Co-reporter:Huan Wang, Yi Wu, Jun-Feng Song
Biosensors and Bioelectronics 2015 Volume 72() pp:225-229
Publication Date(Web):15 October 2015
DOI:10.1016/j.bios.2015.05.013
•The interface potential from the adsorption of human serum albumin (HSA) on multiwall carbon nanotube (MWNT) at the MWNT/solution interface was extracted as sensing parameter for the first time.•The zero current potential (the interface potential) was mentioned with zero current potentiometry.•The fundamental relationship between the zero current potential (the interface potential) and the HSA concentration was established.•For the determination of HSA, the zero current potential is proportional to the HSA concentration with the high slope.In this work, the adsorption of human serum albumin (HSA) on the bare multiwall carbon nanotube (MWNT) was investigated by a new electrochemical method, termed as zero current potentiometry. For this, a MWNT strip was prepared by directly adhering MWNTs on the transparent adhesive tape surface. Moreover, when HSA adsorbed onto MWNT at the MWNT/solution interface, an interface potential Ψ yielded. The interface potential Ψ as the zero current potential Ezcp simply related to it was monitored by zero current potentiometry. The relationship between the zero current potential Ezcp, the HSA concentration and others was established in simple stoichiometric relation. Based on this, both the adsorption of HSA on MWNT and the HSA determination can be studied. For the HSA determination, the theoretic conclusion consisted with experimental results. The zero current potential Ezcp was proportional to the HSA concentration in the range of 2.8×10−8–3.4×10−7 M with the limit of detection 2×10−8 M. The linear regression equation was Ezcp/V (vs, SCE)=(0.159±0.01)+(0.358±0.02)×106CHSA (µM). This determination was fast, high sensitive and good selective
Co-reporter:Jie-Juan Sun, Yi Wu, Jun-Feng Song
Electrochimica Acta 2014 Volume 115() pp:386-392
Publication Date(Web):1 January 2014
DOI:10.1016/j.electacta.2013.10.145
•The voltammetric behavior of ambroxol was studied in detail for the first time.•The possible oxidation mechanism of ambroxol was clearly demonstrated.•The mechanism explained the different scavenging effect of ambroxol on reactive oxygen species reasonably.•SDS played two roles in changing interface properties and stabilizing the free radical of ambroxol.•A more sensitive method was proposed for the voltammetric determination of ambroxol.The voltammetric behavior of ambroxol (AMB) at carbon paste electrode (CPE) in acidic aqueous solution was studied in this work. The possible oxidation mechanism was suggested that amine group of AMB underwent a two-electron and two-proton oxidation to produce an anilino-radical at the higher potential around 1 V (vs. SCE), showing an irreversible oxidation peak. Subsequently, the anilino-radicals dimerized via ‘head-to-tail’ coupling to yield a corresponding 4-amino-diphenylamine derivative in its oxidized form. This generated dimer was reduced and oxidized in the lower potential range of 0.1–0.39 V (vs. SCE), showing a pair of quasi-reversible redox peak. With the mechanism, the different scavenging effect of AMB on reactive oxygen species (ROS) was attributed to that different species of AMB take part in the reaction with ROS. In the case of electrochemical oxidation of AMB, anionic surfactant sodium dodecyl sulfate (SDS) was found to play a dual function in eliminating the electrostatic repulsion between the protonated AMB and the CPE with high positive potential and prolonging the lifetime of the anilino-radical of AMB oxidation. In 0.1 M HAc-NaAc buffer (pH 5.0) solution containing 3.0 × 10−4 M SDS, the oxidation peak of amine group of AMB appeared at 0.93 V (vs. SCE) and the peak current enhanced by 4.5 times in comparison to that in the absence of SDS. Based on this, a single-sweep voltammetric method was proposed for the determination of AMB. The second-order derivative peak current of AMB was rectilinear with its concentration in the range of 3.0 × 10−8–4.0 × 10−7 M. The limit of detection was 5.4 × 10−9 M. The sensitivity of the determination of AMB was improved, the oxidation potential of AMB was reduced and the experimental condition was moderated.The possible oxidation mechanism of ambroxol involves that amino group is irreversibly oxidized to produce an active anilino-radical at a higher potential. Then the free radicals dimerize via ‘head-to-tail’ coupling to yield a dimer 4-amino-diphenylamine derivative. This dimer is reduced and oxidized quasi-reversibly at a lower potential.
Co-reporter:Xiao-xia Guo, Zhang-jun Song, Jie-juan Sun, Jun-feng Song
Biosensors and Bioelectronics 2011 Volume 26(Issue 10) pp:4001-4005
Publication Date(Web):15 June 2011
DOI:10.1016/j.bios.2011.03.021
Since the electrochemical oxidation peaks of both DNA and anti-tumor drug tamoxifen (TAM) overlapped with each other, the known electrochemical methods were limited in the study of the interactions between DNA and TAM. In this paper, zero current potentiometry, a new electrochemical method, was used to study the interaction of calf thymus dsDNA with TAM. The dsDNA was immobilized on the surface of carbon paste (dsDNA/CP). The dsDNA/CP connected in series between the clips of working and counter electrodes of a potentiostat and a reference electrode were immersed in aqueous solution containing TAM, the interaction of dsDNA with TAM produced a change in interfacial potential at the dsDNA/CP/solution interface. When linear sweep potential was applied to the dsDNA/CP and the corresponding I–E curve was recorded, interfacial potential offset applied potential partially, making the I–E curve displace along potential axis. Zero current potential where circuit current I was equal to zero in the I–E curve was measured to check the displacement of the I–E curve. Based on the displacement, the thermodynamic constants of the interaction between dsDNA and TAM were determined. The binding ratio of dsDNA with TAM was found to be 1:1 and the apparent binding constant was (6.85 ± 0.20) × 106 M−1. As zero current potentiometry was independent of the changes in redox potential or current of both dsDNA and TAM themselves, the interaction was studied in their natural forms without damage. Moreover, TAM can be determined. The detection limit was 1.1 × 10−7 M.
Co-reporter:Yao-Dong Liang;Chun-Xia Yu
Luminescence 2011 Volume 26( Issue 3) pp:178-184
Publication Date(Web):
DOI:10.1002/bio.1202
Abstract
A strong electrochemiluminescence (ECL) of palmatine in NaOH medium was observed at a vaseline-impregnated graphite anode. The ECL production could be described as follows: hydroxyl radical (OH•) was generated via the oxidation of hydroxyl group (OH-) in NaOH medium, and the formed OH• subsequently oxidized palmatine base converted from palmatine in NaOH medium to the excited state oxypalmatine (oxypalmatine*). As the oxypalmatine* went back to its ground state, a stronger chemiluminescence was produced. Based on the ECL of palmatine, an ECL method for the determination of palmatine was proposed. An ECL signal of palmatine in NaOH solution was obtained by applying direct current of 15 mA to the vaseline-impregnated graphite anode. The ECL intensity was rectilinear with palmatine concentration in the range of 8.0 × 10−7 to 2.0 × 10−5 mol l−1 and the limit of detection (signal-to-noise = 3) was 3 × 10−7 mol l−1. The proposed method was applied to the determination of palmatine in pharmaceutical preparations. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Yao-Dong Liang;Chun-Xia Yu
Luminescence 2011 Volume 26( Issue 6) pp:662-669
Publication Date(Web):
DOI:10.1002/bio.1293
ABSTRACT
The cathodic electrochemiluminescence (ECL) of peroxydisulphate (S2O82−)–ciprofloxacin (CPF) system at a wax-impregnated graphite electrode was studied. When CPF was absent, S2O82− was electrochemically reduced to sulphate free radical (SO4•−), and dissolved oxygen absorbed on the electrode surface was reduced to protonated superoxide anion radical (HO2•). The HO2• was oxidized by SO4•− to produce molecular oxygen in both singlet and triplet states. Some of the singlet molecular oxygen (1O2) further combined through collision to be an energy-rich precursor singlet molecular oxygen pair (1O2)2. A weak ECL was produced when 1O2 or (1O2)2 was converted to ground-state molecular oxygen (3O2). When CPF was present, a stronger ECL was produced, which originated from two emitting species. The main emitting species was excited state CPF (CPF*), which was produced by accepting energy from (1O2)2. The other emitting species was excited singlet molecular oxygen pair [(1O2)2*], which originated from the chemical oxidation of CPF by SO4•− and dissolved oxygen. Based on the stronger ECL phenomenon, an ECL method for the determination of either S2O82− or CPF was proposed. The proposed ECL method has been applied to the determination of CPF in pharmaceutical preparations. Copyright © 2011 John Wiley & Sons, Ltd.
Co-reporter:Yi Gao, Fuqiang Nie, Junfeng Song
Journal of Electroanalytical Chemistry 2011 650(2) pp: 182-186
Publication Date(Web):
DOI:10.1016/j.jelechem.2010.10.010
Co-reporter:Li Zheng
Journal of Solid State Electrochemistry 2010 Volume 14( Issue 1) pp:
Publication Date(Web):2010 January
DOI:10.1007/s10008-008-0780-3
A modified electrode Ni(II)–Qu–MWCNT-PE has been fabricated by electrodepositing nickel(II)–quercetin [Ni(II)–Qu] complex on the surface of multi-wall carbon nanotube paste electrode (MWCNT-PE) in alkaline solution. Ni(II)–Qu–MWCNT-PE exhibits the characteristic of improved reversibility and enhanced current responses of the Ni(III)/Ni(II) couple compared with Ni(II)–MWCNT-PE and Ni(II)–Qu-carbon paste electrode. It also shows electrocatalytic activity toward the oxidation of methanol and other short chain aliphatic alcohols, such as ethanol, 1-propanol, and 1-butanol. The catalytic peak current and peak potential decrease in exponential form with the increase of carbon number of the chains. Kinetic parameters such as the electron transfer coefficient, α, rate constant, ks, of the electrode reaction, and the catalytic rate constant, kcat, for oxidation of methanol are determined. The stability and reproducibility of the Ni(II)–Qu–MWCNT-PE are good for practical applications.
Co-reporter:Li Zheng, Jiao-qiang Zhang, Jun-feng Song
Electrochimica Acta 2009 Volume 54(Issue 19) pp:4559-4565
Publication Date(Web):30 July 2009
DOI:10.1016/j.electacta.2009.03.047
A modified electrode Ni(II)–Qu–MWCNT–IL–PE has been fabricated by electrodepositing Ni(II)–quercetin [Ni(II)–Qu] complex on the surface of multi-wall carbon nanotube ionic liquid paste electrode (MWCNT–IL–PE) in alkaline solution. The Ni(II)–Qu–MWCNT–IL–PE exhibits the characteristic of improved reversibility and enhanced current responses of the Ni(III)/Ni(II) couple compared with Ni(II)–Qu–MWCNT–PE. It also shows good electrocatalytic activity toward the oxidation of glucose. Kinetic parameters such as the electron transfer coefficient α, rate constant ks of the electrode reaction and the catalytic rate constant kcat of the catalytic reaction are determined. Moreover, the catalytic current presents linear dependence on the concentration of glucose from 5.0 μM to 2.8 mM, with a detection limit of 1.0 μM by amperometry. The modified electrode for glucose determination is of the property of simple preparation, good stability, fast response and high sensitivity.
Co-reporter:Li Zheng, Jun-Feng Song
Analytical Biochemistry 2009 Volume 391(Issue 1) pp:56-63
Publication Date(Web):1 August 2009
DOI:10.1016/j.ab.2009.05.002
A modified electrode, nickel(II)–baicalein complex modified multiwall carbon nanotube paste electrode (Ni(II)–BA–MWCNT–PE), has been fabricated by electrodepositing Ni(II)–BA complex on the surface of MWCNT–PE in alkaline solution. The Ni(II)–BA–MWCNT–PE exhibits the characteristic of improved reversibility and enhanced current responses of the Ni(III)/Ni(II) couple compared with Ni(II)–BA–carbon paste electrode (CPE). It also shows better electrocatalytic activity toward the oxidation of glycine than Ni(II)–MWCNT–PE. Kinetic parameters such as the electron transfer coefficient α, rate constant ks of the electrode reaction, the diffusion coefficient D of glycine, and the catalytic rate constant kcat of the catalytic reaction are determined. Moreover, the catalytic currents present linear dependence on the concentration of glycine from 20 μM to 1.0 mM by amperometry. The detection limit and sensitivity are 9.2 μM and 3.92 μA mM−1, respectively. The modified electrode for glycine determination is of the property of simple preparation, fast response, and good stability.
Co-reporter:Li Zheng, Jun-feng Song
Talanta 2009 Volume 79(Issue 2) pp:319-326
Publication Date(Web):15 July 2009
DOI:10.1016/j.talanta.2009.03.056
A modified electrode Ni(II)–BA–MWCNT-PE has been fabricated by electrodepositing nickel(II)–baicalein [Ni(II)–BA] complex on the surface of multi-wall carbon nanotube paste electrode (MWCNT-PE) in alkaline solution. The Ni(II)–BA–MWCNT-PE exhibits the characteristic of improved reversibility and enhanced current responses of the Ni(III)/Ni(II) couple compared with Ni(II)–BA–CPE. It also shows good electrocatalytic activity toward the oxidation of hydrazine. Kinetic parameters such as the electron transfer coefficient α, rate constant ks of the electrode reaction, the diffusion coefficient D of hydrazine and the catalytic rate constant kcat of the catalytic reaction are determined. Moreover, the catalytic currents present linear dependence on the concentration of hydrazine from 2.5 μM to 0.2 mM by amperometry. The detection limit and sensitivity are 0.8 μM and 69.9 μA mM−1, respectively. The modified electrode for hydrazine determination is of the property of simple preparation, good stability, fast response and high sensitivity.
Co-reporter:Li Zheng, Jun-feng Song
Sensors and Actuators B: Chemical 2009 Volume 135(Issue 2) pp:650-655
Publication Date(Web):15 January 2009
DOI:10.1016/j.snb.2008.09.035
A CM-MWCNT-GCE modified electrode has been fabricated by electrodepositing curcumin (CM) at the surface of multi-wall carbon nanotubes (MWCNT) modified glassy carbon electrode (GCE). The CM-MWCNT-GCE shows a well-defined two-electron and two-proton redox couple with the formal potential of 0.14 V (vs. SCE) that results from the electrochemical oxidation product of CM, a CM derivative in quinone form. It also shows good electrocatalytic activity towards the oxidation of hydrazine at a reduced overpotential as well as an increased peak current compared with those at a CM modified GCE, a MWCNT modified GCE or an activated GCE. The catalytic rate constant kcat is determined to be 6.26 × 103 M−1 s−1 by chronoamperometry. The calibration curve for hydrazine determination is linear in the range of 2–44 μM in pH 8.0 phosphate buffer by amperometry. The detection limit and the sensitivity are 1.4 μM and 22.9 nA μM−1, respectively. The modified electrode is simple in preparation, and is of character of fast response, high sensitivity and good reproducibility for hydrazine determination.
Co-reporter:Yao-Dong Liang, Jun-Feng Song
Journal of Electroanalytical Chemistry 2008 Volume 624(1–2) pp:27-32
Publication Date(Web):1 December 2008
DOI:10.1016/j.jelechem.2008.07.017
This paper reported an electrochemiluminescence (ECL) from direct electrochemical oxidation of organic analyte rutin itself that was different from both annihilation and coreactant ECL in mechanism. The ECL production mechanism could be described as follows: rutin was electrochemically oxidized via one-electron transfer to o-semiquinone radical. Then the radical was further electrochemically oxidized via one-electron transfer to the excited state rutin o-quinone that subsequently emitted light. Based on the ECL of rutin, a flow injection ECL method for the determination of rutin was proposed. In the proposed flow injection system, an ECL signal was generated in rutin–NaOH–cetyl trimethyl ammonium chloride solution by applying direct current of 12 mA to the platinum anode in an ECL flow-through cell with two-electrode system. The ECL intensity of rutin was proportional to its concentration over the range of 6.0 × 10−7–1.0 × 10−5 mol l−1, and the limit of detection (s/n = 3) is 2 × 10−7 mol l−1. The proposed method had been evaluated by the analysis of rutin in pharmaceutical preparations.
Co-reporter:Li LIU;Peng-Fei YU;Bin CUI
Chinese Journal of Chemistry 2008 Volume 26( Issue 1) pp:220-224
Publication Date(Web):
DOI:10.1002/cjoc.200890028
Abstract
Voltammetric response of calcium dobesilate (calcium 2,5-dihydroxybenzene sulfonate, CD) was observably enhanced at lanthanum hydroxide nanowire (LNW) modified carbon paste electrode. The enhancement action was characterized by both the increase of peak current and the reduction of peak potential separation of a pair of the redox peaks of CD, which resulted from both the increase of efficient surface area of the modified electrode and the chemical interaction of LNW with CD. With the sensitive oxidation peak of CD at the LNW/CPE, a linear sweep voltammetric method for the determination of CD was proposed. A linear range of 3.0×10−10−1.0×10−8 mol·L−1 was obtained along with a detection limit of 5×10−11 mol·L−1.
Co-reporter:Yao-Dong Liang, Jun-Feng Song, Min Xu
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2007 Volume 67(Issue 2) pp:430-436
Publication Date(Web):June 2007
DOI:10.1016/j.saa.2006.07.036
A novel electrochemiluminescence (ECL) type was proposed based on successive electro- and chemo-oxidation of oxidable analyte, which was different from both annihilation and coreactant ECL types in mechanism. Rifampicin was used as a model compound. No any chemiluminescence (CL) was produced by either electrochemical oxidation or chemical oxidation of rifampicin in KH2PO4–Na2B4O7 (pH 6.6) buffer–dodecyl trimethyl ammonium chloride (DTAC) solution. However, an ECL was observed by electrochemical oxidization of rifampicin in the same solution in the presence of oxidant such as dissolved oxygen, activated oxygen and potassium peroxydisulfate (K2S2O8). The ECL was attributed to electrochemical oxidation of rifampicin to form semiquinone free radical, and then subsequently chemical oxidation of the formed radical by oxidant to form excited state rifampicin quinone. The proposed ECL type introduced additional advantages such as high selectivity, simple and convenient operation, and effective avoidance of side reaction that often took place in homogenous CL reaction, and will open a novel application field. In addition, with the ECL in the presence of K2S2O8 as oxidant, a flow injection ECL method for the determination of rifampicin was proposed. The ECL intensity was linear with rifampicin concentration in the range of 1.0 × 10−7 to 4.0 × 10−5 mol l−1 and the limit of detection (s/n = 3) was 3.9 × 10−8 mol l−1. The proposed method was applied to the determination of rifampicin in pharmaceutical preparations and human urine.
Co-reporter:Li Zheng, Junfeng Song
Talanta 2007 Volume 73(Issue 5) pp:943-947
Publication Date(Web):31 October 2007
DOI:10.1016/j.talanta.2007.05.015
The voltammetric behavior of urapidil was investigated. In pH 6.8 Britton-Robinson buffer, an irreversible oxidation peak of urapidil at 0.62 V (versus SCE) at a multi-wall carbon nanotube paste electrode (MWNT-PE) was observed, which was more sensitive with lower potential than that at the carbon paste electrode (CPE). The oxidation of urapidil was a two-electron and two-proton process with adsorption character. A differential pulse voltammetric method was proposed for the determination of urapidil. The peak current of the oxidation peak of urapidil was linearly with its concentration in a range from 5.0 × 10−8 to 2.0 × 10−6 mol/L at open-circuit accumulation for 60 s, with a detection limit of 3.8 × 10−8 mol/L. The proposed method was employed to determine urapidil in urapidil tablets.
Co-reporter:Li Liu, Jun-feng Song, Peng-fei Yu, Bin Cui
Talanta 2007 Volume 71(Issue 5) pp:1842-1848
Publication Date(Web):30 March 2007
DOI:10.1016/j.talanta.2006.08.042
A novel voltammetric method for the determination of β-d-glucose (GO) is proposed based on the reduction of Cu(II) ion in Cu(II)(NH3)42+–GO complex at lanthanum(III) hydroxide nanowires (LNWs) modified carbon paste electrode (LNWs/CPE). In 0.1 mol L−1 NH3·H2O–NH4Cl (pH 9.8) buffer containing 5.0 × 10−5 mol L−1 Cu(II) ion, the sensitive reduction peak of Cu(II)(NH3)42+–GO complex was observed at −0.17 V (versus, SCE), which was mainly ascribed to both the increase of efficient electrode surface and the selective coordination of La(III) in LNW to GO. The increment of peak current obtained by deducting the reduction peak current of the Cu(II) ion from that of the Cu(II)(NH3)42+–GO complex was rectilinear with GO concentration in the range of 8.0 × 10−7 to 2.0 × 10−5 mol L−1, with a detection limit of 3.5 × 10−7 mol L−1. A 500-fold of sucrose and amylam, 100-fold of ascorbic acid, 120-fold of uric acid as well as gluconic acid did not interfere with 1.0 × 10−5 mol L−1 GO determination.
Co-reporter:Yao-Dong Liang, Wei Gao, Jun-Feng Song
Bioorganic & Medicinal Chemistry Letters 2006 Volume 16(Issue 20) pp:5328-5333
Publication Date(Web):15 October 2006
DOI:10.1016/j.bmcl.2006.07.084
An electrochemiluminescence (ECL) based on energy transfer from electro-generated triplet sulfur dioxide to pipemidic acid (PPA) was studied. A weak ECL from triplet sulfur dioxide 3SO2∗ was observed when sulfite was electrochemically oxidized in sulfuric acid solution on a Pt electrode. When PPA was present, the weak ECL was enhanced. The enhanced ECL was attributed to energy transfer from 3SO2∗ to PPA. Based on the enhanced ECL, a flow-injection (FIA) ECL method for the determination of PPA was proposed. The proposed method allowed the measurement of PPA over the range of 1.0 × 10−7 to 2.0 × 10−5 mol l−1. The detection limit was 3.9 × 10−8 mol l−1, and the relative standard deviation for 1.0 × 10−6 mol l−1 PPA (n = 9) was 1.3%. This method was evaluated by the analysis of PPA in pharmaceutical preparations and urine samples.An electrochemiluminescence (ECL) based on energy transfer from electro-generated triplet sulfur dioxide to pipemidic acid (PPA) was studied.
Co-reporter:Ning Liu;Wei Gao
Chinese Journal of Chemistry 2006 Volume 24(Issue 11) pp:
Publication Date(Web):3 NOV 2006
DOI:10.1002/cjoc.200690310
Voltammetry using solid electrodes usually suffers from the contamination due to the deposition of the redox products of analytes on the electrode surface. The contamination has resulted in poor reproducibility and overelaborate operation procedures. The use of the chemical catalysis of oxidant on the reduction product of analyte not only can eliminate the contamination of analyte to solid electrodes but also can improve the faradaic response of analyte. This work introduced both the catalysis of oxidant K2S2O8 and the enhancement of surfactant Triton X-100 on the faraday response of amiodarone into an adsorptive stripping voltammetry at a carbon paste electrode for the determination of amiodarone. The method exhibits high sensitivity, good reproducibility and simple operation procedure. In 0.2 mol·L−1 HOAc-NaOAc buffer (pH5.3) containing 2.2×10−2 mol·L−1 K2S2O8 and 0.002% Triton X-100, the 2.5th-order derivative stripping peak current of the catalytic wave at 0.3 V (vs. Ag/AgCl) is rectilinear to amiodarone concentration in the range of 2.0×10−10–2.3×10−8 mol·L−1 with a detection limit of 1.5×10−10 mol·L−1 after accumulation at 0 V for 30 s.
Co-reporter:Jia-Quan Chen, Wei Gao, Jun-Feng Song
Sensors and Actuators B: Chemical 2006 Volume 113(Issue 1) pp:194-200
Publication Date(Web):17 January 2006
DOI:10.1016/j.snb.2005.02.047
A flow-injection biamperometric method for the determination of iron(III) has been described. The detector consists of two chambers separated by a salt bridge, and one platinum wire working electrode is embedded in each chamber, respectively. When iron(III) solution and hydrogen peroxide solution simultaneously flow through two chambers, the reduction of iron(III) at one platinum electrode is associated with the oxidation of hydrogen peroxide at the other platinum electrode, forming such a system as similar to a reversible couple one. The biamperometric system can perform the determination of iron(III) without any external potential difference. The linear relationship is obtained from 1.0 × 10−6 to 1.0 × 10−4 mol l−1 with a detection limit of 6.0 × 10−7 mol l−1. The proposed method exhibits the satisfactory reproducibility with a relative standard derivation (R.S.D.) of 1.4% for 17 successive determinations of 2.0 × 10−5 mol l−1 iron(III) and is applied to the determination of iron(III) in soil.
Co-reporter:Yao-Dong Liang, Jun-Feng Song
Journal of Pharmaceutical and Biomedical Analysis 2005 Volume 38(Issue 1) pp:100-106
Publication Date(Web):1 June 2005
DOI:10.1016/j.jpba.2004.12.010
A flow-injection chemiluminescence method for the determination of tryptophan was proposed, which was based on an intense chemiluminescence of tryptophan in hydrogen peroxide–nitrite–sulfuric acid medium. The chemiluminescence reaction was attributed to peroxidation and epoxidation of tryptophan by peroxynitrous acid, and subsequent decomposition of the formed dioxetane. The chemiluminescence intensity was linear with tryptophan in the range of 6.0 × 10−7 to 3.0 × 10−5 mol l−1 and the limit of detection (S/N = 3) was 1.8 × 10−7 mol l−1. The proposed method was applied to the analysis of tryptophan in pharmaceutical preparations and human serum.
Co-reporter:Maotian Xu, Junfeng Song, Yaodong Liang
Journal of Pharmaceutical and Biomedical Analysis 2004 Volume 34(Issue 3) pp:681-687
Publication Date(Web):18 February 2004
DOI:10.1016/S0731-7085(03)00550-8
The polarographic behaviors of telmisartan (TE) are investigated in 0.8 mol/l NH3·H2O–NH4Cl (pH=8.9) supporting electrolyte. The results demonstrated that the reduction peak is obtained at ca. −1.30 V, which corresponds to a catalytic hydrogen wave. Based on the catalytic hydrogen wave, a novel method has been developed for the determination of telmisartan by linear sweep polarography. Calibration curve is linear in the range 2.0×10−7 to 3.0×10−6 mol/l and the detection limit is 1.0×10−7 mol/l. The proposed method is applied to the rapid determination of the telmisartan in capsule forms and biological sample without pre-separation.
Co-reporter:Ning Li, Junfeng Song, Wei Guo, Maotian Xu
Microchemical Journal 2004 Volume 77(Issue 1) pp:23-28
Publication Date(Web):May 2004
DOI:10.1016/j.microc.2003.10.001
The polarographic currents of lincomycin in the absence and the presence of persulfate are studied by linear potential scan polarography and cyclic voltammetry. The reduction wave of lincomycin in phosphate buffer is a catalytic hydrogen wave, which is the reduction of the proton combined with lincomycin in nature. When S2O82− is present, the atomic hydrogen as intermediate product from the reduction of the combined proton is oxidized by both S2O82− and its reduction intermediate, sulfate radical anion SO4−, to regenerate the original proton, producing the parallel catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave, a novel method for the determination of lincomycin is proposed. In 0.48 mol l−1 KH2PO4–Na2HPO4 (pH 7.4)–8.0×10−3 mol l−1 K2S2O8 supporting electrolyte, the peak potential of the parallel catalytic hydrogen wave is −1.82 V (vs. SCE). The second-order derivative peak current is rectilinear to the lincomycin concentration in the range of 8.5×10−8–9.0×10−5 mol l−1 and the detection limit is 4×10−8 mol l−1. The parallel catalytic hydrogen wave is three orders in magnitude higher than that of the corresponding catalytic hydrogen wave in analytical sensitivity. The proposed method is applied to the rapid determination of lincomycin hydrochloride in eye drops without previous separation.
Co-reporter:Maotian Xu, Huailing Ma, Junfeng Song
Journal of Pharmaceutical and Biomedical Analysis 2004 Volume 35(Issue 5) pp:1075-1081
Publication Date(Web):3 September 2004
DOI:10.1016/j.jpba.2004.03.018
Cephalexin gives a reduction wave in 0.03 mol/l HCl medium at ca. −1.24 V. With cephalexin concentration higher than 2.5×10−5 mol/l, another reduction wave is observed at ca. −0.90 V. These reduction waves are attributed to the reduction of ethylenic bond of a six-membered dihydrothiazine ring. When H2O2 is present, the reduction wave at ca. −0.90 V is catalyzed by H2O2 and its reduction intermediate hydroxyl radical OH, producing a catalytic wave. However, the reduction wave at ca. −1.24 V remains nearly unchanged. A sensitive polarographic method for the determination of cephalexin is proposed based on the reduction wave of cephalexin. The second-order derivative peak current of the wave at ca. −1.24 V is rectilinear to the cephalexin concentration in the range 1.0×10−7 to 2.5×10−5 mol/l, and the detection limit is 5.0×10−8 mol/l. The proposed method is applied to the individual tablet dosage form and human serum.
Co-reporter:Wei Guo, Hong Lin, Limin Liu, Junfeng Song
Journal of Pharmaceutical and Biomedical Analysis 2004 Volume 34(Issue 5) pp:1137-1144
Publication Date(Web):10 March 2004
DOI:10.1016/j.jpba.2003.12.006
A new method for the determination of diazepam was proposed based on its polarographic catalytic wave in the presence of persulfate. In 0.20 M NaAc–HAc (pH 4.7)–2.0×10−2 M K2S2O8 supporting electrolyte, the reduction wave of diazepam with peak potential −0.89 V (versus SCE) was catalyzed, producing a parallel catalytic wave. The peak current of the catalytic wave was 15 times higher than that of the corresponding reduction wave for 4.0×10−6 M diazepam, and was rectilinear to diazepam concentration in the range of 5.6×10−8 to 8.8×10−6 and 8.8×10−6 to 2.0×10−4 M. The detection limit was 9.6×10−9 M. The mechanism of the parallel catalytic wave of diazepam was discussed.
Co-reporter:Maotian Xu, Liangfeng Chen, Junfeng Song
Analytical Biochemistry 2004 Volume 329(Issue 1) pp:21-27
Publication Date(Web):1 June 2004
DOI:10.1016/j.ab.2003.12.033
The polarographic response characteristics of diclofenac sodium were investigated in 0.25 M HAc-NaAc (pH 5.0) supporting electrolyte in the absence and the presence of dissolved oxygen. The results demonstrate that the reduction peak at ca. −1.10 V is a catalytic hydrogen wave after deaeration, and the reduction peak in the presence of dissolved oxygen is a so-called parallel catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave, a novel method has been proposed for the determination of diclofenac sodium by single-sweep polarography. The calibration curve is linear in the range 1.2 × 10−7–2.6 × 10−6 M and the detection limit is 6.0 × 10−8 M. The proposed method is applied to the direct determination of diclofenac sodium in tablet forms and biological samples.
Co-reporter:Yao-Dong Liang, Jun-Feng Song, Xiao-Feng Yang, Wei Guo
Talanta 2004 Volume 62(Issue 4) pp:757-763
Publication Date(Web):10 March 2004
DOI:10.1016/j.talanta.2003.09.017
A new flow-injection chemiluminescence (CL) method for determination of chloroquine is proposed based on a stronger chemiluminescence of chloroquine in hydrogen peroxide–nitrite–sulfuric acid medium. The proposed method allows the measurement of chloroquine over the range of 3.0×10−7 to 1.0×10−5 mol l−1. The detection limit is 8.6×10−8 mol l−1, and the relative standard deviation for 1.0×10−6 mol l−1 chloroquine (n=11) is 1.6%. The CL mechanism is also discussed.
Co-reporter:Maotian Xu, Junfeng Song, Ning Li, Chuan Zhao
Journal of Electroanalytical Chemistry 2003 Volume 553() pp:163-168
Publication Date(Web):30 August 2003
DOI:10.1016/S0022-0728(03)00319-X
A sensitive polarographic method for the determination of platinum is proposed, based on the so-called parallel catalytic hydrogen wave of the Pt (IV)–EDTA complex in the presence of persulfate. At mercury electrodes, the Pt (IV)–EDTA complex produces a catalytic hydrogen wave at −1.10 V (vs. SCE) in 1.0 mol l−1 HOAc+NaOAc (pH 4.4) buffer. When K2S2O8 is present, the catalytic hydrogen wave is catalyzed further by S2O82− and its reduction intermediate sulfate radical anion SO4−, producing a kinetic wave, described as the parallel catalytic hydrogen wave. The second-order derivative peak current of the wave is rectilinear to the platinum concentration in the range 1.3×10−10 to 7.7×10−9 mol l−1 with a detection limit of 6.8×10−11 mol l−1. The proposed method is free of interference from other metal ions except for Ru (IV), and is evaluated by the determination of platinum content in standard reference alloy materials and platinum catalysts.
Co-reporter:Jun-Feng Song, Jia-Quan Chen
Journal of Pharmaceutical and Biomedical Analysis 2003 Volume 33(Issue 4) pp:789-796
Publication Date(Web):24 November 2003
DOI:10.1016/S0731-7085(03)00295-4
A flow-injection biamperometric method for direct determination of calcium dobesilate had been proposed based on biamperometric detection for irreversible couple. The detection was realized by coupling the oxidation of dobesilate at one platinum wire electrode with the reduction of MnO4− at another one with the applied potential difference of 0 V between two platinum wire electrodes. Dobesilate was determined in the range of 4.0×10−6 to 1.0×10−4 M with the detection limit of 8.0×10−7 M (S/N=3). The relative standard derivation of 1.7% was obtained for 24 successive determinations of 4.0×10−5 M dobesilate. The proposed method had been shown to be sensitive, simple and rapid.
Co-reporter:Jun-Feng Song, Yang-Qin Liu, Wei Guo
Analytical Biochemistry 2003 Volume 314(Issue 2) pp:212-216
Publication Date(Web):15 March 2003
DOI:10.1016/S0003-2697(02)00654-1
Human serum albumin (HSA) or anti-human serum albumin (anti-HSA) yields a catalytic hydrogen wave at about −1.85 V (vs Ag/AgCl) in 0.25 M NH3·H2O–NH4Cl (pH 8.58) buffer. When K2S2O8 is present, the catalytic hydrogen wave is further catalyzed, producing a parallel catalytic wave of hydrogen as catalyst in nature, termed the parallel catalytic hydrogen wave. The sensitivity of the parallel catalytic hydrogen wave is higher by two orders of magnitude than that of the catalytic hydrogen wave. Using the parallel catalytic hydrogen wave of anti-HSA or HSA in the presence of K2S2O8, two sensitive methods for the determination of anti-HSA were developed. One is a direct determination based on the parallel catalytic hydrogen wave of anti-HAS itself, and the other is a homogeneous immunoassay based on measuring the decrease of the peak current of the parallel catalytic hydrogen wave of HSA after homogeneous immunoreaction of HSA with anti-HSA. In the direct determination, the second-order derivative peak current of the parallel catalytic hydrogen wave of anti-HSA itself is rectilinear to its titer in the range from 1:1.0×107 to 1:8.4×106. In the homogeneous immunoassay, the decrease in the second-order derivative peak current of the parallel catalytic hydrogen wave of HSA is linearly related to the added anti-HSA in the titer range from 1:3.0×107 to 1:6.0×106. These assays are highly sensitive and rapid in operation and can be used to evaluate such antigens and their antibodies as those that could yield the parallel catalytic hydrogen wave.
Co-reporter:We Guo;Ying-Ying He
Chinese Journal of Chemistry 2003 Volume 21(Issue 12) pp:
Publication Date(Web):26 AUG 2010
DOI:10.1002/cjoc.20030211221
A faradaic response of anionic surfactants (AS), such as linear alkylbenzene sulfonate (LAS), dodecyl benzene sulfonate and dodecyl sulfate, was observed in weak acidic medium. The faradaic response of AS includes (1) a catalytic hydrogen wave of AS in HAc/NaAc buffer that was attributed to the reduction of proton associated with the sulfo-group of AS, and (2) a parallel catalytic hydrogen wave of AS in the presence of hydrogen peroxide, which was due to the catalysis of the catalytic hydrogen wave of AS by hydroxyl radical OH electrogenerated in the reduction of hydrogen peroxide. The parallel catalytic hydrogen wave is about 50 times as sensitive as the catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave, a high selective method for the determination of AS was developed. In 0.1 mol/L HAc/NaAc (pH = 6.2 ± 0.1)/1.0 ± 10−3 mol/L H2O2 supporting electrolyte, the second-order derivative peak current of the parallel catalytic hydrogen wave located at-1. 33 V (vs. SCE) was rectilinear to AS concentration in the range or 3.0 × 10–6-2.5 × 10–4 mol/L, without the interference of other surfactants. The proposed method was evaluated by quantitative analysis of AS in environmental waste water.
Co-reporter:Chuan Zhao, Junfeng Song, Juncai Zhang
Talanta 2003 Volume 59(Issue 1) pp:19-26
Publication Date(Web):2 January 2003
DOI:10.1016/S0039-9140(02)00459-9
A biamperometric method for the direct determination of pyrogallol compounds has been designed for flow-injection analysis. The method is based on the electrocatalytic oxidation of pyrogallol compounds at one pretreated platinum electrode and the reduction of platinum oxide at the other pretreated platinum electrode to form a biamperometric detection system with the applied potential difference of 10 mV. Three important compounds, pyrogallol, gallic acid and tannic acid, have been detected by the method. The linear relationships between currents and the concentrations of pyrogallol, gallic acid and tannic acid are obtained over the range 1.0×10−6–1.0×10−4, 1.0×10−6–1.0×10−4 and 1.0×10−6–2.0×10−4 mol l−1 with the detection limit of 6.0×10−7, 6.0×10−7 and 8.0×10−7 mol l−1 (S/N=2), respectively. The R.S.D. observed for 30 successive determinations of 5.0×10−5 mol l−1 pyrogallol, gallic acid and tannic acid are 1.9, 2.5 and 2.0%, respectively. Most ions and organic compounds tested are found not to cause significant interference in the determinations. The method is simple, selective and efficient (180 h−1), performing well as a routine assay, and has been validated by the determination of pyrogallol compounds in tea and Chinese gall.
Co-reporter:J.-F Song, Ying-Ying He, Wei Guo
Journal of Pharmaceutical and Biomedical Analysis 2002 Volume 28(Issue 2) pp:355-363
Publication Date(Web):15 April 2002
DOI:10.1016/S0731-7085(01)00594-5
The mechanism of the parallel catalytic wave of berberine in the presence of H2O2 was studied. The results showed that the reduction process of the CN bond of berberine was two successive one-electron transfers, in which an intermediate free radical was involved. When H2O2 was present, it oxidized the free radical to the original CN bond, producing the parallel catalytic wave of berberine. In Na2B4O7–Na2CO3 (pH 9.4, 0.08 M)–H2O2(4 mM) supporting electrolyte, the peak current of the catalytic wave was linear to the berberine concentration in the range of 1.0×10−8–3.0×10−7 M. The limit of detection was 7.0×10−9 M. The catalytic wave can be applied to direct determination of berberine in medicinal plant Coptischinensis Franch, after sufficiently diluting the water extraction without preliminary separation.
Co-reporter:Wei Guo;Hong Lin;Li-Min Liu;Zhi-An Guo
Chinese Journal of Chemistry 2002 Volume 20(Issue 5) pp:
Publication Date(Web):26 AUG 2010
DOI:10.1002/cjoc.20020200517
Polarographic catalytic wave of chlordiazepoxide in the presence of K2S2O8 was studied in aqueous and DMF/H2O mixed solutions. The results showed that a single reduction wave in alkaline medium was the reduction of the N = C bond in 1,2-position of chlordiazepoxide via an intermediate free radical in two one-electron successive additions. When K2S2O8 was present, the free radical of the N = C bond was oxidized to regenerate the original, producing a parallel catalytic wave of chlordiazepoxide. It was determined that the apparent rate constant kf of the oxidation reaction was 3.2 × 103 mol−1·L·s−1. Using the catalytic wave the trace of chlordiazepoxide can be determined by linear-potential scan polarography. In NH3/NH4Cl (pH 10.2 ± 0.1, 0.12 mol/L)/K2S2O8(0.016 mol/L) supporting electrolyte, the second-order derivative peak current of the catalytic wave was rectilinear to chlordiazepoxide concentration in the range of 3.20 × 10−8-1.60 × 10−7, 1.60 × 10−7-1.44×10−6 and 1.44×10−6-1.44x 10−5 mol/L, respectively. The limit of detection was 9.0×10−9 mol/L.
Co-reporter:Junfeng Song, Huafeng Fu, Wei Guo
Journal of Electroanalytical Chemistry 2001 Volume 511(1–2) pp:31-38
Publication Date(Web):21 September 2001
DOI:10.1016/S0022-0728(01)00506-X
Benzyl alcohol was oxidized rapidly to electroactive benzaldehyde through a radical-chain reaction initiated by sulfate radical SO4− electrogenerated from reduction of S2O82−. The benzaldehyde formed was reduced via an intermediate free radical. The free radical of benzaldehyde was oxidized by both S2O82− and SO4− to produce a catalytic wave. Based on this a novel method for the determination of benzyl alcohol was proposed. In 0.1 mol l−1 KH2PO4+Na2HPO4 buffer (pH 5.6±0.1)+2.0×10−2 mol l−1 K2S2O8 solution the second-order derivative peak current of the catalytic wave was linearly proportional to the benzyl alcohol concentration in the range of 9.70×10−6–1.54×10−4 mol l−1. The limit of detection was 8.0×10−6 mol l−1. The proposed method was applied to determine the benzyl alcohol content in clinical injection.
![[(sulfonatoperoxy)sulfonyl]oxidanide](http://img.cochemist.com/ccimg/15100/15092-81-6.png)
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