Development Of Membrane Extraction Systems For Measuring Trace Level Organic Compounds In Water
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Development Of Membrane Extraction Systems For Measuring Trace Level Organic Compounds In Water
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Author : Xuemei Guo
language : en
Publisher:
Release Date : 1999
Development Of Membrane Extraction Systems For Measuring Trace Level Organic Compounds In Water written by Xuemei Guo and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with Groundwater categories.
The presence of volatile organic compounds (VOCs) in ground and surface water resources poses a threat to public health. The measurement of these trace level contaminants in water is of significant importance. Conventional methods for analysis of trace volatile organic compounds in water include purge and trap, head space analysis, and solid phase microextraction (SPME). While these are excellent laboratory techniques, none of them can be used for continuous, on-line monitoring of water streams. Membrane separation of organic compounds from water provides an exciting possibility for on-line extraction and analysis. In previous investigations, water continuously flowed on the feed side of the membrane and the analytes were continuously removed by an inert gas stream or a vacuum. The measurement was based on steady state permeation. This approach has several limitations. For example, the steady state can not be reached instantly, resulting in a long analysis time. Another limitation is that this instrument can not be used for analyzing small discrete samples. In this study, a novel approach, referred to as pulse introduction membrane extraction (PIME), is presented. This technique eliminates steady state requirements and can be used for continuous monitoring, as well as for discrete analysis of trace levels of VOCs in water. Water samples are introduced as a pulse into a membrane module. An eluent is used to transport the sample onto the membrane. The permeated organic compounds are extracted by an inert gas, concentrated in a micro-sorbent trap and injected into a GC for analysis. An aqueous boundary layer which forms at the membrane surface due to the poor mixing of water with the membrane appears to be the major resistance to mass transfer for the permeation process. Boundary layer effects were reduced by nitrogen purge of the membrane, and by an alternative membrane module design. A mathematical model which takes into account the aqueous boundary layer effects was developed to describe the nonsteady state, pulse introduction process. A qualitative model of extraction efficiency is also presented here to illustrate the factors that affect analytical sensitivity. The combination of system optimization, nitrogen purge and improved module design results in higher sensitivity and faster response than other methods reported in the technical literature. Detection limits are at ppb levels, precision and extraction efficiency are excellent. As the result of this research, the capability of continuous monitoring of trace levels of organic compounds in water has been demonstrated. The PIME system was compared with previously reported steady state membrane permeation system. The advantages of the PIME system include higher sensitive and faster response and can also be used for discrete sample analysis. Comparison of the PIME with the purge and trap technique, which is currently the most popular method for VOCs analysis, showed that the results are in good agreement. Contaminated ground water samples from the Naval Engineering Research Station were analyzed to demonstrate the practicality of the PIME system. This study was extended to the analysis of sernivolatile organic compounds (SVOCs) in water. Continuous monitoring of SVOCs in water using membrane extraction and on-line HPLC analysis was explored. The system was based on continuous extraction rather than pulse introduction. It demonstrated the capability for enriclunent of SVOCs from water into a solvent. Continuous monitoring of SVOCs was demonstrated at ppb level using HPLC. System parameters which affect the enrichment factors were studied.
Dissertation Abstracts International
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Author :
language : en
Publisher:
Release Date : 2007
Dissertation Abstracts International written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Dissertations, Academic categories.
Liquid Phase Extraction
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Author : Colin F. Poole
language : en
Publisher: Elsevier
Release Date : 2019-08-29
Liquid Phase Extraction written by Colin F. Poole and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-08-29 with Science categories.
Liquid Phase Extraction thoroughly presents both existing and new techniques in liquid phase extraction. It not only provides all information laboratory scientists need for choosing and utilizing suitable sample preparation procedures for any kind of sample, but also showcases the contemporary uses of sample preparation techniques in the most important industrial and academic project environments, including countercurrent chromatography, pressurized-liquid extraction, single-drop Microextraction, and more. Written by recognized experts in their respective fields, it serves as a one-stop reference for those who need to know which technique to choose for liquid phase extraction. Used in conjunction with a similar release, Solid Phase Extraction, it allows users to master this crucial aspect of sample preparation. Defines the current state-of-the-art in extraction techniques and the methods and procedures for implementing them in laboratory practice Includes extensive referencing that facilitates the identification of key information Aimed at both entry-level scientists and those who want to explore new techniques and methods
Analytical Measurements In Aquatic Environments
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Author : Jacek Namiesnik
language : en
Publisher: CRC Press
Release Date : 2009-08-26
Analytical Measurements In Aquatic Environments written by Jacek Namiesnik and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-08-26 with Science categories.
Even a cursory perusal of any analytical journal will demonstrate the increasing important of trace and ultra-trace analysis. And as instrumentation continues to develop, the definition of the term "trace element" will undoubtedly continue to change. Covering the composition and underlying properties of freshwater and marine systems, Analytical Mea
Final Report On Proposal To Develop And Test A Membrane Sampling Module For The Extraction Of Volatile Organic Compounds From Water
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Author :
language : en
Publisher:
Release Date : 1993
Final Report On Proposal To Develop And Test A Membrane Sampling Module For The Extraction Of Volatile Organic Compounds From Water written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with categories.
A new technique is describe for the direct detection of volatile organic compounds in aqueous solutions at levels in the parts per trillion range. The sample is enriched in analyte in two consecutive stages, one utilizes a semi-permeable membrane interface and the other a jet separator. The analyte solution is sampled as it flows coaxially over a semi-permeable capillary membrane, the interior of which is continuously purged by helium. The permeate is pneumatically transported to the mass spectrometer via a jet separator, which is used to remove excess helium and water from the analyte vapor stream. Data are reported for an ion trap mass spectrometer used in conjunction with a conventional fixed-gap quartz jet separator. Typical analyte response times are 2-5 minutes and flow injection methods are used for sample delivery. Detection limits in the range 30 to parts per billion are observed for selected volatile organic compounds and the response is linear over 3 orders of magnitude. Details of the construction of the interface are provided.
Selected Water Resources Abstracts
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Author :
language : en
Publisher:
Release Date : 1991
Selected Water Resources Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991 with Water categories.
Determination Of Toxic Organic Chemicals In Natural Waters Sediments And Soils
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Author : T. R. Crompton
language : en
Publisher: Academic Press
Release Date : 2019-06-07
Determination Of Toxic Organic Chemicals In Natural Waters Sediments And Soils written by T. R. Crompton and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-06-07 with Science categories.
Determination of Toxic Organic Chemicals in Natural Waters, Sediments and Soils: Determination and Analysis reviews the latest techniques for the determination and assessment of both current and emerging organic compounds in a range of important environmental contexts. A wide range of organic compounds in non-saline waters are discussed in the opening chapters, including hydrocarbons, surface active agents and volatile organic compounds. This is followed by multiorganics, pesticides and organometallic compounds in non-saline waters. Organic compounds in aqueous precipitation are then explored before the book goes on to discuss compounds in soils, including extraction techniques, insecticides, herbicides and fungicides, and organometallic compounds. Finally, the concluding chapters focus on compounds in sediments, providing readers with the latest information in the field and supporting them as they address the important issue surrounding organic material throughout ecosystems. Highlights the latest methods for analyzing a wide range of organic compounds Supports researchers by providing detailed information across a range of ecosystems Includes detailed guidance for assessing complex mixtures of organic compounds in the environment
Sampling And Sample Preparation In Field And Laboratory
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Author : Janusz Pawliszyn
language : en
Publisher: Elsevier
Release Date : 2002-09-09
Sampling And Sample Preparation In Field And Laboratory written by Janusz Pawliszyn and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002-09-09 with Science categories.
This title is the first comprehensive book on sampling and modern sample preparation techniques and has several main objectives: to facilitate recognition of sample preparation as both an integral part of the analytical process; to present a fundamental basis and unified theoretical approach for the professional development of sample preparation; to emphasize new developments in sample preparation technology; and to highlight the future impact of sample preparation on new directions in analytical science, particularly automation, miniaturization and field implementation. Until recently, there has been relatively little scientific interest in sampling and sample preparation, however this situation is presently changing as sampling and sample preparation become integral parts of the analytical process with their own unique challenges and research opportunities. Sampling and Sample Preparation for Field and Laboratory is an essential resource for all analytical chemists, and in particular those involved in method development. Not only does it cover the fundamental aspects of extraction, it also covers applications in various matrices and includes sampling strategies and equipment and how these can be integrated into the analytical process for maximum efficiency.
Environmental Protection Research Catalog Indexes
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Author : Smithsonian Science Information Exchange
language : en
Publisher:
Release Date : 1972
Environmental Protection Research Catalog Indexes written by Smithsonian Science Information Exchange and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1972 with Environmental health categories.
Methods For Real Time Measurement Of Thms And Haas In Distribution Systems Part 2
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Author :
language : en
Publisher: American Water Works Association
Release Date : 2007
Methods For Real Time Measurement Of Thms And Haas In Distribution Systems Part 2 written by and has been published by American Water Works Association this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Science categories.
In this project researchers developed a practical, low-cost chemical analyzer for real-time monitoring of trihalomethanes (THMs) and haloacetic acids (HAAs) in drinking water distribution systems. THMs and HAAs are possibly harmful to humans if ingested. For this reason the US Environmental Protection Agency established maximum contaminant levels. Future regulations might lower the MCL of these substances. Real-time monitoring of THMs and HAAs will become necessary for future regulatory compliance.