Processing analytical data obtained from second-order reactions by using continuous reagent addition

Abstract

This paper reports a new approach to second-order kinetic analyses based on the continuous addition of the reagent to the analyte solution at a constant rate. A mathematical model was developed to study the kinetics of the process. Methods for the determination of the analyte and the second-order rate constant were developed and tested experimentally. The Fe( 11 )/SCN~system In the presence of hydrogen peroxide as analyte was used as the model reaction. The methods for the determination of hydrogen peroxide thus developed are compared by using a least-squares fit procedure; those used to obtain the second-order rate constant perform quite well with relative standard deviations between 2-5%.

Computational Neural Networks for Resolving Nonlinear Multicomponent Systems Based on Chemiluminescence Methods

“…When a CL reaction was developed using the CAR technique, such as the chemical system used in this work, the shape of the resulting CL signal vs time plot corresponds to a differential equation (combination of both integrated equations above) which is very difficult to obtain. As can be seen in Figure , the CL signal vs time plots show the characteristic initial concave portion that corresponds to a reaction developed using the CAR technique . The ignorance of the differential equation that describes this process makes more difficult the resolution of mixtures of species using this chemical system.…”

“…The proposed methodology was validated by the simultaneous determination of trimeprazine and methotrimeprazine (two phenothiazine derivatives with very similar kinetic behavior) in mixtures using the classical peroxyoxalate system based on the reaction between bis(2,4,6-trichlorophenyl)oxalate (TCPO) and hydrogen peroxide . The reaction was implemented by using the continuous-addition-of-reagent technique, which increased the nonlinearity of the chemical system studied on account of its second-order kinetic nature …”

“…23 The reaction was implemented by using the continuous-additionof-reagent technique, which increased the nonlinearity of the chemical system studied on account of its second-order kinetic nature. 24 Many data modeling problems pose two difficulties, namely (a) the absence of a complete a priori model for the data generation process and (b) a limited amount of available data. This was the case with the problem addressed in this work, where the underlying distribution of the signal was unknown.…”

An investigation of electroosmotic flow and pressure pumped luminol chemiluminescence detection for cobalt analysis in a miniaturised total analytical systemElectronic Supplementary Information available. See http://www.rsc.org/suppdata/lc/b1/b107061d/

“…The luminol reaction is rapid with the maximum peak height of the transient CL signal being reached in approximately 500 ms. 25 The complete CL emission profile versus time can be obtained in 2-3 s. If the CL system is designed to allow continuous addition of reagent, the reaction can be monitored for much longer than normal and this approach is used for kinetic studies of the reaction. 26,27 It requires the continuous addition of a reagent at a constant rate, as achieved by the electrokinetic pumping system. In the CL method the reaction was monitored for 12 min and the peak area achieved from this continuous, extended reaction was found to be a reproducible way of monitoring the electrically driven reaction.…”

Improved simultaneous reaction-rate determination of phosphate and silicate by use of the continuous addition of reagent technique

“…In this work, we circumvented the above-described shortcomings by using the continuous addition of reagent (CAR) technique, 17 which is inexpensive to implement. It has previously been used with good results in various fields, [18][19][20] including differential reaction rate methods, such as in the simultaneous kinetic determination of the fungicides zineb and maneb in agricultural formulations 21 and of copper and iron in serum samples.…”