We describe an improved method of sample preparation for liquid chromatographic determination of plasma catecholamines. The catecholamines are extracted from plasma by using small, cheaply-made columns of alumina, with or without prior clean-up on commercially available ion-exchange columns. Advantages of this technique over the conventional batch-extraction method of using alumina are speed, c...

background and aims: a selective and sensitive high performance liquid chromatography-electrospray ionization mass spectrometry method has been established for determination of methotrexate in human plasma. methods: methotrexate was extracted from plasma with acetonitrile. the mobile phase consisted of acetonitrile-water-formic acid 74: 25: 1(v/v). twenty µl of sample was chromatographically an...

the present work describes a reverse phase hplc method for the quantitation of drotaverine hydrochloride and mefenamic acid in human plasma. organic solvent system used for liquid extraction composed of dichloromethane, and isopropyl alcohol in the ratio 80:20 (v/v). the compounds were separated on a thermo bds hypersil c8 (25.0 cm×4.6 mm, 5 µm particle size) column in isocratic mode with a mix...

this paper presents the results of a study on the radiation characteristics of a plasma triangular antenna in the vhf band (30-300mhz) applying the method of moment. deriving the current distribution of the antenna, it shows the relationship between radiation characteristics of the plasma antenna and the plasma parameters. both theoretical and numerical results indicate that if the plasma frequ...

A sensitive chemiluminescence (CL) method was developed for determining melamine in urine and plasma samples based on the fact that melamine can remarkably enhance the chemiluminescence of Luminol-K3 Fe(CN)6 system in alkaline medium. The determination conditions were optimized. Under optimum conditions, the chemiluminescence intensity had a good linear relationship with melamine in the range o...

in this study, simple and efficient ultrasound-assisted emulsification microextraction (usaeme) combined with gas chromatography-flame ionization detector (gc-fid) was developed for the preconcentration and determination of carbamazepine in biological samples. in this method, the fine droplets of 1-octanol were formed and dispersed in the sample with the help of ultrasonic waves, which accelera...

numerical study of double-diffusive natural convective heat transfer in a curved cavity filledwith a porous medium has been carried out in the current study. polar system has beenselected as coordinate system. as a result, all equations have been discredited in r and θdirections. brinkmann extended darcy model has been utilized to express fluid flow inporous matrix in the enclosure. smaller and...