Microemulsions in Liquid Chromatography and Capillary Electrophoresis. Lacks and Advantantages

Andrey Pirogov, Chemistry Department, M.V. Lomonosov Moscow State University, Moscow, Russia

Microemulsions are liquid colloidal systems spontaneously formed upon mixing two fluids with limited solubility (water and oil) with adding a surfactant and in some cases co-surfactant. Microemulsions are used in the modern analytical methods of analysis: capillary electrophoresis and chromatography. The same microemulsions can be used as a "reactor" for the reaction of derivatization and for the sample pretreatment.

Recent improvements in formation, emulsification, and characterization are leading to advanced microemulsions that have desirable functionality and well-controlled physical properties. Mechanical, optical, and transport properties of long-lived, metastable microemulsions can be tuned and controlled, and other desirable materials, such as coatings, biomolecules, and chemical additives, can simultaneously be incorporated.

A new approach of the sample pretreatment using the microemulsions as media for the extraction with the subsequent coagulation of surfactants, simultaneous pre-concentration, and gas chromatographic analysis has been suggested. A comparison of the effect of different surfactants in microemulsions on the extraction and recovery has been carried out. A speed-up of chemical reactions in microemulsions has been demonstrated. Advantages and disadvantages of the approach will be outlined. Several examples of MELC will be demonstrated and discussed. For example, a derivatization of ampicillin was carried out with four-fold molar excess of the derivatizing agent (2,3-naphthalene dialdehyde) in water-MeCN and microemulsion media. In the first case, the reaction proceeds under tough conditions, which temperature control at 60 ° C for 1 hour. And when ME were used as a "reactor" for the derivatization, the target product was formed at room temperature in 20 minutes. The conditions for the sensitive and selective chromatographic determining complexes of tetracyclines with fluorescent detecting in pharmaceutical preparations (oil-cream and tablets), and food objects (milk) was optimized. The limits of detection were 5, 8 and 25 ng/ml for tetracycline, oxytetracycline and doxycycline respectively.

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Short Biography of Presenting Author

Prof. PIROGOV Andrey

In 1994 defended a PhD thesis titled “Computer optimization of ion chromatography analysis”. After the defense continued research in the field of HPLC and capillary electrophoresis techniques. From 2004 to this day – major researcher of the Analytical Chemistry Department , Lomonosov Moscow State University, Russia. Doctor of Science (Chemistry) since 2007. Since 2012 – professor of  Analytical Chemistry.  Experience in research – 30 years, author of  112 research papers.  Since 2010 – permanent member of the Higher Attestation Commission at Lomonosov Moscow State University.