Enantiomer fractions instead of enantiomer ratios

The use of enantiomer ratios (ERs) to indicate the relative amounts of a pair of enantiomers in a sample has some disadvantages. Enantiomer fractions (EFs) are proposed as all alternative expression to eliminate the difficulties. (C) 2000 Elsevier Science Ltd

Determination of polychlorinated terphenyls in aquatic biota and sediment with gas chromatography/mass spectrometry using negative chemical ionization.

Polychlorinated terphenyls (PCTs) have been determined in aquatic biota and sediments by gas chromatography/mass spectrometry using negative chemical ionization. The use of various methods of calculation is discussed. Total PCT concentrations expressed as A (Aroclor) 5442 equivalents ranged from 0.28 to 7400 μg/kg of wet weight in biota, with hexachloroterphenyls (hexa-CTs) as the major group of CTs present. In sediments, total PCT concentrations expressed as A5442 equivalents ranged from 22 to 100 μg/kg of wet weight, with hepta-CTs as the dominant group of congeners. Total PCT concentrations in biota were approximately 1-10% of total polychlorobiphenyl (PCB) concentrations and in sediments 1025% of total PCB concentrations. The rather unexpectedly high concentrations of PCTs, especially in the sediment samples, should stimulate further research on their general environmental distribution

Developments in analysis and toxicology of toxaphene compounds

Peer-reviewedOver the last 50 years toxaphene has been produced and used as a pesticide extensively. The US Environmental Protection Agency banned it in 1982. In the early 1990s the presence of toxaphene in marine fish in Europe caused concern with regard to human health in relation with consumption. This paper gives a brief overview of recent developments in the analytical and toxicological research on toxaphene

Setting a baseline for global urban virome surveillance in sewage

The rapid development of megacities, and their growing connectedness across the world is becoming a distinct driver for emerging disease outbreaks. Early detection of unusual disease emergence and spread should therefore include such cities as part of risk-based surveillance. A catch-all metagenomic sequencing approach of urban sewage could potentially provide an unbiased insight into the dynamics of viral pathogens circulating in a community irrespective of access to care, a potential which already has been proven for the surveillance of poliovirus. Here, we present a detailed characterization of sewage viromes from a snapshot of 81 high density urban areas across the globe, including in-depth assessment of potential biases, as a proof of concept for catch-all viral pathogen surveillance. We show the ability to detect a wide range of viruses and geographical and seasonal differences for specific viral groups. Our findings offer a cross-sectional baseline for further research in viral surveillance from urban sewage samples and place previous studies in a global perspective

Onderzoek naar de aanwezigheid van tris (4-chloorfenyl)methanol en tris (chloorfenyl)-methaan in marine toppredatoren uit de Noordzee en Waddenzee

Een methode werd ontwikkeld voor de analyse van tris(4-chloorfenyl)methanol (TCP) in organismen. Met behulp van soxhletextractie, gelpermeatiechromatografie, fractionering over silicagel en gaschromato-grafische analyse met massaspectrometrische detectie (negatieve chemische ionisatie) kan TCP in organismen bepaald worden met een recovery van 90% en een detectiegrens van 0,02 µg/kg

Determination of tris(4-chlorophenyl)methanol and tris(4-chlorophenyl)methane in fish, marine mammals and sediment.

Tris(4-chlorophenyl)methanol (TCP) and tris(4-chlorophenyl)methane (TCPMe) were determined in aquatic organisms and sediment by a method based on Soxhlet extraction, gel permeation chromatography, fractionation over silica and gas chromatography/mass spectrometry (GC/MS) analysis. TCPMe was identified as the 4-substituted isomer after synthesis of this compound. TCP could be determined by GC/MS with negative chemical ionistation (GC/NCI-MS) with a detection limit of 0.02 g kg¿1 and a recovery of 90%. TCP concentrations in marine mammals from the North Sea and Dutch Wadden Sea ranged from 0.2 to 2 mg kg¿1, and those in marine and freshwater fish samples from 0.005 to 0.4 mg kg¿1 on a lipid wt basis. TCP concentrations in two Rhine delta sediment samples were 1.2 and 3.0 ¿g kg¿1 dry wt, respectively. TCPMe concentrations, determined by GC/MS with electron impact (GC/EI-MS), were 10¿50% of the TCP concentration in all samples analyse

Simple nomenclature for chlorinated bornanes, bornenes and bornadienes from which structural information can be directly deduced

Toxaphene is a complex mixture mainly consisting of polychlorinated bornanes, bornenes, bornadienes and camphenes. The systematic nomenclature of the individual compounds is long and, therefore, not very easy to use. There have been several proposals for simpler nomenclatures for these classes of compounds, but these all have serious limitations if structural information has to be deduced. The nomenclature proposed in this paper provides direct structural information. In addition, the presence of a pair of enantiomers can easily be read from the coded name