Effects of a Constant Magnetic Field on the Electrochemical Reactions of Quercetin

Article abstract of DOI:10.1002/open.202000066

The paper presents a study of the effect of a constant magnetic field (CMF) on the basic processes of quercetin electrochemical reactions. According to the observation made in previous studies, the presence of a double bond in the C-ring of quercetin enhances the antioxidant properties of that compound, whereas the presence of ?OH groups also affects the antioxidant properties. Using cyclic voltammetry it was found that the constant magnetic field improves the efficiency of quercetin electrooxidation, especially of the third stage of the process, i. e. the stage in which the oxidation of the OH groups in the A-ring is the most difficult. The use of HPLC confirmed the electrochemical measurements and the results of cyclic voltammetry studies. The beneficial effect of the magnetic field on the efficiency of quercetin oxidation was confirmed by the results of impedance spectroscopy measurements.

Full text of DOI:10.1002/open.202000066

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Effects of a Constant Magnetic Field on the Electrochemical
Reactions of Quercetin
Marek Zieliński, Barbara Burnat, and Ewa Miękoś*[a]
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The paper presents a study of the effect of a constant magnetic
field (CMF) on the basic processes of quercetin electrochemical
reactions. According to the observation made in previous
studies, the presence of a double bond in the C-ring of
quercetin enhances the antioxidant properties of that com-
pound, whereas the presence of À OH groups also affects the
antioxidant properties. Using cyclic voltammetry it was found
that the constant magnetic field improves the efficiency of
quercetin electrooxidation, especially of the third stage of the
process, i.e. the stage in which the oxidation of the OH groups
in the A-ring is the most difficult. The use of HPLC confirmed
the electrochemical measurements and the results of cyclic
voltammetry studies. The beneficial effect of the magnetic field
on the efficiency of quercetin oxidation was confirmed by the
results of impedance spectroscopy measurements.
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1. Introduction
Quercetin belongs to a group of flavonoids that are present in
fruit, vegetables and wine. The presence of a double bond in
the C-ring enhances the antioxidant properties of quercetin.
The presence of À OH groups at positions 3,5,7,3’,4’ not only
affects the antioxidant properties, but also increases the
chelation capacity of divalent metal cations, which catalyze the
oxidation processes, thus affecting significantly the inhibition of
oxidation processes, which are not always beneficial to the
cells.[1–3] Quercetin demonstrates potent anti-inflammatory
properties, prevents cardiovascular diseases and inhibits the
proliferation of tumor cells.
The quercetin electrooxidation process, for example on the
surface of the glassy carbon electrode, occurred in three stages.
The oxidation of catechol OH groups in the B-ring is the easiest
(Figure 1)(within the lowest range of potentials – the highest
antioxidant activity). Then, the OH group in the C-ring is
oxidized. The oxidation process of the OH groups in the A-ring
occurs at the highest potentials.
Figure 1. The chemical structure of quercetin (quercetin: 3,3’,4’,5,7 –
pentahydroxyflavone).
potentials, and is a semi reversible reaction, involving two
protons and two electrons. Then, the oxidized hydroxyl group
undergoes irreversible oxidation and can create intermolecular
hydrogen bonds with an adjacent oxygen. The other two
hydroxyl groups demonstrate a tendency to donate electrons
and their oxidation is reversible.
A. K. Timbola et al. studied the electrochemical water-
alcohol solutions of quercetin within the pH range of 2.2 to
9.2.[5] The study was carried out by means of cyclic voltammetry
and UV-Vis spectroscopy. The cyclic voltammograms obtained
for quercetin showed three oxidation peaks and one reduction
peak depending on the conditions of the experiment. The first
oxidation peak (at 0.15 V vs SCE at neutral pH) corresponds to
the oxidation of catechol (ring B: 3’,4’-dihydroxyphenyl) to the
corresponding orthoquinone (and its proton tautomers). The
reduction peak corresponds to its reduction back to the
catechol (EoxÀ Ered =75 mV, reversible catechol/orthoquinone
redox couple). Orthoquinone, a highly electrophilic molecule,
was shown to be kinetically unstable, reacting rapidly with the
nucleophiles of the medium (water and ethanol) as evidenced
by the dependence of the cyclic voltammogram on the applied
scanning speed. The two other oxidation peaks correspond to
the oxidation of products formed by the reaction of the
orthoquinone (and of its proton tautomers) with water and
ethanol as shown by controlled-potential electrolysis and UV
spectroscopy.[5] I.E. Mulazimoglu and E. Ozkan investigated the
A. M. O. Brett et al. studied the mechanism of electro-
chemical oxidation of quercetin on vitreous carbon electrode
using cyclic, differential and square wave voltammetry methods
at different pH values.[4] As it follows from their study, quercetin
strongly adsorbs on the electrode surface, and its surface is
blocked by the final product of oxidation. The oxidation of
catalytic 3, 4 – catechol group occurs first, at very low positive
[a] Prof. M. Zieliński, Dr. B. Burnat, Dr. E. Miękoś
Department of Inorganic and Analytical Chemistry
Faculty of Chemistry
University of Lodz
Tamka 12
91-403 Lodz (Poland)
E-mail: ewa.miekos@chemia.uni.lodz.pl
© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This
is an open access article under the terms of the Creative Commons Attri-
bution Non-Commercial NoDerivs License, which permits use and distribu-
tion in any medium, provided the original work is properly cited, the use is
non-commercial and no modifications or adaptations are made.
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electrochemical performance of quercetin on a vitreous carbon
electrode modified with procaine and aminophenyl.[6] They
observed that at the first stage quercetin is oxidized electro-
chemically, whereas at the second stage it forms is strong
electrochemical bonded with the electrode surface. M. Medvi-
dović-Kosanović et al. investigated the electrochemical proper-
ties of three structurally different flavonoids: catechin, quercetin
and rutin on a glassy carbon electrode surface at different pH
electrode using chronoamperometry under strong magnetic
field (1,74 T). They concluded a drastic influence of the electro-
lyte dielectric constant on the limiting current.[18]
Constant magnetic field may affect the efficiency and time
of organic syntheses as well as the physicochemical parameters
of materials.[19–20]
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values.[7] It was found that in all the tested compounds 2. Results and Discussion
oxidation of the 3, 4-dihydroxyl groups occurs in the B-ring (the
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first oxidation peak). The process is reversible, pH-dependent
and includes transfer of 2 electrons and 2 protons. Electro-
chemical oxidation products of all the tested flavonoids strongly
adsorbed on the surface of the electrode. H. R Zare et al.
oxidized quercetin electrochemically in 0.1 M phosphate buffer
using the cyclic voltammetry method.[8] They determined
experimentally that the formal potential of quercetin relative to
the saturated calomel electrode (SCE) amounts to 558 mV. The
theoretical formal potential for quercetin in relation to SCE is
568 mV, which shows a high consistency of the experiment
with the theory. D. Zielińska and B. Pierożyński oxidized
quercetin electrochemically using the cyclic voltammetry
method on a vitreous carbon electrode, where the basic
electrolyte was 0.1 M acetate buffer in 90% methanol.[9]
Impedance spectroscopy was also applied in the research. The
study confirmed the cascade mechanism of quercetin oxidation,
in which the initial stage was the oxidation of the hydroxyl
groups of catechol, the intermediate product of the reaction,
strongly adsorbed on the electrode. The paper presented also
an original method of regeneration of vitreous carbon electro-
des blocked by quercetin oxidation products. D. Zielińska et al.
studied also the process of adsorption and electrooxidation of
two quercetin glucosides: quercetin 3-O-b-glucoside (Q 3-glc)
and quercetin 40-O-b-glucoside (Q 40-glc).[10] The methods
applied in the research included cyclic voltammetry, impedance
and UV-VIS spectroscopy, as well as HPLC-MS chromatography.
The experiments were carried out in 0.1 M sodium acetate
buffer and acetic acid in 90% methanol solution of methanol
on a glassy carbon electrode surface. The results of the research
provided new information on the mechanism of electrooxida-
tion of two structurally different glucosides (quercetin deriva-
tives). It was established that there is a close and important
correlation between the structure of the flavonoid molecules
and its antioxidant properties.
Effects of constant magnetic field on chemical processes are
a branch of science that is still developing. In the recent
years, there have been many studies and numerous theories
concerning magnetoelectrochemistry. Analysis of the published
studies investigating the influence of constant magnetic field
on chemical reactions allowed to find several types of magnetic
field effects.[13,14,19,20] Firstly, electrodeposition, electropolymeri-
zation, and some organic reactions occur faster under constant
magnetic field. The surface of metal and alloy coatings obtained
in the presence of magnetic field is smoother, and their grains
are finer. Uniform magnetic field, applied during electrodeposi-
tion, improves corrosion resistance of some coatings. The
effects of constant magnetic field have not been fully inves-
tigated yet. There is no uniform model for controlling constant
magnetic field in electrodeposition. Nevertheless, the studies
described in this paper demonstrate that constant magnetic
field can be widely used in electrochemistry and electro-
deposition industries. This is the reason why it is useful to study
those phenomena and work on further development of
magnetoelectrochemistry. The quercetin oxidation process
occurred in three stages, as evidenced by the three anodic
oxidation peaks recorded on the CV curves. The oxidation of
the catechol OH groups in the B-ring was the easiest (Figure 1)
(within the lowest range of potentials where the antioxidant
activity is the highest). Then, the OH group in the C-ring was
oxidized. The oxidation process of the OH groups in the A-ring
took place at the highest potentials. As it can be seen on the CV
curve (Figure 2), constant magnetic field increased the effi-
ciency especially of the third stage of the quercetin electro-
As previously reported, the constant magnetic field can
affect electrochemical processes.[11–17] The studies indicated that
such changes are caused by the magnetohydrodynamic effect
(MHD). The MHD effect is based on the impact of the Lorentz
force, which induces the movement of the electrolyte and
increases, or decreases, the transport of electroactive particles
to the electrode. Magnetic fields acting on both the electrons
and ionized atoms produce dynamic effects, one of which is
volume movement of the liquid. The movement of the masses
causes in turn modification of the fields. So we have to deal
with the complex coupled system of the matter and fields.
O. Vittori et al. studied the oxidation reactions of hexacya-
noferrate(II) and hydroquinone in KCl media on a platinum disc
Figure 2. The CV curve for 0.01 M quercetin solution under exposure to a
constant magnetic field of magnetic induction B=0 and B=0.6 T, with
potential scan-rate of 0.1 V/s. Basic electrolyte: 0.1 M NaClO4 in an ethanol:
water (1:1)solution.
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oxidation process, i.e. the stage at which oxidation of the OH
groups in the A-ring was the most difficult.
to the third stage of the quercetin electrooxidation process
(peak 3 in Figure 4) both without and with the presence of
CMF. In both cases, a single and distorted semicircle is observed
in the Nyquist impedance plots within the whole frequency
range (see Figure 4a). The obtained characteristics were fitted
by the electrical equivalent circuit presented in Figure 4b. The
circuit exhibits a parallel combination of faradaic charge-trans-
fer resistance Rct and double layer capacitance (represented
here as constant phase element CPE for distributed capaci-
tance) joined in series with uncompensated solution resistance
Rs. The mean values of each element together with the standard
deviation are summarized in Table 1.
Based on the obtained results it can be stated that CMF
changes the diameter of the semicircle in the Nyquist plot, that
represents the charge transfer resistance, thus CMF affects the
kinetics of quercetin electrooxidation as well. In the presence of
CMF, the charge transfer resistance parameter (Rct in Table 1)
reaches a value twice lower as compared to that obtained
without CMF. Such results indicate the positive effect of CMF on
quercetin electrooxidation. Thereby, EIS results confirm the
observation made on the basis of the voltammetric results
described above.
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The value of the current density is 0.545 mA/cm2 (B=0 T)
and 1.227 mA/cm2 (B=0.6 T). Under the influence of a constant
magnetic field, the current density value of the first peak of
quercetin C-ring oxidation (at the lowest potentials) increases
slightly while the potential of the peak is shifted towards the
negative values. This is due to the catalytic effect of a constant
magnetic field. The potentials of the second and third oxidation
peaks of C and A rings, in the constant magnetic field, are
shifted towards positive values. At the same time, the anode
current density of the third oxidation peak increases (ring A).
The reason for these changes may be the fact that due to the
catalytic effect of a constant magnetic field, the increasing
amount of oxidized quercetin molecules may cause increased
adsorption on the surface of the gold electrode (a change of its
surface), and thus also increase the overpotential of process
activation. Under the influence of the magnetic field, unstable
intermediates of the compound may also be formed, which are
a probable reason for shifting the potential of the second and
third quercetin oxidation peaks towards positive values. The
simple dependence of anode peak currents on the square root
of the potential rise rate was linear and passed through the
origin of the coordinate system. The above evidences that the
oxidation processes of antioxidants are the processes controlled
by diffusion. For various values of magnetic induction B=0.2 T;
0.4 T; 0.6 T; 0.8 T; the dependence of the peak anode current
density (Ja) on magnetic induction B for the third stage of the
quercetin electrooxidation process was obtained (Figure 3).
Up to the value of B=0.6 T, constant magnetic field caused
an increase in the efficiency of quercetin oxidation, which then
began to decrease as a result of the magnetohydrodynamic
forces, or too large values of the Lorentz force. The highest
value of the oxidation peak currents was obtained at the
magnetic induction value B=0.6 T for the third stage of
quercetin oxidation process.
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The electrolysis of quercetin with controlled potential was
carried out. The process was carried out in 200 seconds without
the use of a constant magnetic field and in the magnetic field
with induction values of 0.2 T, 0.4 T, 0.6 T, 0.8 T and 1 Tesla at
the potentials of the third peak of the quercetin ring A
The beneficial effect of the magnetic field on the efficiency
of quercetin oxidation was confirmed by the results of
impedance spectroscopy measurements. The impedance char-
acteristics were recorded at the potential value corresponding
Figure 4. a) Impedance characteristics presented as Nyquist and Bode plots
for the third stage of the quercetin electrooxidation (at peak NR) on the gold
electrode without and with the presence of CMF (the dots correspond to
experimental data, the solid lines correspond to representation of the data
according to the equivalent circuit); b) equivalent circuit for the quercetin
electrooxidation at peak NR.
Table 1. Resistance and capacitance parameters for the third stage of the
quercetin electrooxidation process (at peak NR) on gold electrode without
and with the presence of CMF, obtained from the fitting procedure.
Rs/Ωcm2
×106 CPEdl/
FcmÀ 2 snÀ 1
n
Rct/Ωcm2
Figure 3. The dependence of the peak anode current density Ja (surface
area) on magnetic induction B for the third stage of the quercetin
electrooxidation process in the CV method.
without
CMF
with CMF
35.0�1.2 154.6�8.1
38.6�1.5 146.2�7.7
0.850�0.022 740.5�9.9
0.876�0.029 369.0�8.3
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oxidation, for the individual fields. HPLC spectra were prepared
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for the solutions. The use of HPLC confirmed the results of tests
performed using the CV method. The HPLC spectra obtained for
the solutions after electrooxidation of quercetin at different
magnetic induction values are shown in Figure 5.
On the basis of the obtained chromatograms, the areas
under the peaks demonstrating the concentration of quercetin
remaining after the reaction were calculated. The minimum
value of the area under the peaks was observed at B=0.6 T,
and therefore the yield of the reaction was the best at that
magnetic induction value. This is confirmed by the result
obtained by CV. It can be observed on the graph, presenting
the dependence of the area of the peaks in the chromatogram
on the value of magnetic induction, at which the electro-
oxidation process was conducted (Figure 6).
At the beginning of the paper, the antioxidant properties of
quercetin were referred to. The antioxidant capacity of
quercetin was investigated by means of spectrophotometry
using the DPPH (1.1-diphenyl-2-picrylhydrazyl) free radical (Fig-
ure 7).
It was also checked how constant magnetic field affects the
enhancement of these properties. The spectrophotometric
measurements were conducted at a wavelength of λ=517 nm.
In the reaction with quercetin, the radical created the reduced
form. The decrease in absorbance was proportional to the
amount of the oxidized form which remained in the solution.
The method used in the research is commonly used and known
as a percentage reduction of DPPH.[21–22] It is sometimes referred
to as “inhibition” or “quenching”, and defined by the following
equation (1):
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Figure 5. The HPLC spectra for solutions after quercetin electrooxidation for
magnetic induction values from 0 to 1 T.
Figure 6. The dependence of the peaks (surface area) on magnetic induction
B for the concentrations of non-oxidized quercetin, obtained by HPLC.
Q ¼ ½ðA0À AÞ=A0��100 %
(1)
where: A0 – absorbance of the DPPH radical solution, A – mean
value of absorbance of the tested antioxidant-containing
solution.
The Q value denotes the ability of the tested antioxidant to
counteract oxidation reactions. For the reactions taking place
without exposure to constant magnetic field, this ability to
counteract oxidation amounted to 90.2%, while under exposure
to constant magnetic field it reached 97.8%. Constant magnetic
field caused a 7.8% increase in the ability of the tested
antioxidant to counteract oxidation.
The physical essence of the effect of a constant magnetic
field on various research objects is exerting mechanical forces
on the moving charged particles (electrons or ions) that are a
specific form of convection current or conduction. In an
electrolyte solution, constant magnetic field affects both
electrons and ionized atoms inducing the dynamic effects. One
of them is volume movement of the liquid. The movement of
the masses causes in turn modification of the fields. Thus, we
deal with the complex coupled system of the matter and fields.
The most important impact of the CMF on the electrochemical
processes is the magnetohydrodynamic effect (MHD). The
driving force behind this effect is the generated Lorentz force F
(2):
Figure 7. The reduced form of DPPH (1.1-diphenyl-2-picrylhydrazyl) radical:
A) a free radical (an unpaired electron on the valence shell of a nitrogen
atom), B) the reduced form.
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F ¼ j � B
(2)
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where: j – limiting current density [A·mÀ 2], B – magnetic
induction [T].
For configuration BkPE i.e. B⊥j (where: PE – area of the
electrode [m2], j – limiting current density [A·mÀ 2]) this is a
macroscopic effect. It induces additional convection, causing an
increase in mass transport towards the surface of the electrode.
This causes the occurrence of laminar electrolyte flow towards
the surface of the working electrode, which reduces the
thickness of the diffusion layer and causes an increase in the
gradient of potential-forming ions concentration. Generally
speaking, the solution mass flow from and to the electrode may
occur by migration, diffusion and convection. Diffusion is an
important phenomenon occurring always in the process of
electrolysis. The ion mass transfer can be extended with
convection and the phenomenon can be defined as the
convection diffusion. Between the surface of the electrode and
the electrolyte mass there is a layer of the solution of δD
thickness (the Nernst diffusion layer), through which mass
transfer occurs only as a result of diffusion and migration. The
thickness of the δD layer depends on the hydrodynamic
conditions and the viscosity of the solution. If there is no
stirring, the build-up of the diffusion layer takes place over time
under potentiostatic conditions. As a result of CMF, the
resulting force F caused movement of the electrolyte. The
Nernst diffusion layer (δD) was reduced, whereas the new
Navier-Stokes hydrodynamic layer (δH) appeared. It has also
been calculated that the electroactive particle velocity (v)
increases with the rise of magnetic induction (B).[12] The increase
in magnetic induction (B) correlates also with increased thick-
ness of the Navier-Stokes hydrodynamic layer (δH), which
determined the changes in the electrolyte flow under exposure
to CMF.
For comparison, the paper presents a study of the effect of
constant magnetic field (CMF) on the basic processes of
CoÀ Mo, CoÀ W, CoÀ MoÀ W alloys and Co electrodeposition.[13]
On the basis of the coulometry (C) measurements, the relation-
ship between the charge (Q) flowing in the electrolyte and
magnetic induction (B) were determined for Co, specific CoÀ Mo,
CoÀ W and CoÀ MoÀ W alloys. Figure 8 indicates that the more
complicated the structure of the metallic coating, i.e. Co,
CoÀ Mo, CoÀ W, CoÀ MoÀ W, the higher the value of magnetic
induction (B) required to achieve maximum effect of the CMF
on the charge (Q).
At present it seems that all the various effects of magnetic
fields in electrochemistry are somehow related to mass trans-
port. In the process of CoÀ Mo, CoÀ W, CoÀ MoÀ W alloys and Co
electrodeposition, the Lorentz force was generated as a result
of the exposure to CMF. This force induced MHD effects in the
solution, thus causing electrolyte movements, with the resultant
depletion of the Nernst diffusion layer and appearance of a new
Navier-Stokes hydrodynamic layer, which determined the
velocity of electroactive molecules flow to the working
electrode.
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Figure 8. The relationship between the charge (Q) and magnetic induction
(B) during the electrodeposition reaction of Co and CoÀ Mo, CoÀ W and
CoÀ MoÀ W alloys.[13]
We also investigated the effects of magnetic field on the
Kabachnik-Fields reaction.[19] The reaction, which is shown in
Figure 9, was carried out in the refluxing acetonitrile in the
absence and in the presence of 1-T magnetic field, and the
reactions were monitored by 31P NMR spectra. There were two
types of magnetic field effects on Kabachnik-Fields reaction:
improved yields of all the isolated aminophosphonates (3Aa–
3Bf) and increased conversion rates as shown in Figure 10. The
reason for the accelerating effect of magnetic field may be due
to the orientation of substrate molecules. Magnetic field forced
Figure 9. Scheme of Kabachnik-Fields reaction.[19]
Figure 10. Conversion rates of Kabachnik-Fields reaction without (white) and
with (black) 1-T magnetic field A. 2A+1d, B. 2B+1c, C. 2A+1a, and D. 2B
+1e reactions.[19]
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the direction of molecules and reduced the distance between
them.
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3. Conclusions
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The aim of the study was to examine the effect of constant
magnetic field (CMF) on the course of electrochemical reactions
of quercetin, a compound belonging to the flavonoid group.
Quercetin belongs to a group of flavonoids, which are present
in fruit, vegetables and wine. The magnetic induction B with
values from zero to 0.8 Tesla, applied in the studies, was
directed in parallel to the surface of the working electrode, i.e.
perpendicular to the direction of the current flow j. The
quercetin oxidation process occurred in three stages, as
evidenced by the three anodic oxidation peaks recorded on the
CV curves. Increasing the efficiency of the third stage of
quercetin oxidation process enables to conclude that the whole
process can be considered to be catalyzed by the constant
magnetic field. The HPLC method confirmed the results of tests
performed using the CV method. The antioxidant capacity of
quercetin was investigated by means of spectrophotometry
using the DPPH (1.1-diphenyl-2-picrylhydrazyl) free radical. It
was also checked how constant magnetic field affects the
enhancement of these properties. For the reactions taking place
without exposure to constant magnetic field, this ability to
counteract oxidation amounted to 90.2%, while under exposure
to constant magnetic field it reached 97.8%. Constant magnetic
field caused a 7.8% increase in the ability of the tested
antioxidant to counteract oxidation. As observed previously the
constant magnetic field can affect electrochemical processes.
The studies indicated that such changes are caused by the
magnetohydrodynamic effect (MHD). The MHD effect is based
on the impact of the Lorentz force, which induces the move-
ment of the electrolyte and increases or decreases the transport
of electroactive particles to the electrode. The Nernst diffusion
layer (δD) was reduced, whereas the new Navier-Stokes hydro-
dynamic layer (δH) appeared.
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Figure 11. The electrochemical vessel with three-electrode measurement
system, placed between the N and S pole pieces of a laboratory electro-
magnet, with the magnetic induction B perpendicular to the current density
j. F denotes the Lorentz force.
down to 4000 grade), chemically (using a chromic acid cleaning
mixture) and electrochemically (polarization in a stock solution of
0.1 M NaClO4, within the potential range of À 1 V to +2 V, with a
sweep rate of 100 mVsÀ 1).
The magnetic induction B with values from zero to 0.8 Tesla,
applied in the studies, was directed in parallel to the surface of the
working electrode, i.e. perpendicular to the direction of the current
flow j. Under these conditions, the Lorentz force, arising as a result
of the CMF effect, had the maximum value. The test solution of
quercetin (C15H10O7 ·xH2O, Mm =302.24 g/mol, Sigma-Aldrich) (quer-
cetin: 3,3’,4’,5,7-pentahydroxyflavone) used in the research had the
concentration of 0.01 M. The primary electrolyte was sodium
chlorate (VII) (NaClO4, Mm =140,46 g/mol, POCH) at a concentration
of 0.1 M in ethanol: water (1:1) solution. Electrochemical impe-
dance spectroscopic (EIS) measurements were performed using a
PGSTAT 128 potentiostat / galvanostat with FRA2 module (EcoChe-
mie Autolab) operated with FRA software (v. 4.9). Electrochemical
impedance characteristics were registered at peak NR potential by
applying a sinusoidal signal of �5 mV within the frequency range
from 0.06 Hz to 10 kHz. The EIS measurements were carried out
without and with the presence of CMF in triplicate. Chromato-
graphic (HPLC) studies were also conducted. The mobile phase was
a mixture of acetonitrile and sodium dihydrogen phosphate (V)
(45:55 v/v). The flow rate was 1.2 ml/min, the wavelength 202 nm.
Chromatographic separation was conducted using an Alltima C18,
250 mm×4.6 mm column, Grace. Spectrophotometric studies were
carried out with the use of a VIS Metertech SP-830Plus spectropho-
tometer.
Experimental Section
The aim of the study was to examine the effect of constant
magnetic field (CMF) on the course of electrochemical reactions of
quercetin, a compound belonging to the flavonoid group. The
voltammetric curves were obtained by means of the CV method. A
sample CV curve obtained during electrooxidation of quercetin
without exposure to constant magnetic field (B=0) and under
exposure to a constant magnetic field of magnetic induction B=
0.6 T has been presented.
Acknowledgements
This work was supported by the Lodz University.
Cyclic voltammetry (CV) was the method applied in the studies of
electrochemical reactions of quercetin. An Atlas 0531 Electro-
chemical Unit potentiostat was used in this method. Another
element synchronized with the potentiostat was a three-electrode
electrochemical cell made according to our own design containing
(Figure 11): the working electrode (a gold disc) with an area of
0.1 cm2, the auxiliary electrode (platinum, reticular) and the
reference electrode (saturated, calomel). The working electrode was
successively prepared mechanically (with the use of sandpapers,
Conflict of Interest
The authors declare no conflict of interest.
Keywords: quercetin · constant magnetic field · Lorentz force
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Manuscript received: March 7, 2020
Revised manuscript received: May 21, 2020
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The effect of a constant magnetic
field on the processes of quercetin
electrochemical reactions has been
investigated. Using cyclic voltamme-
try and impedance spectroscopy, it
was found that a constant magnetic
field improves the reaction efficiency
at the stage in which the oxidation
of the OH groups in the A-ring is the
most difficult. For comparison, a
study of the effect of magnetic fields
on the basic processes of alloys elec-
trodeposition and on the Kabachnik-
Fields reaction is reported.
Prof. M. Zieliński, Dr. B. Burnat, Dr. E.
Miękoś*
1 – 8
Effects of a Constant Magnetic Field
on the Electrochemical Reactions of
Quercetin
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