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Abstract  

Problem of nitrophenols group analysis as well as separation to individuals is still attracting attention of research and practicing chemists, environmental chemists and the others. Chromatographic behaviour in RPHPLC systems expressed by such parameters as retention time, sorption capacity, selectivity and/or elution order was studied for group of 8 nitrophenols: 2,4,6-trinitrophenol, 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2,5-dinitrophenol, 2,6-dinitrophenol and 4-nitro-3-cresol. Condition for baseline separation of almost all of these nitrophenols on Separon SGX C18 were chosen. Sorption capacities were tested for 4 different RP materials. The data will be used for devising of Solid Phase Extraction (SPE) and/or column switching schema in RPHPLC sample pretreatment.

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Abstract  

Two fractions of both fulvic acids (FA) and humic acid (HA) were prepared by fractionation method of Pierce and Felbeck5 involving acid hydrolysis of soil rests. This step increases recovery of both FA and HA considerably what suggest us need for slight modification of IHSS method in some cases. The weight loss, change in organic carbon content and visible spectra are figures of merit discussed. After detailed characterization these humic substances (HS) will serve as the working standards for study of interactions between organomercurials and organic part of soil.

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Abstract  

Three environmentally and agrochemicaly important mercury species: methylmercury, phenylmercury and mercury(II) are separated within 4 minutes as bromocomplexes by micellar liquid chromatography using very short reversed-phase (RP) C18 columns (up to 30 mm). The micellar mobile phase containig 0.05M cetyltrimethylammonium bromide (CTMA+Br), 1% (v/v) 2-propanol, 0.001M cyclohexylenediaminetetraacetic acid (DCTA) and sulfuric acid (pH 2) showed good selectivity in mixed reversed-phase and anion-exchange mode. The above mentioned separation order in which organomercurials are cluted far behind the void volume of the column, but before the mercury(II) peak is advantageous in all instances where mercury(II) is present in real samaples in great excess. Environmental and agrochemical samples contain humic material which does not interfere in this particular system. The low cost photometric detection at 500 nm after post-column derivatization by CTMA+Br micellized dithizone is almost free from interferences and enables detection limits at the 1–3 ng level (e.g., 0.1 ppm Hg) for 20 μl samples.

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Abstract  

Performance of commercial Trace Mercury Analyser (TMA) originally devoted to total mercury content analyses in solid and liquid samples was tested in off-line combination with HPLC technique for speciation purposes. RPHPLC system optimized for baseline separation of mercury(II), methylmercury and phenylmercury rendered fractions with volumes directly acceptable by TMA. The main problems of this combination via off-line interfacing i.e. volatility of organomercurials and lost of fractions due to overflow from porous nickel and/or platinum transfer boats were solved by addition of wetting agent (cetyltrimethylammonium bromide) and stabilizing agent (dithizone) into the vessels prior to fractions collection. Calibration curves were measured for Hg(II) and methylmercury within range from 25 ppb to 500 ppb and were linear with correlation coefficients better than 0.9997. Detection limits achieved were around 0.3 ng for both mercury species. No matrix effects were observed during analyses of tap and surface water samples spiked at low ppb levels.

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Abstract  

Post-column derivatization detection system based on dithizone solubilized in cetyltrimethyl-ammonium hydrogenesulfate micellar media at pH 2.0 was devised and evaluated for selective detection of mercury(II), methylmercury and phenylmercury in reversed-phase HPLC system with photometric detection at 500 nm. This reagent solution is fully compatible with acidic organo-aqueous mobile phases generally used in RPHPLC. With the aid of the detection systematic study of the retention behaviour of three mercury species on octadecylsilica sorbent was carried out. Influence of pH, acetonitrile volume fraction, complex forming additives was investigated in detail. In mobile phase consisting of 5–30% of acetonitrile in water at pH 2.0 and 2·10–4 mol·I–1 DCTA linear calibration curves were measured in range 20–1000 ppb with correlation coefficient better than 0.99. Detection limits were 1–5 ng for this three mercury species. Interferences of copper(II) and silver(I) are negligible.

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Radiation degradation of waste waters

I. Reverse phase-high performance liquid chromatography and multicomponent UV-VIS analysis of gamma-irradiated aqueous solutions of nitrobenzene

Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Kuruc, M. Sahoo, J. Ločaj, and M. Hutta

Abstract  

Saturated aqueous solutions of nitrobenzene (in water, 0.1M nitric acid and 0.1M potassium hydroxide) were irradiated with60Co -rays in deaerated condition. Radiolytic products were analyzed using reverse phase-high performance liquid chromatography (RP-HPLC) and multicomponent UV-VIS spectrometry. With the aid of RP-HPLC retention times of the radiolytic products were found to be identical with those of isomeric nitrophenols, aminophenols and dinitrophenols. According to the primary information obtained from RP-HPLC and literature, we have chosen ten standards and eleven wavelengths for multicomponent UV-VIS analysis (linear multiparametric regression analysis) and the concentrations of nitrobenzene, nitrophenols, aminophenols and dinitrophenols in water, HNO3 and KOH solutions were calculated.G-values molecules/100 eV) of the radiolytic products and decomposition of nitrobenzene in aqueous solutionsG(-nitrobenzene) were calculated from the dependence of their concentrations with dose. Ph has relatively little influence on the decrease of concentration of nitrobenzene, but has strong influence on the product composition.

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Abstract  

Radiolytic products of the two-phase systems of nitrobenzene-carbon tetrachloride-water mixtures have been identified using HPLC adsorption chromatography on SEPARON SIX silica gel column under an elution gradient from n-hexane to ethyl acetate. That the product formation is a function of the mixture composition is indicated by the chromatograms. Para-nitrophenol constitutes one of the major radiolytic products in the system where the volume ratio of nitrobenzene is more than that of carbon tetrachloride and its radiation yield is dependent on the volume ratio of the aqueous phase.

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Abstract  

Sequential multistep procedure, usually used for the fractionation and characterization of soil organic matter was tested for Hg content in the individual steps and fractions. Under general laboratory conditions serious problems have arosen during the attempt in the Hg mass balance calculation. Several sources of Hg contamination were recognized. The most serious was the background concentration of Hg even in research grade chemicals (what is in general not declared) and laboratory air. The work on operational Hg speciation as non-humic bound, humic acid, fulvic acid bound proceeds from the established status-quo on distribution of mercury of soil organic matter.

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Abstract  

Various sorbents recommended for solid phase extraction (SPE) in sample preparation procedures were studied for use in combination with capillary isotachophoresis (ITP). They were very efficient in achieving trace concentration levels (low ppb, i.e., low parts per 109) for different types of ITP analytes present in environmental and biological matrices. A macroporous carbon sorbent was convenient for sample preparation in ITP analysis of short chain fatty acids (C4–C9) in drinking water. Chelating sorbents based on hydroxyalkyl methacrylate matrix with salicylate, thioglycolate and 8-hydroxyquinolinate functionalities were found to be very suitable for preconcentration of heavy metals with an inherent sample clean-up. An octadecyl-bonded silica sorbent enabled in ITP a photometric detection of -aminobutyrate (labeled with a 2,4,6-trinitrophenyl group) at concentrations considerably lower than required for the determination of this amino acid in cerebrospinal fluid (5·10–8 mol/l).

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