Determination of PCBs in fatty tissues by means of several detection techniques

Difficulties with harmonization of analytical procedures and consequently poor comparability of generated data represent in the Czech Republic the main reason for the delay in issuing of updated legislation for polychlorobiphenyls (PCBs) in foodstuffs. This study draws attention to possible errors (overestimations) that can occur during routine determination of these residues in the fat portion of biotic matrices. We demonstrate the gas Chromatographic (GC) conditions under which interfering contaminants such as phthalates and/or chlorinated pesticides can be separated from analytes. Discussion is focused on the advantages and drawbacks of GC with an electron capture detector, GC mass spectrometry and GC with an atomic emission detector. Various approaches used for calculation of PCBs contents are compared.

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Bestimmung der PCB in Fettgeweben mittels verschiedener Detektionstechniken

Zusammenfassung Das Problem mit der Harmonisierung der analytischen Verfahren und der geringen Vergleichbarkeit der Angaben ist ein Hauptgrund der Verspätung in der neuen Legislative für PCB in Lebensmitteln in der Tschechischen Republik. Die Arbeit beschreibt die möglichen Fehler (Falsch-positive Fehler), die durch die routinierte Bestimmung von PCB-Rückständen in Fettanteilen der biologischen Materialien auftreten können. Es werden die gaschromatographischen Bedingungen beschrieben, unter denen die Interferenzen, wie z. B. Phthalaten und chlorierten Pesticiden, von Stoffen abgetrennt werden können. Die Vorteile und Nachteile der Methoden GC-ECD, GC-MS und GC-AED werden diskutiert. Die verschiedenen für die Kalkulation des PCB-Gehaltes angewendeten Annäherungen werden miteinander verglichen.

     

Some life history parameters and production of Daphnia carinata (king) grown in different culturing media

Estimates of the abundance and production of Daphnia carinata in six mass culture experiments revealed higher values in the cow dung medium compared with other manures tested. Average production ranged from 1.2 to 223 mg m⁻³ wk⁻¹ and average biomass of the population from 1.3 to 194 mg m⁻³ wk⁻¹. The P/B coefficient was highest in the mohua (Madhuca indica) oil cake (1.15) and lowest in the poultry manure (0.77). Daphnia started reproducing at the age of 6–9 days in different culture media. Longevity was higher in the field ( 36 days) than in the laboratory. The total numbers of offspring per female was closely correlated with the mean number of eggs per female in her life span. The intrinsic rate (r) and the finite rate (e') of population of growth of Daphnia were markedly higher in the field than in the laboratory.     

Hall effects on hydromagnetic flow over an impulsively started porous plate

Summary An exact solution has been obtained for the problem of Hall effects on the hydromagnetic flow due to an impulsive start of a porous flat plate. It is observed that in the initial stages there is no inertial oscillation while at large time the steady state is reached through inertial oscillations. The time to attain the steady state increases with increase in Hall parameter.

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Hall-Effekte bei hydromagnetischer Strömung über eine impulsartig gestartete Platte

Zusammenfassung Für das Problem der Hall-Effekte bei der hydromagnetischen Strömung, durch den impulsartigen Start einer porösen, ebenen Platte, wurde eine exakte Lösung erhalten. Es wird beobachtet, daß im Anfangszustand keine Trägheitsschwingung auftritt, wogegen nach längerer Zeit der stationäre Zustand durch Trägheitsschwingungen erreicht wird. Die Zeit um den stationären Zustand zu erreichen, wächst mit dem Anwachsen der Hall-Parameter an.

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With 2 Figures     

Precautionary Money Demand in a Cash-in-Advance Economy with Capital

We use a stochastic cash-in-advance model with capital to analyze the behavior of economic agents with respect to a precautionary money demand. We show that the conditions under which agents demand more money than they actually spend in the shopping session differ according to the agent’s utility function parameter. When agents are highly risk averse, the precautionary money demand may arise under low technology shocks. The circumstances under which a nonbinding cash-in-advance constraint may appear are reversed in a model without capital. The reason of observed differences is the possibility of converting a fraction of output into capital, not only into real balances.JEL Classification: E41; E47     

Gram-scale synthesis of soluble, near-monodisperse gold nanorods and other anisotropic nanoparticles

An aqueous surfactant-based colloidal chemical method is reported for the synthesis of anisotropic noble-metal nanoparticles on the milligram to multigram scale. Fine control of the nucleation-growth kinetics and rodlike micelle-induced breaking of symmetry at the early stage of particle growth are responsible for high-quality anisotropic nanoparticles. Near-monodisperse gold and silver nanorods, spheroids, nanowires, platelets, or cubes of 4-50 nm dimension and controllable aspect ratio can be prepared. The method may also be extended to semiconductor systems.     

Traceability of olive oil based on volatiles pattern and multivariate analysis

An automated head-space solid-phase microextraction (HS-SPME)-based sampling procedure, coupled to gas chromatography–ion trap mass spectrometry (GC–ITMS), was developed and employed for fast characterisation of olive oil volatiles. In total, 914 samples were collected, over three production seasons, in north-western Italy—Liguria (n = 210) and other regions—in addition to the rest of Italy, Spain, France, Greece, Cyprus, and Turkey (n = 704) with the aim to distinguish, based on analytical (profiling) data, the olive oils labelled as “Ligurian” (protected denomination of origin region, PDO) from all the others (“non-Ligurian”). For the chemometric analysis, linear discriminant analysis (LDA) and artificial neural networks with multilayer perceptrons (ANN-MLP) were tested. Employing LDA, somewhat lower recognition (81.4%) and prediction (61.7%) abilities were obtained. The classification model was significantly improved using ANN-MLP. Under these conditions, the recognition (90.1%) and prediction (81.1%) abilities were achieved. The diagnostic value of the data obtained by one-dimensional GC–ITMS were compared with those generated by two-dimensional gas chromatography–time-of-flight mass spectrometry (GC × GC–TOFMS), allowing a comprehensive analysis of olive oil volatiles.     

Genetic evaluation of dairy cattle using a simple heritable genetic ground

The evaluation of an animal is based on production records, adjusted for environmental effects, which gives a reliable estimation of its breeding value. Highly reliable daughter yield deviations are used as inputs for genetic marker evaluation. Genetic variability is explained by particular loci and background polygenes, both of which are described by the genomic breeding value selection index. Automated genotyping enables the determination of many single‐nucleotide polymorphisms (SNPs) and can increase the reliability of evaluation of young animals (from 0.30 if only the pedigree value is used to 0.60 when the genomic breeding value is applied). However, the introduction of SNPs requires a mixed model with a large number of regressors, in turn requiring new algorithms for the best linear unbiased prediction and BayesB. Here, we discuss a method that uses a genomic relationship matrix to estimate the genomic breeding value of animals directly, without regressors. A one‐step procedure evaluates both genotyped and ungenotyped animals at the same time, and produces one common ranking of all animals in a whole population. An augmented pedigree–genomic relationship matrix and the removal of prerequisites produce more accurate evaluations of all connected animals. Copyright © 2010 Society of Chemical Industry     

Some perspectives on modelling the effect of temperature on the erosion-corrosion of Fe in aqueous conditions

In this paper, a model is generated of the effect of temperature on the erosion-corrosion of Fe in aqueous conditions, for room temperature to 373 K. The results indicate how the transition from active to passivation dominated regimes for Fe is favoured as the temperature is increased. 2D and 3D maps are constructed showing the transitions between erosion-corrosion regimes.     

Testing endocrine disruption in biota samples: a method to remove interfering lipids and natural hormones

A cleanup method was developed to remove coextracted lipids and natural hormones from biota samples in order to test the endocrine-disrupting (ED) capacity of their extracts in in vitro bioassays. Unspiked and spiked fish tissues were cleaned with a combination of dialysis, gel permeation chromatography (GPC), and normal-phase liquid chromatography (NP-HPLC). The spiking mixture consisted of a broad range of environmental pollutants (endocrine disruptors and genotoxic compounds). Chemical recoveries of each test compound, and thyroid-hormone-like and (anti)androgenic activities of the cleaned extracts were investigated. Despite the chemical and toxicological complexity of the spiking mixture and the sequential sample treatment, chemical analysis revealed acceptable recoveries on average: 89 ± 8% after each cleanup step separately and 75 ± 3% after the whole extraction and cleanup procedure in the extracts. In addition, recovered activities in the bioassays were in good agreement with the spiking levels. The developed cleanup method proved to be capable of lipid and natural hormone removal from fish extracts, enabling the measurement of selected endocrine-hormone-like activities in T(4)*-TTR and AR-CALUX bioassays. The method can be used as a sample preparation method of biota samples for toxicity profiling and effect-directed analysis (EDA).