Alexander I. Nadezhdinskii

Human breath trace gas content study by tunable diode laser spectroscopy technique

Abstract Measurements of carbon monoxide, ammonia, methane and carbon dioxide concentrations by registration of high resolution absorption spectra are described. A description of the automated tunable diode laser (TDL) system developed for simultaneous CO and CO 2 measure, and the TDL system developed for CH 4 and NH 3 measure is given. Calibration of concentration calculated on the base of a priori data on strength and broadening coefficients of detected lines is described. A clarified correct manner of value definition of spontaneous fraction of TDL radiation allows an accuracy improvement of concentration measurement of several percent. The same level of CO surplus content of about 400–800 ppb in non-smokers respiration was detected under different ambient conditions of CO content varied within one order of magnitude. A surplus content in human respiration of CH 4 equal to ∼3–8 ppm and NH 3 equal to 100–250 ppb were detected. The accumulation of CH 4 and NH 3 by the human organism seems to be rather negligible for a short time exposure, e.g. like smoking. Data obtained on non-invasive CO/CO 2 ratio detection in human breath shows that after 10–20 sec of breath holding time the organisms compensation reactions on acuity oxygen shortage for breath holding appear. Prospects for the development and application of diode laser spectroscopy to trace gas analysis in medicine are also discussed.

Tunable diode laser spectroscopy accessories based on middle IR halide and chalcogenide fibers

The use of mid-IR fiberoptic components in spectroscopy and analysis using A4B6 tunable diode lasers has been studied, and the results are reported. Spectral parameters of the fibers and complete spectroscopic systems based on the fibers and Pb-salt diode lasers are presented. The further development of the presented systems for applications in remote monitoring, multicomponent gas mixtures analysis, and evanescent wave spectroscopy of gases is addressed.

Spectral gas analysis of polyatomic molecules by tunable diode lasers

The application of high-resolution tunable diode laser spectroscopy to the trace gas analysis of polyatomic molecules is experimentally investigated. A trace detection limit of 10 exp -8 vol pct was obtained for Freon-12, allowing the concentration of this gas in the atmosphere to be measured.

Infrared diode laser chemical sensors with multipass cell based on silver halide and chalcogenide fibers

A high sensitive chemical analyzer of molecular gases is presented. Its based on measurements of high resolution molecular absorption spectra obtained with infrared tunable diode lasers (TDL). To transmit radiation from lasers to an analytical cell and back to detectors, infrared fibers with low optical losses are used. A multipass optical cell is used to enhance the essential sensitivity of the sensor. Various gaseous molecular objects could be detected by this analyzer due to the wide spectral range of available TDLs and fibers. Use of fibers for laser transfer could provide remote monitoring and multicomponent mixture analysis and evanescent spectroscopy of gases in the near future.

New generation of tunable diode laser based systems

Abstract A family of tunable diode laser based systems was developed for different applications. The system is operating under full computer control. Due to the model proposed, diode laser frequency tunnig can be predicted with high precision. The computer determines the laser operation mode, identifies the observed spectral line, and using spectral data base information, calculates the concentration of molecules to be measured. A new generation of “Chernin” multipass optical was developed and incorporated in the TDL based systems. The instruments developed were used in atmosphere monitoring, high technology, etc.

Tunable diode laser spectroscopy: new methods and applications

The goal of this paper is to present an overview of results obtained recently in General Physics Institute of Russian Academy of Sciences and collaborating organizations. The results are related to several topics of tunable diode laser spectroscopy such as development of tunable diode laser based systems and their applications. This paper discusses properties of diode lasers available in Russia and their importance for monitoring as well as several diode laser based systems developed in GPI. Some features enabling us to develop such systems under full computer control for long-term monitoring are touched upon.

Tunable diode laser spectroscopy application for ammonia and methane content measurements in human breath

Measurements of ammonia and methane concentrations by registration of high resolution absorption spectrum in 10.34 micrometers for NH3 and 3.27 micrometers for CH4 spectral region are described. Specific features of tunable diode lasers (TDL) system developed to ammonia and methane content measurements in human breath are discussed. Data on measurements of these trace gases in the exhalations of different people are presented. A brief overview of NH3, CH4, CO and CO2 content measurements by the tunable diode lasers technique in human breath is given. Future prospects of medical application of TDL spectroscopy are discussed.

Human expiration content diagnostics by tunable diode lasers in middle infrared

Results on the application of tunable diode laser gas analysis to determining the trace components of human breath are presented. Schemes of the analyzers specially developed for measurement of both carbon oxides in expiration are described. A few results illuminating possible applications of TDL in high sensitive medical diagnostics have been obtained. For nonsmokers, the expired concentration of CO is slightly higher than inhaled air. Specific surplus value depends on the persons age. The surplus CO content increased significantly just after intensive physical exercises like jogging. For smokers, the farmacokinetical curve of abundant CO removal from the organism could be investigated. The smoking status of tested individuals becomes easy available. Breath-hold simultaneous measurements of CO and CO2 have shown the difference in the dependencies of their concentrations on breath-holding time. The possibility to investigate phenomena like molecular pulmonary diffusion of the alveolar-capillary membrane and an organisms compensation reactions to oxygen shortage seems to become real. Perspective leads for development and the application of diode laser spectroscopy methods to the analysis of gaseous microimpurities in medicine are also discussed.

Middle-infrared fiber optic accessories for molecular spectroscopy and gas analysis with tunable diode lasers

A highly sensitive chemical analyzer of molecular gases is presented. It is based on measurements of molecular absorption in high resolution spectra obtained with infrared tunable diode lasers (TDL). To transmit radiation from lasers to an analytical cell and back from the cell to detectors, infrared fibers with low optical losses are used. A multipass optical cell is used to enhance a sensitivity of the sensor. Various gaseous molecular objects could be detected by this analyzer due to wide spectral range of available TDLs and fibers. Use of fibers for laser radiation transfer could provide remote monitoring, multicomponent mixture analysis, and evanescent wave spectroscopy of gases in the near future.

Outdoor, indoor, and human breath content measurements of ammonia by tunable diode laser spectroscopy technique

Trace contents of ammonia in outdoor, indoor and exhaled air were measured on the base of high resolution absorption spectra. Tunable diode laser system developed for this purpose possesses approximately one second time constant, approximately 200 cm3 sample volume, 5 ppb sensitivity. The calibration of unit was based on measurements of relative intensities of sQ(3,1)...sQ(3,3) absorption lines of v2s and following calculation on the base of a priori data on strength and broadening coefficients of detected lines. Measured indoor contents of ammonia was in 5-10 times higher than outdoor contents. Approximately two times drop in NH3 room content after 6 p.m. was detected. Obtained behavior of ammonia content in respiration right after the smoking demonstrates that the removing of ammonia from lungs has the ventilation character. Measured contents of NH3 in human respiration was ranged between 120 and 220 ppb. The absence of ammonia content differences from respiration of smoking and non smoking persons demonstrates that the accumulation of NH3 by human organism seems to be rather negligible for a short time exposure, e.g. like smoking.