共查询到20条相似文献，搜索用时 15 毫秒
1.
Dawn A. Zemo Kirk T. O'Reilly Rachel E. Mohler Asheesh K. Tiwary Renae I. Magaw Karen A. Synowiec 《Ground Water Monitoring & Remediation》2013,33(4):44-56
Polar metabolites resulting from petroleum biodegradation are measured in groundwater samples as TPHd unless a silica gel cleanup (SGC) is used on the sample extract to isolate hydrocarbons. Even though the metabolites can be the vast majority of the dissolved organics present in groundwater, SGC has been inconsistently applied because of regulatory concern about the nature and toxicity of the metabolites. A two‐step approach was used to identify polar compounds that were measured as TPHd in groundwater extracts at five sites with biodegrading fuel sources. First, gas chromatography with mass spectrometry (GC‐MS) was used to identify and quantify 57 individual target polar metabolites. Only one of these compounds—dodecanoic acid, which has low potential human toxicity—was detected. Second, nontargeted analysis was used to identify as many polar metabolites as possible using both GC‐MS and GC×GC‐MS. The nontargeted analysis revealed that the mixture of polar metabolites identified in groundwater source areas at these five sites is composed of approximately equal average percentages of organic acids, alcohols and ketones, with few phenols and aldehydes. The mixture identified in downgradient areas at these five sites is dominated by acids, with fewer alcohols, far fewer ketones, and very few aldehydes and phenols. A ranking system consistent with systems used by USEPA and the United Nations was developed for evaluating the potential chronic oral toxicity to humans of the different classes of identified polar metabolites. The vast majority of the identified polar metabolites have a “Low” toxicity profile, and the mixture of identified polar metabolites present in groundwater extracts at these five sites is unlikely to present a significant risk to human health. 相似文献
2.
High-performance thin-layer chromatography with automated multiple development (AMD-HPTLC) was applied for the examination of pulp mill bleachery effluents from an alkali-oxygen-peroxide (EOP) bleaching stage of a sulfite pulp. A gradient based on methanol and dichloro-methane was developed for the separation of the effluent compounds over a wide range of migration distances. A series of reference substances such as lignin phenols and other aromatic acids, aldehydes, and alcohols as well as two resin acids were investigated in parallel using the AMD-HPTLC method. Characterization of the effluent compounds was possible using the migration distances and the recorded spectra. The composition of different samples of effluent were found to be very similar. The application of the AMD-HPTLC to effluent fractions from acidic liquid-liquid extraction using diethyl ether and from RP C18 solid-phase extraction allowed us to follow the behaviour of the effluent compounds in the extraction procedure. 相似文献
3.
After their extraction from water, 16 water pollutants of the families of triazines, urea herbicides, phenoxycarboxylic acids and organochlorine and organophosphorus insecticides are separated and identified by thin-layer chromatography. The method is suitable for routine analyses and was tested on model waters, inclusive of water from the Elbe river. The rate of redetection is up to 80%, the detection limit is at 0.5… 2 μg of the individual pollutants. 相似文献
4.
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
5.
The bile liquid is preserved with ethanol and the protein is precipitated. Prefractionating is done by liquid-liquid extraction by chloroform and ethyl acetate. The extracts are column-chromatographically separated on Florisil and subsequently detected by thin-layer chromatography. For determining the identity of substances, the penta fluorobenzyl derivatives are prepared and chromatographed under the same conditions. Detection is carried out with the aid of ammoniacal silver nitrate reagency and ultraviolet irradiation. The highly polar conjugates of chlorophenoxyalkane acids and chlorophenols which are present in the bile are cracked by acid hydrolysis and then cleaned by re-extraction. In this way, 2, 4-D, MCPA, MCPP, 2,4-dichlorophenol and 2-methyl-4-chlorophenol were detected from Salmo gairdneri. 6… 21 d after the application of the herbicides in the catchment area their concentration in the fish bile amounted to about 200 mg/l, 90% of them having been conjugates. Thus, the biliary excretion of xenobiotic substances offers an important new aspect of biomonitoring by means of fish tests, especially in the range of subacute and chronic toxicity. 相似文献
6.
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
7.
W. Huber 《洁净——土壤、空气、水》1992,20(1):6-8
Determination of aminopolycarboxylic acids by ion pair chromatography. A method for the determination of aminopolycarboxylic acids, especially NTA and EDTA, is described, based on ion pair chromatography. The detection is done in UV at about 260 nm. The analytes are transformed into the Fe(III)-complexes before separation. For lower concentrations this can automatically be achieved by injecting the analyte into the Fe(III)-containing eluent. For higher concentrations, Fe(III) has to be added separately. Determination is possible down to 10 μg/1 concentration. 相似文献
8.
The rational use of pesticides generates an impact which is normally reversed and eliminated by the environment itself. However, the indiscriminate use of pesticides makes its natural degradation rhythm difficult, prolonging their presence in the soil for a great deal of time. Aiming towards a decrease in the environmental impact of pesticides, soil microorganisms capable of degrading pesticides, such as propanil, were investigated. An Enterobacter cloacae strain, isolated from rice field soil, was exposed to the herbicide propanil alone and in a mixture containing also bentazone, clomazone, quinclorac, and 2,4‐D. This bacterium was able to eliminate 100% of the applied propanil in 28 days. Propanil degradation in the 5‐herbicide mixture was much lower than that of individual pesticide degradation. The aeration of the system helped to degrade propanil and its subproduct 3,4‐dichloroaniline much faster. LC with UV detection was used to determine the remaining concentrations of the herbicides and their subproducts. 相似文献
9.
Waste water from ammunition production sites and aqueous samples (ground and surface water) on or near former military sites on which explosives were produced or filled, e.g. into shells, may be contaminated by the original explosives—mainly nitrotoluenes (such as dinitrotoluenes, trinitrotoluene (TNT)) and nitramines (such as hexogen (RDX), octogen (HMX), and tetryl) or hexyl, but also by byproducts and compounds formed by biodegradation of the explosives such as aminonitrotoluenes, chlorinated nitrobenzenes and nitrophenols. These compounds can be extracted from aqueous samples by liquid/liquid extraction (using dichloromethane or toluene) or by solid phase extraction using C-18 adsorbents with high recoveries (usually ≥85%) provided they contain only one amino group. Nitrotoluenes, chlorinated nitrobenzenes and aminonitrotoluenes (nitrotoluidines) may be determined by gas chromatography (GC) using selective detectors such as an electron capture detector (ECD), a nitrogen-phosphorus detector (NPD) or a chemiluminescence detector (thermal energy analyzer, TEA). The use of combined gas chromatography/mass spectrometry (GC/MS) under electron impact conditions is even more specific. Detection limits comparable to an ECD or NPD, however, are only achieved if the mass spectrometer is operated under selected ion monitoring (SIM). Nitrophenols are derivatized after extraction by heptafluorobutyric anhydride or by acetic anhydride where the latter method can be directly applied to the aqueous sample. The nitramine explosives, such as RDX, HMX, and tetryl, hexyl, the nitrate esters, such as nitropenta (PETN) and nitroguanidine as well as picric acid cannot, or only with difficulty, be analyzed by gas chromatography. They may be determined by high performance liquid chromatography (HPLC) with UV-detection. The HPLC analysis can be extended to include also nitrotoluenes and nitroaminotoluenes. 相似文献
10.
A characterization method for AOX in surface water samples was developed and tested. The method involves fractionation using a hydrophobic C18 resin and a weak anionic exchange resin and allows the fractionation of the AOX pool of surface water samples into four fractions: (1) hydrophilic acidic, (2) hydrophilic non‐acidic, (3) hydrophobic acidic, and (4) hydrophobic non‐acidic. The adsorption analysis was verified with AOX‐relevant model compounds and was applied to characterize the AOX pool of a stream sample from the Moskva river (Russia). In addition to the fractionation analysis, size‐exclusion chromatography was used to characterize the AOX pool of the sample studied. Hydrophilic acids made up the major fraction of the AOX pool (55 %). Among this fraction chlorinated high‐molecular acids (humic substances) made up the main fraction (35 %). 相似文献
11.
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
12.
The gel-permeation chromatography system with multicomponent detection of organic carbon, organic nitrogen, organic halogen, and UV/vis absorption measurement is shown to be a useful tool for characterization of industrial wastewaters and wastewater treatment processes. The proposed system was used to investigate biologically treated wastewater from chemical industry, whereby one branch stream was identified to be the main source of persistent halogenated organics. Various treatment processes of pulp mill wastewater were also evaluated revealing that precipitation with aluminium is very effective for the removal of the high molecular fraction whereas the biological treatment is generally less selective. In the biological treatment of tannery wastewaters, it has been shown that the aerobic treatment, in contrast to anaerobic step, causes evident alterations of the composition of the polar DOC fraction. The nitrogen containing compounds are also better decomposed in the aerobic step compared to the anaerobic one. 相似文献
13.
GC/MS Nontarget Analysis to Examine an Organic Groundwater Contamination. Part I: Sampling – Analysis – Identification GC/MS nontarget analysis is a combination of an extraction sequence and a GC/MS analysis without standards. The extraction sequence should enrich a wide range of organic substances with different chemical and physical properties. The GC/MS analysis without standards evaluates the total chromatogram whereas the possibilities of compound identification are limited. This kind of view is suited very well if the task of examinations are unknown organic contaminations and the conventional target analysis has to be expanded to a large number of compounds with the uncertainty of detecting the main contaminants. The extraction sequence is similar to the EPA 625 analysis of base/neutral and acid extractable organic compounds. Basis are liquid extraction and solid-phase extraction at different pH values. This extraction procedure covers approximately 30 % of total organic carbon of these groundwater samples from a contaminated area near a low temperature carbonization plant. Relevant groups of organic compounds analyzed in the contaminated groundwater or in the reference sample are substituted aromatics, phenols, benzoamines (anilines), and derivates of benzothiophene. Differences in the trace substance mixtures between the contaminated samples and the reference sample are demonstrated by applying modern graphical methods. 相似文献
14.
15.
Dissolved organic carbon (DOC) distributions in water from Lake Ipê, MS, Brazil, were investigated. The samplings were performed monthly (surface, 1 m depth, and bottom) from June 1999 to June 2000. Absorbance at 285 nm and DOC concentrations in mg dm—3, p(DOC), were highly correlated for the three depths. 77% of the surface, 85% for 1 m and bottom samples presented a variation between 20 dm3 g—1 cm—1 and 50 dm3 g—1 cm—1 of A(285 nm)/p(DOC), that characterizes the dissolved organic matter in lake water as essentially fulvic. The ratio A(254 nm)/p(DOC) was also sensitive for fulvic matter, and an A(250 nm)/A(365 nm) = 4 ratio was characteristic of strongly colored waters. The ratios A(436 nm)/p(DOC) for the three depths also showed a significant correlation. The predominance of fulvic acid is explained by environmental characteristics such as the tropical climate, temperatures above 18 °C, and the lake environment. It was demonstrated that the variation in the water carbon content due to different compartments in the lake can be monitored by UV‐vis spectroscopy ratios. 相似文献
16.
H. Hellmann 《洁净——土壤、空气、水》1995,23(3):121-130
Fine Resolution of UV Spectra by Differentiation of 1st and 2nd Order in Hydrocarbon Analysis Basic UV spectra (0th order) in unpolar solvents such as cyclohexane are useful — though with some reservations — in characterizing mineral oils occuring in pure form and aromatic fractions in environmental samples separated by chromatographic techniques. The common standard raffinates, biogenic hydrocarbons or other mixes of hydrocarbons including polycyclic aromatics can be approximately identified. The spectra of 1st and 2nd order improve the reliability of the results and permit above all to detect polycondensated aromatics even in traces. Finally, partial spectra of 1st and 2nd order in the wavelength ranges 205…240, 220…260, and 260…320 nm allow because of their very specific structures a simple and fast practically definite assignment to the above-mentioned groups of aromatics. Analogously, substituted aromatics in detergents and other technical products have already been identified. The method is suitable as a fast preliminary test, at least. 相似文献
17.
The proximity of the Great Barrier Reef (GBR) Marine Park to areas of intensive agriculture and increasing urbanisation places the park under potential threat of contamination by land-based pollutants. Passive samplers were deployed at inshore reef and river mouth sites in the Wet Tropics region of the GBR during a dry and a wet season to measure levels of land-based organic pollutants in this environment. Two types of passive sampling devices were deployed: (i) a polar sampler, which can be used to monitor polar herbicides and (ii) semipermeable membrane devices (SPMDs) which sequester more hydrophobic compounds (e.g. PAHs, chlorpyrifos). Herbicides (diuron, simazine, atrazine, hexazinone and/or flumeturon) were detected at low concentrations (ng L−1) at all sites sampled and in both seasons. Chlorpyrifos was not detected while PAHs were present in SPMDs at levels below limits of detection. The results show that the GBR environment does contain low levels of organic pollutants and that passive sampling provides a sensitive monitoring tool for measuring waterborne organic pollutants. 相似文献
18.
Solid Phase Extraction of Phenols from Water by Highly Porous Cross-linked Polystyrene The extraction of organic trace components from water by solid phase extraction has largely substituted liquid/liquid extraction. For the isolation of many underivatized phenols with significant water solubility however, the conventional surface-modified silicagels are unsuitable. In the following, results are reported of experiments with a novel, highly porous material of cross-linked polystyrene. Using columns with 0.2 g of the adsorbent, the isolation of more than 60 differently substituted phenols, including 6 pesticides and 31 metabolites, in the concentration range of 25 to 125 ng/L has been accomplished. After adsorption from 1 L of sample water, derivatization and gas chromatographic determination recoveries ranged from 70 to 100%. 相似文献
19.
The more sensitive an analysis method the more care must be given to sample preparation. Solid phase extraction (SPE) onto RP 18 phases has established itself as a general purification and enrichment technique for trace components in aqueous samples. Various factors may thereby influence the recovery rate. For example, the ratio amount of sorbent and sample volume should be taken into account to avoid breakthrough of the investigated substance. Extracting phenylurea herbicides from drinking water, the ratio should be 1 g RP 18 sorbent per 1 L water sample. Concerning the flow rate for the fungicides procymidone, vinclozolin, and iprodione, the recovery rate decreases using higher flow rates than 3 or 6 mL/min. In the case of phenylurea herbicides, a flow rate of 10 or 14 mL/min showed best results. Even the coefficient of variation is below ± 5% at these flow rates. Furthermore, the company dependence should be considered because the recovery rate might differ by up to 40% using the nominally identical material. The same applies to the batch dependence of quality from the same company. The concentration of the eluate must also be monitored and carried out with great care to avoid decreasing the recovery rate. Considering these factors of influence, SPE is a very useful tool in sample preparation, particularly if an automated system is used. 相似文献
20.
Mobilization Potential of Hydrophobic Organic Compounds (HOCs) in Contaminated Soils and Waste Materials. Part II: Mobilization Potential of PAHs, PCBs, and Phenols by Natural Waters To evaluate the hazard potential of organic pollutants in a soil, the mobilization potential of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and phenol derivatives in different waters was ascertained by elution experiments and compared to common elution procedures. Furthermore, dissolved organic matter from different sources was examined with regard to its influence on solubility. The results of the elutions pointed out that depending on the composition of the water sample, the leaching behaviour of the PAHs and PCBs is very different and is determined not only by the concentration of the dissolved organic carbon (DOC) but particularly by its quality. The separation of DOC-associated and “free” dissolved pollutants with the solid-phase extraction on C18-reversed phases revealed the responsibility of the sorption of the pollutants to the DOC for their solubility and mobilization. Moreover, an increase of association of pollutants to the DOC was observed with growing hydrophobicity corresponding to their octanol/water partition coefficient Kow. The comparison of the elutions showed that the exclusively used S4-elution (German standard DIN 38414 part 4) is not appropriate to evaluate the mobilization of hydrophobic organic pollutants realistically. The eluted PAHs (PCBs) of the S4-elution were exceeded in landfill leachate by a factor of 7 (7), in the pond water by a factor of 9 (15), and in the compost saturation extract even by a factor of 35 (56). In contrast, a realistic “worst-case” leaching could be simulated with a tensidic SDS-solution corresponding to an elution process evaluating the mobilization of organic pollutants. The DOC of real waters and surfactants has little influence on the mobilization of the comparatively polar phenols. Concerning a “worst-case” evaluation of mobilization, the S4-elution under alkaline conditions is doubtlessly useful for water-soluble phenols. 相似文献