a simple, sensitive and rapid method for determination of trace amounts of nitrite ion in real samples is reported. the reaction is initiated by adding known volumes of a nitrite ion solution of identified concentration to acidic solutions of thionine which causes decolorizaiton of reagent with time. the absorbance changes is then monitored spectrophotometrically at lmax = 602nm at 25 °c. calib...

a new, simple, rapid, and cheap method for determination of trace amounts of nitrite ion is reported.determination is based on reduction of bromate ion by nitrite ion, in the presence of murexide inacidic media. during reaction of bromate ion with nitrite ion, the reaction mixture is decolorized.the absorbance changes is then monitored spectrophotometricaly at 520 nm, at 25 °c. dynamicrange of ...

The kinetic (KIE) and solvent (SIE) isotope effect methods were used to investigate the mechanism of enzymatic hydroxylation of halogenated derivatives of l-tyrosine to l-DOPA catalyzed by the enzyme tyrosinase (EC 1.14.18.1). The values of deuterium KIE and SIE were obtained using the non-competitive method with spectrophotometric measurements. The Lineweaver-Burk plots were used for determina...

A new, simple, rapid, sensitive and selective spectrophotometric kinetic method for Ag(I) traces determination at room temperature was elaborated in this paper. It is based on catalytic effect of silver ions upon the oxidation of methylene blue B (MBB) by K2S2O8 (PPS) in citric buffer (BUF) solution. The method was confirmed by determination of Ag(I) in PbO. The obtained results were compared t...

Coenzyme A (CoA or CoASH) is one of the most important biologically active compounds, and for this reason a reliable, fast and simple determination of CoASH is needed. Here we are described a simple and fast way of determinating CoASH using potentiometric flow-injection analysis and spectrophotometric kinetic determination. The described methods are suitable for use over a wide concentration ra...

The present work reports a kinetic spectrophotometric method for the determination of traceamounts of sulphite that is based on inhibitory effect of sulphite on the oxidation of Methyleneblue (MB) in acidic media. The reaction is followed spectrophotometrically by monitoring thedecrease in absorbance of MB at 664 nm with a fixed time of 0.5-4.5 minutes. It was found thatsulphite exert a strong ...