María R. Gomez

Simultaneous determination of dextromethorphan, diphenhydramine and phenylephrine in expectorant and decongestant syrups by capillary electrophoresis

The separation of basic nitrogenous compounds commonly used as active ingredients in cold medicine formulations by micellar electrokinetic capillary chromatography and capillary zone electrophoresis with direct absorptiometric detection was investigated. The type and composition of the background electrolyte (BGE) were investigated with respect to separation selectivity and BGE stability. BGE of 10 mM sodium dihydrogenphosphate-sodium tetraborate buffer containing 10 mM SDS and 10% acetonitrile, pH 9.0 was found to be optimal. Dextromethorphan hydrobhromide, diphenhydramine hydrochloride and phenylephrine hydrochloride were baseline-separated in less than 11 min, giving separation efficiencies of up to 494,000 theoretical plates, reproducibility of corrected peaks areas below 3% relative standard deviation and concentration detection limits from 2.5 to 5.5 microg ml(-1). Detection was performed at 196 and 214 nm.

On-line cloud point preconcentration and determination of gadolinium in urine using flow injection inductively coupled plasma optical emission spectrometry

The on-line incorporation of cloud point extraction (CPE) into flow injection analysis (FIA) associated with ICP-OES for determining metal ions is presented and evaluated. The methodology is based on the complexation of Gd(III) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of non-ionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 25 °C and loaded into the FIA manifold at a flow rate of 5 ml min−1, and the surfactant rich-phase was retained in a micro-column packed with cotton, at pH 9.2. The surfactant-rich phase was eluted with 4 mol l−1 nitric acid at a flow rate of 1.5 ml min−1 directly into the nebulizer of the plasma. An enhancement factor of 20 was obtained for the preconcentration of 10 ml of sample solution. The detection limit for the preconcentration of 10 ml of aqueous solution of Gd was 40 ng l−1. The precision (RSD) for 10 replicate determinations at the 2.0 µg l−1 Gd level was 1.9%, calculated from the peak heights obtained. The calibration graph using the preconcentration system for gadolinium was linear, with a correlation coefficient of 0.9997 at levels near the detection limit up to at least 50 µg l−1. The method was successfully applied to the determination of gadolinium in urine.

Analysis of potential adulteration in herbal medicines and dietary supplements for the weight control by capillary electrophoresis

Four different phytopharmaceutical dosage forms for use in weight control programs were analyzed. Two different ground herbal blends and their correspondent infusions, a capsule and a tincture were investigated for the presence of compounds used as adulterants in these products. A capillary electrophoresis (CE) method was developed and validated. The optimized experimental conditions were: BGE, sodium tetraborate buffer 20mM, pH 9.2, voltage applied 30kV, capillary temperature 25°C, injection sample at 0.5Psi during 5s. Ephedrine, norephedrine, caffeine and furosemide were baseline separated in less than 7min; the migration times were found to be 2.65, 2.90, 3.75 and 6.58min, respectively. The analysis showed in sample 3 concentrations of 0.45±0.03mgg(-1) (ephedrine), 0.33±0.02mgg(-1) (norephedrine), 1.09±0.41mgg(-1) (caffeine) and 0.80±0.17mgg(-1) (furosemide). Caffeine content in samples 1, 2 and 4 was 0.61±0.06mgg(-1), 15.66±1.05mgg(-1) and 2.27±0.13mgml(-1), respectively. Linearity was obtained in the concentration range of 1-1000μgml(-1). Limits of detection (LOD) and quantification (LOQ) were determined as 0.42μgml(-1) and 1.40μgml(-1) (ephedrine), 0.47μgml(-1) and 1.40μgml(-1) (norephedrine), 0.12μgml(-1) and 0.48μgml(-1) (caffeine), 0.22μgml(-1) and 0.73μgml(-1) (furosemide). The common constituents of the samples did not interfere with the potential adulterants. Repeatability was better than 0.24% RSD for the retention time and 1.43% for the peak area. Intermediate precision was tested by changing the capillary, the day of operation and the operator, in all the cases the %RSD was better than 3.06.

Metal content monitoring in Hypericum perforatum pharmaceutical derivatives by atomic absorption and emission spectrometry

Metals have been investigated in different plant materials in order to establish their normal concentration range and consider their role in plants as part of human medicinal treatment. Metal monitoring as a pattern recognition method is a promising tool in the characterization and/or standardization of phytomedicines. In the present work measurable amounts of Ca, Cu, K, Li, Mg, Mn, Na, Ni, and Zn were detected in phytopharmaceutical derivatives of Hypericum perforatum by atomic techniques. Atomic methodologies like flame atomic absorption spectrometry (FAAS) and electrothermal atomic absorption spectrometry (ETAAS) allow reliable determination of mineral content in pharmaceutical quality control of medicinal plants. Additionally, capillary electrophoresis (CE) patterns of characteristic components (fingerprints) have been performed for the search of adulterants in phytopharmaceutical products.

Simultaneous determination of cloramphenicol, salicylic acid and resorcinol by capillary zone electrophoresis and its application to pharmaceutical dosage forms

This study demonstrates the separation of active ingredients in acne formulations (salicylic acid, cloramphenicol and resorcinol in presence of azulene) by capillary zone electrophoresis. Factors affecting their separations were the buffer pH and concentration, applied voltage, sample preparation, and presence of additives. Optimun results were obtained with a 50 mM sodium tetraborate-50 mM sodium phosphate, pH 9.0. The carrier electrolyte gave baseline separation with good resolution, short migration times (<6 min), great reproducibility and accuracy. Calibration plots were linear over at least three orders of magnitude of analyte concentrations, the lower limits of detection being within the range 0.39-1.25 mug ml(-1). The procedure was fast and reliable and commercial pharmaceuticals could be analysed without prior sample clean-up procedure.

Sensitive ergotamine determination in pharmaceuticals and biological samples using cloud point preconcentration and spectrofluorimetric detection

A new cloud point extraction (CPE) method for ergotamine analysis using fluorimetric detection is described. Ergotamine from an aqueous solution was preconcentrated into a smaller surfactant-rich phase using nonionic surfactant polyoxyethylene(7.5)nonylphenylether (PONPE 7.5). Differently from the conventional CPE procedure in which the resulting surfactant-rich phase is diluted by a fluidificant before its analysis, in this method the fluorescence measurements were carried out directly onto the undiluted surfactant-rich phase. The high viscosity provided by the undiluted surfactant rich phase greatly improved the fluorescence emission of ergotamine, leading to a total enhancement factor of 1325. This spectral advantage plus the preconcentration factor achieved, contributed to the method sensitivity allowing the ergotamine determination at trace level concentration. Under optimal experimental conditions, a linear calibration curve was obtained from 3.81×10(-7) to 1.10μgmL(-1), with detection and quantification limits of 0.11 and 0.38pgmL(-1), respectively. The accuracy and versatility of the present methodology were proved by analyzing ergotamine in real samples of different natures such as pharmaceuticals, urine and saliva.

Simultaneous separation of ergot alkaloids by capillary electrophoresis after cloud point extraction from cereal samples

A new and sensitive analytical methodology for ergot alkaloids (EA) determination from cereal samples based on cloud point extraction (CPE) prior to CE‐UV absorbance was developed. The methodology involves extraction under acid conditions and subsequent preconcentration by applying a simple, rapid and environmentally friendly low volume surfactant extraction procedure. After extraction, CE analysis was carried out by performing dilutions on preconcentrated surfactant rich phase, achieving a single peak or simultaneous alkaloids determination. A real preconcentration factor of 22 of total EA was obtained, demonstrating the efficiency of this methodology. The limits of detection were 2.6 and 2.2 μg/kg for ergotamine and ergonovine, respectively. Validation procedure revealed suitable linearity, accuracy and precision. The average extraction and clean‐up recoveries were compared with the theoretical values and were better than 92%. This method was successfully applied to the determination of EA in different varieties of commercial flour samples, two grain samples and one of the leading brands cereal‐based product for infant feeding. The high sensitivity achieved for EA determinations in real samples suggests CPE procedure as an interesting approach to improve CE‐UV visible detection limits. Moreover, the whole process could be considered as a contribution to green chemistry because nonorganic solvents were involved, demonstrating its great potential over conventional techniques.

Monitoring of Phenolic Compounds for the Quality Control of Melissa officinalis Products by Capillary Electrophoresis

INTRODUCTION Official assays for the quality control of Melissa officinalis L. (Lamiaceae) leaves establish the quantification of total hydroxycinnamic derivatives expressed as rosmarinic acid. OBJECTIVE The goal of this work was to develop a simple, fast and reliable method for monitoring the phenolic composition in herbs from the Lamiaceae family and for rapidly detecting M. officinalis adulteration or substitution in commercial medicinal samples in Argentina. METHODOLOGY A capillary zone electrophoresis (CZE) method was performed under the following conditions: the background electrolyte (BGE) consisted of 20 m m sodium tetraborate buffer, pH 9.2; the applied voltage was 25 kV; the capillary and sample temperatures were kept at 25 °C; the hydrodynamic mode was selected for the sample injection (3.45 kPa during 5 s). RESULTS A CZE method that achieved the separation and simultaneous determination of eight related phenolic compounds in less than 11 min was optimised for application to control quality analysis of M. officinalis-based products. The method was validated according to the US Federal Drug Agency requirements and offers advantages in terms of analysis time, cost and operation. CONCLUSIONS The proposed methodology can be applied to the standardisation and quality control of plant material and phytopharmaceutical products derived from the Lamiaceae family, as indicated by the results obtained in the analysis of commercial medicinal products in Argentina.

A simple and highly selective molecular imprinting polymer-based methodology for propylparaben monitoring in personal care products and industrial waste waters

Graphical abstract Figure. No caption available. HighlightsA MISPE‐HPLC analytical system was developed and validated for propylparaben analysis.The MISPE procedure was highly selective for its application in complex matrixes.The method is simpler and faster than previous and shows high stability.Lower LOQ and good recovery factor were obtained with routinely used equipment.The whole procedure avoid the use of large volumes of pollutant solvents. ABSTRACT In this work, a novel molecularly imprinted polymer (MIP) proposed as solid phase extraction sorbent was developed for the determination of propylparaben (PP) in diverse cosmetic samples. The use of parabens (PAs) is authorized by regulatory agencies as microbiological preservative; however, recently several studies claim that large‐scale use of these preservatives can be a potential health risk and harmful to the environment. Diverse factors that influence on polymer synthesis were studied, including template, functional monomer, porogen and crosslinker used. Morphological characterization of the MIP was performed using SEM and BET analysis. Parameters affecting the molecularly imprinted solid phase extraction (MISPE) and elution efficiency of PP were evaluated. After sample clean‐up, the analyte was analyzed by high performance liquid chromatography (HPLC). The whole procedure was validated, showing satisfactory analytical parameters. After applying the MISPE methodology, the extraction recoveries were always better than 86.15%; the obtained precision expressed as RSD% was always lower than 2.19 for the corrected peak areas. Good linear relationship was obtained within the range 8–500 ng mL−1 of PP, r2 = 0.99985. Lower limits of detection and quantification after MISPE procedure of 2.4 and 8 ng mL−1, respectively were reached, in comparison with previously reported methodologies. The development of MISPE‐HPLC methodology provided a simple an economic way for accomplishing a clean‐up/preconcentration step and the subsequent determination of PP in a complex matrix. The performance of the proposed method was compared against C‐18 and silica solid phase extraction (SPE) cartridges. The recovery factors obtained after applying extraction methods were 96.6, 64.8 and 0.79 for MISPE, C18‐SPE and silica‐SPE procedures, respectively. The proposed methodology improves the retention capability of SPE material plus robustness and possibility of reutilization, enabling it to be used for PP routine monitoring in diverse personal care products (PCP) and environmental samples.

On-Line Preconcentration Method Using Normal Stacking Mode and Dynamic pH Junction for the Quality Control of Herbal Medicines Containing Related Phenolic Compounds

Fil: Acosta, Maria Gimena. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico San Luis. Instituto de Quimica de San Luis; Argentina