Development of two analytical strategies using capillary electrophoresis for the quantification of quinolones in environmental samples

L. VERA CANDIOTI; M. R. ALCARAZ; M. J. CULZONI; H. C. GOICOECHEA

Congreso; LACE 2012. 18 Simposio Latinoamericano en Aplicaciones de la Electroforesis Capilar y Tecnología del Microchip; 2012

Fluoride quinolones (FQ) are antibiotics developed in 1970?s and 1980?s for human andveterinary medical use. Its presence in the environment has been determined in the lastdecade, and has been found in aquatic and solid media in concentrations about μg/L andμg/Kg, respectively.In the present work two analytical strategies based on capillary electrophoresis are proposedto determine 4 FQ?s, enoxacin (ENO), ciprofloxacin (CPF), ofloxacin (OFN) and enrofloxacin (ENF), in aquatic media in combination with two alternatives to achieve preconcentration.The first strategy includes the maximization of the complete separation of analytes by means of experimental design methods. The second one consists in the minimization of both the separation between the FQ and analysis time in order to solve overlapping by means ofchemometric modeling of the second order data obtained from time evolution with a diodearray detector. The MCR-ALS algorithm was used to quanttate the FQs in the presence of nonmodeled interferences.The experimental design consisted in a mixed design (factorial and mixture design) combining process variables (voltage and pH) and a mixture of salts that constitute the electrolyte background. After adjusting the responses (three resolutions between adjacent peaks) optimization was carried out using the desirability function. For each of the aforementioned strategies, the optimization criteria were established: to minimize or maximize the resolutions, which ever was needed.With both methodologies, and under optimal experimental conditions, pure standard solutions of each analyte were used to perform a linearity study. Afterwards, the FQ?s were quantitated in mixtures containing different levels of concentration. For the first strategy, zero-ordercalibration was implemented, while for the second one, mixtures were solved with second order calibration, using the MCR-ALS algorithm by dividing the data matrix in two regions, one containing ENO and CPF, and the other one containing OFN and ENF. Statistics tests applied showed accurate fit.In addition, for the analysis of real samples two alternatives of preconcentration wereproposed, based on off-line solid phase extraction. Commercial cartridges of SPE Oasis HLB were employed in one case, and ordered mesoporous silica (SBA-15) on the other, the latter one synthesized in our laboratory.Finally, artificial samples were analyzed, containing mixtures of analytes and interferences,previously subjected to preconcentration. Results showed that it is possible to quantitate allfour FQs in water samples at a μg/L level.ConclusionsThe utility of optimization techniques to develop total or partial electrophoretic separation has been shown.The generation of second order data and its convenient modeling, allowed the determinationof FQs in environmental samples with an analytical efficiency comparable to that obtained in a complete separation.At last, the synthesis of new mesoporous materials to selectively preconcentrate analytes can play a promissory role in the development of strategies to determine emergent contaminants.