Zur Bildung von Artefakten und deren Vermeidung bei der Bestimmung leichtflüchtiger Halogenkohlenwasserstoffe in Wasser mittels Headspace-Gaschromatographie unter den Bedingungen der DIN 38407 Teil 5 (DEV-F5). Teil I: Bildung von Dehydrohalogenierungsprodukten aus gesättigten LHKW

Formation of Artefacts and its Suppression during the Determination of Volatile Halogenated Hydrocarbons in Water by Means of Headspace Gas Chromatography under the Standard Conditions of DIN 38407-F5. Part I: Formation of Dehydrohalogenation Products from Saturated Halogenated Hydrocarbons Under the conditions recommended by DIN 38407-F5 for the headspace gas-chromatographic determination of volatile halogenated organic substances in water (equilibration at 60…80°C for a least 60 min) several halocarbons are degraded by dehydrohalogenation resulting in the formation of unsaturated artefacts with one halogen atom less. Thus pentachloroethane and 1,1,2,2-tetrachloroethane are decomposed to form tetrachloroethylene and trichloroethylene, respectively. This leads to low results of the analytes and to false-positive detection of the reaction products. The unwanted degradation reactions can be reduced by decreasing the temperature and duration of equilibration, and they are completely suppressed by acidification of the samples.     

Artefaktfreie GC-Bestimmung von Trihalogenmethanen in Schwimmbeckenwasser nach Anreicherung mittels Headspace-Festphasenmikroextraktion

Artefact-free Determination of Trihalomethanes in Chlorinated Swimming-pool Water Using Headspace Solid-phase Microextraction and Gas Chromatography Headspace solid-phase microextraction (headspace SPME) is a rather new technique for the solvent-free extraction and concentration of volatile substances from water into an organic polymer layer covering a fused-silica fiber. In combination with gas chromatography, the method represents a powerful tool for sensitive headspace investigations. As the adsorption of low boiling substances is favoured at low temperatures, the method can be operated at ambient temperature without formation of artefacts. Therefore, the method is ideally suited for the analysis of volatile disinfection by-products in water including several thermolabile THM-precursors. For the artefact-free determination of trihalomethanes it is superior to headspace gas chromatography under the conditions of the German standard method DIN 38407-F5. Compared to gas chromatography after pentane extraction (DIN 38407-F4), headspace SPME is simpler, less- laborious, better reproducible, and, especially for polar, easily water-soluble components, much more sensitive. In addition, it operates solvent-free and can be automated. Using a 100-μ polydimethylsiloxane-coated fiber, the method is linear over at least 2 orders of magnitude and has a relative standard deviation of 2… 7% in the upper ng/L range. With a 65-μ polydimethylsiloxane/divinylbenzene-coating on the fiber, the sensitivity of the method can be extended to limits of quantitation in the low ng/L range. However, this fiber, shows an increased susceptibility to matrix effects as observed in the presence of diisopentyl ether, which can only be compensated by using the method of standard addition.     

Bildung bromhaltiger Desinfektionsnebenprodukte nach Chlorung von Bodenseewasser in Abhängigkeit von Aufbereitungsschritten und der Bromidkonzentration

Formation of Brominated Disinfection By-products after Chlorination of Water from Lake Constance Depending on Treatment Steps and Bromide Concentration The formation of halogenated disinfection by-products (DNP) (trihalomethanes (THM), haloacetic acids (HES), haloacetonitriles (HAN), haloketones (HKE) and chloropicrin (TCNM)) was studied after chlorination (0.5 mg/L) of raw water and drinking water from Lake Constance. The objectives of this study were to investigate the effect of bromide ion on the distribution of DNP-species resulting from chlorination and to draw up a bromide mass-balance. The treatment of water from Lake Constance with ozone decreased the formation of DNP about 35% and of total organic halogens (AOX) about 45%. This decline in DNP-formation is mainly due to the formation of chloroform, dichloro- and trichloroacetic acid. Though there is only a small amount of bromide (6.2 μg/L) in water from Lake Constance, about 32% of THM, 16% of HES, and 30% of HAN contained bromine after chlorination of treated water. The addition of bromide ion (up to 1 mg/L) shifted the DNP-composition to more brominated species. The distribution of the DNP-species depends on the initial molar bromide-to-chlorine ratio. A mathematic model showed the same pattern of DNP-species depending on the initial molar bromide-to-chlorine ratio that was observed experimentally in microstrained raw water and drinking water from Lake Constance. After chlorination of microstrained raw water, 27% of the bromide were incorporated in known DNP, 34% in unknown substances, and about 39% of bromide were not converted to organic bromine. After chlorination of treated water, only 16% of the bromide were incorporated in unknown substances, whereas 34% were found in known DNP. About 50% were found as bromide again. After addition of bromide (up to 25 μg/L) to ozonated and treated water from Lake Constance, between 60 and 72% of the bromide that had reacted after chlorination were found in analyzed low-molecular DNP.     

Application of AMD to the Determination of Crop Protection Agents in Drinking Water. Part IV: Fundamentals of a Confirmatory Test

A method is described for the determination of fifteen active ingredients of plant protecting products in ground-, raw, and drinking water. After extraction and enrichment of the pesticides from the water sample with solid-phase extraction, the extract is fractionated on silica-coated TLC plates, first in a so-called screening gradient by AMD (automated multiple development). The detection of the pesticides is performed by UV multidetection. Positive results from the first separation are confirmed by a second separation on silica in an AMD gradient of distinctly different selectivity, compared to the first separation. Following this strategy, it is possible to distinguish nearly all nonvolatile, from water extractable, active ingredients of plant protecting products in the market. UV spectra are taken for further confirmation of positive results. In most cases, this is possible even at the limit of determination. All chromatograms and spectra shown are raw data, resulting from the confirmatory test DIN 38407 part 11, in the laboratory of one participant*). The method is standardized in the meantime as DIN V 38407-11.     

Effect of Preozonation on the Formation of Chlorinated Disinfection By‐products for River Ruhr

The purpose of the study is to gain a better understanding about the formation of THM (trihalomethanes), HAA (haloacetic acids), and AOX (adsorbable organic halogen) in river water (river Ruhr, Essen) through a chlorination kinetics approach. The effect of chlorination time and preozonation on the formation of THM, HAA, and AOX substances was studied. Preozonation can reduce the chlorine demand and the precursors for AOX and THM. THM generation was reduced further, when the ozone dosage consumed increased from 3.5 to 12.5 mg in the 1.4 L reaction vessel. AOX and TCAA (trichloroacetic acid) concentrations also decreased dramatically when 3.5 mg of ozone had reacted with the river water, but a higher dose of ozone did not further reduce AOX and TCAA formations. Besides, the characteristics of organic matter in raw water, ozonated water, and preozonated/chlorinated water was investigated. The results suggest the formation of low‐molecular‐weight acids with low UV absorbance when high‐molecular refractive matter is oxidized.     

GC/MS-Nontargetanalytik zur Aufklärung einer organischen Grundwasserkontamination. Teil I: Probennahme – Analytik – Identifikation der organischen Verbindungen

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.     

Zur Analytik von Chlorphenoxyalkansäuren und Chlorphenolen. Teil 2: Nachweis von Chlorphenoxyalkansäuren und Chlorphenolen in der Fischgalle

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.     

顶空气相色谱法测定水中挥发性有机污染物

介绍静态顶空气相色谱分析的原理,研究温度、相比、分配常数和无机盐等参数对顶空分析灵敏度的影响.此方法对8个挥发性苯系物的线性相关系数0.999,相对标准偏差0.95%,方法检出限1μg/L.在炼油厂废水中,检出104个色谱峰,其中苯、甲苯、乙苯、间,对二甲苯和邻二甲苯均有检出,浓度范围在268-1622μg/L.污水处理厂出口水样和废水库样品中挥发性有机物均未检出.采集15个安徽巢湖水样,挥发性苯系物和挥发性有机物均未检出(1μg/L).     

Gaschromatographische Bestimmung von polychlorierten Biphenylen in Wasser nach Headspace-Festphasenmikroextraktion

Gas-chromatographic Determination of Polychlorinated Biphenyls in Water after Headspace Solid-phase Microextraction Headspace-analytical techniques are usually applied to the determination of easily volatile substances in water, whereas semivolatiles are generally isolated by liquid-liquid or solid-phase extraction. In the present paper, a method is presented for isolating high boiling polychlorinated biphenyls (PCB) using headspace solid-phase microextraction at elevated temperature. In spite of their low vapor pressure, the analytes are adsorbed very efficiently on a poly-dimethylsiloxane-coated fiber. Thus, in combination with GC/ECD, a very simple and sensitive solventless determination of PCB is accomplished. Using the simplest possible standard conditions, limits of determination in the lowest nanogram-per-liter range are achieved. Further increased sensitivity down to the ppq (parts per quadrillion) range is possible by stirring and increasing the sample volume and adsorption time. Moderate matrix effects have been observed in some surface and groundwaters.     

Vergleich ausgewählter Elutionsverfahren zur Beurteilung der Mobilität von Metallen

Comparison of Selected Elution Procedures for the Valuation of the Mobility of Metals from Sediment and Sewage Sludge Several methods of extraction are generally used to evaluate environmental or ecological toxicity and deposition of waste material. In this paper, the application of the German standard methods DIN 38414-S7, DIN 38414-S4, pH_stat method, “Schweizer method” (elution test, Switzerland), and some variants of the pH_stat method on two very different samples are described. A rudimental sediment and a municipal sewage sludge are chosen as sample materials. The metal contents of extract solutions are determined by ICP-OES. The results of the DIN-S4 extractions depend definitely on the mechanic way of movement, i.e. the amount of heavy metals which are mobilized out of the samples differs considerably. In fact, DIN-S7 in combination with DIN-S4 is not sufficient to estimate the mobility of heavy metals. Solid samples should only be evaluated by applying a combination of several methods of extraction. The usefulness of the pH_stat method for an evaluation is discussed.     

Zum Umweltverhalten von Fluortensiden. Teil 3: Reinigung der industriellen Abwässer

Four fluorotensides which are used mainly industrially are investigated with respect to their removability from waters. Since, in general, fluorotensides are difficult to remove or not at all removable biochemically, the effects of chemical or physicochemical treatment processes are tested. As the results represented in pictures and tables show, different modes of behaviour can be recognized with respect to the respective purification effect for the investigated fluorotensides, partly among them. Flocculation with Al- and Fe-salts as well as chlorination and ozonization show only partial effects. But all the investigated fluorotensides can be adsorptively eliminated by means of powder or granular active charcoal and adsorbent resin Wofatit EA₆₀.     

Problems and Solutions in Pesticide Analysis Using Solid‐phase Extraction (SPE) and Gas Chromatography Ion‐trap Mass Spectrometry Detection (GC‐MS)

In the present study an analytical method was tested for the determination of selected pesticides and metabolites using solid‐phase extraction (SPE) and gas chromatography ion‐trap mass spectrometry (GC‐MS). The extraction efficiency of C18, Isolut ENV+, and Lichrolut EN for SPE was compared for trifluralin, fenitrothion, endosulfan, propargite, 2,4‐D, 3‐methyl‐4‐nitrophenol, 2‐(4‐tert‐butylphenoxy)cyclohexanol, endosulfan sulfate, and 2,4‐dichlorophenol. Isolut ENV+ and C18 showed good results as sorbents and acetone as an elution solvent for SPE for the selected pesticides. Recoveries varied between 36% and 176% with a relative standard deviation of 2...18%. Because of coextracts from the SPE materials, recovery values higher than 100% were obtained for fenitrothion, endosulfan sulfate, and 2,4‐D with C18 as well as for endosulfan sulfate and 3‐methyl‐4‐nitrophenol with Isolut ENV+. A standard addition method was used to verify the occurrence of coextracts in the sample after SPE.     

Identifizierung ausgewählter Pestizide im Wasser mit Hilfe eines screening-Systems auf Grundlage der Dünnschichtchromatographie

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.     

Analysis of Nitroaromatics and Nitramines in Ammunition Waste Water and in Aqueous Samples from Former Ammunition Plants and Other Military Sites Analyse von Nitroaromaten und Nitraminen in Munitionsabwasser und wäßrigen Proben ehemaliger Munitionsfabriken und anderen Rüstungsaltlasten

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.     

Groundwater Sampling at ISCO Sites: Binary Mixtures of Volatile Organic Compounds and Persulfate

In situ chemical oxidation involves the introduction of a chemical oxidant into the subsurface for the purpose of transforming groundwater contaminants into harmless by‐products. Owing to oxidant persistence, groundwater samples collected at hazardous waste sites may contain both the contaminant(s) and the oxidant in a “binary mixture.” Binary mixtures composed of sodium persulfate (2.5 g/L; 10.5 mM) and volatile organic compounds (VOCs) (benzene, toluene, m‐xylene, perchloroethylene, trichloroethylene) were analyzed to assess the impact on the quality of the sample. A significant decline (49 to 100%) in VOC concentrations was measured in binary mixtures using gas chromatography (GC) purge and trap, and GC mass spectroscopy headspace methods. Preservation of the binary mixture samples was achieved through the addition of ascorbic acid (99 to 100% VOC average recovery). High concentrations of ascorbic acid (42 to 420 mM) did not interfere in the measurement of the VOCs and did not negatively impact the analytical instruments. High concentrations of ascorbic acid favored the reaction between persulfate and ascorbic acid while limiting the reaction between persulfate and VOCs. If an oxidant is detected and the binary sample is not appropriately preserved, the quality of the sample is likely to be compromised.     

Selective chemical degradation of kerogen from Nenjiang Formation of the southern Songliao Basin

A sequential selective chemical degradation has been performed on the kerogen from the Nenjiang Formation of the southern Songliao Basin by using a series of mild chemical degradations (alkaline hydrolysis, cleavage of ether-bonds and sulfur-bonds, and ruthenium tetroxide (RuO4) oxidation). Subsequently, the GC-MS analyses are carried out on different degradation products. The results show that chemical degradations can release a great number of GC/MS-determinable biomarkers from insoluble kerogen, such as, alkaline hydrolysis products mainly comprise n-alkanes, fatty acids and alkanols; thiophene compounds are predominantly ether-bound to kerogen matrix; the products from the cleavage of sulfur-sulfur and sulfur-carbon bonds in the kerogen include fatty acids, alkanols and some n-alkanes with high carbon numbers; RuO4 oxidation products are predominantly monocarboxylic acids and α,ω-dicarboxylic acids. The distributions of main degradation products indicate that organic matter in this kerogen is predominantly derived from algae and bacteria, and that small amounts of high plant-derived organic matter are possibly combined into kerogen matrix at the late stage by sulfur bonds and other means. This study will provide an important approach for further discussing sources of organic matter in source rocks and their depositional paleoenvironments.     

Ermittlung der Nachweis-, Erfassungs- und Bestimmungsgrenze nach DIN 32645 mit Hilfe eines Programms Calculation of Detection Limit,Identification Limit and Determination Limit according to DIN 32645 with the Aid of a Computer Programs

The new German standard specification DIN 32645 defines detection, identification and determination limit of analytical experiments and contains formulas for their calculation. The detection limit is a qualitative value, only at the determination limit a quantitative statement is possible. The identification limit is no limit of decision for analyses. The expenditure for calculating these parameters is considerable. Therefore, a computer program was developed and tested at the analysis of herbicides with GC-MS after enrichment with solid phase extraction (SPE). It proved that the program is also very useful at the development of analytical methods, because it allows a quick examination of changes of the analytical method. After optimization detection limits for the herbicides were achieved which amount 10–20% of the limit of the German drinking water regulation.     

Bestimmung geringer Wassergehalte in getrocknetem Klärschlamm mit Hilfe der Karl-Fischer-Titration

Determination of Low Water Contents in Dried Sludge with the Help of Karl Fischer Titration The accomplished investigations lead to the conclusion that direct water detection in sludge is impossible. This is due to the numerous possible reactants present. Even the extraction of the water by an inert solvent did not permit any realistic deductions. The water detection in sludge requires an external extraction. This may be realized by means of an additional extracting gas or the gaseous phase of the Karl Fischer reagent. The latter method was realized with the apparatus made by the company ECH Elektrochemie Halle. This alternative offers the benefit of avoiding a separate desiccation of the extracting gas. By means of a temperature gradient, the optimum heating conditions for the extraction of water from sludge may be determined. As there are only small quantities of water to be detected in the dried sludges, the best possible method seems to be microcoulometry.     

Alkaline Degradation of Dissolved Organic Matter

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.     

Mineralization of Catechol by Fenton and Photo‐Fenton Processes

Catechol is one of the most abundant phenolic components of olive mill wastewaters. In this article, the mineralization of this compound in synthetic aqueous solutions by the Fenton and photo‐Fenton processes is studied. It has been found that for 1.44 mM catechol, the total organic carbon of solutions is reduced about 94.4% at best after 60 min of Fenton treatment at optimized conditions of pH 3.0, 0.2 mM Fe²⁺, 7.09 mM H₂O₂, and 25°C. A faster and overall mineralization is attained by applying photo‐Fenton with UVA irradiation. o‐Benzoquinone, 1,2,3‐trihydroxybenzene and 1,2,4‐trihydroxybenzene were identified by GC–MS as primary quinonic and polyhydroxylated derivatives. Small amounts of generated carboxylic acids like muconic, maleic, malonic, acetic, oxalic, and formic acids were detected by ion‐exclusion chromatography. The Fe(III) complexes of these acids persist in the medium under Fenton conditions, while their photolysis by UVA light and that of other by‐products account for by the faster degradation and total mineralization achieved in the photo‐Fenton process. A reaction sequence for catechol mineralization by Fenton and photo‐Fenton involving all intermediates detected is proposed.