less interference; Fast speed and easy to realize automation; Many measurable elements and wide range; Simple structure and low cost.
after the birth of atomic absorption spectrometry in p>1955, it was quickly applied to various fields of analytical chemistry because of its strong vitality. The domestic large-scale application began in the 199s, and the most widely used ones were metallurgy, geological exploration, quality supervision, environmental detection, disease control and so on. Atomic absorption spectrometry is regarded as the "gold standard" in the Center for Disease Control. With the development of clinical medicine, atomic absorption spectrometry has been widely used to detect trace elements in clinical practice.
atomic absorption spectrometer can be divided into flame atomic absorption and graphite furnace atomic absorption according to different atomization methods. Atomic absorption in graphite furnace needs instantaneous large current, which requires the system to have high anti-interference ability. With the development of science and technology, the world's major manufacturers have begun to realize a completely integrated design, integrating all the components of spectroscopic detection system, flame, graphite furnace and heating and electric heating into the same instrument body, and realizing the free conversion between flame and graphite furnace.
3. the method of TH-AAS.
this method is characterized by integrated flame and built-in graphite furnace, which can be switched freely. One device can detect lead, zinc, copper, calcium, magnesium, iron and other elements in blood. The sample pretreatment process is simple, less sampling, less pollution, rapid detection and good accuracy. Just add trace blood to the reagent, and it can be detected on the computer, so that trace elements such as lead, copper, zinc, calcium, magnesium and iron can be tested in trace blood.