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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1996-10-10
pubmed:abstractText
A theoretical analysis of deviations from ideality in ionic transport is presented to correct mobilities, mu, measured in free solution capillary electrophoresis (CE) to mobility at infinite dilution, mu degree (limiting mobility). Non-ideality is treated at the same level of approximation as in equilibrium, using a correction factor for the sum of the analyte and counter-ion radius originally suggested by Robinson and Stokes (Electrolyte Solutions, 1961). Unlike previous corrections using Debye-Hückel-Onsager theory, which are strictly applicable only at very low ionic strengths, this treatment is expected to be valid for univalent ions migrating in a uni-univalent background electrolyte for ionic strengths up to 0.075 mol kg-1, a range typical of CE experiments. The analysis is applied to the determination of mu degree in acidic and basic buffers for oligoalanines and oligoglycines with degree of polymerisation 2 to 6. Limiting mobilities for the fully protonated and deprotonated peptides are found to be numerically equal but opposite in sign, consistent with a change in charge from +1 to -1. In all uni-univalent buffers studied (borate, citrate, low pH lithium phosphate and sodium phosphate) mu degree values established using data over a range of pH and ionic strength are found to be identical and in excellent agreement with previous values from isotachophoresis. Values of mu degree in high pH sodium phosphate buffer are systematically 0.2.10(-8) m2 V-1 s-1 higher than those in other buffers; this may be attributed to limitations of the model for a buffer with 1+:2- and 1+:3- ions. This self-consistent framework for standardising mobilities in free solution CE is expected to be widely applicable to univalent analytes migrating in a 1:1 background electrolyte.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0021-9673
pubmed:author
pubmed:issnType
Print
pubmed:day
9
pubmed:volume
741
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
99-113
pubmed:dateRevised
2009-1-15
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Self-consistent framework for standardising mobilities in free solution capillary electrophoresis: applications to oligoglycines and oligoalanines.
pubmed:affiliation
Department of Chemistry, University of York, UK.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't