Input of hydrocarbons into the North Sea by the river Elbe

An analytical procedure for evaluating the conditional stability constants K of aluminum/humic substance complexes, based on ²⁷Al nuclear magnetic resonance spectroscopy, is described. It is well suited for the determination of Al(III) dissociated from dissolved humic substances at slightly acidic pH values. The new procedure offers a good sensitivity and requires neither special preparation of the sample nor the evaluation of complex coupled chemical equilibria. The pK values range from 2.0 to 4.3 depending on the ratio [Al_complex] to dissolved organic carbon and the pH.Dedicated to Professor Dr. Dieter Klockow on the occasion of his 60th birthday     

On-line determination of mercury in river water at the German monitoring station Schnackenburg/Elbe

A monitor is described which provides the on-line determination of mercury in river water at concentrations from 20 to 1000 ng/L. The measurement includes an on-line digestion with Br-/BrO3- and UV-radiation. Each determination is controlled by an on-line addition of 50 and 100 ng/L mercury carried out by pre-dilution of a 500 and 1000 ng/L stock solution using sequential injection analysis (SIA). One cycle of analysis takes 20 min and results in nine signals. A five days stand-alone operation has been performed successfully. Details are also published at web page: "http/www.rzbd.fh-hamburg.de/-prmercol".     

On-line determination of mercury in river water at the German monitoring station Schnackenburg/Elbe

A monitor is described which provides the on-line determination of mercury in river water at concentrations from 20 to 1000 ng/L. The measurement includes an on-line digestion with Br^–/BrO₃ ^– and UV-radiation. Each determination is controlled by an on-line addition of 50 and 100 ng/L mercury carried out by pre-dilution of a 500 and 1000 ng/L stock solution using sequential injection analysis (SIA). One cycle of analysis takes 20 min and results in nine signals. A five days stand-alone operation has been performed successfully. Details are also published at web page: “http/www.rzbd.fh-hamburg.de/¶～prmercol”     

Mass spectrometric identification of polychlorinated dibenzothiophenes (PCDBTs) in surface sediments of the River Elbe

HRGC/MS was applied to six sediment samples from River Elbe for the determination of polychlorinated dibenzothiophenes (PCDBTs). Among the studied tri-, tetra- and octa-chlorinated isomers, trichlorinated species were found to be the dominating ones. The estimated concentration levels of the compounds were in the range of approximately 0.02–2 μg/kg dry weight for trichlorinated and 0.1–0.3 μg/kg for octachlorinated species. Tetrachlorinated dibenzothiophenes could not be detected. Received: 7 October 1997 / Revised: 4 February 1998 / Accepted: 9 February 1998     

Mass spectrometric identification of polychlorinated dibenzothiophenes (PCDBTs) in surface sediments of the River Elbe

HRGC/MS was applied to six sediment samples from River Elbe for the determination of polychlorinated dibenzothiophenes (PCDBTs). Among the studied tri-, tetra- and octa-chlorinated isomers, trichlorinated species were found to be the dominating ones. The estimated concentration levels of the compounds were in the range of approximately 0.02–2 μg/kg dry weight for trichlorinated and 0.1–0.3 μg/kg for octachlorinated species. Tetrachlorinated dibenzothiophenes could not be detected.     

A review of the determination of persistent organic pollutants for environmental forensics investigations

The field of environmental forensics emerged in the 1980s as a consequence of legislative frameworks enacted to enable parties, either states or individuals, to seek compensation with regard to contamination or injury due to damage to the environment. This legal environment requires stringent record keeping and defendable data therefore analysis can sometimes be confined to data to be obtained from certified laboratories using a standard accredited analytical method. Many of these methods were developed to target specific compounds for risk assessment purposes and not for environmental forensics applications such as source identification or age dating which often require larger data sets. The determination of persistent organic pollutants (POPs) for environmental forensic applications requires methods that are selective but also cover a wide range of target analytes which can be identified and quantified without bias. POPs are used in a wide variety of applications such as flame retardants, fire suppressants, heat transfer agents, surfactants and pesticides mainly because of their chemical inertness and stability. They also include compounds such as dioxins that can be unintentionally produced from industrial activities. POPs are persistent in the environment, bioaccumulative and/or toxic and therefore require analytical methods that are sensitive enough to meet the low detection limits needed for the protection of the environment and human health. A variety of techniques, procedures and instruments can be used which are well suited for different scenarios. Optimised methods are important to ensure that analytes are quantitatively extracted, matrix coextractables and interferences are removed and instruments are used most effectively and efficiently. This can require deviation from standard methods which can open the data up to further scrutiny in the courtroom. However, when argued effectively and strict QA/QC procedures are followed the development and optimization of methods based on investigation specific scenarios has the potential to generate better quality and more useful data.     

Mass spectrometric determination of the heats of formation of the silane bromides

The reaction of SiBr₄(g) with H₂(g) in the temperature range 900–1143 K has been studied by a mass spectrometric method. Second and third law reaction enthalpies were obtained for SiBr₄(g) + H₂(g) = SiHBr₃(g) + HBr(g), SiHBr₃(g) + H₂(g) = SiH₂Br₂(g) + HBr(g), and SiH₂Br₂(g) + H₂(g) = SiH₃Br(g) + HBr(g). From the heats of reaction, third-law ΔH_£298 values of ?72.5 ± 1, ?43.2 ± 1.5 and ?15.3 ± 0.5 kcal/mole were obtained for SiHBr₃(g), SiH₂Br₂(g), and SiH₃Br(g), respectively.     

Optimized cleanup methods of organic extracts for the determination of organic pollutants in biological samples

The analytical performances of various adsorbents used to clean up an organic extract of biological samples, particularly for the determination of polycyclic aromatic hydrocarbons (PAHs), polychlorobiphenyls (PCBs), both in mussel tissue and in krill samples, are critically compared. DDT and its degradation products, namely DDE and DDD, are also considered. Silica gel, alumina, aminopropyl-silica, cyanopropyl-silica, florisil, graphitized nonporous carbon and silica gel–alumina mixture (3:1) were used for column chromatography cleanup in combination with modified supercritical CO₂ as a mobile phase. Recovery and reproducibility were evaluated by analyzing standard solutions and standard reference materials containing various classes of pollutants. A silica gel–alumina mixture was found to be the most effective in the cleanup of organic extracts, allowing quantitative recoveries of all analytes to be obtained. Finally, the application of the optimized procedure to the determination of PCBs in Antarctic krill samples is presented.     

Mass spectrometric determination of the nitrogen-15 content of different Egyptian fertilizers

Different nitrogen fertilizers produced in Egypt were analyzed mass-spectrometrically for their¹⁵N content. The results indicate that nitrate fertilizers are relatively enriched in¹⁵N compared with ammonium fertilizers. The isotopic fractionation of nitrogen encountered in the production processes of fertilizers are discussed.     

A rapid method for the determination of radiostrontium in river water

A rapid analytical method, applicable for the selective separation and determination of⁹⁰Sr and⁸⁹Sr in river water, is described. Strontium is extracted from the water sample at pH 10.5 by TTA/TOPO in cyclohexane in the presence of Tiron as masking agent for interfering ß-emitters. Radiostrontium is measured by liquid scintillation after back-extraction into 1N nitric acid. The distribution coefficient of strontium is over 400 and the separation factors from other radionuclides are higher than 5.0×10³.     

Monitoring of total Hg in the river Elbe: FIA-device for on-line digestion

The development of an apparatus for the on-line sampling, digestion and quantification of total mercury in surface water is described. Detection and quantification is done by flow injection cold vapor atomic absorption spectroscopy (FI-CVAAS). Three digestion methods were tested, chemical, microwave and UV. The influence of the digestion parameters (digestion method, digestion time, microwave power, concentration of oxidation solution) on the recovery of mercury in water of the river Elbe have been investigated. Mercury can be determined almost quantitatively (recovery rate > 85%) with some digestion procedures described. The best results were reached by UV digestion. The technique is fast, simple to handle and robust. Each complete analysis only take four minutes. The working range is 10 to 1000 ng/L. The measuring arrangement has been applied successfully in a governmental monitoring station at Schnackenburg/Elbe, Germany.     

Mass spectrometric determination of the configuration of the 4-substituted 1,2-dimethyl-4-hydroxydecahydroquinolines

The mass spectra of a number of the epimeric 1,2-dimethyl-4-alkyl-4-hydroxydecahydroquinolines (alkyl: C?CH, CH?CH₂, C₂H₅ and COCH₃) have been studied. The configuration at C-2 and C-4 in these molecules is proposed on the basis of the data obtained. Some aspects of the fragmentation pathways under electron-impact are discussed.     

Monitoring of total Hg in the river Elbe: FIA-device for on-line digestion

The development of an apparatus for the on-line sampling, digestion and quantification of total mercury in surface water is described. Detection and quantification is done by flow injection cold vapor atomic absorption spectroscopy (FI-CVAAS). Three digestion methods were tested, chemical, microwave and UV. The influence of the digestion parameters (digestion method, digestion time, microwave power, concentration of oxidation solution) on the recovery of mercury in water of the river Elbe have been investigated. Mercury can be determined almost quantitatively (recovery rate > 85%) with some digestion procedures described. The best results were reached by UV digestion. The technique is fast, simple ¶to handle and robust. Each complete analysis only take four minutes. The working range is 10 to 1000 ng/L. The measuring arrangement has been applied successfully in a governmental monitoring station at Schnackenburg/Elbe, Germany.     

Mass spectrometric study of the vacuum pyrolysis of perfluorohexene-2 and determination of the ionization potential of the perfluoro-2-buten-4-yl radical

The ionization potential (IP) of the perfluoro-2-buten-4-yl radical, generated at 950C and 1·10⁵ torr by vacuum pyrolysis of perfluorohexene-2, was found to be 10.3 ± 0.1 eV by the electron impact method. This value is close to the IP of the perfluoro radicals n-C₃F₇ (10.06 ± 0.1 eV) and i-C₃F₇ (10.5 ± 0.1 eV); however, it is 1.8 eV higher than that of the perfluoroallyl radical, possibly because of the weak delocalization of the unpaired electron. At pyrolysis temperatures above 800C, the perfluoro-2-buten-4-yl radical decomposed to the tetrafluoroallene and trifluoromethyl radicals.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1220–1223, May, 1991.     

Rapid-resolution HPLC with spectrometric detection for the determination and identification of isoflavones in soy preparations and plant extracts

A rapid-resolution HPLC/UV-VIS DAD separation method (which takes <1 min) for the determination and identification of genistin, genistein, daidzein, daidzin, glycitin, glycitein, ononin, formononetin, sissotrin and biochanin A in fmol quantities in submicroliter sample volumes was optimized. A linear gradient elution (0 min 22% B, 1.0 min 80% B, 1.4 min 100% B, 1.8 min 22% B) using a mobile phase containing 0.2 % (v/v) acetic acid (solvent A) and methanol (solvent B) was applied on a Zorbax SB C₁₈ column (1.8 μm particle size) at 80 °C. The method was verified using samples of bits of soy and methanolic extracts from Trifolium pratense, Iresine herbstii and Ononis spinosa plants. Pseudobaptigenin glucoside, irilone, prunetin, texasin, tlatlancuayin and other isoflavones, in addition to aglycones of isoflavones and their β-glucosides and malonyl and acetyl derivatives, were identified by UV-VIS DAD and electrospray mass spectrometric (ESI-MS) detection in the extracts. Figure Rapid resolution HPLC for determination and identification of isoflavones in soy preparations and plant extracts     

Mass spectrometric approach for the analysis of food proteins

In the study of food proteins, the need for accurate protein structural analysis has been acknowledged because of the fact that nucleotide sequencing alone is of limited analytical value if not combined with relevant information regarding the specific protein expressed and the occurrence of phosphorylation, glycosylation and disulphide bridges, and with the modification induced by the technological treatment. Mass spectrometry, whether used alone or to complement the traditional molecular-based techniques has become fundamental to the structural analysis of proteins. It is, moreover, virtually irreplaceable in determining post-translational modifications as conventional methods cannot deliver reliable data. What lies at the root of this methodological breakthrough is the combination of high-resolution separation techniques such as two-dimensional electrophoresis or capillary reverse- phase high-performance liquid chromatography with mass spectrometric analysis, what is termed "proteomic" analysis. Thus, it appears appropriate to state that the new mass spectrometric techniques have been established as a valuable and efficient tool for protein and peptide analysis in complex mixtures, like those from food matrices, enabling us therefore to provide accurate information on molecular weight and also to put forth a structural assessment at a low-picomole level of material. Thus, a series of alternative approaches have been developed based on advanced mass spectrometric analysis in conjunction with classic protein chemistry in order to provide an in-depth view of food protein structure. This review outlines several of these novel methodologies as they apply to structural characterization of food products.     

On-line continuous-flow extraction system in liqud chromatography with ultraviolet and mass spectrometric detection for the determination of selected organic pollutants

An on-line extraction system with completely continuous-flow analysis prior to the liquid chromatographic (LC) column was used for the determination of the organophosphorus pesticides tetrachlorvinphos and parathion-methyl and their degradation products 2,4,5-trichlorophenol and 4-nitrophenol, respectively, and the chlorinated phenoxy acids 2,4-D, 2,4,5-T and silvex in water samples. The extent of extraction varied from 100% for chlorinated phenoxy acids to 60% for organophosphorus pesticides and 2,4,5-trichlorophenol. The extraction of 4-nitrophenol was less than 10% under these conditions. By employing positive-ion mode thermospray LC-mass spectrometry, the characterization of tetrachlorvinphos was feasible, indicating [M + NH₄]⁺ as the base peak and a second peak with 20% relative intensity corresponding to [M + H]⁺. When the negative-ion mode was used, the chlorinated phenoxy acids and 2,4,5-trichlorophenol exhibited [M + HCOO]^? as the base peak and a second peak with 30% relative intensity corresponding to [M ? H]^?. The determination of 1 mg l^?1 of tetrachlorvinphos spiked in a surface water sample is reported.     

On-line dual-precolumn-based trace enrichment for the determination of polar and acidic microcontaminants in river water by liquid chromatography with diode-array UV and tandem mass spectrometric detection

Dual-pre-column-based trace enrichment combined on-line with liquid chromatography-diode-array UV and tandem mass spectrometric detection was used to determine a wide polarity range of organic microcontaminants in river water. Various sorbents were studied for their extraction efficiency of (highly) polar and acidic compounds and their ability to selectively remove humic substances, which are normally co-extracted and interfere in the UV detection of polar microcontaminants. An optimised on-line dual-pre-column set-up with PLRP-S in the first pre-column and Hysphere-1 in the second pre-column was used to study the analytical performance of the procedure. Tandem MS was used for confirmation purposes and to quantify the organic microcontaminants in river water at the low-ng/l level. In addition, the influence of the type of sample (drinking and river water) on suppression of analyte responses in electrospray ionization MS was studied.