PMID- 16385601
OWN - NLM
STAT- MEDLINE
DCOM- 20060518
LR  - 20060213
IS  - 0173-0835 (Print)
IS  - 0173-0835 (Linking)
VI  - 27
IP  - 3
DP  - 2006 Feb
TI  - Origin of peak asymmetry and isotherm nonlinearity in micellar electrokinetic 
      chromatography: variation of peak shape with buffer concentration.
PG  - 572-83
AB  - The diffuse fronts and sharp rears of peaks of nitrobenzene (nbz) solubilized at 
      high concentrations in 50 mM SDS and 2.5, 25, and 50 mM sodium tetraborate 
      buffers were modeled in MEKC by measurements of, and fits to, concave upward 
      isotherms, and by numerical solution of the continuity equation. The isotherms 
      varied with buffer concentration, with the smallest limiting slope and largest 
      curvature found for the 50 mM tetraborate buffer. The Brunauer, Emmett, and 
      Teller isotherm described the peak profiles in all buffers, with symmetrical 
      peaks observed at sub- and low-mM levels of nbz, anti-Langmuirian peaks observed 
      at 10-20 mM levels, and aquiline peaks resembling curved noses observed at 20-30 
      mM levels. The variation of the partition coefficient with nbz and buffer 
      concentrations was shown to result from nonideal thermodynamics. High-buffer 
      concentrations salt out nbz from the mobile phase, as quantified by a 
      mobile-phase activity coefficient related to the Setchenov constant of nbz in 
      sodium tetraborate. The activity coefficient of nbz in SDS micelles was shown to 
      resemble that measured by other researchers for benzene in micelles of sodium 
      octyl sulfate, i.e. it decreases with increasing solute concentration and 
      increases with electrolyte concentration. Many examples from the literature are 
      discussed, in which the variation of the intramicellar activity coefficient with 
      solute mole fraction is consistent with peaks having diffuse fronts and sharp 
      rears.
FAU - Williamson, Yuping
AU  - Williamson Y
AD  - Department of Chemistry and Biochemistry, Southern Illinois University at 
      Carbondale, Carbondale, IL 62901-4409, USA.
FAU - Davis, Joe M
AU  - Davis JM
LA  - eng
PT  - Journal Article
PL  - Germany
TA  - Electrophoresis
JT  - Electrophoresis
JID - 8204476
RN  - 0 (Buffers)
SB  - IM
MH  - Buffers
MH  - Chromatography, Micellar Electrokinetic Capillary/*methods
MH  - Thermodynamics
EDAT- 2005/12/31 09:00
MHDA- 2006/05/19 09:00
CRDT- 2005/12/31 09:00
PHST- 2005/12/31 09:00 [pubmed]
PHST- 2006/05/19 09:00 [medline]
PHST- 2005/12/31 09:00 [entrez]
AID - 10.1002/elps.200500686 [doi]
PST - ppublish
SO  - Electrophoresis. 2006 Feb;27(3):572-83. doi: 10.1002/elps.200500686.