Technology of ion mobility spectrometry is a well-known method of modern analytical highly sensitive equipment. This technology has grown out of specialized fields of science, connected with safety, for raising of productivity and mobility of analytical devices, used both in scientific research and a wide range of applications, including medicine and control of product quality.

Currently the technology of ion mobility spectrometry is one of the most sensitive analytical methods, which is used mainly for detection of ultralow doses of explosives and drugs in the air and in samples.

Principles of ion mobility spectrometry are simple for understanding and on practice provide the users comfort, quick analysis, device portability together with high reliability and comparatively low cost of exploitation. The gist of the analysis is the following: pairs of analysed substances are ionised under atmospheric pressure, and then a temporary division of ions takes place in high-voltage electric field as a consequence of the difference of mobilities of different ion classes. Ions are neutralized by a detector (anode), as the result of which there appears current, which is then strengthened and transformed into voltage. The obtained data is shown at the device display as a range, characterizing changes of output voltage in the process of time.

However, in this analytical highly sensitive equipment there is a problem of efficient sample transfer without losing a part of the analysed substance. This problem is relevant in detection of ultralow concentrations of explosives and drug substances by the method of ion mobility spectrometry. The sample losses in adsorptions on the surface of gas passages and diffusion through walls of penetrable gas passages could be compared with the size of the sample itself. There is also a problem of accumulation and penetration of the researched substance into the walls of the sample port which deforms the received range.

Sample losses in adsorption on the surface of gas passages can be compared to the size of the very sample (in low concentrations of the substance detection)

For lowering of the sample loss in adsorption on the surface of gas passages and diffusion through walls of penetrable gas passages it is necessary to make the right choice of the material, which will accumulate research substances.

A group of scientists of the Department of micro-and nano-electronics (A.Rodionov, D.Lipatov under the supervision of V.Belyakov) have conducted the research of materials, applied in the sample selection of substance for soiling resistance and substance sorption in a wide range of temperatures.

Scientists have taken the following materials for the research: a PTFE polymer (teflon), which is currently widely used in the ion mobility spectrometry; PEEK polymer; borosilicate glass; silanized borosilicate glass; steel with special coating SilcosteelTM; quartz glass; silanized quartz glass. The samples of these materials were thus used as pipes of sizes and diameters, identical to the real construction of the device. The experiment was conducted at fixed temperature, chosen from the range (24-100°С) and was split into 2 stages: the blow down of the researched material at a specially manufactured model which emulates the mode of the sampling selection, and the second stage – measuring of the stage of the researched tube by the ion mobility spectrometry method.

Data processing and analysis of the curve of the magnitude dynamics by the ion mobility spectrometry marker

A new method of research and data processing of ranges has appeared as the result of work. The statistics of a big quantity of experiments (several hundred for each material) has allowed build a mathematical model for understanding of processes, going on in the sample selection system of the device, and the practical result was the detection of new materials and their properties, which will be applied in new generations of ion mobility spectrometry devices.

“The best results have been shown by heatproof materials like quartz glass and steel with special coating SilcosteelTM. This choice of materials for sample selection system of the device will guarantee success, quality and competitiveness of Russian ion mobility spectrometry devices at the world market in future,” said one of the researchers Dmitry Lipatov.

The results of the research have been shown at the 25th International Conference on Ion Mobility Spectrometry in the USA and have provoked a great interest of scientists – developers of the analytical highly sensitive equipment.