Biomedical subjects

Carme Aguilar

Publications and source records attributed to Carme Aguilar.

9 recordsLinked to original sources

PubMed2006

Different sample stacking strategies to analyse some nonsteroidal anti-inflammatory drugs by micellar electrokinetic capillary chromatography in mineral waters.

Three on-column preconcentration techniques were compared to analyse a group of nonsteroidal anti-inflammatory drugs (NSAIDs) using micellar electrokinetic capillary chromatography (MEKC) under pH-suppressed electroosmotic flow (EOF) in water samples. The analysed drugs were ibuprofen, fenoprofen, naproxen, ketoprofen, and diclofenac sodium. The micellar background electrolyte (BGE) solution was formed by 75 mM sodium dodecyl sulfate (SDS), 40% (v/v) acetonitrile, and 25 mM sodium phosphate at pH 2.5. When this BGE solution was used the applied voltage was reversed, -10 kV, and the drugs were separated within 20 min. The on-column preconcentration modes, characterised all of them for the sample matrix removal out of the capillary by itself under a reverse potential at the same time as the EOF was reduced, were stacking with reverse migrating micelles (SRMM), stacking with reverse migrating micelles-anion selective exhaustive injection (SRMM-ASEI), and field-enhanced sample injection with reverse migrating micelles (FESI-RMM). The sensitivity was improved up to 154-, 263-, and 63-fold, respectively when it was calculated through the peaks height. The optimised methods were validated with spiked mineral water by combining off-line solid-phase extraction (SPE) and the proposed on-line sample stacking strategies. The detection limits (LODs) of NSAIDs in mineral water were at ng/L levels.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2005

Sample stacking for the analysis of penicillins by microemulsion electrokinetic capillary chromatography.

We present a method for determining eight penicillin antibiotics using microemulsion electrokinetic chromatography (MEEKC). We studied how the composition of the microemulsion affected separation by modifying such parameters as the surfactant or the addition of organic solvents. The best microemulsion system consisted of 0.5% ethyl acetate, 1.2% 1-butanol, 2% Brij 35, 10% 2-butanol and 86.3% 10 mM borate buffer at pH 10. We studied the suitability of this microemulsion composition for analyzing a commercial drug. To improve the sensitivity of the method, we used the stacking technique reversed electrode polarity stacking mode (REPSM), which increased the detection limits by about 40-fold.

Buffers↗

PubMed2005

Sample stacking for the analysis of eight penicillin antibiotics by micellar electrokinetic capillary chromatography.

We studied the use of micellar electrokinetic capillary chromatography for separating eight penicillins. The method consists of (i) an electrophoretic separation based on micellar electrokinetic capillary chromatography, which uses sodium dodecyl sulfate (SDS) as surfactant; (ii) a sample stacking technique called reverse electrode polarity stacking mode (REPSM); and (iii) direct UV detection. The background electrolyte that gave complete separation contained 20 mM sodium borate buffer and 60 mM SDS. The sensitivity of the method was improved by an enrichment step that used on-column stacking. The limits of detection were at the microg.L(-1) level for the penicillins and did not detract from the peak resolution.

Anti-Bacterial Agents↗

PubMed2005

Separation and on-column preconcentration of some nonsteroidal anti-inflammatory drugs by microemulsion electrokinetic capillary chromatography using high-speed separations.

Various strategies have been investigated for separating a group of nonsteroidal anti-inflammatory drugs (NSAIDs) by microemulsion electrokinetic capillary chromatography (MEEKC) using high-speed separations. The parameters that of affect the separation, such as the nature of the oil droplet and the buffer, and the surfactant concentration have been studied. In addition, several organic solvents were used to decrease the retention of the analytes in the oil droplet phase and to improve the resolution of the NSAIDs. The optimum microemulsion background electrolyte (BGE) solution made of 0.8% w/w ethyl acetate, 6.6% w/w butan-1-ol, 6.0% w/w acetonitrile, 1.0% w/w sodium dodecyl sulfate (SDS), and 85.6% w/w of 10 mM sodium tetraborate at pH 9.2 resolved the drugs within 8 min. The short-end injection procedure is an alternative for reducing the analysis time. When this procedure was used, the microemulsion BGE solution consisted of 0.8% w/w ethyl acetate, 6.6% w/w butan-1-ol, 17.0% w/w methanol, 1.0% w/w SDS, and 74.6% w/w of 10 mM sodium tetraborate, pH 9.2, and the NSAIDs were separated within 3 min. The reversed electrode polarity stacking mode (REPSM) technique was applied to the on-line concentration of the NSAIDs. In this technique, the sample matrix was pumped out of the capillary using a polarity-switching step. When this technique was applied, the sensitivity was enhanced up to 40-fold and the limits of detection (LODs) were in the low microg.L(-1) levels.

2-Propanol↗

PubMed2004

Application of capillary electrophoresis with different sample stacking strategies for the determination of a group of nonsteroidal anti-inflammatory drugs in the low microg x L(-1) concentration range.

Several on-column sample preconcentration modes--large-volume sample stacking using the EOF pump (LVSEP), LVSEP with anion-selective exhaustive injection (LVSEP-ASEI) and field-amplified sample injection with sample matrix removal using the electroosmotic flow (EOF) pump (FAEP)--were used to analyze some nonsteroidal anti-inflammatory drugs (NSAIDs) by capillary electrophoresis, and then compared. Methanol was the background electrolyte solvent to suppress the EOF. The effect of the type and length of the solvent plug, and the sample injection time were investigated in FAEP to determine the conditions that provided the best response. LVSEP, LVSEP-ASEI, and FAEP improved the sensitivity of the peak area by 100-, 1200-, and 1800-fold, respectively. The methodology developed, in combination with solid-phase extraction (SPE), was applied to the analysis of water samples.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2004

Determination of some acidic drugs in surface and sewage treatment plant waters by capillary electrophoresis-electrospray ionization-mass spectrometry.

We describe an analytical method involving solid-phase extraction (SPE) and capillary zone electrophoresis-electrospray ionization-mass spectrometry (CZE-ESI-MS) for determining some pharmaceutical compounds - naproxen, clofibric acid and bezafibrate - in real water samples. The electrospray parameters were optimized to maximize sensitivity. When a mixed aqueous-organic solvent and CZE-ESI-MS were used to analyze these drugs in water samples, the capillary was coated with hexadimethrin bromide (HDB) to permanently reverse the EOF. The method was developed from off-line SPE-CZE-MS and was validated with surface water. The detection limits were 100 ng.L(-1) for all analytes. The method was applied to analyze water samples from the influent and effluent of a sewage treatment plant. A liquid-liquid extraction step was required before SPE, and the compounds studied were found, some of them between detection and quantification limits.

Acids↗

PubMed2003

Improving sensitivity by large-volume sample stacking using the electroosmotic flow pump to analyze some nonsteroidal anti-inflammatory drugs by capillary electrophoresis in water samples.

Large-volume sample stacking using the electroosmotic flow (EOF) pump (LVSEP) has been used to analyze some nonsteroidal anti-inflammatory drugs (NSAIDs) in water samples. With methanol as the run buffer solvent to suppress the EOF, sensitivity was enhanced by 80-100-fold. The sample for the analysis of real water sample was pretreated by solid-phase extraction (SPE). When the method was based on off-line SPE-LVSEP-CE, sensitivity improved by as much as 1000 times.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2002

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.

Animals↗

PubMed2002

Isotachophoretic focusing and mass spectrometry detection as tools for improving the determination of aromatic sulfonates in capillary electrophoresis.

We explored isotachophoresis-capillary zone electrophoresis (ITP-CZE) with diode array detection on a single capillary to find out how to increase the injection volume and decrease the detection limits of aromatic sulfonates in CZE. The ITP was performed by applying a negative voltage in conjunction with hydrodynamic backpressure programming, and the terminating buffer was removed before the CZE separation, which resulted in highly sensitive determinations. The ITP increased the signal response of conventional hydrodynamic injection by a factor of 100, whereas the separation efficiency was unaffected. The limits of detection of the method were between 3 and 5 nugL(-1). The method was successfully used to determine these compounds in water samples. Experimental conditions for capillary electrophoresis-mass spectrometry were optimized and applied to determine aromatic sulfonates in water samples. These techniques enables the 2-naphthalenesulfonate to be determined in water samples.

Arylsulfonates↗