Simultaneous determination, by capillary zone electrophoresis, of multiple components of different industrial products

Potential determination of aminated pesticides and metabolites by cyclodextrin capillary electrophoresis-laser-induced fluorescence using FITC as labelling

We describe a detailed study on the possibility of analyzing aminated pesticides and metabolites using pre-column derivatization with fluorescein isothiocyanate (FITC) and their subsequent separation and detection by cyclodextrin capillary electrophoresis-laser-induced fluorescence (CE-LIF) detection. Different variables affecting the derivatization reaction (pH, FITC concentration, reaction time and temperature) and those related with the separation itself (buffer concentration, addition of various organic modifiers, pH, applied voltage and injection time) were studied. The limit of detection obtained was between 0.45 and 3.48 microg litre(-1) showing a relative standard deviation between 0.26 and 2.08% at a concentration level of 50 microg litre(-1).

Optimization by experimental design and artificial neural networks of the ion-interaction reversed-phase liquid chromatographic separation of twenty cosmetic preservatives

Particular attention are recently receiving antimicrobial agents added as preservatives in hygiene and cosmetics commercial products, since some of them are suspected to be harmful to the human health. The preservatives used belong to different classes of chemical species and are generally used in their mixtures. Multi-component methods able to simultaneously determinate species with different chemical structure are therefore highly required in quality control analysis. This paper presents an ion interaction RP-HPLC method for the simultaneous separation of the 20 typical antimicrobial agents most used in cosmetics and hygiene products, that are: benzoic acid, salicylic acid, 4-hydroxybenzoic acid, methyl-, ethyl-, propyl-, butyl-, benzyl-benzoate, methyl-, ethyl-, propyl-, butyl-, benzyl-paraben, o-phenyl-phenol, 4-chloro-m-cresol, triclocarban, dehydroacetic acid, bronopol, sodium pyrithione and chlorhexidine. For the development of the method and the optimization of the chromatographic conditions, an experimental design was planned and models were built by the use of artificial neural network to correlate the retention time of each analyte to the variables and their interactions. The neuronal models developed showed good predictive ability and were used, by a grid search algorithm, to optimize the chromatographic conditions for the separation of the mixture.