PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 10705534

Improved extraction procedures for polychlorinated biphenyls in solid samples with aqueous sodium hydroxide under autoclave conditions.

Y Akimoto·Y Inouye
View original source ↗Export metadata ↓

Abstract

The efficacy of the extraction of polychlorinated biphenyls (PCBs) from varnish-infiltrated insulating papers as a model of solid materials with an aqueous sodium hydroxide (NaOH) by autoclaving at 121 degrees C for 30 min was compared with those for the conventional procedures, i.e., saponification with 1 N ethanolic NaOH in a boiling water bath for 60 min and extraction with benzene in a Soxhlet apparatus. The newly invented autoclaving method was found to be superior to the conventional ones, yielding approximately 5- to 6-fold cumulative PCB congeners without being accompanied by extended decomposition. Therefore, the autoclave-based sample treatment is recommended for more accurate determination of PCBs in the case of PCB-impregnated solid materials such as hardened oils and resin-coated or -infiltrated papers instead of being treated conventionally.

Explore related subjects

Chemistry Techniques, AnalyticalEnvironmental PollutantsPolychlorinated BiphenylsSodium HydroxideComparative StudyJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Y Akimoto, Y Inouye. 2000. Improved extraction procedures for polychlorinated biphenyls in solid samples with aqueous sodium hydroxide under autoclave conditions.. https://doi.org/10.1016/s0045-6535(99)00290-8

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

New strategies to screen for endocrine-disrupting chemicals in the Portuguese marine environment utilizing large volume injection-capillary gas chromatography-mass spectrometry combined with retention time locking libraries (LVI-GC-MS-RTL).

A new analytical strategy to screen for endocrine-disrupting chemicals (EDCs) in environmental matrices is presented. The strategy uses solid-phase extraction followed by large volume injection and capillary gas chromatography coupled to mass spectrometry combined with retention time locking libraries (SPE-LVI-GC-MS-RTL). Characterization of the proposed methodology (SPE-LVI-GC-MS) for selected classes of EDCs enabled high reproducibility and robustness at the ultratrace level. The RTL databases used allowed hundreds of non-target semivolatiles (i.e., pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls and other classes of suspected EDCs from a great number of unknown environmental matrices) to be simultaneously screened for in an easy, fast and remarkable manner. The application of the proposed methodology to real environmental samples demonstrated its remarkable selectivity and sensitivity at the ultratrace level. Screening assessments performed on water and sediment matrices from eight Portuguese estuaries and coastal waters identified EDC "hotspots." These EDCs mainly come from agricultural and a wide variety of industrial sources, and include pesticides and pesticide metabolites, phenolic derivatives and polycyclic aromatic hydrocarbons, which are included in the lists of priority substances published by international environmental agencies. The estuaries that contained relatively high levels of pesticides were Guadiana, Sado and Mondego, while Minho, Douro and Formosa showed enhanced levels of phenolic derivatives. Dibutyltin and tributyltin, selected as target compounds to be monitored by SPE-LVI-GC-MS in the selected ion monitoring mode, were shown to be widespread contaminants at trace levels in almost all of the sediment matrices assessed. The reliability of the proposed methodology undoubtedly makes it a valuable tool that could replace other analytical strategies currently used to screen for EDCs present in the environment at ultratrace levels.

Chemistry Techniques, Analytical↗
PubMed2007

A faster plant stem-water extraction method.

Oxygen and hydrogen isotope ratios of stem water have been used by several studies which relate the ecophysiology of plants to their water source. Undoubtedly, there are several other applications and research areas which could use this type of analysis. However, the most often used methods of extracting stem water are slow, limiting the rate of sampling and consequently preventing a deeper understanding of spatial and temporal plant water source use. We have developed a faster batch method of stem-water extraction and compare it with the most commonly used online method of stem-water extraction. Samples are sealed in 18 cm long ampoules having their extremities placed sample end in a heating block and the condensing end in a cooling block, and allowed to distill overnight. Up to 72 samples can be distilled overnight and sealed the next morning. The isotope ratios of water distilled by the batch method introduced here compared with those from the online method were in excellent agreement. In addition to being faster, this method does not need the monitoring of hot water baths and liquid nitrogen traps during distillation and does not require a complex vacuum system.

Chemistry Techniques, Analytical↗
PubMed2007

Rapid circular microfluidic mixer utilizing unbalanced driving force.

This paper proposes a novel rapid circular microfluidic mixer for micro-total-analysis-systems (mu-TAS) applications in which an unbalanced driving force is used to mix fluids in a circular chamber at low Reynolds numbers (Re). The microfluidic mixer has a three-layered structure and is fabricated on low-cost glass slides using a simple and reliable fabrication process. Using hydrodynamic pumps, fluids are driven from two inlet ports into a circular mixing chamber. Each inlet port separates into two separate channels, which are then attached to opposite sides of the 3-dimensional (3-D) circular mixing chamber. The unequal lengths of these inlet channels generate an unbalanced driving force, which enhances the mixing effect in the mixing chamber. Numerical simulations are performed to predict the fluid phenomena in the mixing chamber and to estimate the mixing performance under various Reynolds number conditions. The numerical results are verified by performing flow visualization experiments. A good agreement is found between the two sets of results. The numerical and experimental results reveal that the mixing performance can reach 91% within a mixing chamber of 1 mm diameter at a Reynolds number of Re=3. Additionally, the results confirm that the unbalanced driving force produces a flow rotation in the circular mixer at low Reynolds numbers, which significantly enhances the mixing performance. The novel micromixing method presented in this study provides a simple solution for mixing problems in Lab-on-a-chip systems.

Chemistry Techniques, Analytical↗