A large-volume sample injection (> 5 microL) with an extremely high theoretical plate number (N > 10(7)) was achieved when the sweeping-MEKC mode and a coupled-capillary (100 - 50 microm i.d.) were simultaneously used in a capillary electrophoresis (CE) separation. A low-cost and compact violet-LED ( approximately 2 mW) was used as the fluorescence excitation source. As a result, the theoretica...

Received 29/9/2011 Accepted 23/12/2011 (005487) 1 Department of Food Science, Faculty of Food Engineering, University of Campinas – UNICAMP, 13083-862, Campinas, SP, Brazil, e-mail: [email protected] 2 Water and Soil Department, Faculty of Agricultural Engineering, University of Campinas – UNICAMP, Cidade universitária Zeferino Vaz, Barão Geraldo, CEP 13083-970, Campinas, SP, Brazil *Corres...

This study focuses on the spectrofluorimetric behaviour of a pharmaceutically and analytically important molecule 1-naphthoic acid in the presence of various surfactant solutions. Micellar solubilization is a powerful alternative for dissolving hydrophobic compounds in aqueous environment. Fluorescence and absorption spectroscopy are the two techniques used to monitor the micellar solubilizatio...

The values of pseudo-first-order rate constants (k(obs)) for alkaline hydrolysis of 1, obtained at 1.0 mM NaOH and within [C(m)E(n)]T (total concentration of C(m)E(n)) range of 3.0-5.0 mM for C(12)E(23) and 10-20 mM for C(18)E(20), fail to obey pseudophase micellar (PM) model. The values of the fraction of near irreversible C m E n micellar trapped 1 molecules (F(IT1)) vary in the range ~0-0.75...

The feasibility of combining the techniques of on-line concentration and capillary electrophoresis/low-temperature fluorescence spectroscopy (CE/LTFS) for the detection and identification of trans-resveratrol in red wine at 77 K is demonstrated for the first time. This technique, involving sweeping-micellar electrokinetic chromatography (sweeping-MEKC), was used for the initial on-line concentr...

An electrokinetic trapping (EKT)-based nanofluidic preconcentration device with the capability of label-free monitoring trapped biomolecules through real-time dual-loop electric current measurement was demonstrated. Universal current-voltage (I-V) curves of EKT-based preconcentration devices, consisting of two microchannels connected by ion-selective channels, are presented for functional valid...

Speciation of copper in a contaminated soil during electrokinetic remediation (EKR) assisted by H3PO4 was studied by in situ X-ray absorption near edge structural (XANES) spectroscopy. The least-square fit of the XANES spectrum showed that CuCO3 (68%) and CuCl2 (32%) were the major copper species in the contaminated soil. In the presence of H3PO4 (40%), most of CuCl2 and about 24% of CuCO3 were...