Novel optimization method for complex mixtures in capillary electrophoresis. Application for the analysis of Harmala alkaloids in edible algae by CE-MS.

MARCOS TASCÓN; FERNANDO J. BENAVENTE MORENO; LEONARDO G. GAGLIARDI

Lima

Conferencia; 19th Latin-American Symposium on Biotechnology, Biomedical, Biopharmaceutical and Industrial Applications of Capillary Electrophoresis and Microchip Technology (LACE 2013).; 2013

P { margin-bottom: 0.21cm; direction: ltr; color: rgb(0, 0, 0); }P.western { font-family: "Liberation Serif","MS PMincho",serif; font-size: 12pt; }P.cjk { font-family: "WenQuanYi Micro Hei","MS Mincho"; font-size: 12pt; }P.ctl { font-family: "Lohit Hindi","MS Mincho"; font-size: 12pt; } In capillary electrophoresis, not only separations between partially ionized analytes are important but also, the relative separation of them from the electroosmotic flow is also important. If we don't take into account this consideration, those compounds, which have low effective mobilities, can be separated from the neutral substances presents in real samples and comigrates with the electroosmotic flow. In this work, we present a new optimization parameter, which describes the selectivity between two analytes and between each analyte with the neutral compounds or EOF marker. Based in this parameter, a general function for complex mixes was constructed as a function of pH, allowing us to find a maximum which concurs with the optimum separation pH. The equation was achieved taking into account physical fundamentals, as a consequence, there is no need to make experimental designs for this variable and could be applied for all separation problems. However, other interactions or no precise physical constants can exist, for these reason, a pH evaluation around the maximum achieved theoretically is strongly recommend. The model was tested for Harmala alkaloids (Halks), which are a family of compounds with psychotropic effects on humans. All the HAlks are based on a similar basic molecular structure, changing only few of the substituent without significant molecular mass differences. All of them have, at least, one -amine- ionizable group. These properties become the HAlks an interesting challenge for analytical separations and, particularly for capillary electrophoresis. These are present in invasive algae on atlantic coast of the patagonian sea (Undaria pinnatifida), commercially known as Wakame. Very low concentrations or absence of HAlks becomes these algae eatable and with potential uses in food industry. On the other hand, significant concentration of HAlks becomes the algae not eatable, but the possibility to extract them provides potential uses in the pharmaceutical industry. Finally, we evaluated the optimization model for Halks and analyze them in wakame by capillary electrophoresis coupled to ion trap mass spectrometry (CE-IT-MS) 3. Moreover, the theoretically optimum pH was experimentally evaluated in a short range of pH (± 0.2 pH units). In addition, the optimized CE-IT-MS was complemented with a MS-MS study in order to confirm the compounds found.