he masses and their relative content (concentration) is called the mass spectrum. Mass spectroscopy uses a vacuum separation of ions of different masses under the influence of electric and magnetic fields. Therefore, the investigated substance, firstly, is subjected to the process of ionization (Price & Phil 1991). The process of ionization is excluded the study of ionic structure already ionized gases, such as electrical discharge in the ionosphere or planets. In the case of liquid and solid substances they are pre-evaporated and then ionized. Mostly the positive ions are researched, because the existing methods of ionization allow receiving them in a more direct way and in larger quantities than negative. However, in some cases tested and negative ions (Schwartz, Michael, Senko, John, Syka, 2002). The first mass spectra were obtained in the UK by JJ Thomson and F. Aston. They led to the discovery of stable isotopes. Initially, mass spectroscopy was used primarily to determine the isotopic composition of elements and precise measurement of atomic masses (March, 2000). Now mass spectrometry is one of the main method by which can be obtained the data of the masses of nuclei and atomic masses of elements (Rena, Sowell, Koeniger, Valentine, Moon, Clemmer, 2004). The variations of the isotopic composition of elements can be determined with relative error В± 10-2%, and mass nuclei - with a relative error В± 10-5% for light and В± 10-4% for heavy elements (Gothard, Busst, Branthwaite , Davies, Denison, 1980). The accuracy of quantitative molecular analysis achieves with the precision isotopic analysis, but quantitative molecular analysis often is difficult because of the equality of masses of different ions that are formed by ionization of different substances. To overcome these difficulties the "soft" ionization methods are used, which give little fragmentation of ions (Price & Phil, 1991). Sum up, the molecular structural mass spectral analysis is based on the fact that the ionization of molecules of some substance is converted into ions, having been not destroyed, and some parts thus divided into fragments. Measurement of mass and relative content of molecular and fragmentation ions (molecular mass range) provide information not only on molecular, but also on the structural level.
of the uses in forensic analysis
Infrared Analysis and Mass Spectrometry are widely used in forensic analysis.of all, photographing in infrared rays allow to detect the soot of shots in dark tissues, where it is visually hard to observe. With help of such method it can be set some details of the object that is filled with blood, without removing them. By the way, the imagein the infrared rays can be observed visually by means of electron-optical converter (EOC). For example, while analyzing the clothes, soaked with blood, in cases of gunshot injuries, using infrared rays can be detected many additional factors under a layer of blood shot (soot from the combustion of gunpowder) (Price & Phil, 1991). The method is quite effective, does not affect the object and also allows reliably documented by photographing the result of research. Using infrared it can be easily detected the traces, suspicious for the presence of blood, semen, mineral oil (eg oil residues around the entrance gunshot hole or where contact with body parts of vehicles in road traffic accidents). Thus, the usage of infrared gives lots of advantages in the leading investigation. Firstly, this non-destructive method, allows to get the examples of the materials saving all the shapes and structures. Secondly, it provides the accurate measurements that do not require external calibration. Finally, it is easy in exploitation and provides the fast results, defines the things that can `t be gathered in the natural way. Mass spectrometry used a vacuum separation of ions of different masses under the influence of electric and magnetic fields. Therefore, the investigated substance is firstly subjected to the process of ionization. The process of ionization is excluded in the study of ionic structure of already ionized gases, such as electrical discharge in the ionosphere or planets. In the case of liquid and solid substances, they are pre-evaporated and then ionize. Often the positive ions are investigated, so that existing methods of ionization can receive them no more direct way and in larger quantities than negative. However, in some cases tested and negative ions. This method are used to make the expertise of the little pieces, that can `t be defined it the natural environment. The example can be the blood, pieces of skin and nails, drugs and even the pieces of dandruff., The introduced methods give lots of advantages in the leading investigation. Firstly, these are non-destructive methods. They allow to get the examples of the materials saving all the shapes and structures. ...
