The technique of microemulsion liquid chromatography (MELC) was first reported in 1992 and has been successfully applied for the analysis of pharmaceuticals and biological liquids since then. Nevertheless, such important questions as stability of the described mobile phases, ways to improve selectivity of the separation and features of sample pretreatment have never been touched upon.

In current work different ways of the synthesis of microemulsions were compared and the technique, allowing to obtain microemulsion, stable for two weeks at room temperature was chosen. Influence of the microemulsion composition on the eluting power of the mobile phase was investigated. An addition of the second surfactant was suggested as an additional way to affect selectivity of the separation.

A methylene selectivity in MELC mode was investigated. It was found that in contrast to reversed-phase mode the retention dependence fit linear for all microemulsions.

A compatibility of microemulsions with different detectors was studied. It was found that in case of fluorescent detection sensitivity may be increased up to three orders in comparison with RP-HPLC. It was also demonstrated that using microemulsions as a reaction media for on-line derivatization allowed to accelerate the reaction greatly.

Advantages of microemulsions as extragents for the sample pretreatment were shown. Different types of objects with complex matrices were analyzed using the suggested technique. In comparison with other techniques (liquid-liquid, solid-phase or Soxhlet extractions) simple dissolvation of samples with the microemulsion gave better recoveries and was much more rapid and simple.

A number of different applications of MELC for the analysis of pharmaceuticals, cosmetic products and food were suggested. Microemulsions of the L2 type were successfully used for the determination of highly hydrophobic compounds in complex matrices.

Microemulsion can be used as a reaction medium for providing many chemical reactions due to its unique composition. This permits the reaction to proceed in the capillary in on-line mode (MEEKC).