Alternative electrodes in electroanalysis LABORATÓRIO DE ANALÍTICA BIOANALÍTICA BIOSSENSORES ELETROANALÍTICA & SENSORES DQ UFSCar Orlando Fatibello-Filho LABBES / Departamento de Química Universidade Federal de São Carlos (UFSCar)

3 São Carlos

7 LABBES POTENTIOMETRICS AMPEROMETRICS /VOLTAMMETRICS PIEZOELECTRICS PVC electrodes Metal-metal Oxide electrodes Biosensors Composites electrodes Amalgam electrodes Bismuth film electrodes Carbon nanotubes, carbon paste and carbon composite electrodes Boron-doped diamond (BDD) electrode Amorphous carbon nitride (a-CNx) electrode Biosensors

Advantages  Determination of analyte in colored solutions and/or with material in suspension  In situ determination of analyte: portability of the instrument  Simultaneous determination of inorganic and/or organic analytes  Speciation of analyte Disadvantages  Adsorption of substances in the electrode surface  Low stability of work electrode low reproducibility Introduction: Electroanalytical Methods

Electrolysis with a Dropping Mercury Cathode Heyrovský`s article (1922) J. Heyrovský, Chimické Listy, 16, 256 (1922)

Polarography Fig. J. Heyrovsky, Masuzo Shikata and the apparatus for measuring current- voltage curves in electrolysis with dropping mercury electrode (DME) and a sensitive photographic paper) J. Heyrovský, M. Shikata, Rec. Trav. Chim. Pays-Bas, 44, 496 (1925)

Fig. (A) Polarograph, (B) December 10 th, 1959 received from the hands of King of Sweden Gustav Adolph VI Nobel Prize for his invention of polarography and (C) Nobel Prize Certificate (A) (B) (C)

Characteristics of the dropping-mercury electrode (DME) Advantages  High hydrogen overpotential  Good stability  Good reproducibility  Characteristics of noble metals (Au, Pt) Disadvantages  O 2 should be removed from solutions  Flow analysis  Use is limited in positive potentials  Toxicity

ISE 2010 Nice, France Clarkson University, Potsdam, NY

Alternative electrodes in electroanalysis

Amalgam Electrodes for Electroanalysis Fig. Dental and/or Amalgam Electrode E. Mikkelsen, K.N. Schroder, Electroanalysis, 15(8), 679 (2003) B. Yosypchuc, J. Barek, Crit. Rev. Anal. Chem., 39, 189 (2009) D. de Souza, L. H. Mascaro, O. Fatibello-Filho, J. State. Electrochem., 15, 2023 (2011) D. de Souza, L.C. Melo, A.N. Correa, P. Lima-Neto, O. Fatibello-Filho, L. H. Mascaro, Quim. Nova, 34(3), 487 (2011) C. M. A. Brett, F. Trandafir, J. Electroanal. Chem., 572(2), 347 (2004).

Classification of amalgam electrodes

Approximate potential ranges for platinum, mercury, carbon, boron-doped diamond (BDD), amorphous carbon nitride (a-CNx) and bismuth electrodes 3.0 vs SCE M H 2 SO 4 1M NaOH Pt 1M NaOH 1M H 2 SO 4 1M KClHg 1M HClO M KCl C 0.5 M H 2 SO 4 BDD 1M HClO M NaOH Bi 0.5 M H 2 SO 4 a-CNx

Good negative potential window Interference of dissolved oxygen is minimal Low toxicity Electrochemical behavior is similar to that of mercury Bismuth film electrodes L.C.S. Figueiredo-Filho, D.C. Azzi, B.C. Janegitz, O. Fatibello-Filho, Electroanalysis, 24(2), 303 (2012) L.C.S. Figueiredo-Filho, B.C. Janegitz, R.C. Faria, O. Fatibello-Filho, L. H. Marcolino-Jr, F.R. Caetano, I.L de Mattos, Quim. Nova, 35(5), 1016 (2012) L.C.S. Figueiredo-Filho, V.B. dos Santos, T.B. Guerreiro, O. Fatibello-Filho, R.C. Faria, L.H. Marcolino-Jr, Electroanalysis, 22(11), 1260 (2010) A. Caldeira, C. Gouveia-Caridade, R. Pauliukaite, Brett, C. M. A., Electroanalysis, 23(6), 1301 (2011)

Bismuth film electrode for in situ determinations A B C (A): PalmSens and (B): DropSens potentiostats and (C) BiSPE preparation

L. C. S. Figueiredo-Filho et al., Analytical Methods, 5, 202 (2013)

TT-type connector for printers Fig. A) electrochemical cell built with inexpensive materials and B) set for analysis: connector, minisensor and electrochemical cell (ink color container) for in situ determinations Bismuth film electrode for in situ determinations L.C.S. Figueiredo-Filho, B.C. Janegitz, R.C. Faria, O. Fatibello-Filho, L. H. Marcolino-Jr, F.R. Caetano, I.L. de Mattos, Quim. Nova, 35(5), 1016 (2012)

A BC Fig. FEG-SEM (Field emission gun scanning electron microscope) micrographs of the bismuth film electrodeposited onto a copper electrode: A) copper substrate, B) BiFE X and C) XRD (X-ray Diffraction): Bi black and Cu (gray) Bismuth film V vs. Ag/AgCl (3.0 mol L -1 KCl) during 200 s 0.02 mol L -1 Bi(NO 3 ) 3, 1.0 mol L -1 HCl in 0.15 mol L -1 sodium citrate Bismuth film electrode for in situ determinations

Bismuth film electrode (BiFE) for paraquat determination Fig. DP voltammograms of paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride) in 0.1 mol L -1 acetate buffer solution (pH 4.5) L.C.S. Figueiredo-Filho, V.B. dos Santos, B.C. Janegitz, T.B. Guerreiro, O. Fatibello- Filho, R.C. Faria, L.H. Marcolino-Jr, Electroanalysis, 22(11), 1260 (2010) N H 3 C NCH 3 e H 3 C CH 3 - N N H 3 C CH 3 e - H 3 CNCH 3 NN N E 2 = V vs. (Ag/AgCl) PQ2 E 1 = V vs. (Ag/AgCl) PQ1 (PQ 2+ )(PQ + ) (PQ + ) (PQ º )

Bismuth film electrode (BiFE) for atrazine determination Fig. Proposed mechanism for reduction of 2-chloro-4-(ethylamine)-6- (isopropylamine)-s-triazine (ATZ) L.C.S. Figueiredo, D.C. Azzi, B.C. Janegitz, O. Fatibello-Filho, Electroanalysis, 24, 303 (2012)

Pb 2+ : 1.3 – 13.0 µmol L -1, LD: 0.83 µmol L -1 Cd 2+ : 0.99 – 12 µmol L -1, LD: 0.53 µmol L -1

Instrumentação portátil (bateria), robusta, exata e precisa Análises rápidas Controle térmico  Uso de ferramentas de tecnologia da informação (TI): Comunicação Wi-Fi, Bluetooth, GPS, GSM, telefonia 3G (SMS). Rede Wi-Fi  Determinação in situ e on-line  analitos orgânicos e cátions metálicos GPS Potentiostat

Fig. Structures of (a) glassy carbon, (b) graphite, (c) carbon nanotubes, (d) graphite powder, (e) carbon fibres, (f) boron-doped diamond, (g) fullerene (h) graphene and (i) pyrolitic graphite (not shown) E.T.G. Cavalheiro, C.M;.A. Brett,, A. M. Oliveira-Brett, O. Fatibello-Filho, Bioanal. Rev, 4, 31 (2012); Pauliukaite, R., Ghica, M.E., Brett, C.M.A., Fatibello-Filho, O., Anal. Chem., 81, 5164 (2009); Ghica, M.E., Pauliukaite, R., Brett, C.M.A., Fatibello- Filho, O., Sensors and Actuactors, 142, 308 (2009) (g) Carbon, carbon paste and carbon composite electrodes

Schematics of an individual (A) SWCNT and (B) MWCNT A: 1-2 nm diameter B: 2 to 100 nm separated by a distance of nm Single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) Iijima, S., Nature, 354, 56 (1991); Merkoçi, A. et al. Trend Anal. Chem., 24, 826 (2005)

Carbon nanotubes  Good electrical conductivity and mechanical strength  Relatively chemically inert in most electrolyte solutions  High surface activity  Wide operational potential window  Insolubility of CNTs in all solvents Wildgoose, G. G. et. al. Microchim. Acta, 152, 187 (2006); Banks, C. E. et al. Chem. Commun., (2005); Merkoçi, A. et al. Trend Anal. Chem., 24, 826 (2005).

Treatment of carbon nanotubes Treatment of the carbon nanotubes increases the sensitivity of the electrodes, because there is the appearance of reactive groups such as -COO -,-OH, C=O and others The literature reports several treatments, which use mainly concentrated 2 mol/L HCl, H 2 O and conc. H 2 SO 4 / HNO 3 3:1 v/v B.C. Janegitz, L.H. Marcolino-Junior, S.P. Campana-Filho, R.C. Faria, O. Fatibello-Filho, Sens. Actuators B-Chem., 142, 260 (2009) H.H. Takeda, B.C. Janegitz, R.A. Medeiros, L.H.C. Mattoso, O. Fatibello- Filho, Sens. Actuators B-Chem., 161, 755 (2012)

Fig. Cyclic voltammograms (50 mV s −1 ), after background subtraction, of a (a) GCE and (b) MWCNTs-PAH/GCE for 250 µM AA and a 450 µM sulfite in 0.1 M acetate buffer solution (pH 4.6). Simultaneous Voltammetric Determination of Ascorbic Acid and Sulfite in Beverages Employing a Glassy Carbon Electrode Modified with Carbon Nanotubes within a Poly(Allylamine Hydrochloride) (PAH) Film E.R. Sartori, O. Fatibello-Filho, Electroanalysis, 24(3), 627 (2012). (PAH)

Chemical equilibrium of chitosan in solution Chitosan (linear  -1,4-linked polysaccharide) Pauliukaite, R. ; Ghica, M. E. ; Fatibello-Filho, O. ; Brett C.M.A., Anal. Chem., 81, (2009) Pauliukaite, R. ; Ghica, M. E. ; Fatibello-Filho, O. ; Brett C.M.A. Electrochimica Acta, 55, 6239 (2010)

EDC 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) NHS N-hydroxysuccinimide (NHS) EDC-NHS

Possible mechanism of covalent binding of CNTs using Chit crosslinking and EDC/NHS (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N- hydroxysuccinimide) Pauliukaite, R., Ghica, M.E., Brett, C.M.A., Fatibello-Filho, O., Anal. Chem., 81, 5164 (2009) Ghica, M.E., Pauliukaite, R., Brett, C.M.A., Fatibello-Filho, O., Sensors and Actuactors, 142, 308 (2009)

A B Scheme of possible ways of enzyme immobilization at the electrode modified with chitosan and MWCNTs: (A) enzyme attachment directly to CNTs by EDC-NHS and (B) enzyme linked to both chitosan and to CNTs by EDC-NHS and GA.

Carbon paste electrodes C. Vieira, O. Fatibello-Filho, Talanta, 52(4), 681 (2000) M. F. S. Teixeira, A. Z. Pinto, O. Fatibello-Filho, Talanta, 45(2), 249 (1997) B. C. Janegitz, L. C. S. Figueiredo-Filho, L. H. Marcolino-Jr, O. Fatibello- Filho, J. Electroanal. Chemistry, 660(1), 209 (2011) F. C. Vicentini, L.C.S. Figueiredo-Filho, B. C. Janegitz, A. Santiago, E.R. Pereira, O. Fatibello-Filho, Quim. Nova, 34(5), 825 (2011)

T. Navratil, J. Barek, Crit. Rev. Anal. Chem., 39, 131 (2009) Composite Electrodes

Fig. Composite Electrode C. M. F. Calixto, P. Cervini, E. T. G. Cavalheiro, Quim. Nova, 31(8), 2194 (2008) I. Cesarino, C. Gouveia-Caridade, R. Pauliukeite, E. T. G. Cavalheiro, Brett, C. M. A., Electroanalysis, 22(12), 1437 (2010) I. Cesarino, E. T. G. Cavalheiro, Brett, C. M. A., Microchimica Acta, 171 (1-2), ) Composite electrode

Boron-doped diamond electrode  corrosion stable in very aggressive media  very low and stable background current  very low adsorption of organic/inorganic species  extreme electrochemical stability in both alkaline and acid media  high response sensitivity  very wide working potential window (3.5 V) K. Pecková et al. Critical Reviews in Analytical Chemistry. 39 (2009) 148 L.S. Andrade, G. R. Salazar-Banda, R. C. Rocha-Filho, O. Fatibello-Filho, Cathodic Pretreatment of Boron-Doped Diamond Electrodes and Their Use in Electroanalysis, In: Synthetic Diamond Films: Preparation, Electrochemistry, Characterization, and Applications, (Eds. E. Brillas and C. A. Martínez-Huitle), John Wiley & Sons, Inc., Hoboken, NJ, USA, 2011.

Experimental  Working electrode: Boron-doped diamond film (8000 ppm) on a silicon wafer from Centre Suisse de Electronique et de Microtechnique SA (CSEM), Neuchatêl, Switzerland  Cathodic pretreatment: –1.0 A cm –2 for 180 s in a 0.5 M H 2 SO 4 solution  Anodic pretreatment: +1.0 A cm -2 for 180 s in a 0.5 M H 2 SO 4 solution Counter electrode : Pt wire Reference electrode : Ag/AgCl (3.0 M KCl) Potentiostat/galvanostat : Autolab PGSTAT-30 (Ecochemie) controlled with the GPES 4.0 software Electrochemical pre-treatments

Characteristics of the procedure: simple and rapid low cost good intra- and inter-day repeatabilities Electrochemical pre-treatments Cathodic pre-treatment Hydrogen-terminated BDD (HT-BDD) Anodic pre-treatment G.R. Salazar-Banda, L.S. Andrade, P.A.P. Nascente, P.S. Pizani, R.C. Rocha- Filho, L.A. Avaca. Electrochimica Acta, 51, 4612 (2006) Oxygen-terminated BDD (OT-BDD)

Square-wave voltammetric determination of acetylsalicylic acid in pharmaceutical formulations using a BDD electrode without the need of previous alkaline hydrolysis step E.R. Sartori, R.A. Medeiros, R.C. Rocha-Filho, O. Fatibello-Filho. J. Braz. Chem. Soc., (2009); T.A. Enache, O. Fatibello-Filho, A. M. Oliveira-Brett. Combinatorial Chemistry & High Throughput Screening, 13, 569 (2010) HTB: 2-(hydroxyl)-4-(trifluoromethyl)-benzoic acid LOD = 2.0  M Highlight: first voltammetric method in the literature!

Paracetamol (A) and caffeine (B) in pharmaceuticals B.C. Lourenção, R.A. Medeiros, R.C. Rocha-Filho, L.H. Mazo, O. Fatibello-Filho, Talanta, 78, 748 (2009) Differential pulse voltammetry Paracetamol: 0.50 – 83  M LOD =  M Caffeine: 0.50 – 83  M LOD =  M Highlight:LODs lower than those reported; higher sensitivity and larger linear concentration range of the analytical curve 17  M 38  M

Repeatability study for  M Ascorbic acid  M caffeine in 0.1 M H 2 SO 4 (n = 10) RSD = 8.7 % for glassy-carbon (GC) electrode RSD = 1.0 % for boron-doped diamond (BDD) electrode Repeatability study GCBDD Highlight: higher repeatability of the BDD electrode B.C. Lourenção; R.A. Medeiros; R.C. Rocha-Filho; O. Fatibello-Filho; Electroanalysis, 22, 1717 (2010)

Simultaneous voltammetric determination of synthetic colorants in food using a cathodically pretreated BDD electrode R. A. Medeiros, B.C. Lourenção, R. C. Rocha-Filho, O. Fatibello-Filho, Talanta, 97, 291 (2012); R. A. Medeiros, B.C. Lourenção, R. C. Rocha-Filho, O. Fatibello-Filho, Talanta, 99, 883 (2012) TT/SY TT TT/SY SY BB BB/SY LOD = 62.7, 13.1 and 143 nmol L -1 for TT, SY and BB, respectively. Fig. Chemical structures of the Tartrazine (TT), Sunset yellow (SY) and Brilliant blue (BB) and DP voltammograms

Simultaneous Square-Wave Voltammetric Determination of Phenolic Antioxidants (BHA and BHT) in Food Using a Boron-Doped Diamond Electrode R.A. Medeiros, R.C. Rocha-Filho, O. Fatibello-Filho, Food Chemistry, 123, 886 (2010) BHA = butylated hydroxyanisole; BHT = butylated hydroxytoluene

BHA: 0.60 – 10  M; LOD = 0.14  M BHT: 0.60 – 10  M; LOD = 0.25  M BHA BHT Highlight: LODs lower than those previously reported

Flow Injection analysis system Potentiostat/galvanostat: Autolab PGSTAT-30 (Ecochemie)

Flow electrochemical cell Working electrode : BDD 8000 ppm; 0.33 cm 2 Reference electrode Ag/AgCl (3.0 mol L –1 KCl) Counter electrode : stainless steel tube E. M. Richter et al. Quim. Nova, 26(6), 839 (2003) L. Andrade et al. Anal. Chim. Acta 654, 127 (2009)

Flow injection simultaneous determination of BHA and BHT with multiple pulse amperometric detection at a BDD electrode Fig. Hydrodynamic voltammograms obtained for (A) 0.10 mmol L -1 BHA and (B) 0.10 mmol L -1 BHT by use BDD; flow rate = 2.4 mL min -1 and V sample = 250 µL R.A. Medeiros; B.C. Lourenção; R.C. Rocha-Filho, O. Fatibello-Filho; Anal. Chem.,82, 8658 (2010)

(A) MPA waveform applied to the cathodically pretreated BDD working electrode as a function of time. (B) Flow-injection pulse amperometric responses in triplicate for solutions containing 50 μmol L -1 BHA or BHT or both analytes simultaneously at this concentration. Supporting electrolyte: aqueous ethanolic (30% ethanol, v/v) 10 mmol L -1 KNO 3 solution (pHcond =1.5) adjusted with concentrated HNO 3 ); flow rate 2.4 mL min -1 ; injected volume 250 μL.

FIA-MPA amperograms obtained after injections of solutions containing BHA ( μmol L -1 ) and BHT ( μmol L -1 ) simultaneously or different samples of mayonnaise (A-D). Supporting electrolyte: aqueous ethanolic (30% ethanol, v/v) 10 mmol L -1 KNO 3 solution (pHcond =1.5) adjusted with concentrated HNO 3 ); flow rate 2.4 mL min -1 ; injected volume 250 μL.

(A) Diagram of the multicommutated stop-flow system: V 1 and V 2 : solenoid valves; A: sample or standard solution; C: carrier solution (BR buffer pH 7.0). (B) Transient DPV signals in triplicate for sulfamethoxazole (1.0 – 8.0 mg L –1 ) and trimethoprim (0.2 – 1.6 mg L –1 ) determination in pharmaceuticals. Sampling Rate = 30 h -1

Fig. (A) Schematic representation of Tyr-AuNPs/BDD biosensor fabrication process and (B) SEM image of BDD and (C) BDD/AuNPs. Electrodeposition potential = -0.4 V and electrodeposition time = 40 s. (A) (B)(C) Tyr-AuNPs/BDD biosensor B. C. Janegitz, R. A. Medeiros, R. C. Rocha-Filho, O. Fatibello-Filho, Diamond and Rel. Mater., 25, 128 (2012); J.T. Matsushima, L.C.D. Santos, A.B. Couto, M.R. Baldan, N.G. Ferreira, Quim. Nova, 35(1), 11 (2012)

Amorphous carbon nitride (a-CNx) electrode CV voltammograms (v = 50 mV s –1 ) for a-CNx electrode in 0.5 mol L –1 H 2 SO 4 supporting electrolyte. Lagrini et al. Electrochemistry Communications 6, 245 (2004) R.A. Medeiros, R. de Matos, C. Debiemme-Chouvy, A. Pailleret, H. Cachet, C. Deslouis, R. C. Rocha-Filho, O. Fatibello-Filho, Electrochemistry Communications, (2012)

Fig. CV voltammograms (ν = 50 mV s –1 ) for 1.0 x 10 –3 mol L –1 [K 3 Fe(CN) 6 ] in 0.5 mol L –1 KCl using the a-CN x film as-received and after PTA and PTC. Electrochemical pretreatment

Fig. CV voltammograms (ν = 50 mV s –1 ) obtained for 0.5 mmol L –1 dopamine (black) and 1.0 mmol L –1 ascorbic acid (gray) in 0.1 mol L –1 HClO 4 using an a-CN x electrode anodically (A) or catodically (B) pretreated in 0.1 mol L –1 KOH Pretreatment conditions Current density: 3 mA cm –2 for PTA;  3 mA cm –2 for PTC in a 0.1 mol L –1 KOH Time: PTA: 180 s; PTC: 180 s

Dental and/or Amalgam Electrode Alloy electrodes: Sn-Bi; Pt-Ru, Pt-Pd, Pt-Rh, Pt-Ir, Pt-Au, Pd-Au, Cu-Au... Bismuth film electrode, Antimony film electrode Carbon, carbon paste and carbon composite electrodes: Glassy carbon, Graphite, Pyrolitic graphite electrodes carbon nanotubes fullerene boron-doped diamond (BDD) carbon fibres graphene amorphous carbon nitride (a-CNx) Conclusions and prospects Dropping mercury electrode (DME) vs Alternative electrodes

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