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Ion Mobility Spectrometry

Ion Mobility Spectrometry How to identify minute quantities of matter ? The specialists IC ” Birüch ” developed an efficient device, which works based on the method of ion mobility spectrometry (Ion Mobility Spectrometry – IMS). Devices that operate on this principle , have a number of advantages: the analysis takes only a few seconds , low power consumption , in addition, portable devices can do . The sensitivity of this device is large enough : it allows to determine the content of a substance even at 1 molecule per trillion ( 10 ¹ ²) surrounding air molecules ( such concentration is denoted as 1 ppt). Thanks to these properties, the device can be used for rapid and reliable detection of trace explosive , poisonous, narcotic substances. For example, the packaging into which wrapped explosive inevitably has on its surface a number of substances in the ambient air creates a certain concentration of vapors. Even sealed plastic packaging is not an obstacle for getting trace amounts of vapors into the air. Trace amounts of substances remain on fingers and clothes of any person working with explosives. These concentrations is sufficient for reliable detection device. By far the most sensitive detector of explosives and narcotics have been specially trained dogs . However, such “live detectors ” can ” turn off ” at any time – it’s living creatures. Ion mobility spectrometers are inferior dogs in sensitivity , but operate smoothly and provide an objective evaluation of the object . In addition , the spectrometer provides information not only on the availability of explosives , but also determines its type , which is a unique feature of the method . Scope spectrometers is not limited to finding explosives, toxic and narcotic substances . Devices with high sensitivity and speed can be used in various industries . In the food industry spectrometers can be used to check the quality of the product . Traditionally used for such control organoleptic evaluation method – tasters evaluate products , but the result depends essentially on the experience of experts and may not exclude subjective factors. Application of ion mobility spectrometry allows for an objective monitoring system parameters and evaluate the quality of products, due to the fact that gives full quantitative information product. Application of ion mobility spectroscopy opens up new possibilities for medicine . In today’s world a lot of attention is paid to problems of early diagnosis of human diseases. High sensitivity spectrometer allows to identify the slightest changes in health status , so-called biomarkers contained in the exhaled air and in vivo human excreta . For example, the known possibility of effective determination of acetone in exhaled air – a biomarker of diabetes. In combination with a short analysis of the results , this method will allow for quick and efficient diagnosis of the state of health and to detect the presence of the disease in the early stages of the disease . It can be used in the aftermath of disasters and natural calamities . Detection sensitivity of the device provides a living person on the results of functioning of the body ( in particular, lactic acid ) . Due to this the emergency services to quickly find survivors under the rubble . High speed, sensitivity of the device you can use it to control various processes . Ekspertsnost analysis makes it possible to incorporate such devices into the automation system as sensitive sensors. On what is this based efficiency ion mobility spectrometry ? The bottom line is that the ionized molecule of any substance has a strictly defined mobility in a weak electric field. Measuring the ion mobility , can identify molecules of different substances . Measurement of ion mobility (getting spectrum) consists of the following stages: Ionization of molecules of a test sample ; Ion drift in the flow of neutral gas under the influence of an electric field ; Determination of the ion drift detector molecules by registration , recording the ion current . For ionization of molecules , radioactive isotopes can be used , ultraviolet radiation , corona discharge, laser radiation , surface ionization. Ion drift in the flow of neutral gas under the influence of an electric field allows you to divide the ions along the drift direction according to their mobility. Different types of ions reach the detector at different times and form ion spectrum of the test substance . Opportunities IMS spectrometer can be significantly enhanced by using compact polikapilyarnyh chromatographic columns . Test sample in the first stage is flagged column , where the preliminary separation of substances by gas chromatography. In the second phase previously separated molecules fall within the IMS spectrometer , where it is their detection. Such a combination of the two methods in one instrument allows you to get a much better separation and identification of substances , which is especially important in the study of multi-component mixtures . Along with IMS exists fundamentally different method – ion mobility spectrometry increment (differential ion mobility spectrometry, DIMS). Method is based on the nonlinear dependence of ion mobility on the electric field . Preparation of analyte spectrum DIMS spectrometer consists of the following stages: Ionization of molecules of a test sample ; Ion drift in the flow of neutral gas between the capacitor plates , which are attached to the high asymmetric polarity signal and compensating (scan ) field ; Measurement of ion current detector. For ionization of molecules using the same methods as in the IMS spectrometers. Capacitor plates can be as flat parallel plates , and coaxial cylinders . For each type of ions there is a combination of high- and compensating fields for which the effective trajectory of its motion is parallel to the capacitor plates , causing it to reach the detector and be registered. Other ions will not reach the detector and will be discharged on the capacitor plates . The spectrum in this case is a plot of ion current at the detector of the value of the offset voltage . Our company is working on the creation of ion mobility spectrometers . Created layout DIMS spectrometer , whose key characteristics comparable to those of the best units produced in series . The theoretical description of the processes occurring in the ion drift , and the calculation of the electric fields in the device allowed to determine the optimal design of the instrument , which intelligently combines high resolution, sensitivity, compact size, the basic elements and low power consumption . Selection of the optimal design of the drift tube , the use of modern technical solutions in the construction of the control electronics , the use of a powerful mathematical apparatus for processing spectra obtained allows to develop an apparatus with high resolution and sensitivity . The unique combination of speed , sensitivity and ability to detect a wide range of materials opens the possibility of using ion mobility spectrometry in a variety of fields.

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