Long-term monitoring of atrazine contamination in soil by ELISA

An enzyme-linked immunoassay (ELISA) was used for screening atrazine residues in soil. Samples were annually collected in Southern Germany between 1993 and 1998. An average of 419.5 samples was analyzed per year amounting to 2517 samples. The fraction of positive samples defined by atrazine concentrations >100 microg/kg soil decreased successively from 8% (corresponding to 33 samples) in 1993 to 0.6% (corresponding to 2 samples) in 1998. All positive samples and a selection of negative samples were subsequently validated by HPLC. Comparison of ELISA and HPLC data yielded correlation coefficient values of r = 0.958-0.981 (n = 18-47), except for 1995 when only a correlation of r = 0.864 (n = 18) was obtained. Four samples were overestimated and another 4 were underestimated with respect to the atrazine threshold value of 100 microg/kg soil as revealed by HPLC validation. Thus, 99.68% of 2,517 analyzed samples were correctly evaluated. The precision and reproducibility of the ELISA were adequate for a prescreening tool. The low cost per sample and the high sample throughput are not yet achievable by conventional analytical methods. The described combination of ELISA and HPLC has the potential to take advantage of both methods and to restrict determination errors to a minimum.     

Recombinant antibodies for environmental analysis

Initial steps of antibody engineering in the late eighties revolutionized the technology of antibody production, particularly in the area of immunotherapy and diagnostics. Hallmarks that seemed to be out of reach for a long time are now the state of the art, e.g. tailoring of antibodies to match particular needs or by-passing immunization by use of antibody libraries. Despite the apparent benefits of recombinant antibody technologies, this field has been opened up hesitantly for other applications. This review addresses the development of recombinant antibody synthesis in environmental analysis. Examples are given of the molecular evolution of pesticide antibodies and their application for the analysis of real samples.     

Kohle und Koks

Ohne Zusammenfassung     

Generalized three-dimensional windowed Fourier transform for fringe analysis

A 3D windowed Fourier transform is proposed for fringe sequence analysis, which processes the joint spatial and temporal information of the fringe sequence simultaneously. The 2D windowed Fourier transform in the spatial domain and the 1D windowed Fourier transform in the temporal domain are two special cases of the proposed method. The principles of windowed Fourier filtering and windowed Fourier ridges are developed. Experimental verification shows encouraging results despite a longer processing time.     

Gas chromatography—mass spectrometry analysis of termite defence secretions in the subfamilyNasutitermitinae

Summary Mono- and diterpenoid components of severalNasutitermitinae soldier secretions have been characterised by gas chromatographymass spectrometry. Patterns in monoterpene distribution are useful, but not sufficient for chemotaxonomic purposes without determination of the diterpene distribution. Diterpenoids are structurally complex and can have tetracyclic, tricyclic and bicyclic skeletal structures with various degrees of oxygenation. The relative retention indices for several identified diterpenoid compounds have been determined on OV-1 and OV-17 columns. The amount and distribution of the terpenoid components are useful aids to chemotaxonomy forNasutitermitinae termites.

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Gaschromatographisch-massenspektrometrische Analyse der Verteidigungs-Sekrete der Termiten-Subfamilie Nasutitermitinae

Zusammenfassung Mono- und Diterpenderivate in den Sekreten verschiedenerNasutitermitinae-Soldaten wurden mit Hilfe der Gaschromatographie-Massenspektro-metrie charakterisiert. Verteilungsmuster der Monoterpene sind nützlich, aber für chemotaxonomische Zwecke ohne Bestimmung der Diterpen-Verteilung nicht ausreichend. Diterpenabkömmlinge sind in struktureller Hinsicht komplex und haben tetracyklische, tricyklische und bicyklische Strukturen mit wechselndem Sauerstoffgehalt. Die relativen Retentionsindices für einzelne identifizierte Diterpenabkömmlinge wurden auf OV-1- und OV-17-Säulen bestimmt. Menge und Verteilung der Terpenabkömmlinge sind nützliche Hilfsmittel für die Chemotaxonomie der genannten Termiten.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

A host-guest optical sensor for aliphatic amines based on lipophilic cyclodextrin

A host-guest optical sensor for the determination of aliphatic amines as exemplified by octylamine is proposed. It is based on the reversible fluorescence enhancement of heptakis(2,6-di-O-isobutyl)-β-cyclodextrin(DOB-β-CD) hosting tetraphenylporphyrin (TPP) immobilized in poly(vinyl chloride) (PVC) membrane by aliphatic amine extracted from aqueous phase into membrane phase. The optimum membrane contained 1.15 wt % TPP, 6.15 wt % DOB-β-CD as sensing reagent and other membrane materials. The fluorescence enhancement of the membrane resulted from the formation of a stable three-component complex among DOB-β-CD, TPP, and aliphatic amines. With the optimum conditions described, the fluorescence response of the sensor to octylamine shows a good correlation with the theoretically derived equation in the range 1.0 × 10^–6 to 8.0 × 10^–4 mol/L. The response characteristics including reversibility, response time, reproducibility and lifetime and selectivity of this optical device are also discussed in detail. This sensor has also been applied for the determination of octylamine in water samples containing interferents with satisfactory recovery.     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.     

Untersuchungen gef?rbter ?therischer Oele mittelst des Spectralapparates

Ohne Zusammenfassung     

Bestimmung aller imaginär-quadratischen Zahlkörper der Klassenzahl Eins mit Hilfe eines Satzes von Baker

Ohne Zusammenfassung