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This study presents the theoretical and practical aspects of the new technique, namely Mat Glass - Thin Layer Chromatography (MG-TLC) and application of invasion model. Our research is focused on the development and clarification of the phenomena that occur in thin layer separation technique: process flow, spreading on mat glass surface, impregnation of porous layers and the improvement of the quality of thin layer chromatographic separations by overlapping some mat glass plates, over the chromatographic plates. The experiments have confirmed the possibility that the movement of the invasive type displacement, which occurs on rough surface will influence favorably the chromatographic separation processes. Good results have been obtained in separation of the lipophilic dyes and the hydrophilic dyes by small adjustments, e.g., height of the free zone of porous layer h, or the roughness of glass plates. The results obtained demonstrate that this method can be successfully used in thin layer chromatography technique being easy to apply and inexpensive compared with other methods derived from chromatography. [ABSTRACT FROM AUTHOR]

This paper purpose was to develop a sensitive and selective method for the determination of glyphosate, and aminomethylphosphonic acid (AMPA) residues in water and glyphosate from soil samples. The method involves a derivatization step with 9-fluorenylmethylchloroformate in borate buffer of these compounds and liquid chromatography separation with fluorescence detection (HPLC-FLD). Separation of derivatized glyphosate and AMPA compounds was performed on an Agilent ZORBAX C18 reversedphase column. The mobile phase consisted of a mixture of acetonitrile and 0.05 M KH2PO4 solution [30:70 v/v]. Limits of detection (LOD) was 0.28 µg L-1 for glyphosate, and 0.35 µg L-1 for AMPA, and limits of quantification (LOQ) was 0.84 µg L-1 for glyphosate and 1.05 µg L-1 for AMPA. The method has been validated for surface water and soil by recovery studies with samples spiked at 25 and 5 µg L-1. In water samples, the mean recoveries values ranged between 86.44 - 103.9% for glyphosate, and 71.27 - 99.08% for AMPA. The mean recoveries values for glyphosate ranged from 57 - 81.5% in soil samples. The developed method has been applied for determination of these compounds in water and soil samples from agricultural and rural areas of Roma community from some Transylvania Counties. [ABSTRACT FROM AUTHOR]

Antibiotics are natural or semi-synthetic compounds used for many decades in human, veterinary and plant medicine to prevent and/or to treat bacterial infections and also to promote productivity in animal farming. Traces of antibiotics are found in waste, surface and ground waters, the main source of water pollution being considered waste waters from the industrial production, hospitals, livestock farms, households and incompletely metabolized drugs. The uncontrolled input of antibiotics in surface waters can lead to some unexpected health effects and to an increased resistance to these drugs. The aim of this work consists in the monitoring of six antibiotics (Ampicillin, Amoxicillin, Penicillin G, Ceftazidime, Tetracycline and Doxycycline) in river waters and sediment samples from the Romanian Tisza River Watershed. Solid-phase extraction (SPE) on Oasis HLB Waters cartridges was used for the isolation of antibiotics from water matrices and ultrasound-assisted extraction (USAE) followed by SPE for the sediment samples. Then, the antibiotics were analysed by high-performance liquid chromatography coupled with diode array detector or mass spectrometer (HPLC-DAD/MS). The developed SPE/USAEHPLC-DAD/MS procedures were applied to monitor these antibiotics in river waters during thirteen months and to analyse them in some sediment samples. The obtained results showed the presence of Tetracycline, Doxycycline and Ceftazidime in the investigated samples. [ABSTRACT FROM AUTHOR]

A method for the identification of different classes of volatile organic compounds in the municipal landfill leachate using solid phase microextraction and comprehensive two dimensional gas chromatography coupled with mass spectrometry (SPME-GCxGC-qMS) is elaborated. The results showed that the proposed protocol is able to separate and identify in a single run different classes of volatile organic compounds responsible for the odor of leachate such as carbonyl compounds, aromatic compounds, terpenes, phenolic compounds and nitrogen and sulfur containing compounds. The use of solid phase microextraction not only eliminate the solvent from the samples processing step but also considerably reduces the time and the volume of the sample necessary for this step, being a viable green alternative for this type of analysis. The use of mass spectrometry gives the possibility to indentify many other compounds responsible for municipal landfill leachate odor, creating the premises for a better assessment of chemical composition of leachate. The developed protocol shows good performances in term of repeatability, linearity, limit of detection and limit of quantification being applicable for the real municipal landfill leachate analysis. [ABSTRACT FROM AUTHOR]

This study is focused on the determination of some important antibiotics from different classes in waste water samples using solid phase extraction followed by high performance liquid chromatography with two detectors, diode array and mass spectrometer in positive ionisation mode. The investigated antibiotics include three penicillins (amoxicillin, ampicillin, penicillin G), two cephalosporins (ceftazidime, ceftriaxone), and two tetracyclines (tetracycline, doxycycline). The studied antibiotics were extracted from waste water samples using hydrophilic-lipophilic balanced cartridges. The extraction of antibiotics from water matrices was tested at several pH values. The best recoveries were obtained at pH 3 and 7 respectively. Depending on the nature of antibiotic, the limits of detection and quantification were obtained in the range of 0.07-0.92 µg mL and 0.21-2.77 µg mL respectively. Influent and effluent waste water samples were collected from a Waste Water Treatment Plant from Romania in order to detect the studied antibiotics. The antibiotics detected in the influent waste water samples were ceftriaxone (334 µg L), tetracycline (146 µg L) and doxycycline (110 µg L). In effluent waste water samples no target antibiotics were detected. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Waste waters produced by the textile industry and the animal wastes from the intensive farming which are generally used for field irrigation are considered pollutant sources for the environment. These pollutants can be taken by soil and then by plants. The flavonoids are secondary metabolites of plants; therefore their determination in plants is necessary because they have different important roles in body of plants. The spectrophotometric determination of the total flavonoid content from Triticum aestivum L. (wheat) and Secale cereale L. (rye) treated with two potential environmental pollutants (Nylosan Red N- 2RBL - textile azo dye and ampicillin - antibiotic) is presented in this paper. The studied plants were periodically watered with solutions of Nylosan Red N-2RBL and ampicillin respectively, prepared at different (1.5·10-5, 1.5·10-4, 1.5·10-3, 1 mg/L) concentrations. The total flavonoids from plants were extracted by sonication in a solvent mixture of ethanol:water in a ratio of 80:20 (v/v). The quantitative determination of total flavonoids was performed with an UV-Vis 1800 Shimadzu spectrophotometer using aluminium chloride as reagent and rutin as standard. In both treatments, a decrease in total flavonoid content compared to the control (wheat and rye untreated samples) has been observed. [ABSTRACT FROM AUTHOR]

The parameters of a vibrational band are sensitive to the environment created by solvents. The effects of the two solvent mixtures cyclohexane/tetrahydrofuran and carbon tetrachloride/acetonitrile on the frequency and half bandwidth of ?(C-Br) band of 1- and 2-bromopropane are investigated. The first mixture can be considered "ideal" and the frequency and half bandwidth of ?(C-Br) bands varies linearly on the mole fraction of the polar solvent. In the case of carbon tetrachloride/acetonitrile mixture, a process of "preferential solvation" with the maximum effect at 2 : 1 volume ratio was evidenced. [ABSTRACT FROM AUTHOR]

Work reported here was performed with the goal of reducing the concentration of 4-nitrophenol (4-NP) and 2,6-dinitrophenol (2,6-DNP), present in synthetic solutions to values below 0.5 mg L-1, the maximum concentration level tolerated by international environmental regulations [1, 2]. In the electrochemical reduction of 4-NP the final product was 4-aminophenol, as assessed by HPLC. Three methods were used for decreasing 4-NP and 2,6-DNP concentrations: electrochemical reduction, adsorption on active carbon, and the combined electrochemical reduction-adsorption. Best results were obtained by applying the combined procedure, which employed as the cathode granular activated carbon in fluidized bed. In these experiments 95-97% removal of 4-NP and 2,6-DNP from solutions occurred within the first 20 min. [ABSTRACT FROM AUTHOR]