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Analytical methods for the analysis of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) are widely available
and are the result of a vast amount of environmental analytical method development and research on persistent organic pollutants
(POPs) over the past 30–40 years. This review summarizes procedures and examines new approaches for extraction, isolation,
identification and quantification of individual congeners/isomers of the PCBs and OCPs. Critical to the successful application
of this methodology is the collection, preparation, and storage of samples, as well as specific quality control and reporting
criteria, and therefore these are also discussed. With the signing of the Stockholm convention on POPs and the development
of global monitoring programs, there is an increased need for laboratories in developing countries to determine PCBs and OCPs.
Thus, while this review attempts to summarize the current best practices for analysis of PCBs and OCPs, a major focus is the
need for low-cost methods that can be easily implemented in developing countries. A “performance based” process is described
whereby individual laboratories can adapt methods best suited to their situations. Access to modern capillary gas chromatography
(GC) equipment with either electron capture or low-resolution mass spectrometry (MS) detection to separate and quantify OCP/PCBs
is essential. However, screening of samples, especially in areas of known use of OCPs or PCBs, could be accomplished with
bioanalytical methods such as specific commercially available enzyme-linked immunoabsorbent assays and thus this topic is
also reviewed. New analytical techniques such two-dimensional GC (2D-GC) and “fast GC” using GC–ECD may be well-suited for
broader use in routine PCB/OCP analysis in the near future given their relatively low costs and ability to provide high-resolution
separations of PCB/OCPs. Procedures with low environmental impact (SPME, microscale, low solvent use, etc.) are increasingly
being used and may be particularly suited to developing countries.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
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The sphingolipids 1a , b and 2a , b which play important roles in epidermal barrier function, were synthesized by N-acylation of C18-sphingosine 3 and 1-O-glucosylated C18-sphingosine 6 , respectively, with ω-acyloxy-substituted fatty acids 4 and 5 (Scheme 1). These fatty acids were obtained from ω-hydroxy-substituted fatty acids 8 and 9 by esterification with linoleic acid ( 7 ). The C34-fatty acid 8 was prepared as follows: C25-Compound 18 was obtained by means of a Wittig reaction of C13-aldehyde 13 with C12-phosphonium salt 15 or of C12-aldehyde 24 with C13-phosphonium salt 21 , respectively, and subseqent hydrogenation and O-deprotection (Scheme 2). Alternatively, 8 was prepared via 30 by copper-catalyzed coupling of C13-alkyl halide 19 with the Grignard reagent derived from C12-alkyl bromide 14 (Scheme 2). Oxidation of 18 to aldehyde 39 and Wittig reaction with C9-phosphonium salt 41 furnished the desired ω-hydroxy-substituted fatty acid 8 , after O-deprotection (Scheme 3). Similarly, Wittig reaction of C11-phosphonium salt 22 with C12-aldehyde 24 furnished C23-aldehyde 40 , after hydrogenation, O-deprotection, and oxidation; Wittig reaction with compound 41 and subsequent deprotection afforded the desired C32-fatty and 9 (Scheme 3). an alternative strategy furnished compound 8 by a coupling reaction of alkyne 53 with ω-bromo-substitued fatty acid 52 , obtained from compounds 24 and 47 by Wittig reaction, hydrogenation, and introduction of bromide (Scheme 4). Hydrogenation (Lindlar's catalyst) of the resulting C34-alkyne 54 and deprotection furnished 8 . 相似文献
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The poly-methylene interrupted fatty acid 5(Z),11(Z)-eicosadienoic acid and its tetradeuterated analogue were prepared via a convergent synthetic sequence. 相似文献
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