Extraction of steroids from urine with C18 solid-phase extraction cartridges results in an extract containing impurities. If, during the extraction of hydrolyzed urine, an amino (NH2) column is placed in series with the C18 column, then one obtains a sample that is sufficiently clean for gas-chromatographic analysis. Analytical recovery of dehydroepiandrosterone from urine is considerably decre...

the purpose of this study was to prepare and characterize nimodipine loaded microspheres using ethyl cellulose (ec) as a carrier polymer through an emulsion solvent evaporation method. these evaluations characterized the pattern of drug release from prepared microspheres. nimodipin loaded microspheres were prepared using an emulsification solvent evaporation method. the effect of process variab...

Efforts to increase the mass transfer coefficient, enhance the contact area, and decrease the power input of contractors have given risen to the development of the pre-dispersed solvent extraction (PDSE) contactor and the devise of the new dissolved nitrogen PDSE (DNPDSE) contactors. The studies conducted after the design of the new contactor to determine the working conditions for its suitable...

acetonitrile used as a solvent in manufactures and affects to central nervous system from inhalation exposure. the aim of this study was to develop a micro-solid phase extraction method for  the determination of acetonitrile in the air matrix. the sampling was performed with a small diameter fused silica fiber coated with a thin film of stationary phase and was subsequently desorbed and analyze...

A high-performance liquid chromatographic multiresidue method was developed for the determination of 8 penicillin compounds (benzylpenicillin, phenoxymethylpenicillin, ampicillin, amoxicillin, nafcillin, oxacillin, cloxacillin, and dicloxacillin) at trace levels in muscle tissue. This method involves extraction of the penicillins with phosphate buffer pH 9 followed by cleanup and concentration ...

A simple, rapid and precise HPLC method has been developed for the assay of hydrochlorothiazide in urine. The clean-up of the urine samples was carried out by solid-phase extraction using HLB cartridges. Extraction recovery was 94.00-100.28 %. HPLC separation was performed with isocratic elution on Hypersil BDS C18 column (100 x 4.0 mm I.D., 3 μm particle size) protected with appropriate guard ...

For the analysis of blue-green algal food supplements for cylindrospermopsin (CYN), a C18 solid-phase extraction column and a polygraphitized carbon solid-phase extraction column in series was an effective procedure for the clean-up of extracts. Determination of CYN was by liquid chromatography with ultraviolet light detection. At extract spiking levels of CYN equivalent to 25-500 µg g(-1), blu...