Biomedical subjects

V Bulatov

Publications and source records attributed to V Bulatov.

4 recordsLinked to original sources

PubMed2003

Diffusion-limited extraction of organic ions by a track-membrane interfaced vacuum inlet.

Glycerol-wetted track membranes (polyethylene terephthalate) were used to interface a low-vacuum facility (approximately (10(-3) Torr) to an ambient pressure liquid analyte. High-field charge extraction conditions were routinely maintained between the liquid samples and a grid collector. The latter was positioned just near to the vacuum-facing side of such membranes. Upon establishing a steady-state charge extraction regime, the collector currents were monitored and recorded at various solute concentration levels. The collector currents, which depend on solute concentration, were found to agree with recent theoretical treatments of such processes. Both positively- and negatively-charged species from organic solutions were routinely extracted. Ion injection for the low- and the high-mobility species has favored the diffusion-limited and the evaporation-limited schemes, respectively. Variable concentrations of 1-pyrenoyl-methylpyridinium bromide as well as naphthylacetic and anthracenecarboxylic acids in glycerol were used.

Journal Article↗

PubMed2001

Direct mass-quantification of particulate deposits of polycyclic aromatic hydrocarbons by Fourier transform imaging microscopy.

Successful coupling of imaging microscopy with Fourier transform spectrometry provides a new methodological approach. This was applied to the direct analysis of particulate deposits of polycyclic aromatic hydrocarbons (PAHs). The fluorescence signals of single microscopic particulates were found to be proportional to their mass, obtained from the corresponding HPLC results. Special fluorescence characteristics related to individual particle analysis were studied. The sensitivity of the proposed method to PAHs in soil is in the sub-ppb range, similar to HPLC results. Analysis of inhomogeneous PAH-particulates was demonstrated, as well as the resolution of photochemical products of PAHs. The effects of particulate orientation relative to the detector upon quantification are discussed.

Chromatography, High Pressure Liquid↗

PubMed2001

Photochemical study of anthracene crystallites by Fourier transform spectroscopic imaging.

Fourier transform-based spectroscopic imaging was used for direct, time-resolved, analysis of UV-irradiated anthracene crystallites. Well-resolved fluorescence spectra were obtained at a spatial resolution of 1 microm. The appearance of such photochemical by-products as dianthracene and anthraquinone was monitored throughout the irradiation experiments. Under deaerated conditions, photolysis of anthracene was accompanied by formation of dianthracene. When performed under aerated conditions, however, the spectral data indicated formation of both dianthracene and anthraquinone. Spectral features obtained for the directly monitored photolysis of anthracene are discussed in respect to the structural and compositional modifications in such crystallites. Capabilities of the spectral imaging device for the quantification of the photochemical products of anthracene are discussed.

Journal Article↗

PubMed2000

Converting spatial to pseudotemporal resolution in laser plasma analysis by simultaneous multifiber spectroscopy

Traditional chemical analysis based on laser plasma spectroscopy (LPS) requires time-gated detectors, to avoid the initial signal from the hot plasma. These detectors are expensive and often need to be cooled and protected against vapor condensation. We suggest a low-cost setup that may replace these gated detectors, while maintaining acceptable analytical performance. The proposed setup is a result of investigation of plasma-front propagation in LPS analysis. It is known that the LPS plasma propagation is similar to the shock wave propagation after a strong explosion in the atmosphere. We found that the propagation of the plasma fits well the Sedov blast wave theory, providing a good agreement between the theoretical and experimental figures. A proper observation geometry, which is perpendicular to the plasma expansion vector, enables converting spatial to temporal resolution. We take advantage of the fact that the plasma reaches a given distance above the analyzed surface at a certain time delay. Therefore, a single optical fiber, positioned at a well-defined geometry, can provide spectral information corresponding to a certain time delay. A multifiber imaging spectrometer provides information corresponding to a series of delay times, which is adequate for analysis of a variety of matrixes. It was found that the performance of the nongated detector observing a narrow solid angle is similar to that of a gated one observing the whole plasma. For one particular example, observing the plasma from a distance of 4.5 mm is equivalent to a delay of 4 micros and integration time of 2 mircos. The ratio of spectral lines of two elements was investigated using the spatially resolved (nongated) setup, and it was found that this mode is advantageous when internal calibration is applied. It was concluded that sensitive LPS analyses can be carried out by less expensive (nongated) detectors.

Journal Article↗