untitled ISSN 2 Study of in the aq Esam Araf Chemistry Depa * Corresponding Tel.: +2.050.218 ARTICLE IN DOI: 10.5155/e Received: 21 Ju Received in rev Accepted: 14 Ju Published onlin Printed: 30 Sep KEYWORDS Copper Amino acids Voltammetry Charge transfer Electrochemist Cyclic voltamm 1. Introduct Copper i many biolog Complexes attention in against bact coccus aureu provides, etc occurring tw essential to Transition m proteins are oxygen conv sites of enzy ions complex human to sy is considered acids. This r supplement temperature are used for spectrophoto defect such a choose cycli 2153‐2249 (Prin f redox be queous m fa Gomaa, A artment, Faculty of g author at: Chemis 81608. Fax: +2.050.2 FORMATION eurjchem.7.3.341- une 2016 vised form: 12 July uly 2016 ne: 30 September 2 ptember 2016   S r ry metry tion is an importan gical processes of Cu(II)‐amin recent years as terial activity s us, and used for c. [1,2]. Struct wenty amino a perform a lar metals‐amino a consumed in s veyer, electron ymes which are xes in these pr ynthesize amino d to be one of t reason makes and as a drug es and in bad st determination ometry, and flu as long time, h ic voltammetry E nt) / ISSN 2153‐ h Euro ehavior o medium us Amr Negm an Science, Mansoura stry Department, Fa 2181608. E‐mail ad -346.1471 2016 2016 t metal which inside human no acids hav s they proved to such as Escher r humans and a tural units of p acids, which a rge number of acids complex several biologic oxidation, and e very specific, f ocesses [4]. Du o acid lysine in the very impor lysine be use g. Lysine can b torage conditio n of lysine such uorimetry but ea igh cost and in y technique for uropean Journal Europ 2257 (Online)  http://dx.doi.org/1 pean Jo Journal we f Cu(II) an sing cyclic nd Mohame a University, 35516, Faculty of Science, M ddress: tahooon_87 ABSTRACT Potassium chl behavior of Cu +1500 mV an electrode. Silv used is Pt. On cyclic voltamm between meta constant (ks) interaction wa peak current r Cite this: Eur. plays a vital r n and animal b ve received gr o be powerful a richia coli, Stap animals as nutr proteins are n re chemical sp f vital function es in peptides cal processes su transfer. The forms divalent ue to an inabilit side the body, rtant essential a d as a food d be destroyed at ons. Many techn as chromatogr ach technique h naccurate result r this present l of Chemistry 7 pean Journal of C 2016 Atlanta Pub 10.5155/eurjchem ournal ebpage: www nd intera c voltamm d Abdel Kha , Mansoura, Egypt Mansoura University 7@yahoo.com (M. T loride (0.1 M) a u(II) ions in abs nd ‐1000 mV wa ver/silver chlori e pair of cathod mograms indica al and ligand is s values. Concen as also studied. ratio and peak po J. Chem. 2016, 7 role in bodies. reater agents phylo‐ ritious atural pecies ns [3]. s and uch as active metal ty of a lysine amino dietary t high niques raphy, has its ts. We study due elec spe to t con abil larg that thes not (e.g tech met suc inte in th 2. E 2.1. sulf pot (3) (2016) 341‐ Chemistry blishing House LL m.7.3.341-346.14 of Che w.eurjchem.co ction of C metry alek Tahoon ty, 35516, Mansour Tahoon). and acetate buffe ence and presen as used to stud de is used as a dic and anodic p ating the prese upported by the ntration effect o The quasi‐rever otential separati 7(3), 341‐346 e to its efficie ctroactive ions ectroscopic tech the ability to d nstants from p lity of differen ge variety of st t can be applie se techniques h t possible once a g. to prevent co hniques are les try techniques h situation. Th eraction with ly he current stud Experimental . Chemicals The chemicals fate (Oxford Co tassium chlori ‐346 LC ‐ All rights rese 471 emistry om Cu(II) with n * ra, Egypt. er of different p nce of lysine am dy the redox pro reference electr peaks for the Cu nce of two‐elec e shift of peak po of Cu(II) ions a rsible process is ion (ΔE). ency in exami . It is well kno hniques take lar determine accu potentiometric nt spectroscop tructural inform ed for the stud have a limitation a large concent omplex precipit ss sensitive at can be an alt e redox behavi ysine is investig dy. s used in the o., India), lysine de (MERCK, erved ‐ Printed in y h lysine pH are used to s mino acid. The po operties at solid rode and the co u(II)/Cu(0) syste ctron transfer. otential and char and solution pH s indicated by a ning the redo own that poten rge and special urate values fo techniques an ic methods an mation [5,6] am dy of complexa n that makes th tration of the lig tation), this def high concentra ternative suitab ior of metal ion gated in the aq present study e amino acid ( Germany), so n the USA study the redox otential window d glassy carbon ounter electrode em is showed in The interaction rge transfer rate H effect on the higher value of ox behavior of ntiometric and l attention, due or the stability nd due to the nalysis to give mong the plans ation. However, heir application gand is present fect make these ations. Voltam‐ ble solution in n Cu(II) and its queous medium y were copper (Cambrian Co.), odium acetate x w n e n n e e f f d e y e e s , n t e ‐ n s m r , e 342 (Oxford Co., nitrogen (Ta 2.2. Instrum This stu multichanne magnetic sti tape, a pH m consisting o Teflon cap. T as a counter reference ele working elec was polished powder. The alcohol and thoroughly w particles. De high purity n Three measu each param analyzed usi 3. Results an Cu (II) r lysine have electrolytes u 3.1. Cu(II) el chloride Cyclic vo between 15 addition of noticeable ch two reductio V, respectiv according to Cu2+ + e‐ → C Cu+ + e‐ → Cu Two pro scan was re ponding to o Cu → Cu+ + e Cu+ → Cu2+ + Figure 1. Cycl electrolyte and India), acetic alkha Co.). mentation udy was carrie el potentiostat irrer, and its m meter (±0.03) a of three electro The three electr r electrode, sil ectrode and so ctrode. The gla d to a mirror e GCE was wa double‐distille with water agai eoxygenation o nitrogen before urements were meter is quoted ng origin softw nd discussion redox behavior e been deter using cyclic vol lectrochemical oltammetry be 00 to ‐1000 m copper ions t hange of the re on peaks that a ely, which refl reaction: Cu+ u ominent anodic eversed at arou oxidation of cop e‐ e‐ lic voltammogram (b) 0.1 M KCl at 0. Go acid (Sigma‐Al ed out using for voltamme magnetic bar th and an electro odes inserted rodes used wer lver/silver chlo lid glassy carb ssy carbon elec state using 1.0 ashed ultrason d water, respe in to remove an of solutions w e each electroc repeated and d for discussi ware. rs, in the prese rmined in d tammetry. l behavior in 0. havior of Cu ( mv is introduce to the basic e edox behavior. C are observed at lect the reduc c peaks were und 0.085 V a per according t ms of (a) 6×10‐3 .1 V/sec. omaa et al. / Eur drich) and 99. DY2000, DY20 etry measurem hat coated by T chemical cell t in Pyrex glass re a Pt wire that oride that used on disk that us ctrode (GCE) su 00‐0.03 μm alu ically with ab ectively, after r ny adhering alu was performed chemical experi the average va on. The data ence and absen ifferent suppo .1 M potassium (II) (6×10‐3 M) ed in Figure 1 electrolyte sho Cathodic scan s t 0.411 V and 0 tion of copper observed whe and 0.247 V c to reaction: M CuSO4 in 0.1 ropean Journal of 997% 000EN ments, Teflon that is s with t used d as a sed as urface umina solute insing umina using iment. alue of were nce of orting m ) scan 1. The ows a shows 0.0063 r ions (1) (2) en the orres‐ (3) (4) M KCl 3.2. red 4×1 100 of a is a incr pre incr with syst betw ran 0.00 sen from µM to t Figu 1×10 3.3. was and 4, t sho pea cur 5 in dep f Chemistry 7 (3) . Effect of conce Changing copp ox behavior. Cu 10‐3, 3×10‐3 and 0 mV/s are show anodic peak cur a successive l reasing the am sence of a la reasing concent h concentration tem may be di ween anodic p ges from 0.001 06 with a ver nsitivity of elec m the slope of t that calculated the basic electro ure 2. Cyclic voltam 0‐3 M CuSO4. Figure 3. Anod . Effect of pH ch The variation s studied. The d 5 at 100 mV/s the CVs are com ow electro catal ak current is sho rent is observe ndicates that re pendent. ) (2016) 341‐346 entration chan per ions concen uSO4 CVs of va d 1×10‐3 M) in wn in Figure 2 rrent against co linear increase mount of copper arge amount tration [7,8]. Th n increase also iffusion control peak current, 1 to 0.003, 0.00 ry good linear ctrode is found the plot. The de d from concentr olyte. mmograms of (a) 6 dic peak current va hange of reduction p CVs of CuSO4 i s are introduce mpared. At pH lytic activity. V own in Figure 5 d at pH = 5. Com edox behavior 6 nge ntrations has a arious concentr 0.1 M potassiu and 3 that show oncentration fo e in the centr r ions that may of electroactiv his increasing o o gives the indi lled [9,10]. Fro we can obtain 03 to 0.004 and r correlation r d to be 0.001 A etection limit is ration that gave 6×10‐3, (b) 4×10‐3, ariations with conc properties with n acetate buffe d to study pH e H range from 3 Variation of pH 5. The best reso mparable CVs a of copper ions great effect on rations (6×10‐3, um chloride at w the variation or CuSO4. There ral wave with y be due to the ve species by of peak current ication that the om the relation n three linear d from 0.004 to r2 = 0.98. The A.M‐1 obtained s found to be 8 e signal similar (c) 3×10‐3 and (d) centration. h pH variation er of pH = 3, 4, effect. In Figure 3 to 5, the GCE against anodic olution for peak at pH = 3, 4 and s on GCE is pH n , t n e h e y t e n r o e d 8 r ) n , e E c k d H Table 1. Curren ν(V/s) ν1/2 0.10 0.3 0.05 0.2 0.02 0.1 0.01 0.1 Peak pot (pH) is move this electrod low concent detection at variation can 56.1 This valu to 59.1 mV/p Figure 4. Cyclic 3 (a), pH = 4 (b) Figure 5. Ano voltammogram 3.4. Effect of The effec Cyclic voltam different sca Figure 6. The peak curren rates is reco cathodic pea peaks, the pe that is a plot the peak po nt‐potential data, p 2 Epa ( 16 0.04 23 0.05 41 0.04 00 0.03 tential by increa ed to lower pot de shows a ver trations and d pH = 5. The dep n be suggested a 1.203 ue is very close pH at 298 K. c voltammograms ) and pH = 5 (c) at dic peak current ms of 6×10‐3 CuSO4 f scan rate on r ct of scan rate mmograms of th an rates ranging e peak potentia t ratio of the v orded in Table aks potentials a eak potentials a t of ΔEp vs. scan otential separa Gomaa et al peak potential sepa (v) Epc (v 44 0.46 4 0.37 44 0.28 4 0.25 asing hydrogen tentials. These ry good respon different pH v pendence of red as follow: 0.9765 e to the theoret of 6×10‐3 M Cu(II) 100 mV/s. variation with pH in acetate buffer. redox behavior on redox beha he Cu(II) soluti g from 100‐10 al separation, cu voltammogram 1. By increasin are increased w are decreased. A n rate, with incr ation (Ep) inc l. / European Jou aration, peak curre v) ‐ipa ( 2 0.670 1 0.594 9 0.489 7 0.402 n ions concentra results indicat se to copper io values and the dox properties tical value that ) in acetate buffer H changes for the r avior of was stu ion were record mV/s and sho urrent‐potentia s at mentioned ng the scan rat while for the a As shown in Fig reasing the sca creases becaus rnal of Chemistry ent ratio of the volt mA) i 0 0 4 0 9 0 2 0 ations te that ons at e best on pH (5) equal of pH = e cyclic udied. ded at own in l data, d scan te, the anodic gure 7 n rate se the cath ano pot ind (oh [11 Figu 50, ( Figu the c in w alm dep rate con ads sev rela [13 the can is fo ry 7 (3) (2016) 34 tammogram of 0.1 ipc (mA) 0.518 0.359 0.255 0.200 hodic peak shi odic toward pos tential [E0 = (Ep ependent of sca mic potential) ,12]. ure 6. Cyclic voltam (c) 20 and (d) 10 m ure 7. Peak potent cyclic voltammogr The process is which the cat most linearly w pendency of an es is also indica ntrolled. In the orbed and des erally. Figure 9 is a ation indicating ,14]. Each char peak current [ n be approved b ound to be over 41‐346 1 M CuSO4 in 0.1 M ΔE = Epc ‐ Epa (v 0.418 0.317 0.245 0.223 ifts toward ne sitive potential pc + Epa)/2] is a an rate. This ma or due to slow mmograms of 1×10 mV/s. tial separation var ams of 1×10‐3 M Cu s adsorptive con thodic and ano with square roo nodic and cath ating that the pr e electrochemic sorbed ions ar plot of log i v g that the pro ge transfer and [15]. The system by the peak curr r than unity. KCl at different sc ) egative potenti but the value o almost constant ay be due to the w kinetics of ele 0‐3 CuSO4 in 0.1 M riations with chan uSO4. ntrolled as sho odic peak cur ot of scan rat hodic peak cur rocess is surfac cal process th e proportional vs. log v and s ocess is diffus d mass transpor m is quasi‐reve rent quantitativ 343 can rates. ipa/ipc 1.293 1.654 1.917 2.010 al and that of of formal redox t and is almost e decrease of iR ectron transfer KCl at (a) 100, (b) nging scan rate for own in Figure 8 rrents increase e (SQRT). The rrents on scan ce and diffusion e currents for to ν1/2 and ν, shows a linear sion controlled rt is controlling ersible and this ve relation that f x t R r ) r 8 e e n n r , r d g s t 344 Figure 8. Pea voltammogram Figur 3.5. Cu (II) e 0.1 M potass Cu(II) re in 0.1 M pot same condit was used fo Figure 10 de position of presence of those of 6×1 been modif confirms the of metal‐am potentials ‐3 3.6. Effect of Figure 1 in acetate bu peak current 12. As seen i is a peak shif The resoluti decreased by copper lysine 3.7. Effect of Figure 1 presence of different sca ak current varia m of 1×10‐3 M CuSO4 re 9. log i vs. log ν p electrochemica sium chloride dox behavior in tassium chlorid ions (potential or Cu(II) free i emonstrate that the voltammo 6×10‐3 M lysine 10‐3 M CuSO4. A fied. This beh e Cu‐amino acid ino acid intera 314.14 mV and a f pH change 1 shows the CV uffer of pH = 3 t is changed wi in the figure, th ft to right with ion of redox pr y the addition e interaction. f scan rate 3 shows a num 6×10‐3 M lysin n rates. CVs sho Go ation with SQRT 4. plot for the CV of 1 al behavior in p n the presence de at room tem window and s ions. The give t both the anod ogram of 6×10 e moves toward Additionally, th havior of pos d interaction. In action, there is anodic peak at Vs of Cu(II) in th , 4 and 5 at 10 th pH change a he redox behavi respect to that roperties at di of lysine. This mber of CVS of 6 ne in 0.1 M po ow almost simil omaa et al. / Eur of scan rate f 1×10‐3 M CuSO4. presence of lysi of lysine was st mperature with same electrode n voltammogra dic and cathodic 0‐3 M CuSO4 i d left with resp e peak intensit ition and int n the voltammo s a cathodic pe 129.6 mV. he presence of 00 mV/s. The a as indicated in F ior is changed. t for free a Cu(I ifferent pH valu may result fro 6×10‐3 M CuSO4 otassium chlor lar behavior lik ropean Journal of for the ine in tudied in the e) that am in c peak n the pect to ty has ensity ogram eak at lysine anodic Figure There I) ion. ues is m the in the ide at ke that of t rate pos par sep 14 s scan pot Cath with pro cur sur pro pro diff ν (F is c rev mu con Figu 6×10 100 Figu acet 3.8. coef elec dete rev f Chemistry 7 (3) the free Cu(II) i e, there is a neg sitive potential rameters that o aration increas shows in which n rate. This m tential) or slo hodic and ano h SQRT of scan ocess is adsorp rents on scan r face and diff ocess, the peak c oportional to ν fusion controlle Figure 16) [13,1 controlling the ersible indicate ch over than ntrolled as show ure 10. Cyclic vol 0‐3 M lysine, (b) 6× mV/s. ure 11. CVs of 6× tate buffer of pH = . Charge transf efficient (D) The diffusion ctrochemical an ermined from ersible or quas 2.69 10 ) (2016) 341‐346 on. It is observ gative potentia shift for anod obtained from F ses by increasi h peak potentia may be due to ow kinetics of dic peaks curr n rate as in Figu ptive controlle rates is indicat fusion controll currents for ad ν1/2 and m, sev ed as indicated 14]. Each mass e peak current ed by peak cur unity [9,10]. wn in Figure 15. ltammograms of ( ×10‐3 M CuSO4, and ×10‐3 M CuSO4 in 3 (c) (black), 4 (b) fer rate consta coefficients we nalysis. The dif the cathodic i‐reversible sys / / / 6 ed that by incre al shift for catho dic peaks. Tabl Figure 13. The ng the scan ra al separation is o the decrease f electron tra ent increases a ure 15, which p d. The depend ting that the re led. In the e sorbed and des verally [16]. T by a linear plo transfer and ch t [15]. The sys rrent ratio that The process . (a) 6×10‐3 M CuS d (c) 6×10‐3 M lysi the presence of 6 (blue), and 5 (a) ( ants (ks) and di ere calculable fr ffusion coefficie peak current stem as in equa easing the scan odic peaks and e 2 shows the peak potential te as in Figure plotted against e of iR (ohmic ansfer [11,12]. almost linearly proves that the dency of peak edox process is electrochemical sorbed ions are The process is t of log i vs. log harge transport stem is quasi‐ is found to be is adsorptive O4 in presence of ine in 0.1 M KCl at 6×10‐3 M lysine in (red) at 100 mV/s. iffusion rom a series of ent (D) will be equation of a tion (6) [17]. (6) n d e l e t c . y e k s l e s g t ‐ e e f t n f e a Table 2. Curren of lysine at diffe ν (V/s) ν 0.10 0 0.05 0 0.02 0 0.01 0 Table 3. Curren ID Cu(II) in KCl Cu(II)‐lysine in * T = 298 K, n = Figure 12. Var CuSO4 with lysi Figure 13. Cyc M lysine in 0.1 M where A (cm the sample coefficient, ν constant and electrons, an and charge t the reductio associated coefficient, c 2.18 nt‐potential data, p erent scan rates. ν1/2 Epa (v 0.316 0.117 0.223 0.109 0.141 0.085 0.100 0.065 nt‐potential data, d ν (V 0.1 0.0 0.0 0.0 n KCl 0.1 0.0 0.0 0.0 = no of electron tran riation of anodic p ine in acetate buffe clic voltammogram M KCl at (a) 100, (b m2) is the surfac e concentratio ν (V/s) is the p d has its usual v nd T is the abs transfer kinetic n process. The with both di an be described / Gomaa et al peak potential sep v) ‐Ep 7 0.3 9 0.2 5 0.2 5 0.1 diffusion coefficien V.s‐1) Epc (v) 0 0.462 5 0.371 2 0.289 1 0.257 0 ‐0.310 5 ‐0.261 2 ‐0.220 1 ‐0.168 nsferred = 2, R = 8 peak current with er. ms of 6×10‐3 M CuS b) 50, (c) 20 and (d ce area of elect n, D (cm2/s) otential scan r value, n is the nu solute tempera cs are the majo e charge transfe iffusion coeffi d as equation (7 l. / European Jou aration, peak curre c (v) ‐ 10 0 61 0 20 0 68 0 nt, D and the charg ipc (mA) 0.5180 0.3590 0.2550 0.2000 0.0010 0.0010 0.0007 0.0005 .314 J/K.mol, F = 9 pH in the interac SO4 in presence of d) 10 mV/s. trode, C (mmol ) is the diff ate, F is the Fa umber of transf ature in K. Diff or factors that er rate constan cient and tra 7) [18]. rnal of Chemistry ent ratio of the vol ‐ipa (mA) 0.002 0.001 0.001 0.001 e‐transfer rate con Diff. Coff. (Cm‐2. 0.90998 2.23×10‐6 96,500, A = surface ction of f 6×10‐3 l/L) is fusion araday ferred fusion affect nt (ks) ansfer (7) con grea tem velo 25] Figu coor Figu Cu(I 4. C abo pre ry 7 (3) (2016) 34 ltammogram of 0.1 ipc (mA) 0.0010 0.0010 0.0007 0.0005 nstant, ks, for M(II) S‐1) e area of the electro From results nstant ks (Table ater value tha mperature that ocity as a result . ure 14. Variation rdinated Cu(II) ion ure 15. Peak curre II) ions. Conclusions Cyclic voltamm out the electroc sent work he 41‐346 1 M CuSO4 in 0.1 M ΔE =Epc ‐ Epa (v 0.193 0.152 0.135 0.103 and M(II)‐lysine i Charge tran 4.1485 ‐3.0877 ode = 2.01 cm2, Co of the heterog e 3), it is observ an that of the predicts the r t of Cu(II)‐lysin n of peak potent ns. ent variations wit metry techniqu chemical behav redox behavio M potassium chlori v) ipa/ipc 2.000 1.000 1.428 2.000 nteraction on GCE nsfer rate constan nc. = 1 mM. geneous charge ved that free C Cu‐lysine sys reduction of c ne amino acid in tial separation wi th SQRT of scan ra ue provides goo ior of studied m ors of Cu(II) in 345 de in the presence *. nt (log KS) e transfer rate u(II) ions have tem at 298 K charge transfer nteraction [19‐ ith scan rate for ate for complexed od information material. In the n absence and e e e K r ‐ r d n e d 346 presence of and in acet Cu(II)/Cu(0) controlled. quantitative support tha reversible. T (ks) for Cu(I smaller than confirms the the electroly Figure 16. 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