Nonlinear Multicomponent Kinetic Analysis for the Simultaneous Stopped-Flow Determination of Chemiluminescence Enhancers

Abstract

Protocatechuic and caffeic acids were determined from kinetic data of luminol chemiluminescence induced by hexacyanoferrate(III) enhanced by phenolic acids. The phenolic acids could be quantified both separately and together using the stopped-flow technique and monitoring intensity at 0.3 s and the initial rate. Synergy was observed when two or more enhancers acted simultaneously. The interaction between components was analyzed by surface response methodology and modeled by least-squares matrix methodology that used as the independent variable a measurement parameter (chemi-

Use of an Artificial Miniaturized Enzyme in Hydrogen Peroxide Detection by Chemiluminescence

“…The observed LS vertically increased with the increase in luminol initial concentration and reached its maximum at 0.1 mM (Figure 4b). The observed trend has been previously documented, and it is expected when considering that at very high amounts of catalyst, hydrogen peroxide is rapidly and entirely consumed to produce the luminol radical, and no H 2 O 2 is then available to react with the diazaquinone (formed upon radical dismutation) to give the 3-AP (Scheme 1) [41][42][43][44][45].…”

“…When 3 mM hydrogen peroxide was added to a solution containing 0.5 mM of luminol and 2 nM of FeMC6*a, a very intense LS at 425 nm was developed that lasted more than 10 min, corresponding to the relaxation time of the 3-AP [35] (Figure 2). A very brilliant LS peak approached its maximum after approximately 1 min and then rapidly quenched, following a kinetic trace that has been previously observed in the literature when a very high concentration of peroxidase was adopted [19,37,44], or when luminol was in high excess with respect to hydrogen peroxide [41][42][43][44][45]. Instead, in the presence of HRP as a catalyst, only a modest LS was observed in the first 600 s, under these conditions, as previously reported for this catalytic system in the absence of enhancers [46].…”

“…Both batch and flow assays have been developed, even though only a limited response, in terms of linearity range and limit of detection (LOD), could be achieved [9,[21][22][23][24][25]. A substantial upgrade of the sensing capacity was accomplished both by enzyme immobilization onto different matrices and by LS enhancers [9,[22][23][24][25]45,46]. LS could be modulated by the presence of different organic molecules (generally aromatic), detergents, and metal ions, both in the enhancement and in the suppression of the emitted light, allowing the determination of several analytes [23][24][25].…”

“…Sensors 2020, 20, x FOR PEER REVIEW 6 of 14 the luminol radical, and no H2O2 is then available to react with the diazaquinone (formed upon radical dismutation) to give the 3-AP (Scheme I) [41][42][43][44][45]. Based on the FeMC6*a concentration dependence of LS (see Figure 3b), we selected 0.3 μM as the FeMC6*a concentration to be used for the optimization of other experimental conditions.…”

Multiway analysis applied to time‐resolved chemiluminescence for simultaneous determination of paracetamol and codeine in pharmaceuticals

“…Chemometric methods such as partial least squares (PLS) , artificial neural network (ANN) and support vector regression have also been used in CL methods for the simultaneous determination of analytes in a mixture.…”