Research and Development

@article{Aranas2011,

title = {Sweeping–micellar electrokinetic chromatography for the simultaneous analysis of tricyclic antidepressant and β-blocker drugs in wastewater},

author = {Agnes T. Aranas and Armando M. Guidote Jr. and Paul R. Haddad and Joselito P. Quirino},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0039914011002372},

doi = {10.1016/j.talanta.2011.03.032},

issn = {0039-9140},

year  = {2011},

date = {2011-03-15},

journal = {Talanta},

volume = {85},

number = {1},

pages = {86-90},

abstract = {The simultaneous analysis of tricyclic antidepressant (amitriptyline, clomipramine, doxepin and nortriptyline) and β-blocker (alprenolol, labetalol and propranolol) drugs in wastewater was developed via sweeping–micellar electrokinetic chromatography (MEKC) together with a simple liquid–liquid extraction step. For sweeping–MEKC, the amount of organic modifier in the separation electrolyte, the concentration of phosphoric acid in the sample matrix and the injection time of the sample were optimized. Sensitivity enhancements of up to 305-fold were achieved via sweeping. This allowed limits of detection (LOD) from 7 to 27 ng/mL. The relative standard deviations of migration time, corrected peak area and peak height were less than 3.2%, 7.8% and 4.5%, respectively. Liquid–liquid extraction using dichloromethane as solvent afforded up to 21-fold enrichment of the drugs from spiked wastewater. No interference of the sample matrix was observed and recoveries were obtained in the range of 77–113% for all analytes except labetalol at three spiking levels of 16, 80 and 160 ng/mL. Detection at the ng/mL level makes this simple, environmentally friendly and cost effective method competitive against recently reported methods using advanced liquid-phase separation techniques for monitoring similar drugs in wastewater.},

keywords = {micellar electrokinetic chromatography, on-line sample preconcentration, sweeping, tricyclic antidepressant drugs, β-blocker drugs},

pubstate = {published},

tppubtype = {article}

}

@article{Quirino2010,

title = {Two-step stacking in capillary zone electrophoresis featuring sweeping and micelle to solvent stacking: II. Organic anions},

author = {Joselito P. Quirino and Armando M. Guidote Jr.},

url = {https://www.sciencedirect.com/science/article/abs/pii/S0021967310018182},

doi = {10.1016/j.chroma.2010.12.095},

issn = {0021-9673},

year  = {2010},

date = {2010-12-21},

journal = {Journal of Chromatography A},

volume = {1218},

number = {7},

pages = {1004-1010},

abstract = {Two-step stacking of organic anions by sweeping and micelle to solvent stacking (MSS) using cationic cetyltrimethylammonium micelles in co-electroosmotic flow (co-EOF) capillary zone electrophoresis (CZE) is described. The co-EOF condition where the direction of the EOF is the same as the test anions was satisfied by positive dynamic coating of a fused silica capillary with hexadimethrine bromide. The strategy was as follows. After conditioning the capillary with the background solution (BGS), a micellar solution (MS) was injected before the sample solution (S). The BGS, MS and S have similar conductivities. Voltage was applied at negative polarity. The analytes in the micelle-free S zone were swept by micelles from the MS. The swept analytes were brought by the micelles to the MSS boundary where the second stacking step was induced by the presence of organic solvent in the BGS. Finally was the separation of concentrated analytes by CZE. The effect of electrolyte concentration in the S, injection time of the MS and the S and surfactant concentration in the MS were studied. A 20–29, 17–33 and 18–21 times increase in peak height sensitivity was obtained for the test hypolipidaemic drugs (gemfibrozil, fluvastatin and atorvastatin), non-steroidal anti-inflammatory drugs (diflunisal, naproxen, ketoprofen, indoprofen and indomethacin), and herbicides (mecoprop and fenoprop), respectively. The LODs (S/N = 3) were from 0.05 to 0.55 μg/mL. The intraday and interday repeatabilities (%RSD, n = 12) in terms of retention time, corrected peak area, and peak heights was less than 3.6, 8.9, and 10.8%, respectively. The application of sweeping and MSS in co-EOF CZE together with a simple extraction procedure to a waste water sample spiked with the test herbicides was also demonstrated.},

keywords = {capillary zone electrophoresis, herbicides, hypolipidaemic drugs, micelle to solvent stacking, non-steroidal anti-inflammatory drugs, on-line sample concentration, sweeping},

pubstate = {published},

tppubtype = {article}

}

@article{Aranas2009,

title = {Sweeping and new on-line sample preconcentration techniques in capillary electrophoresis},

author = {Agnes T. Aranas and Armando M. Guidote Jr. and Joselito P. Quirino},

url = {https://link.springer.com/article/10.1007/s00216-009-2646-7},

doi = {10.1007/s00216-009-2646-7},

year  = {2009},

date = {2009-03-03},

journal = {Analytical and Bioanalytical Chemistry},

volume = {394},

pages = {175-185},

abstract = {Sweeping is a powerful on-line sample preconcentration technique that improves the concentration sensitivity of capillary electrophoresis (CE). This approach is designed to focus the analyte into narrow bands within the capillary, thereby increasing the sample volume that can be injected, without any loss of CE efficiency. It utilizes the interactions between an additive [i.e., a pseudostationary phase (PS) or complexing agent] in the separation buffer and the sample in a matrix that is devoid of the additive used. The accumulation occurs due to chromatographic partitioning, complexation or any interaction between analytes and the additive through electrophoresis. The extent of the preconcentration is dependent on the strength of interaction involved. Both charged and neutral analytes can be preconcentrated. Remarkable improvements—up to several thousandfold—in detection sensitivity have been achieved. This suggests that sweeping is a superior and general approach to on-line sample preconcentration in CE. The focusing mechanism of sweeping under different experimental conditions and its combination with other on-line preconcentration techniques are discussed in this review. The recently introduced techniques of transient trapping (tr-trapping) and analyte focusing by micelle collapse (AFMC) as well as other novel approaches to on-line sample preconcentration are also described.},

keywords = {analyte focusing by micelle collapse, capillary electrophoresis, on-line sample preconcentration, sample stacking, sweeping},

pubstate = {published},

tppubtype = {article}

}