PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 12433103

Microscale continuous ion exchanger.

Petr Kuban·Purnendu K Dasgupta·Kavin A Morris
View original source ↗Export metadata ↓

Abstract

A microscale continuous ion exchanger based on two liquid streams flowing in parallel is presented. The ion exchange reaction occurs through diffusional transfer of molecules between the ion exchanger phase and the eluent phase and is applied for conductivity suppression. Two approaches are demonstrated. In the first approach, a liquid ion exchanger (i.e. a strongly basic compound, e.g., tetraoctylammonium hydroxide, or a secondary amine, e.g., Amberlite IA-2) is dissolved in an organic solvent immiscible with the aqueous eluent. The system allows for sensitive suppressed conductivity detection of various inorganic cations. When the weakly basic secondary amine is used, conductometric detection of heavy metals is possible. In the second approach, a suspension of finely ground ion-exchange resin is used as the ion exchanger phase. In this case, the suspension need not involve an organic solvent. Theoretical models and computations are presented along with experimental results. The potential of such a system as a chip-scale post-separation suppressor/reactor is evident.

Explore related subjects

CationsChromatography, Ion ExchangeIon Exchange ResinsMetals, HeavyParticle SizeSolventsJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Petr Kuban, Purnendu K Dasgupta, Kavin A Morris. 2002-11-01. Microscale continuous ion exchanger.. https://doi.org/10.1021/ac0258397

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

KEEP EXPLORING

Related citations

PubMed2003

Roles of the histidine and tryptophan side chains in the M2 proton channel from influenza A virus.

The M2 protein form influenza A virus forms a tetrameric ion channel, which enables proton passage across biological membranes when the N-terminal side is acidified. Among the amino acid residues in the transmembrane domain of the M2 protein, His37 and Trp41 are essential for the pH-regulated proton conductance. Current knowledge about the structures and interactions of His37 and Trp41 suggests a model for the M2 ion channel, in which the channel is closed by a network of His37 hydrogen bonds at neutral pH and is opened by a His37-Trp41 cation-pi interaction at acidic pH.

Cations↗
PubMed2003

Oxidation of thioanisole and p-methoxythioanisole by lignin peroxidase: kinetic evidence of a direct reaction between compound II and a radical cation.

The reaction of H2O2 with thioanisole and p-methoxythioanisole catalysed by lignin peroxidase from Phanerochaete chrysosporium has been studied spectrophotometrically under turnover and single turnover conditions with a stopped-flow apparatus. Pre-formed lignin peroxidase compounds I and II are each able to react with the sulphides to form a sulphide radical cation. The radical cation is then converted into the sulphoxide either by reaction with the medium or by reaction with compound II. This is the first report of a direct reaction between compound II and the substrate radical cation. With thioanisole, significant enantiomeric selectivity and high oxygen incorporation in the sulphoxide are obtained because compound II is preferentially reduced by the enzyme-bound thioanisole radical cation compared with the neutral substrate. By contrast, with p-methoxythioanisole, the data imply formation of an intermediate ternary complex comprising compound II, radical cation and neutral substrate, such that a chain of electron transfer reactions starting from neutral molecule and progressing to oxidized haem via substrate radical cation is facilitated, yielding the native enzyme and two molecules of p-methoxythioanisole radical cation as products. The reactions of compounds I and II with sulphides imply flexing of the apoprotein moiety during catalysis.

Cations↗
PubMed2003

Hypertonic activation of a non-selective cation conductance in HeLa cells and its contribution to cell volume regulation.

In whole-cell recordings on single HeLa cells, the hypertonic activation of a cation conductance with a selectivity ratio P(Na):P(Li):P(K):P(Cs):P(NMDG):P(Ca):P(Cl) of 1.00:0.86:0.84:0.56:0.10:0.07:0.15 was observed. This (non-selective) cation conductance was reduced to 59 and 30% of maximal stimulation by Gd(3+) and flufenamate, respectively, but it was insensitive to amiloride (with each compound applied at 100 microm/l). As was determined by the Coulter counter technique, the cation conductance was the main mechanism of regulatory volume increase (RVI) in HeLa cells. Whereas a significant contribution of Na(+)/H(+) antiport was also detectable, Na(+)-K(+)-2Cl(-) symport most likely did not contribute to RVI.

Cations↗