Direct electrochemistry of alpha-lipoic acid (ALA) was performed at a glassy carbon electrode using cyclic, differential pulse and square wave voltammetry over a wide range of pH. The oxidation of ALA is an irreversible process, pH independent, and involves the charge transfer of one electron. The diffusion coefficient of ALA was calculated from the results obtained at pH 6.9 in 0.1 M phosphate...

A general strategy is proposed for determining the very low aqueous solubility limits of bilayer-forming phospholipids. The strategy exploits the inherent surface activity of phospholipids and has been termed EDSB, which stands for Equilibrium Distribution between Surface and Bulk phases. In this report, EDSB has been used to determine the critical bilayer concentration of dilauroylphosphatidyl...

The suitability of analytical protocol for determination of sulfonamides in honey was investigated. Sulfonamides were extracted from honey with acetate buffer, and cleaned up by solid phase extraction (SPE) procedure. The liquid chromatography (LC) separation was carried out on RP C18 column and sulfonamides were monitored with fluorescence detector, after pre-column derivatisation. Recoveries ...

A simple and rapid method involving high-performance liquid chromatographic separation, followed by photodiode array (PDA) and electrospray ionization-mass spectrometric (ESI-MS) detection of aromatic sulfonates in waste-water effluents of industrial units producing optical whitening agents, has been developed. The separation was achieved on a reversed-phase Hypersil C18 column using gradient e...

This paper describes the methodological optimization and validation of a simple micellar electrokinetic chromatography for the rapid simultaneous separation of 2-methyl-4-isothiazolin-3-one, methylparaben, ethylparaben, propylparaben, and butylparaben. By using a 30 mM phosphate buffer (pH 7.2) containing 30 mM sodium dodecyl sulfate (SDS), an applied voltage of 10 kV and a separation temperatu...

Imipenem and cilastatin concentrations in serum were determined by using reverse-phase high-pressure liquid chromatography. Serum samples were stabilized with 0.5 M morpholineethanesulfonic acid buffer (pH 6.0) and subjected to ultrafiltration before chromatography. The elution solvent consisted of water or potassium phosphate buffered to pH 2.5 and methanol. The imipenem and cilastatin peaks w...