Determination of oxytetracycline and some impurities in plasma by non-aqueous capillary electrophoresis using solid-phase extraction

Nonaqueous capillary electrophoresis in pharmaceutical analysis

This review presents different solvents and electrolytes commonly used as BGEs in NACE for the analysis of pharmaceutical compounds. Most NACE applications carried out since 1998 for the analysis of compounds of pharmaceutical interest are presented in four tables: (i) analysis of drugs and related substances, (ii) analysis of chiral substances, (iii) analysis of phytochemical extracts and (iv) analysis of drugs in biological fluids. These selected examples are used to illustrate the interest in NACE versus conventional aqueous CE.

Simultaneous determination of streptomycin and oxytetracycline in agricultural antimicrobials by CZE after an experimental design

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.

Literature-Based Generation of Hypotheses on Chemical Composition Using Database Co-occurrence of Chemical Compounds

Candidates for identification of unknown constituents in a sample to be chemically analyzed are hypothetical. It is proposed to generate these hypotheses according to the co-occurrence of different chemical compounds with a known sample constituent in the chemical literature. The efficiency of the co-occurrence approach for predicting chemical compositions was tested for 67 impurities in 17 chemical/pharmaceutical products. The relative co-occurrence of impurity compounds and these products in the Chemical Abstracts Service database was evaluated and compared with corresponding values for several reference groups of probability sampled compounds from the literature. Almost all impurities (97%) and only < or = 8% randomly sampled compounds co-occurred with these chemical products. Mean and median values of relative co-occurrence for impurities are much higher than those of probability sampled compounds which co-occurred with the products. For the combination of impurities and the probability sample of 396 interfering compounds, the power to predict the chemical composition using the highest co-occurrences is 0.49-0.59. The co-occurrence value can also be considered as an "empiric" indicator of chemical similarity useful to generate new hypotheses on relationships both between compounds and between compounds and their properties.

Determination of ciprofloxacin, enrofloxacin and flumequine in pig plasma samples by capillary isotachophoresis--capillary zone electrophoresis

Quinolones are a group of synthetic antibiotics that are widely used in veterinary medicine. Their residues may remain in tissues, milk, etc. intended for human consumption. The European Union fixes the maximum residue limits (MRLs) of veterinary medicinal products in foodstuffs of animal origin. Analytical methods are therefore needed to determine them in biological samples. In this study, we describe capillary isotachophoresis-capillary zone electrophoresis (ITP-CZE) to analyze three quinolones, enrofloxacin (ENR), ciprofloxacin (CPR) and flumequine (FLU), in pig plasma samples. We used solid-phase extraction with Oasis HLB cartridges as a sample pretreatment clean-up step. Capillary zone electrophoresis (CZE) requires low amounts of sample and is not as sensitive as one would wish. ITP-CZE is an easy way to increase the sample loadability and sensitivity. With this system sensitivity increases 40-fold. The detection limits for CPR, ENR and FLU were 70, 85 and 50 microg l(-1), respectively, which were lower than their MRLs in different kinds of samples. This method is simple and sensitive, and is therefore an alternative tool to the existing HPLC methods for analyzing the residuals of these quinolones in biological samples.

Analysis of antibiotics by capillary electrophoresis

This article reviews recent developments in the characterization of antibiotics. Many capillary electrophoretic techniques have been utilized in their analyses, addressing various aspects of quantifying, profiling and monitoring. Sensitive electrochemical and laser-induced fluorescence detection systems have been utilized, demonstrating trace level determinations in clinical settings and in environmental samples. Different sample introduction methods have been explored, enhancing detection sensitivity, or reducing or eliminating sample manipulation prior to injection.