When analyses of mixtures of small molecules are carried out at mobile phase velocities close to (for isocratic runs) or somewhat above (for gradient runs) the optimum velocity, the eddy diffusion term contributes to at least 75% of the band broadening. Future improvements in column performance may come only from a reduction of the eddy diffusion term. The classical models of axial dispersion o...

A convenient method for the separation of molecular species of complex lipids such as sphingomyelin and ceramide by argentation high performance liquid chromatography (HPLC) is described for the first time. Molecular species separation of these complex lipids was achieved for quantitative analysis and preparative work by the combined use of argentation and reversed-phase HPLC.-Smith, M., P. Mon...

We have carried out a single-dose comparison of three different dextromethorphan cough mixtures in 10 healthy human volunteers. Dextromethorphan was administered in a single dose of 60 mg in random order. The concentrations of dextromethorphan and its main metabolite, dextrorphan, were determined from the plasma samples using high performance liquid chromatography. The concentrations of dextror...

Monomeric and oligomeric proanthocyanidins present in a range of plant-derived foods and beverages were separated by degree of polymerization and identified using a modified normal-phase high-performance liquid chromatography (HPLC) method coupled with on-line mass spectrometry (MS) analysis using an atmospheric pressure ionization electrospray chamber. In addition, ultraviolet (UV) and fluores...

prostate-specific antigen (psa) was purified to homogeneity from human seminal plasma by ion-exchange chromatography on a cm-sephadex c-50 and by gel filtration on a sephacryl s-200 column. a single 33-kda protein band appeared in sds-page. high pressure liquid chromatography (hplc) of the purified protein produced a single peak, while isoelectric focusing demonstrated the presence of five diff...

An accurate and simple analysis method by high-performance liquid chromatography-mass spectrometry for the riboflavin crude product of semisynthesis is established in this study. In this method, a C(18) column is used, and the mobile phase is methanol-water. Under the optimal analysis conditions established in this study, all components in the riboflavin crude product are well separated and ide...

The quantitative parameters and method performance for a normal-phase HPLC separation of flavanols and procyanidins in chocolate and cocoa-containing food products were optimized and assessed. Single laboratory method performance was examined over three months using three separate secondary standards. RSD(r) ranged from 1.9%, 4.5% to 9.0% for cocoa powder, liquor and chocolate samples containin...

kinetic parameters of the ammonolysis reaction of dichloroethane in nonaqueous media are studied and the optimum reaction conditions are reported. a suitable reactor for running the reaction under high pressure in the range of 50 to 500 °c is designed. kinetic behaviours of the system is studied and other reaction parameters such as rate constant, kinetic order, and activation energy are determ...