Ml. Ye et al., Separation of acidic and neutral compounds by strong anion-exchange capillary electrochromatography dynamically modified with sodium dodecylsulfate, CHROMATOGR, 53(7-8), 2001, pp. 425-430
Acidic and neutral compounds have been separated by strong anion-exchange c
apillary electrochromatography (SAXCEC) dynamically modified by addition of
sodium dodecylsulfate (SDS). It was found that separation of neutral solut
es by SAXCEC without addition of SDS is difficult because of the weak inter
action of the solutes with the hydrophilic packing surface. The hydrophobic
ity of the packing surface increases on addition of SDS to the mobile phase
, however, and the capacity of separating neutral solutes increases. Acidic
solutes are retained, mainly because of the ion-exchange properties of thi
s system. The influence of mobile phase composition, e.g. SDS concentration
, ionic strength, and organic modifier fraction, on the retention of acidic
and neutral solutes was investigated. Three acids and five neutral solutes
were separated in only 5 min under optimized conditions, because the direc
tion of the strong electroosmotic flow (EOF) was the some as that of electr
ophoretic migration of the acids under the conditions used. The repeatabili
ty of this system in terms of migration time relative standard deviation (R
SD) is good - less than 0.48% for 10 consecutive runs of oil the solutes te
sted. Column efficiencies for acids were > 125000 plates m(-1); those for n
eutral solutes varied from 25 000 to 100 000 plates m(-1).