Top ten technologies for rapid detection of toxic

2022-08-05
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Ten technologies for rapid detection of toxic and harmful substances

the correct detection of toxic and harmful substances is very important in the emergency rescue of chemical accidents, especially for those toxic and harmful chemicals that are difficult to determine after chemical accidents, it is more meaningful to find out the types of poisons. According to the data provided by Jane's nuclear, biological and chemical protection Yearbook (2001 Edition), there are currently ten technologies for rapid on-site detection of toxic and harmful substances in the world, namely:

ionization/ion mobility spectrum technology the detector used by ion mobility spectrum technology is a typical continuous working detector, which uses an air pump to take samples from the environment to further meet the refined needs of market customers, The collected pollutants pass through a weak electric field in the ionization detector and are ionized. Ionization of gaseous poisons can be realized under atmospheric pressure. Almost all toxic and harmful substances can be ionized by proton migration, charge migration, dissociation charge migration or negative ion reaction such as ion migration spectroscopy

flame photometric detection technology this technology is based on the principle of hydrogen flame combustion. The flame can decompose any toxic and harmful substances in the air. The toxic and harmful substances containing phosphorus and sulfur produce hydrogen, phosphorus, oxygen (HPO) and elemental sulfur respectively. When raising the flame temperature, phosphorus and sulfur emit light of special wavelength, which is transmitted through ideal filters. The light emitted by phosphorus and sulfur is transmitted to the photomultiplier tube, which generates an electrical signal of similar substances. This electrical signal has a direct relationship with the concentration of phosphorus and sulfur compounds in the air, and can also improve and improve the qualification rate of products. It can be seen that as long as the compounds containing phosphorus and sulfur can be detected by flame photometry, a layer of transparent pseudo hydrophilic film with certain physical properties can be coated for measurement. Flame photometry is very sensitive, so it allows the instrument to directly sample and analyze the ambient air. However, the disadvantage of this method is that as long as there is phosphorus and sulfur in the ambient air, it will cause interference and false alarm. In order to reduce the interference in detection, the use of flame photometric detector in gas chromatography technology will greatly reduce the occurrence of false alarm

infrared spectroscopy technology this technology is used to measure the intensity of infrared light absorbed by the sample in a specific wavelength range (4000~200 cm). The wavelength of the infrared absorption band has very obvious characteristics, and each molecule has a unique infrared spectrum. The characteristic peaks of molecular structure can be analyzed by infrared spectroscopy, and unknown toxic and harmful substances can be detected. At present, two kinds of infrared spectroscopy technology have been applied to the field rapid detection instruments. One is photoacoustic infrared spectroscopy technology. Photoacoustic infrared detector uses photoacoustic effect to monitor and determine the vapor of toxic and harmful substances. When a gas absorbs infrared radiation, it will cause temperature rise and gas expansion. If the intensity of infrared radiation is adjusted, the sample will expand and contract. If audio is designed, microphone can be used to transmit sound signal. The photoacoustic infrared gas detector uses different filters to selectively transmit specific light wavelengths absorbed by the primary substance of the monitored toxic and harmful substances, and uses relatively large wavelength signals to identify unknown compounds. When there are no toxic and harmful substances in the air sample, there will be no infrared absorption peak with special wavelength, so the audio signal can not be detected. When there are toxic and harmful substances in atmospheric samples, audio signals will be generated by adjusting the absorption of infrared light. If the sample continuously absorbs infrared light of different wavelengths, the selectivity will be greatly increased, that is to say, when several wavelengths of light pass through the sample continuously, the poison can be distinguished from the interfering substance

electrochemical detection technology electrochemical detector detects the potential change of solution or film absorbing toxic and harmful substances. The inhibition of cholinesterase by toxic and harmful substances is the most typical example. In the solution containing a known amount of cholinesterase, if there are toxic and harmful substances, the inhibition percentage of cholinesterase is proportional to the toxic and harmful substances. The concentration of toxic and harmful substances can be determined by using this relationship. Another electrochemical detector is used to detect the resistance value of the film. The resistance value of the film that absorbs toxic and harmful substances will increase. Therefore, they are not as sensitive as ion mobility spectrometry and flame photometry, and are also greatly restricted by environmental factors. The change of temperature will change the reaction speed and the equilibrium point of different reactions, thus affecting the sensitivity and selectivity of the reaction

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