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In this article, we proposed very simple procedures to analyze important phenolic compounds in olive oil samples from different olive varieties. A nonaqueous CE method has been employed. The main phenolic alcohols in virgin olive oil (tyrosol and hydroxytyrosol) and some among the most abundant secoiridoid aglycone derivatives (dialdehydic form of decarboxymethyl elenoic acid linked to hydroxytyrosol, an isomer of oleuropein aglycone and the dialdehydic form of decarboxymethyl elenoic acid linked to tyrosol) were determined by a direct injection into the capillary of the olive oil dissolved in 1-propanol 1:1 v/v. For the determination of compounds present at lower concentrations, a very simple liquid-liquid extraction method with ethanol has been proposed. The extraction was performed using a relationship 5:1 w/v olive oil/ethanol to achieve the necessary preconcentration of the analytes and the ethanolic extracts were directly injected into the capillary to obtain a very important time reduction. Good recoveries were obtained with both the procedures, using an internal standard. Finally, these procedures were applied to the analysis of these compounds in extra virgin olive oil samples from different varieties of olive., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In the present work we report a non-aqueous electrophoresis method (NACE) for the separation and determination of eight tricyclic antidepressants (TCAs) in human serum. Separation is carried out in 1 M acetic acid, 50 mM ammonium acetate and 10 mM SDS in ACN. Standards and samples were prepared in 0.8 M acetic acid in ACN and introduced by electrokinetic injection. The interactions between TCAs and acetate ions were studied and deduced from comparison of both the actual experimental and theoretical mobility. The establishment of calibration curves in the presence or absence of serum matrix, between 20 and 200 ng/mL, together with the determination of most important analytical parameters and a study of robustness were performed. Validation of the CE method was carried out with serum samples spiked with the analytes. The NACE determination method offers better resolution and higher sensitivity than the determination of TCAs in aqueous media.

Resveratrol and its 3-glucoside (piceid), are stilbene-like molecules produced by plants. Both of them are weakly fluorescent, but highly fluorescent compounds are obtained when their hydroethanolic solutions are UV-irradiated, which implies a substantial improvement in the sensitivity of analytical methods. Experimental design (central composite design) together with the response surface methodology have been used to find optimum conditions for the fast, sensitive, and precise chromatographic analysis (with isocratic elution) of resveratrol and piceid in wine samples. These compounds have been UV-transformed into their respective photoproducts, which have been separated in a C18 column (Novapack C(18) 150x3.9 mm, 4 microm) by isocratic elution, using a mobile phase made up of acetonitrile and 4.1 vol% aqueous acetic acid, 19:81 v/v, at a flow rate of 0.8 mL/min, and fluorimetrically detected at 364 nm (lambda(exc) = 260 nm). Detection limits (S/N = 3) are 0.29 and 0.28 microg/L for resveratrol and piceid, respectively. The method has been applied to the analysis of these compounds in wine samples without a clean-up step. The analysis is completed in only 20 min. The standard addition method has been applied to the analysis of a commercial red wine and average recoveries near 100% were obtained for resveratrol and piceid. Three wine pools were satisfactorily analysed by external calibration.

The work presented here explores the possibilities of the electrokinetic injection (EK) to achieve sensitive methods for the determination of tricyclic antidepressants in biological samples (serum). The addition of ACN to the sample, with high content in salts, causes stacking at the tip of the capillary, in a similar way as for hydrodynamic injection. An experimental design with the response surface methodology has been used to find the optimum composition of the matrix of the sample (sodium chloride and ACN percentages) and the conditions for the EK (water-plug length, time, and voltage of injection) in few experiments. The composition of the separation buffer was the same as utilized in a previous paper. The use of a bubble capillary to reach lower detection limits implies a loss of the resolution and requires a new optimization. Finally, a comparison between electrokinetic and hydrodynamic injections is made.

Stacking methods are very important in overcoming the poor detection limits in capillary electrophoresis (CE). In this paper, the separation and determination of several tricyclic antidepressants by a stacking method is described. The inclusion of acetonitrile (ACN) in the sample causes stacking (transient pseudoisotachophoresis) especially in presence of sodium chloride. An experimental design (central composite design) together with the response surface methodology has been used to find the optimum composition of the separation buffer and the optimal stacking conditions in few experiments. The response functions used are the product of the total resolution by the number of peaks, for the optimization of the separation buffer, and the product of the total resolution by the mean of the peak heights, for the optimization of the stacking conditions. About 28% of the capillary volume is loaded with sample. The calibration curves are linear over the working range (50-300 ng/mL). With a bubble capillary, the limits of detection (LODs) are in the order of 5 ng/mL. For the analysis of serum samples, enrichment with sodium chloride and the protein precipitation with ACN are enough to avoid interferences and to get stacking. Recoveries between 91.6 and 104% and RSD between 0.6 and 12% are obtained in the analysis of samples of lyophilized human serum and non-lyophilized human serum, spiked with the drugs.