Authors:Ivan Givechev, Dimitar Tanev, and Dancho Danalev
Introduction The group of polycyclic aromatic hydrocarbons (PAHs) is largely distributed in the nature [ 1 ]. They contain two or more fused aromatic rings. They are formed as a result of many natural and anthropogenic processes. The two main
The degradation of a mixture of 18 different polycyclic aromatic hydrocarbons (PAHs) has been studied in acetonitrile solution
by usingg-radiation at radiation doses of 100, 200 and 300 kGy. The mixture of radiolyzed PAHs was analyzed by liquid chromatography
(HPLC) using a diode array detector. Radiolysis at 100 kGy total dose is already sufficient to cause the complete disappearance
of all PAHs with the exception of fluorene and crysene which still survive in small amounts. They are known to be among the
most radiation-resistant PAHs and can be completely eliminated from the radiolyzed solution by a treatment with ozone. Alternatively
higher radiation dose (200 kGy) is needed to eliminate fluorene and crysene completely from the acetonitrile solution. PAHs
can be degraded completely with an excess of ozone but the distribution of products is of course different from that obtained
by radiolysis and radiolysis followed by ozonolysis.
Authors:D. Janković, D. Djokić, T. Maksin, and M. Orlić
The purpose of this study was to compare some physicochemical characteristics as well as pharmacokinetic behavior of 99mTc-PAH, as a novel renal agent, with 99mTc-MAG3 and 131I-OIH. 99mTc-PAH was prepared from lyophilized kit by adding 99mTcO4–. Labeled complex was stabile and high radiochemical purity radiopharmaceutical, with a low percentage of protein bound to human albumin and hydrophilic character. In spite of its smaller renal uptake, 99mTc-PAH gave satisfactory renal images. 99mTc-PAH showed faster urinary elimination than 99mTc-MAG3 and similar to those one for 131I-OIH. The comparison of pharmacokinetic parameters of 99mTc-PAH, 99mTc-MAG3 and 131I-OIH indicated the favorable characteristics of 99mTc-PAH.
Authors:Irena Malinowska, Marek Studziński, and Henryk Malinowski
The effect of a magnetic field on the planar chromatographic retention of some PAH has been investigated. The horizontal chamber was placed between two neodymium magnets and chromatograms were developed in the magnetic field created. The effect of the magnetic field was tested for single-component and binary mobile phases containing
-alkanes and aromatic hydrocarbons. PAH were used as solutes. The results obtained showed that magnetic fields can affect the retention and shape of the chromatographic bands of the solutes investigated. The effect depends on the type of mobile phase, the properties of the adsorbent layer and the mode of development of the chromatogram (development distance).
Authors:Bernd Spangenberg and Karl-Friedrich Klein
In-situ densitometry for qualitative or quantitative purposes is a key step in thin-layer chromatography (TLC). It is a simple means of quantification by measurement of the optical density of the separated spots directly on the plate. A new scanner has been developed which is capable of measuring TLC or HPTLC (high-performance thin-layer chromatography) plates simultaneously at different wavelengths without damaging the plate surface. Fiber optics and special fiber interfaces are used in combination with a diode-array detector. With this new scanner sophisticated plate evaluation is now possible, which enables use of chemometric methods in HPTLC. Different regression models have been introduced which enable appropriate evaluation of all analytical questions. Fluorescent measurements are possible without filters or special lamps and signal-to-noise ratios can be improved by wavelength bundling. Because of the richly structured spectra obtained from PAH, diode-array HPTLC enables quantification of all 16 EPA PAH on one track. Although the separation is incomplete all 16 compounds can be quantified by use of suitable wavelengths. All these aspects are enable substantial improvement of in-situ quantitative densitometric analysis.
Authors:Bárbara Borges, Armindo Melo, Isabel M.P.L.V.O. Ferreira, and Catarina Mansilha
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in the atmosphere, soil, water, and food. PAHs are known for their potential teratogenicity, carcinogenic, and mutagenic properties. Due to their
Authors:Bernd Spangenberg, Klemens Lorenz, and Steffen Nasterlack
In-situ densitometry for qualitative or quantitative purposes is a key step in thin-layer chromatography. It offers a simple way of quantifying by measuring the optical density of the separated spots directly on the plate. A new TLC scanner has been developed which is able to measure TLC plates or HPTLC plates, at different wavelengths simultaneously, without destroying the plate surface. The system enables absorbance and fluorescence measurements in one run. Fluorescence measurements are possible without filters or other adjustments.The measurement of fluorescence from a TLC plate is a versatile means of making TLC analysis more sensitive. Fluorescence measurements with the new scanner are possible without filters or special lamps. Improvement of the signal-to-noise ratio is achieved by wavelength bundling. During plate scanning the scattered light and the fluorescence are both emitted from the surface of the TLC plate and this emitted light provides the desired spectral information from substances on the TLC plate. The measurement of fluorescence spectra and absorbance spectra directly from a TLC plate is based on differential measurement of light emerging from sample-free and sample-containing zones.The literature recommends dipping TLC plates in viscous liquids to enhance fluorescence. Measurement of the fluorescence and absorbance spectra of pyrene spots reveals the mechanism of enhancement of plate dipping in viscous liquids — blocked contact of the fluorescent molecules with the stationary phase or other sample molecules is responsible for the enhanced fluorescence at lower concentrations.In conclusion, dipping in TLC analysis is no miracle. It is based on similar mechanisms observable in liquids. The measured TLC spectra are also very similar to liquid spectra and this makes TLC spectroscopy an important tool in separation analysis.
Authors:G. Csósza, K. Karlócai, G. Losonczy, V. Müller, and Z. Lázár
-capillary PH is the remodeling of the arterial wall, particularly in pulmonary arterial hypertension (PAH, WHO group 1). The increased proliferation and inhibited apoptosis of lung vascular endothelial cells, pulmonary arterial smooth muscle cells (PASMC) and