Chemometrics study of the kinetics of the Griess reaction

Abstract

The kinetics of the Griess reaction in which 3‐nitroaniline acts as a nitrosation agent and 1‐naphtylamine as a coupling reagent was studied by chemometrics methods. The kinetic reaction was investigated under pH 1.0 and 25°C by UV‐vis spectrophotometry. The concentrations of nitrite, 3‐nitroaniline and 1‐naphtylamine were such that a second‐order kinetic reaction took place. Data explorations based on principal component analysis and multivariate curve resolution–alternating least squares were performed to obtain information about the reaction. Calculation of band boundaries of the multivariate curve resolution–alternating least squares solutions showed that the rotational ambiguities associated with the calculation of spectra and concentration profiles have been completely removed. The decrease in the ambiguity of the recovered solutions was closely related to the application of the equality constraint. The results of the exploratory data analysis showed that the kinetic reaction proceeds through a two‐step mechanism. Moreover, the two‐steps are second order. Data analysis approaches based on hard modeling and global hard modeling were used to resolve profiles of the reactants, intermediates and products and to evaluate the rate constants. Copyright © 2013 John Wiley & Sons, Ltd.

Ratiometric Fluorescent Hydrogel Test Kit for On-Spot Visual Detection of Nitrite

“…Interestingly, after adding N -(1-naphthyl)­ethylenediamine dihydrochloride to the reaction solution of m -CDs and NO 2 – , we observed that the mixed solution immediately changed from colorless to magenta, and the absorbance of the magenta dye was positive in proportion to the concentration of NO 2 – , as shown in the inset of Figure D. These data confirmed the diazonium reaction between m -CDs and NO 2 – under 0.1 M H 2 SO 4 and produced diazonium salt. − The diazonium salt was an electron-withdrawing group, and the electron cloud of the n-electron lone pair was not coplanar with the π-electron cloud on the benzene ring, and the transition from n to π* was a forbidden process. The probability of an intersystem crossing transition between S 1 and T 1 was large, inducing the fluorescence quenching of m -CDs.…”

Determination of Nitrate in Natural Waters by Vanadium Reduction and the Griess Assay: Reassessment and Optimization

“…Traditionally, the Griess reagents, SUL and NED, are added sequentially for nitrite analysis simply because the Griess reaction involves several different steps. , Sequential addition allows diazonium to form first before the addition of the NED reagent to elicit the pink color; the t 90% value for the PAD reaction is normally <20 s, and the maximum absorbance is obtained within 4 min at room temperature (Figure , right). However, while using premixed reagents, PAD formation becomes much slower, with a t 90% of >170 s, and the complete reaction may take as long as 20 min.…”