Surfactants as a preferred option to improve separation and electrochemical detection in capillary electrophoresis

The addition of surfactants to the separation electrolyte is one of the most convenient ways to modify the electro-osmotic flow (mu(EOF)) in capillary electrophoresis. However, surfactants spontaneously adsorb to most surfaces; therefore, their presence in the running electrolyte may also affect the electrochemical detection. Changes in selectivity and sensitivity due to dynamic coating of electrode surfaces have been systematically reported during the last 30 years. In this review, some pertinent papers related to the use of surfactants to perform dynamic coatings of the capillary surface are discussed. The proposed mechanisms to explain the enhancements produced by surfactants at the detection step are also discussed along with some specific applications. A particular emphasis was placed on recent reports from our group dealing with the effects of anionic surfactants on the separation and detection of phenolic compounds.