Capillary electrophoresis (CE) is becoming an established method for the de
termination of chiral trace impurities. This paper provides an overview of
the state of the art of CE for such determinations. Detection limits of 0.1
% impurity is widely accepted as a minimum requirement for chiral trace imp
urity determinations. This can be relatively easily achieved with CE. Howev
er, determination of lower concentrations requires careful optimization of
the separation system. Four factors that are of particular significance for
trace enantiomeric determinations: resolution, limit of detection, linear
range and type of detection, are discussed. Further, the advantages and dis
advantages of derivatization in this context are treated as well as the sep
aration approach, i.e., direct chiral separation or separation after the fo
rmation of diastereomers. It is concluded that the limit of impurity detect
ion can be about 0.05% when UV detection is employed. Using laser-induced f
luorescence detection, a quantitative determination at the 0.005% level is
often possible.