betadex and ethylbenzene

The inclusion complex of ethyl benzoate with hydroxypropyl-β-cyclodextrin (HPCD) was prepared by a freeze-drying method and its characterizations were investigated by different analytical techniques including UV, FT-IR and phase solubility methods. All these approaches indicated that ethyl benzoate was able to form an inclusion complex with HPCD, and the ethyl benzoate/HPCD inclusion compounds exhibited different spectroscopic features and properties from ethyl benzoate. The stoichiometry of the complex was 1:1 and it was the benzene ring part of the ethyl benzoate molecule included into the HPCD cavities from the wider edge. The calculated apparent stability constant of the complex was 9485 M(-1). Moreover, the water solubility of ethyl benzoate was significantly improved by phase solubility studies. The release of ethyl benzoate was also regulated by the form of the inclusion complex. The results showed that HPCD was a proper excipient for increasing the solubility and controlled release of ethyl benzoate.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Benzene Derivatives; beta-Cyclodextrins; Calorimetry, Differential Scanning; Flavoring Agents; Solubility; X-Ray Diffraction

An HPLC method for the determination of benzene, toluene, ethylbenzene and o-xylene, m-xylene and p-xylene in occupational environments was developed and compared with a GC-MS method. Chromatographic analysis using a beta-cyclodextrin stationary phase was performed after active and passive air sampling by adsorption on activated charcoal and pressurized fluid extraction. The analytes were completely separated and quantified using both methods, although GC-MS provided better resolutions and lower detection limits than HPLC. The HPLC method was unsuccessfully applied to the determination of benzene in real samples because its sensitivity was too low. Both methods were applied to the analysis of certified reference materials and air samples collected in several workplaces. Statistical comparison showed that HPLC and GC-MS provided analogous accuracy.

Topics: Benzene; Benzene Derivatives; beta-Cyclodextrins; Chromatography, Gas; Chromatography, Liquid; Occupational Exposure; Toluene; Xylenes

Cyclodextrin-modified capillary electrophoresis has been developed for separation and analysis of benzene and its derivatives. The procedure used a mixture of negatively charged sulfobutyl ether-beta-cyclodextrin (SB beta CD) and neutral hydroxypropyl-beta-cyclodextrin (HP beta CD) to effect differential distribution (partitioning) of the aromatic hydrocarbons between the buffer and CD phases. In 80 mM phosphate buffer, containing 15 mM SB beta CD and 5 mM HP beta CD, benzene, toluene, ethyl benzene and three xylene isomers (BTEXs) were well resolved with a number of theoretical plates well above 100,000, for 50 cm of effective length. Some halogenated benzenes were also observed to separate well from the BTEX components to indicate their suitability as an internal standard for BTEX analyses. Equilibrium complexation models were used for investigating the effect of the cyclodextrin(s) at different concentrations and temperature on the electrophoretic mobility.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Benzene; Benzene Derivatives; beta-Cyclodextrins; Cyclodextrins; Electrophoresis, Capillary; Models, Chemical; Toluene; Xylenes

Chromatographic separation of the metabolites derived from toluene, ethylbenzene, styrene and xylene was carried out on untreated urine samples from factory workers. The elution sequence was as follows: phenylglyoxilic acid, 3-hydroxy-2-butanone, hippuric acid, o-methylhippuric acid, p-methylhippuric acid, m-methylhippuric acid, p-cresol, m-cresol and o-cresol. The stability constants (K(G)) of cresol and methylhippuric acid derivatives were evaluated. The capacity factor (k'), selectivity factor (alpha) and resolution (Rs) are described with a variety of mobile phases containing beta-cyclodextrin (beta-CD). The optimum concentration ratio of ethanol-water-acetic acid-beta-CD was determined to be 20:80:0.3:1.4%. Under these conditions, k' values of the five metabolites were 2

Topics: Air Pollutants, Occupational; Benzene Derivatives; beta-Cyclodextrins; Chromatography, High Pressure Liquid; Cyclodextrins; Humans; Reproducibility of Results; Sensitivity and Specificity; Solvents; Styrene; Styrenes; Toluene; Xylenes