A selective, specific and stability-indicating gradient reverse phase high-performance liquid chromatographic (HPLC) method was developed for the determination of Ranitidine in presence of its impurities, forced degradation products and placebo substances such as saccharide and parabens. Ultraviolet detection was performed at 230 nm. Separate portions of the drug product and ingredients were ex...

inclined retaining walls with slopes less than perpendicular are appropriate candidates in several engineering problems. yet, to the knowledge of authors, only a few analytical solution for calculation of active earth pressure on such walls, which will be usually smaller than the same pressure on vertical ones, has been presented neither in research papers nor in design codes. considering limit...

A new positional isotope exchange method has been developed that can be used for the analysis of enzyme-catalyzed reactions which have ping-pong kinetic mechanisms. The technique can be used to measure the relative rates of ligand dissociation from enzyme-product complexes. Enzyme is incubated with the labeled substrate and an excess of the corresponding unlabeled product. The partitioning of t...

A new method for the determination of dissociation rates of enzyme-substrate complexes has been developed. The rate of exchange of a labeled product back into the substrate is measured during catalysis of the forward reaction when the forward reaction is kept far from equilibrium by the enzymatic removal of the nonexchanging product. The ratio of the exchange rate and the net rate for product f...

This paper presents a method for the determination of phenylephrine hydrochloride in pharmaceuticals by spectrophotometric flow injection analysis exploiting the reaction with potassium ferricyanide and 4-aminoantipyrine, which leads to the formation of a condensation product with strong absorptivity at 500 nm. The linear dynamic range was between 0.95 and 9 mg/L, with a limit of detection of 0...

A spectrophotometric method for the detection of tyrosinase activity is developed by utilizing the product-triggered aggregation of boronic acid-functionalized gold nanoparticles. Based on the changes of absorbance in UV-visible spectra, the assay shows extremely high sensitivity and lowered limit of detection of 1 × 10(-10) u mL(-1).