Ein Beitrag zur Bestimmung von partikulärem organischen Kohlenstoff in Wasserproben

The method after Strickland and Parsons is modified for fresh water as follows: filtration on glass-fibre paper, oxidation with K₂Cr₂O₇ in cone. H₂SO₄ for 2 h at 130 °C, dilution to 2.5 times the volume by aqua dest., centrifuging-off of the turbidity and extinction measurement at 445 nm against the blank value, the sample solution being balanced to the transmission of 100% (extinction = 0). Here, the following calibration line holds for the concentration C and the quantity of oxidation solution Ox: C = E_1cmc · 0.162 · Ox, C in mg filter. The oxidation solution contains 4.8 g K₂Cr₂O₇ as dissolved in 20 ml aqua dest. and made up with conc. H₂SO₄ to 11. With 5 ml of this solution one is able to determine 0.05 … 1 mg C/filter. Calibration is performed with 125 mg/l glucose solution. Comparative investigations have shown a good agreement with elementary-analytically obtained measured values. The occurring errors have been determined mainly by sampling. In the range of very small values we have to take into account a blank value of the filter due to the adsorption of dissolved organic substances on the filter.     

Eine rationelle Variante der ΔpH-Methode zur Bestimmung von Cholinesterasehemmern in Wasserproben

Water samples of 100 ml are salted out with 35 g NaCl and extracted with 3 × 10 ml chloroform, the extract is dried and taken up with 0.2 ml ethanol. The ethanol extract is incubated with 7.857 mmol/l acetylcholinhydrochloride and an enzymatic activity of 88.8 U/l cholinesterase from horse-serum. An inhibition of cholinesterase and, therefore, of the formation of acetic acid from acetylcholin is caused by P-organic insecticides present in the investigated extract. Since the reaction proceeds in a buffer at pH 8.2 … 8.3, the pH-difference occurring between sample and control constitutes a measure of the cholinesterase inhibition. Prior to reaction, an oxidation is required for thio-compounds, which is carried out with bromine water for parathion and with potassium permanganate for dimethoat. The detection limits of the method are in the nanogram-range. Extractives from plants as well as substances from faecal matter may have a disturbing effect.     

Bestimmung eines Gruppenparameters für organische Halogenverbindungen in Wasserproben mit hohen Salzgehalten unter Verwendung von XAD-4-Harz

Determination of a Group Parameter for Organic Halogen Compounds in High Salt-laden Water Samples Using XAD-4 Resin Concerning the often discussed ‘chloride error’ in AOX determination, a method is described with allows the determination of the group parameter organic halogen compounds (OX) for chloride concentrations more than 1 g/L. In opposite to the standard method DIN 38409 part 14, no chloride influence up to a concentration of 10 g/L in real water samples occurs. The basis of the method is the adsorption of the organic compounds from the water sample on XAD-4 resin, a nonpolar copolymer of styrene and divinylbenzene. The organic compounds are concentrated on the XAD-4 resin conditioned with methanol. After the enrichment step, the adsorption columns are treated with sodium nitrate solution. Model experiments with p-chlorophenol and chloride concentrations of 50 g/L showed the effectiveness of this method. The loaded and washed adsorption columns are first eluated with acetone and then with ethyl acetate. Quantification of the OX compounds in the eluates is carried out by microcoulometric detection after combustion in a furnace equipped with a special injector for eluates. For optimal work, the instrument was modified and improved. The presented method was developed on model samples and tested on different real samples.     

Bestimmung von Organochlorpestiziden in Schlämmen und Sedimenten

A method for the determination of organohalogens by gas chromatography using electron capture (EDC) and mass-spectrometric (MS) detection was developed for sediments from lakes and sludges of water treatment plants. The method was described and separate techniques for sample preparation were investigated to compare the retrieval rates and the best approach to the “real value”. With the help of solid-liquid-phase- and liquid-liquid-phase extraction sulphur, most of the organosulphur compounds and carbon acids were effectively removed. The compounds were identified by comparing temperature programmed retention indices with those of reference compounds and by high-resolution GC/MS.     

Bestimmung von Pflanzenbehandlungsmitteln in Wasser durch Online-Fest-Flüssig-Extraktion und HPLC-DAD

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.     

Die gravitationelle Deklination,ihre Bestimmung und ihre Elimination

Summary The gravitational declination appears here as the analogue of the wellknown magnetic declination. The photographic recording theodolit in connection with a high frequency impulse transmitter allows, by a method of simultaneousness on two fieldstations, its direct and connected measurement and its elimination with regard to geodetic directions. The method has been based on linear equations, with the only request of horizontal angle measurements to a plain system of stars, abstracting from any transportable clocks. The method promises a higher accuracy and a multiple as great working velocity, comparatively to the state at present.

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Résumé Le déclinaison gravitationelle apparaît ici comme analogue à la déclinaison magnétique. Le théodolite photographique enrégistreur utilisé avec des signaux horaires radiotélégraphiques spéciaux permet par une méthode de simultanéité, appliquée à deux stations de campagne, sa détermination et son élimination rélativement à des directions géodésiques. La méthode est basée sur des équations linéaires et ne demande que des mesures horizontales par rapport à un système simple d'étoiles sans avoir recours aux pendules transportables. Elle fournit probablement une exactitude bien améliorée et une vitesse plusieurs fois plus grande comparées à l'état actuel.

     

Ein kompetitiver Immunoassay zur Bestimmung des Herbizids Fluazifop in Trink- und Grundwasser

A Competitive Immunoassay for the Determination of the Herbicide Fluazifop in Drinking Water and Groundwater A competitive solid-phase enzyme immunoassay using rabbit polyclonal antibodies was developed for the detection of the herbicide fluazifop [(RS)-2-[4-(5-trifluoromethyl-2-pyridyloxy)phenoxy]propionic acid] in drinking water and groundwater. Present regulatory limits for drinking water in Germany were taken as the critical level. The carrier protein was bovine serum albumin; horseradish peroxidase was used as marker enzyme with 3,3′,5,5′-tetramethylbenzidine as substrate. A high concentration of high-affinity antibodies in the serum, optimization of test conditions (antibody and enzyme tracer concentration, incubation time etc.), and very low cross reactivities to substances of similar structures led to a highly sensitive and specific ELISA with a detection limit below 0.1 μg/L for fluazifop as free acid. On testing the suitability of the assay's use as a screening test with one hundred drinking-water samples, the three samples which had been spiked in the laboratory were recognized as positive with respect to their fluazifop content. Confirmation by gas chromatography-mass spectrometry showed the test results of two other samples to be false positive. False negative results did not appear. The concentration was in the detection limit region of 0.1 μg/L.     

Beitrag zu Bessels Bestimmung der Gleichheit Schwerer und Traeger Masse

Summary The experiment ofFr. W. Bessel, 1832, with a fluid pendulum (water) is not in accordance with all other experiments, performed by solid pendulums. But the disaccordance is only an apparent one. With some little corrections to the experiment ofBessel with fluid it will be possible to attain full accordance with all other ones and therefore the general law of the equality of masses will be stated.

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Résumé L'expérience deFr. W. Bessel, faite en 1832 avec un pendule à eau diffère de tout'autre expérience effectuée avec des pendules solides. Mais il s'agit seulement d'une discordance apparente. En effet, au moyen de corrections peu sensibles, il est possible d'atteindre un plein accord entre les deux expériences et ainsi de confirmer la loi générale de l'égalité des masses.

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Ursprünglich geschrieben zum 100. Todestag vonFriedrich Wilhelm Bessel (geb. 22-7-1784 zu Minden, gest. 14-3-1846 in Königsberg).     

Bestimmung von gelöstem Sauerstoff und Stickstoff in Wasser mittels Gaschromatographie

Zusammenfassung Es wird eine Methode zur gleichzeitigen Bestimmung von im Wasser gel?stem Sauerstoff und Stickstoff vorgeschlagen. Nach der Probenahme in Glasgef?ssen wird das Wasser teilweise durch Helium aus den Gef?ssen verdr?ngt. Die im Wasser gel?sten Gase treten ins Helium über, in welchem der Sauerstoff- und Stickstoffgehalt gaschromatographisch bestimmt wird. Die erhaltenen Messwerte werden mit Ergebnissen der Sauerstoffbestimmung nach Winkler verglichen.

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Summary A method is proposed for the concomitant determination of nitrogen and oxygen, dissolved in water. After sampling in glass flasks, the water is displaced partially by helium. Nitrogen and oxygen, dissolved in water, are then transferred into helium, in which the two gases are determined by gas chromatography. The results obtained are compared with those received by the Winkler method for determination of oxygen.

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Résumé Une méthode pour la détermination simultanée de l'oxygène et de l'azote dissous dans l'eau est proposée. Après le prélèvement d'échantillons dans des récipients en verre, l'eau est partiellement chassée hors des récipients au moyen d'hélium. Les gaz qui sont dissous dans l'eau passent dans l'hélium dont la teneur en oxygène et en azote est déterminée par chromatographie en phase gazeuse. Les valeurs de ces dosages sont comparées aux résultats obtenus par la détermination de l'oxygène d'après Winkler.

     

Enzymatische Bestimmung von Glucose,Fructose und Saccharose in Gewässern

Zusammenfassung Die Anwendung der vonBergmeyer mitgeteilten enzymatischen Bestimmung von Glucose, Fructose und Saccharose in Gew?ssern erfordert bei Zuckerkonzentrationen unter 50 μMol/l eine spezielle Vorbereitung des Analysengutes, die anhand eines Beispiels beschrieben wird. Reproduzierbarkeit und analytische Ausbeute der Methode werden angegeben. Es wird auf die M?glichkeit hingewiesen, die Methodik auch bei der Untersuchung geologischer Proben einzusetzen.

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Summary Enzymatic analysis of glucose, fructose and sucrose by the method given byBergmeyer requires a special procedure when these sugars are determined in natural waters at concentrations below 50 μMol/l. The modified method, its reproducibility and analytical yield are described. The possibility of applying this method also to geological samples is considered.

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Résumé Le méthode du dosage enzymatique de la glucose, la fructose et la saccharose, indiquée parBergmeyer, est modifiée pour les cas où ces sucres doivent être déterminés dans des eaux naturelles à des concentrations inférieures à 50 μMol/l. On examine la variation statistique et l'exploitation analytique de la méthode modifiée. Celle-ci pourrait également être utilisée pour l'analyse d'échantillons géologiques.