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1.
The reductive amination of low‐molecular‐weight saccharides, uronic acids, and amino sugars, followed by a separation of the derivates by means of ion‐pair chromatography or RP‐HPLC, offers an interesting alternative to HPAEC‐PAD for the environmental analysis of these compounds. Under this aspect various potential amination reagents, i.e., p‐amino‐benzoic acid (p‐AMBA), p‐AMBA propyl ester, 1‐aminopyrene, 2‐(2‐aminophenyl)indole, and 4‐aminoazobenzene, were tested with regard to the formation of derivates and to the chromatographic properties of the formed derivates. p‐AMBA, p‐AMBA propyl ester and 4‐aminoazobenzene proved to be especially suited, because they facilitate the amination of all carbohydrate reference components together with a complete separation and sensible detection (detection limits < 0.5 mg/L) of the derivates. Mainly the following elution sequence was ascertained: amino sugars (hexosamines) / disaccharide(s) / monosaccharides (hexoses) / hexuronic acid(s) / N‐acetyl‐D‐glucosamine. Detection limits down to 0.1 μmol/L were realized using p‐AMBA as reagent, facilitating the determination of the target compounds in landfill leachates and lysimeter percolates. Applying the p‐AMBA propyl ester for derivatization, chromatographic interferences with weakly retained derivates and the coelution of the reagent with its galactosamine derivate can be avoided, since the ester elutes after its derivates unlike p‐AMBA itself.  相似文献   

2.
Many organic compounds or their precursorsfound in meteorites originated in the interstellar or circumstellarmedium and were later incorporated intoplanetesimals during the formation of thesolar system. There they either survivedintact or underwent further processing tosynthesize secondary products on themeteorite parent body.The most distinct feature of CI and CM carbonaceouschondrites, two typesof stony meteorites, is their high carbon content(up to 3% of weight), either in theform of carbonates or of organic compounds. The bulkof the organic carbon consistsof an insoluble macromolecular material with a complexstructure. Also present is asoluble organic fraction, which has been analyzedby several separation and analyticalprocedures. Low detection limits can be achievedby derivatization of the organicmolecules with reagents that allow for analysisby gas chromatography/massspectroscopy and high performance liquidchromatography. The CM meteoriteMurchison has been found to contain more than70 extraterrestrial amino acids andseveral other classes of compounds includingcarboxylic acids, hydroxy carboxylicacids, sulphonic and phosphonic acids, aliphatic,aromatic and polar hydrocarbons,fullerenes, heterocycles as well as carbonylcompounds, alcohols, amines and amides.The organic matter was found to be enriched indeuterium, and distinct organiccompounds show isotopic enrichments of carbon andnitrogen relative to terrestrialmatter.  相似文献   

3.
Leachate, ground-, and surface water from former ammunition sites and areas which are known to be contaminated by nitroaromatic compounds in Lower Saxony (Germany) were investigated in order to identify and quantify acidic nitroaromatic compounds (e.g., nitrobenzoic acids, aminonitrobenzoic acids, nitrophenols, and nitrocresols). Acidic and neutral nitroaromatic compounds were enriched by solid-phase extraction (SPE) on a polystyrenedivinylbenzene copolymer and routinely screened for acidic compounds by means of HPLC/photodiode array detection (HPLC/PDA). Qualitative and quantitative results obtained in this way were corroborated by proton nuclear magnetic resonance spectroscopy (1H-NMR). Validation data for the quantification procedure using this technique are given. The results show that all samples contaminated with 2,4,6-trinitrotoluene (TNT) and related compounds are also contaminated by acidic nitroaromatic compounds (e.g., 2,4-dinitrobenzoic acid, 3,5-dinitrophenol, and especially with 2-amino-4,6-dinitrobenzoic acid) in the μg/L range. This current work shows that 1 H-NMR allows the quantitative determination of protoncarrying analytes in mixtures after solid-phase extraction down to the upper ng/L range after addition of an internal standard to the SPE extract. This is even possible when reference compounds are not commercially available.  相似文献   

4.
In this study the occurrence of diclofenac and sub‐products in effluent emerging from the University Hospital at the Federal University of Santa Maria was investigated. One metabolite was identified and, in aqueous solution, three degradation products. The quantification was conducted by means of HPLC‐DAD, and the determination of metabolite and degradation products by LC–ESI–MS/MS–QTrap. For the HPLC‐DAD method, a 70:30 mixture of methanol/sodium phosphate was used in isocratic mode. For the LC–ESI–MS/MS–QTrap determinations, a mobile phase, where phase A was an ammonium acetate solution 5 × 10?3 mol L?1, and phase B was methanol (5 × 10?3 mol L?1)/ammonium acetate (9:1, v/v), on gradient mode. The LDs for the HPLC and LC–MS/MS methods, respectively, were 2.5 and 0.02 µg L?1, the LQs, 8.3 and 0.05 µg L?1, and the linear range from 10 up to 2000 µg L?1 and 0.05 up to 10 µg L?1. As expected, the LC–ESI–MS/MS–QTrap method was more sensitive and less laborious. The metabolite 4′‐hydroxy‐diclofenac was identified. Photolysis was used for the degradation studies and three products of diclofenac were identified (m/z of 214, 286 and 303) in aqueous solution. These results notwithstanding, no degradation products of diclofenac were found in the hospital effluent.  相似文献   

5.
The separation of vanillin from the lignin of empty fruit bunch oil palm is presented in this study. The lignin was extracted from soda black liquor derived from oil palm empty fruit bunches (EFB) using 20% sulfuric acid. Nitrobenzene oxidation was carried out by adding 50 mg of dry EFB lignin into a mixture of 7 mL of 2 M NaOH and 4 mL of nitrobenzene in a 15 mL steel autoclave. The autoclave was sealed tightly with a screw cap fitted with a Teflon gasket and heated to 165°C for 3 h in a preheated thermostatic oil bath. High performance liquid chromatography (HPLC) was used to determine the concentration of each compound present in the lignin. There were eight compounds detected in the HPLC chromatogram. The crystallization process was then used as a method to separate vanillin from other compounds. Based on the solubility of vanillin in acetone, 15 mL of acetone was added to the residue of the oxidized products and heated to 60°C for 10 min. A yield of 1.6% vanillin was isolated from a 50 mg lignin sample. The isolated compound was analyzed with HPLC, Fourier transform infrared spectrophotometry (FT‐IR) and nuclear magnetic resonance (13C‐NMR) for structural verification. The results of the characterization studies proved that the isolated compound is vanillin.  相似文献   

6.
Explosives belonging to the group of nitrotoluenes may be readily extracted with C18 adsorbent in the off-line mode and also in on-line coupling of the extraction unit to HPLC, while polar explosives like hexyl, HMX, and RDX show a substantial breakthrough and low recoveries. However, these compounds are quantitatively extracted using a new polymeric phase, LiChrolut EN, in the off-line mode. Preliminary results show that this new adsorbent may in principle also be used in the on-line mode for explosives. In this case, the cartridges have to be eluted in the backflush mode. Method detection limits of ? 0.1 μg/L are achieved for on-line extraction of explosives and related compounds with water samples as small as 10…30 mL.  相似文献   

7.
A method for the determination of di- and tetrachlorinated ethers (haloethers) in aqueous samples using solid-phase microextraction (SPME) combined with capillary GC has been developed. Using 100-μm polydimethylsiloxane fibers, the influence of several parameters on the SPME procedure like the exposure time of the fiber in the aqueous sample, the desorption temperature, and the salt content of the sample have been studied. Salt addition has a strong effect on the extraction efficiency of the haloethers investigated. Working with saturated salt solutions, the factor increase of the peak areas was in the range from 5 to 12. These improvements are accompanied by decreased precision and increased equilibration times. The SPME method combined with several detectors (FID, ECD, MS in SIM mode) was evaluated with respect to detection limits, linearities, and precisions. Working with salt addition and FID, detection limits of all compounds investigated were in the range of 0.3 to 1.2 μg/L. Using ECD, the LOD values (limits of detection) were only improved for the tetrachlorinated bis(propyl) ethers (<10 ng/L). Employing mass-spectrometric detection in SIM mode for all chlorinated ethers, detection limits lower than 100 ng/L could be reached. Working with saturated salt solutions, the coefficients of variation were <9% RSD. However, without salt addition, the precision is better than 2.5% RSD for all analytes. Investigations showed that the analysis of the haloethers with SPME is not influenced significantly by the matrix Elbe water. The results of two series of samples demonstrate that SPME-GC-MS allows the sensitive determination of the di- and tetrahalogenated ethers in Elbe river water.  相似文献   

8.
In presence of disinfectants, PAH are remobilized from the coal tar lining of water distribution mains. Reactions of the PAH with chlorine and chlorine dioxide can lead to chlorinated PAH that might show higher mutagenic effects than the parent PAH. The application of the solid-phase microextraction as a sampling preparation method in combination with a gas chromatographic mass spectrometric device is a reliable and useful method to achieve detection limits in the lower nanogramme-per-liter level for PAH and chlorinated PAH. Thus, the reactions of four PAH (anthracene, fluoranthene, fluorene, and phenanthrene) with chlorine and chlorine dioxide under conditions prevalent in drinking water distribution systems could be investigated. In batch experiments with demineralized and drinking water at pH 7, the concentrations of fluoranthene, fluorene, and phenanthrene remained constant, whereas anthracene reacted quantitatively with both disinfectants. In these reactions, no chlorinated products could be detected, only mono-hydroxyanthracene and anthraquinone were formed. A reaction mechanism for both reaction products is proposed. The results suggest that oxidation is the major pathway of the reaction of PAH with disinfectants in the systems under investigation.  相似文献   

9.
Sulfonamides (SAs) are one of the most frequently used antibiotics. SAs have been found in various environmental compartments. If SAs are not degraded in the environment, they can affect bacteria by their antibiotic properties and contribute to bacterial antibiotic resistance. Therefore, the biodegradability of 11 SAs (sulfanilamide, sulfaguanidine monohydrate, sulfadiazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamethoxypyridazine, sulfachloropyridazine, sulfamethazine, sulfamethoxazole, and sulfadimethoxine) was studied. For this purpose, the Closed Bottle Test (CBT, OECD 301D) was performed, which includes a toxicity control. In order to monitor the environmental fate of the parent compound and to check for transformation products, a simple, efficient, and reliable HPLC–UV method for the simultaneous determination of these SAs has been developed. Acetonitrile and water (with 0.1% formic acid) were used as mobile phase solvents for gradient elution. The method was validated in terms of precision, detection and quantitation limits, selectivity, and analytical solution stability. In the CBT, none of these SAs was readily biodegradable. The HPLC–UV analysis confirmed that no degradation of any SA took place. In the toxicity control, these SAs showed no toxic effect in the used concentration of environmental bacteria applied in the test.  相似文献   

10.
The electrochemical oxidation (EO) of diethyl phthalate (DEP) in aqueous solution was studied at Pb/PbO2 and Ti/SnO2 anode materials under galvanostatic‐experimental conditions. Results obtained clearly demonstrated that the anode plays a significant role for the optimization of the oxidation process, deciding the mechanisms and by‐products formed. DEP and by‐products of oxidation were also analyzed during various stages of the electrolysis reaction by HPLC and GC/MS techniques. Before the analysis by GC/MS technique, the samples were treated by solid phase microextraction (SPME) in order to concentrate the compounds from the reaction solution and identify all electrolysis intermediates. Current efficiencies (instantaneous current efficiency; ICE and total current efficiency; TCE) achieved during EO experiments were dependent on anode used and current density (20–40 mA cm?2) at 40°C. The results obtained demonstrated that the environmental electrochemical methods can be a feasible alternative for the wastewater treatment containing hazardous phthalates.  相似文献   

11.
Determination of Atrazine, Terbutylazine and their Deethyl- and Hydroxymetabolites in Soil by SFE and HPLC/UV-DAD The supercritical fluid extraction (SFE) (CO2 and CH3OH as modifier) of the herbicides atrazine and terbutylazine as well as their deethyl- and hydroxymetabolites from soil was investigated. The analytes were determined after extraction by HPLC/UV-DAD using a C18 column. The limits of detection of the chromatographic step were between 0.01 μg/mL and 0.07 μg/mL, the relative standard deviations between 0.8% and 1.4%. With the aid of a control chart, the stability of the chromatographic system was evaluated. For extraction, soil was spiked with 5 μg/g for each component. For SFE, CO2 and methanol as modifier were used, and a pressure program was applied. Beside SFE, Soxhlet extraction with methanol and a solid-liquid extraction with acetone/water by shaking were carried out. For chlorine-containing triazines, the recovery rates were comparable for all extraction methods. The following recovery rates for SFE were obtained: deethylterbutylazine 77.4%, terbutylazine 80.2%, deethylatrazine 87.4%, atrazine 92.6%. However, the recovery rates for the hydroxymetabolites (4.1% for hydroxyatrazine, 21% for hydroxyterbutylazine) were not satisfying compared with the “classical” methods of extraction (above 50%). The limits of detection for the total process (SFE and HPLC/UV-DAD) estimated by the signal to noise ratio amounted 0.08 μg/g soil for chlorine-containing derivates, for hydroxyatrazine 2…3 μg/g, and for hydroxyterbutylazine 0.8 μ/g.  相似文献   

12.
Determination of Organophosphorus Pesticides in Water by HPLC‐MS‐MS In the EC Water Framework Directive 2000/60/EG and in CEC 76/464/EEC there are 16 organophosphorus pesticides (insecticides and acaricides) listed which belong to so‐called priority substances. The committed quality aims of these substances frequently require maximum concentrations below 0.1 μg/L. In this paper a HPLC‐MS‐method is described. The reported limits of determination of organophosphorus pesticides are lower than the demanded limits. High analytical sensitivity is reached by solid‐phase extraction (SPE) and by injecting large volumes. For some of these substances no sample enrichment is needed and low detection limits are obtained by direct injection of the original water sample.  相似文献   

13.
The occurrence of selected human pharmaceutical compounds in UK estuaries   总被引：2，自引：0，他引：2  
This report describes a scoping study conducted in order to establish whether pharmaceutical compounds may be present in UK estuaries. Surface water samples collected from five UK estuaries were analysed for the presence of 14 pharmaceutical compounds selected from the priority lists of the UK Environment Agency and the Oslo and Paris Commission (OSPAR). The pharmaceutical compounds/metabolites clofibric acid, clotrimazole, dextropropoxyphene, diclofenac, ibuprofen, mefenamic acid, propranolol, tamoxifen and trimethoprim were detected at measurable concentrations in the samples collected. The concentrations of erythromycin, lofepramine, paracetamol, sulfamethoxazole and acetyl-sulfamethoxazole were all below the limits of detection of the methods used (between 4 and 20 ng l(-1)). The anti-fungal agent clotrimazole was the most frequently detected at a maximal concentration of 22 ng l(-1) and a median concentration of 7 ng l(-1). The analgesic compound ibuprofen was detected at a maximal concentration of approximately 930 ng l(-1) and a median concentration of 48 ng l(-1), whilst the other pharmaceutical compounds were detected between the limits of detection of the method used and 570 ng l(-1).  相似文献   

14.
The role of external ammonium inputs in freshwater acidification   总被引：4，自引：0，他引：4  
Gaseous ammonia released into the atmosphere from animal manure, fertilizer and industrial processes, neutralizes acid oxidation products of sulphur and nitrogen oxides in precipitation. This results in a substantial increase in pH of precipitation. Once deposited in soil or water, the ammonium compounds may be oxidized to nitric acid. This means that hydrogen ions neutralized in the atmosphere are now released. This paper concerns bulk precipitation sampled at some selected northern Italian and Dutch sites, representing areas with different regional industrial and agricultural impact. In addition the role of external loads of ammonium in freshwater acidification is discussed considering an ammonium sulphate polluted subalpine lake in northern Italy and the results of experimentla studies on susceptible soft water systems in The Netherlands. In these cases the acidifying effect of biochemical ammonium conversions, particularly ammonium oxidation, was evident, reaching pH values below 4. Regarding the deleterious chemical and ecological effects, a reduction in the emission of gaseous ammonia is programmed for The Netherlands. In the Alpine region atmospheric ammonia and ammonium also constitute a threat for sensitive ecosystems.  相似文献   

15.
Determination of Pesticides in Water by On-line Solid-phase Extraction and HPLC-DAD This paper describes an HPLC on-line procedure for the determination of 29 relevant pesticides in water by diode-array detection using a compact HPLC-system with integrated column-switching. The sample – 5 mL – is injected with a large volume injection system on a precolumn cartridge (RP-C18). Enriched compounds are eluted in frontflush mode by columnswitching to a microbore column and separated with a gradient water/acetonitrile. During desorption the precolumn cartridge is heated at 80°C resulting in a comparable efficiency to the separation with direct injection. The procedure is fully automated for continuous monitoring of drinking-, ground-, and surface water with low contamination levels. Sample preparation is limited to a filtration step with an anion-exchange membrane filter to reduce natural contaminations e.g. humic acids simultaneously. For a concentration of 50 ng/L, the signal to noise ratio varies from 3:1 (Ethidimuron) up to 25:1 (Chloridazon). The standard deviations compare to the standardized HPLC-method DIN EN ISO 11369; the recovery rates are 100% and reproducible. The method was successfully tested on ruggedness with several sequences from a monitoring program. The precolumn cartridge needs replacement after 100 sample injections. Finally, this method was coupled with a benchtop mass-spectrometer (electrospray mode) without changing the chromatographic conditions. With selected ion monitoring (SIM) selectivity and detection sensitivity could be improved considerably compared to DAD-detection.  相似文献   

16.
The incorporation of fullerenes and carbon nanotubes into electronic, optical and consumer products will inevitably lead to the presence of these anthropogenic compounds in the environment. To date, there have been few studies isolating these materials from environmental matrices. Here we report a method commonly used to quantify black carbon (BC) in soils, the benzene polycarboxylic acid (BPCA) method, for measurement of two types of single walled carbon nanotubes (SWCNTs), two types of fullerenes and two forms of soot. The distribution of BC products (BPCAs) from the high pressure and high temperature oxidation illustrates the condensed nature of these compounds because they form predominantly fully substituted mellitic acid (B6CA). The conversion of carbon nanoparticles to BPCAs was highest for fullerenes (average of 23.2 ± 4.0% C recovered for both C60 and C70) and lowest for non-functionalized SWCNTs (0.5 ± 0.1% C). The recovery of SWCNTs was 10 times higher when processed through a cation-exchange column, indicating the presence of metals in SWCNTs compromises the oxidation chemistry. While mixtures of SWCNTs, soot and sediment revealed small losses of black carbon during sample processing, the method is suitable for quantifying total BC. The BPCA distribution of mixtures did not agree with theoretical mixtures using model polyaromatic hydrocarbons, suggesting the presence of a matrix effect. Future work is required to quantify different types of black carbon within the same sample.  相似文献   

17.
The degradation of dissolved organic matter (DOM) was studied in alkaline solution. The products were characterised using UV/vis spectroscopy, size‐exclusion chromatography (SEC), and by the analysis of low‐molecular‐weight organic acids (LMWOA). The degradation experiments were performed with water from a brown water lake or its isolated fulvic acid fraction and sodium hydroxide at different reaction times and temperatures. Depending on the wavelength and the reaction time, the UV/vis absorbance between 230 nm and 600 nm increased or decreased. The behaviour of model compounds during reactions in alkaline media was compared to the UV/vis spectroscopic behaviour of DOM. The release of LMWOA was described by kinetic data and compared to the data of model reactions. Evidence was given for the carboxylic esters playing a significant role in the release of LMWOA only during the beginning of the alkaline degradation. The results gained by SEC with on‐line UV and DOC detection showed that the average size of DOM was decreasing, and that a major part of the degradation products consisted of low‐molecular‐weight mono‐ and dicarboxylic acids.  相似文献   

18.
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19.
The paper describes the state of a standardized method for the determination of polycyclic aromatic hydrocarbons (PAH) in water, sludges, sediments, and soils by high performance liquid chromatography (HPLC). The separation of PAH on different specific PAH-columns is illustrated and the chromatographic conditions in relation to the subsequent programmed fluorescence detection are displayed. A method for the treatment of soil samples using a simple but efficient extraction method by ultrasonication using tetrahydrofuran or acetonitrile as extractants is presented. By means of selected samples, it is demonstrated that the extractive recovery rates of the presented method can compete with those of the conventional soxhlet extraction.  相似文献   

20.
A simple and selective solid phase extraction procedure for the trace analysis of iron(III) in water samples has been developed. Sodium dodecyl sulfate coated alumina, modified with polyphenolic compounds (extracted from black tea) was used for the extraction and preconcentration of iron(III) from water samples before determination by flame atomic absorption spectrometry. Due to the complexation reaction between iron(III) and polyphenol compounds, iron(III) was quantitatively extracted on the proposed sorbent and then eluted by 2.0 mL of HCl (1.0 mol/L). The effects of extraction parameters, such as pH and volume of sample solution, amount of polyphenolic compounds, type of eluting agent and the effect of interfering ions on the extraction of iron(III), were investigated. It was found that the proposed method had a good linear range (15.0–100.0 μg/L) and a low detection limit (10.0 μg/L). The procedure was successfully applied for iron determination in drinking water samples.  相似文献   

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