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A capillary zone electrophoresis (CZE) method was developed and validated for the simultaneous determination of both streptomycin (STP) and oxytetracycline (OTC) in bactericidal products to be used in agriculture. Using fused-silica capillaries, the influence of the electrolyte composition, pH and concentration, as well as temperature and applied voltage were investigated using a central composite design to optimize the method. The optimized electrophoretic conditions were as follows: 0.10 M sodium phosphate, pH 2.5, 7.0 kV and 20.0 degrees C. The method was validated for STP and OTC determination in agricultural formulations through the following performance criteria: linearity and linear range, sensitivity, selectivity, intra-day and inter-day precision, detectability, accuracy and ruggedness. This optimized CZE-method for the identification and quantification of STP and OTC is a potential alternative method to the HPLC methods described by the US Pharmacopeia, with the advantage that the same method could be used for the simultaneous determination of these different antibiotics.

A simple method for the simultaneous determination of Cd and Pb in medicinal plants by differential pulse anodic stripping voltammetry, using a hanging mercury drop electrode, was developed. The pre-concentration of the metals was performed in 0.8 mol L(-1) HCl at -0.73V for 180s. The sample preparation was carried out by dry-ashing 1.0g of finely pulverized plant samples for 2.5h at 500 degrees C. The determination limit of the method was 0.12 and 0.010 mg kg(-1) for Pb and Cd, respectively. The method was applied to the quantification of cadmium and lead in samples of Hypericum perforatum, Mikania guaco, Mikania glomerata and Peamus boldus. The voltammetric method was shown to be useful for the control of contaminants in medicinal plants.

Objectives: We devised liposome-entrapped antimony with the negatively charged lipid phosphatidylserine-liposome-entrapped antimony (Sb-LP)-in order to improve their targeting to infected macrophages through the interaction with scavenger receptors (SRs)., Methods: SR production was indirectly evaluated by its mRNA synthesis in infected and uninfected peritoneal macrophages using RT-PCR. The interaction and cytotoxicity of Sb-LP with SRs and their metabolism were determined by incubation with macrophages in the presence of cytochalasin B, chloroquine or different competitive ligands, with determination of the 50% inhibitory concentration (IC50) in vitro in infected macrophages. The intracellular trafficking of Sb-LP was evaluated by confocal microscopy using trapped fluorescent dyes., Results: Our results showed an up-regulation of macrophage SR mRNA during the initial steps of Leishmania (L.) chagasi infection. By competitive ligand assays, we demonstrated the preferential uptake of Sb-LP by macrophage SRs. Sb-LP was 16-fold more effective (IC50=14.11 microM) than the free drug (IC50=225.9 microM) against L. (L.) chagasi-infected macrophages. The binding and uptake of Sb-LP in macrophages were shown to be energy-dependent and were reduced in the presence of cytochalasin B, showing the dependency of the cell microfilament system. Confocal analysis using trapped fluorescent dyes showed fluorescence of parasites or in their close proximity, compatible with the localized delivery of the liposomes., Conclusions: The uptake of Sb-LP was reduced in infected macrophages, despite their effectiveness and targeting ability, suggesting a low metabolic rate in infected macrophages that could be overcome by the higher efficiency of the liposomal formulation. These in vitro results suggest that liposomes could improve the therapeutic index of old drugs, such as pentavalent antimony, via targeted delivery to Leishmania-infected cells.

The use of EDTA in the medium to avoid the passivation of a solid electrode during electrochemical analysis of acetaminophen is presented in this work. The performance of this system was investigated with respect to pH, applied potential and supporting electrolyte concentration. The major advantage in using EDTA in the supporting electrolyte is the significant increase in sensitivity, precision and stability of the measurements, when compared to the system in absence of the chelating agent. The sensitivity increases 5.5 times (21.5 and 3.9 mA l mol(-1) in the presence and the absence of EDTA, respectively), the repeatability (n=20) is 3.5 times better, expressed by within-run-precision of 4.0% for 6.0 x 10(-5) mol l(-1) acetaminophen in the presence of EDTA while, in its absence, the within-run-precision was higher than 14%. Moreover, the system showed excellent stability, allowing more than 120 measurements with no significant changes.

A liquid chromatographic/atmospheric pressure chemical ionization tandem mass spectrometric method (LC-APCI-MS-MS) for the determination of glybenclamide in human plasma is described. Glypizide, an analogue of glybenclamide, was used as internal standard. The analyte was extracted from plasma with diethyl ether/dichloromethane (70:30 v/v). The chromatography uses C18 and 0.01 mol L(-1) acetic acid/acetonitrile (20:80 v/v) as stationary and mobile phase, respectively. Quantitation was preformed by using multiple reaction monitoring (MRM) of the precursor ion (m/z 494.2-->368.8) and the related product ion (m/z 446.0-->347.3) using the internal standard method. The analytical curve was linear in the range 1-300 ng mL(-1), and for a 400-microL sample of human plasma, the limit of determination of the method was 1 ng mL(-1). The coefficients of variation of the method for intra-assay (within-run precision) and inter-assay (between-run precision) were less than 10%. The method was shown to be suitable for pharmacokinetic studies.