نتایج جستجو برای:  preconcentration

تعداد نتایج: 2262  

Journal: :Journal of chromatographic science 2013
Zhaoxiang Zhang Fei Zhang Ying Liu

An extensive search of published research and review articles indicates that enhancing the sensitivity and resolution of capillary electrophoresis (CE) is a very active area of interest. This review focuses on developments and applications in this field over several years, especially from 2009-present. It first reviews developments in the fields of online sample preconcentration and highly sens...

2004
Kevin L. Linker

A trace explosives detection system typically contains three subsystems: sample collection, preconcentration, and detection. Sample collection of trace explosives (vapor and particulate) through large volumes of airflow helps reduce sampling time while increasing the amount of dilute sample collected. Preconcentration of the collected sample before introduction into the detector improves the se...

2003
Wassana Yantasee Yuehe Lin Glen E. Fryxell Brad J. Busche

A new sensor was developed for simultaneous detection of cadmium (Cd2+), copper (Cu2+), and lead (Pb2+), based on the voltammetric response at a carbon paste electrode modified with carbamoylphosphonic acid (acetamide phosphonic acid) self-assembled monolayer (SAM) on mesoporous silica (Ac-Phos SAMMS). The adsorptive stripping voltammetry (AdSV) technique involves preconcentration of the metal ...

2010
Honggu Chun J. P. Alarie J. M. Ramsey

We report on a microfabricated device for sample preconcentration and capillary electrophoresis (CE) separation in a glass microchip. The device allows highly efficient anion-selective preconcentration to be performed with a micro-nanomicrochannel structure. An integrated cross channel enables gate-injection of the preconcentrated sample into the analysis channel for CE separation. Sample preco...

Journal: :Journal of chromatographic science 2013
Xueju Lv Yi Hao Qiong Jia

Phthalate esters are endocrine disrupters or mutagens. They are widely used as plasticizers and can be usually found in environmental samples, such as food, soil and polluted air. However, it is difficult to directly determine phthalate esters owing to their relatively low concentration and complex matrices. Therefore, preconcentration and separation have become increasingly important. In recen...

Journal: :Talanta 2002
M Zougagh A García de Torres J M Cano Pavón

Two flow injection inductively coupled plasma atomic emission spectrometric methods for the preconcentration and determination of trace amounts of cadmium in sea-water and waste-water samples are described based on the adsorption of the metal ion on a micro-column placed in the injection valve of the FI manifold and packed with silica gel funtionalised with 1,5-bis(di-2-pyridyl) methylene thioc...

Journal: :Lab on a chip 2014
Il Hyung Shin Ki-Jung Kim Jiman Kim Hee Chan Kim Honggu Chun

A cation-selective microfluidic sample preconcentration system is described. The cation sample was electropreconcentrated using a reversed-direction electroosmotic flow (EOF) and an anion-permselective filter, where an electric double layer (EDL) overlap condition existed. The anion-permselective filter between microchannels was fabricated by three different methods: 1) extending a positively c...

2008
RENMIN GONG DEMIN ZHANG KEDING ZHONG MIN FENG XINGYAN LIU

This paper reports the preparation of a phosphorylated cotton chelator (PCC) by solid phase esterification of phosphoric acid (PA) onto defatted cotton fibres using urea as the catalyst. The synthesized PCC was employed for the preconcentration of copper from water samples prior to its determination by flame atomic absorption spectrometry (FAAS). The preconcentration of copper was studied under...

Journal: :Journal of environmental monitoring : JEM 2011
Brandy J Johnson Brian J Melde Iwona A Leska Paul T Charles Alan D Hewitt

A novel porous organosilicate material was evaluated for application as a solid phase extraction sorbent for preconcentration of nitroenergetic targets from aqueous solution prior to HPLC analysis. The performance of the sorbent in spiked deionized water, groundwater, and surface water was evaluated. Targets considered included 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, RDX, HMX, and nitroglyce...

Journal: :Analytical chemistry 2016
Konstantin Chingin Yunfeng Cai Juchao Liang Huanwen Chen

Significant efforts are being made to develop more practical and versatile approaches for the preconcentration and purification of complex chemical samples. Inspired by the naturally occurring enrichment of organic compounds in sea aerosols, in this study we demonstrate the potential of induced bubble bursting as an approach for the preconcentration of organic solutes in various aqueous solutio...

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