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...

Determination of carbamate pesticides such as carbaryl, carbofuran, propoxur and bendiocarb was demonstrated on a microchip with newly designed microchannels developed for efficient solvent extraction. The pesticides were hydrolyzed to corresponding naphthols, coupled with p-nitrobenzenediazonium fluoroborate reagent, and then extracted into 1-butanol as colored azo derivatives and detected wit...

Abstract A sweeping micellar electrokinetic chromatography (sweeping-MEKC) enrichment model was established for the determination of three chlorophenols (CPs) in cosmetics, namely, bithionol, pentachlorophenol (PCP), and 2,4,6-trichlorophenol (2,4,6-TCP). The optimum electrophoretic conditions were 20 mM NaH 2 PO 4 -80 sodium dodecyl sulfate (SDS) 30% (v/v) acetonitrile (pH 2.3). on-line concen...

A comparison of the use of aqueous and nonaqueous buffers in association with beta-CD for the chiral separation of (R)- and (S)-3,4-methylenedioxymethamphetamine and related compounds is described. The (R)- and (S)-isomers of 3,4-methylenedioxymethamphetamine (MDMA) and its major metabolite 3,4-methylenedioxyamphetamine (MDA) were prepared. Under aqueous and nonaqueous buffer conditions and bas...

Precolumn derivatization and chiral separation of DL-amino acids based on diastereomerization have been performed on an integrated poly(dimethylsiloxane) microchip. Diastereomeric derivatives were formed in a microfabricated precolumn reactor by the reaction of amino acid enantiomers with o-phthaldialdehyde/2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose (OPA/TATG), and separated by MEKC in ...

Cation-selective exhaustive injection and sweeping followed by a MEKC separation is evaluated for the sensitive analysis of 5-nitroimidazoles in untreated human serum and urine. Deproteinized serum and urine samples were diluted 76 and 143 times, respectively, in a low-conductivity solvent (5.00 mM orthophosphoric acid containing 5.0% v/v methanol). Samples were electrokinetically injected at 9...

Many steroid hormones can be considered as potential biomarkers and their determination in body fluids can create opportunities for the rapid diagnosis of many diseases and disorders of the human body. Most existing methods for the determination of steroids are usually time- and labor-consuming and quite costly. Therefore, the aim of analytical laboratories is to develop a new, relatively low-c...

deproteinisation with acetonitrile (along with methanol or other reagents) is a useful and rapid technique in analysis of drugs or their metabolites in human serum. in this paper application of this simple technique in biopharmaceutical analysis using capillary electrophoresis (ce) is evaluated. some drugs with different ionic and protein binding properties were selected and dissolved in human ...