PREFACE The goal of textbook is to cover the full scope of modern electroanalytical techniques and devices. The main emphasis is on electroanalysis, rather than physical electrochemistry. The objective … 1 ABBREVIATIONS AND SYMBOLS a Activity A Absorbance A Area of Electrode 2 DAFTAR ISI PREFACE…........ .......................................................................................................... 1 ABBREVIATIONS AND SYMBOLS .......................................................................... 2 DAFTAR ISI……. ......................................................................................................... 3 DAFTAR TABEL ........................................................................................................ 10 DAFTAR FIGURE ...................................................................................................... 11 CHAPTER 1 Fundamental Concepts .................................................................. 12 1 Why Electroanalysis?............................................................................................ 12 2 Faradaic Process.................................................................................................... 12 1.2 Mass Transpot-Controlled Reactions ............................................................. 12 1.21 Potensial-Step Experiment ....................................................................... 13 2.21 Potensial-Sweep Experiment ................................................................... 13 2.2 Reactions Controlled by the Rate of Electron Transfer ................................. 14 1.22 Activated Complex Theory ...................................................................... 14 3 The Electrical Double Layer ................................................................................. 14 4 Electrocapillary Effect .......................................................................................... 14 5 Supplementary Reading ........................................................................................ 14 6 References ............................................................................................................. 14 7 Questions............................................................................................................... 14 CHAPTER 2 Study of Electrode Reaction .......................................................... 15 3 1 Cyclic Voltammetry .............................................................................................. 15 1.1 Data Interpretation ......................................................................................... 15 1.11 Reversible Systems .................................................................................. 15 2.11 Irreversible and Quasi-Reversible Systems ............................................. 15 2.1 Study of Reaction Mechanisms ..................................................................... 15 3.1 Study of Adsorption Processes ...................................................................... 15 4.1 Quantitative Applications .............................................................................. 15 2 Spectroelectrochemistry ........................................................................................ 15 1.2 Experimental Arangement ............................................................................. 16 2.2 Principles and Applications ........................................................................... 16 3.2 Other Spectroelectrochemical and Spectroscopic Techniques ...................... 16 3 Scanning Probe Microscopy ................................................................................. 16 1.3 Scanning Tunneling Microscopy ................................................................... 16 2.3 Atomic Force Microscopy ............................................................................. 17 3.3 Scanning Electrochemical Microscopy.......................................................... 17 4 Electrochemical Quartz Crystal Microbalance ..................................................... 17 5 References ............................................................................................................. 17 6 Examples ............................................................................................................... 17 7 Questions............................................................................................................... 17 CHAPTER 3 Controlled Potential Techniques ................................................... 18 1 Chronoamperometry ............................................................................................. 18 4 2 Polarography ......................................................................................................... 18 3 Pulse Voltammetry................................................................................................ 18 1.3 Normal Pulse Voltammetry ........................................................................... 18 2.3 Differential Pulse Voltammetry ..................................................................... 19 3.3 Square Wave Voltammetry ............................................................................ 19 4.3 Staircase Voltammetry ................................................................................... 19 4 AC Voltammetry................................................................................................... 19 5 Stripping Analysis ................................................................................................. 19 1.5 Anodic Stripping Voltammetry...................................................................... 19 2.5 Potentiometric Stripping Analysis ................................................................. 19 3.5 Adsorptive Stripping Voltammetry and Potentiometry ................................. 19 4.5 Cathodic Stripping Voltammetry ................................................................... 19 5.5 Applications ................................................................................................... 20 6 Flow Analysis ....................................................................................................... 20 1.6 Principles........................................................................................................ 20 2.6 Cell Design..................................................................................................... 20 3.6 Mass Transport and Current Response .......................................................... 21 4.6 Detection Modes ............................................................................................ 21 7 References ............................................................................................................. 21 8 Examples ............................................................................................................... 21 9 Questions............................................................................................................... 21 5 CHAPTER 4 Practical Consideration .................................................................. 22 1 Electrochemical Cells ........................................................................................... 22 2 Solvents and Supporting Electrolytes ................................................................... 22 3 Oxygen Removal .................................................................................................. 22 4 Instrumentation ..................................................................................................... 22 5 Working Electrodes .............................................................................................. 22 1.5 Mercury Electrodes ........................................................................................ 22 2.5 Solid Electrodes ............................................................................................. 23 1.52 Rotating Disk and Ring Disk Electrodes ................................................. 23 2.52 Carbon Electrodes .................................................................................... 23 1.522 Glassy Carbon Electrodes .................................................................. 23 2.522 Carbon Paste Electrodes .................................................................... 24 3.522 Carbon Fiber Electrodes .................................................................... 24 3.52 Metal Electrodes ...................................................................................... 24 3.5 Chemically Modified Electrodes ................................................................... 24 1.53 Self Assembled Monolayers .................................................................... 24 2.53 Sol Gel Encapsulation of Reactive Species ............................................. 24 3.53 Electrocatalytic Modified Electrodes ....................................................... 24 4.53 Pre concentrating Electrodes.................................................................... 24 5.53 Permselective Coatings ............................................................................ 24 6.53 Conducting Polymers ............................................................................... 25 6 4.5 Microelectrodes.............................................................................................. 25 1.54 Diffusion at Microelectrodes ................................................................... 25 2.54 Configuration of Microelectrodes ............................................................ 25 3.54 Composite Electrodes .............................................................................. 25 6 References ............................................................................................................. 25 7 Examples ............................................................................................................... 26 8 Questions............................................................................................................... 26 CHAPTER 5 Potentiometry................................................................................. 27 1 Principles of Potentiometric Measurements ......................................................... 27 2 Ion Selective Electrodes ........................................................................................ 27 1.2 Glass Electrodes ............................................................................................. 27 1.21 pH Electrodes ........................................................................................... 27 2.21 Glass Electrodes for Other Cations .......................................................... 27 2.2 Liquid Membrane Electrodes ......................................................................... 27 1.22 Ion Exchanger Electrodes ........................................................................ 27 2.22 Neutral Carrier Electrodes ....................................................................... 27 3.2 Solid State Electrodes .................................................................................... 28 4.2 Coated Wire Electrodes ................................................................................. 28 3 Online and in Vivo Potentiometric Measurements ............................................... 28 4 References ............................................................................................................. 29 5 Examples ............................................................................................................... 29 7 6 Questions............................................................................................................... 29 CHAPTER 6 Electrochemical Sensors ................................................................ 30 1 Electrochemical Biosensors .................................................................................. 30 1.1 Enzyme Based Electrodes .............................................................................. 30 1.11 Impractical and Theoretical Considerations ............................................ 30 2.11 Enzyme Electrodes of Analytical Significance........................................ 30 1.112 Glucose sensors .............................................................................. 30 2.112 Ethanol Electrodes .......................................................................... 30 3.112 Urea Electrodes............................................................................... 30 4.112 Toxin (Enzyme Inhibition) Biosensors ........................................... 30 3.11 Tissues and Bacteria Electrodes............................................................... 31 2.1 Affinity Biosensors ........................................................................................ 31 1.12 Immunosensors ........................................................................................ 31 2.12 DNA Hybridization Biosensors ............................................................... 31 3.12 Receptor Based Sensors ........................................................................... 31 2 Gas Sensors ........................................................................................................... 31 1.2 Carbon Dioxide Sensors ................................................................................ 32 2.2 Oxygen Electrodes ......................................................................................... 32 3 Solid State Devices ............................................................................................... 32 1.3 Microfabrication of Solid State Sensor Assemblies ...................................... 32 2.3 Microfabrication Techniques ......................................................................... 32 8 4 Sensor Arrays ........................................................................................................ 32 5 References ............................................................................................................. 32 6 Examples ............................................................................................................... 32 7 Questions............................................................................................................... 32 INDEX………….. ....................................................................................................... 33 9 DAFTAR TABEL Table 1 Properties of Controlled Potential Techniques ............................................ 12 Table 2 Functional Groups Reducible at the Dropping Mercury Electrode ............. 18 Table 3 Reprentative Application of Stripping Analysis .......................................... 20 Table 4 Commonly Used Membrane Barriers .......................................................... 25 Table 5 Some Common Enzyme Electrode .............................................................. 31 10 DAFTAR FIGURE Figure 1 The Three Modes of Mass Transport ....................................................... 13 Figure 2 STM image of an electrochemically activated glassy carbon surface ...... 16 Figure 3 Design of a system for in-situ electrochemical scanning tunneling microscopy................................................................................................ 17 Figure 4 The Dropping Mercury Electrode............................................................. 23 Figure 5 Coated Wire Ion Selective Electrode........................................................ 28 11 CHAPTER 1 Fundamental Concepts 1 Why Electroanalysis? Electroanalytical techniques are concerned with the interplay between electricity and chemistry, namely the measurements of … Table 1 Properties of Controlled Potential Techniques 2 Faradaic Process The objective of controlled-potensial electroanalytical experiments is to obtain a current response that is related to the concentration of the target analyte. This objective is … 1.2 Mass Transpot-Controlled Reactions Mass transport occurs by three different modes : 12 Figure 1 The Three Modes of Mass Transport 1.21 Potensial-Step Experiment Let us see, for example, what happens in a potensial-step experiment involving the reduction of O to R, a … 2.21 Potensial-Sweep Experiment Let us move to a voltammetric experiment involving a linear potensial scan, the reduction of O to R and a quiescent … 13 2.2 Reactions Controlled by the Rate of Electron Transfer In this section we consider experiments in which the current is controlled by the rate of electron transfer (i.e., reactions with … 1.22 Activated Complex Theory The effect of the operating potential upon the rate constans (equations 1-18 and 1-19) can be … 3 The Electrical Double Layer The electrical double layer is the array of charged particles and/or oriented dipoles that exists at every material interface. In electrochemistry such a layer reflects the … 4 Electrocapillary Effect Electrocapilarry is the study of interfacial tension as a function of the electrode potential. Such a study can provide useful insight into … 5 Supplementary Reading Several international journals bring together papers and reviews covering innovations and trends in the field of electroanalytical chemistry : 6 References J.R.Maloy, J. Chem. Educ., 60, 285 (1983) 7 Questions Show or draw the concentration profile/gradient near the electrode surface during a linear scan voltammetric experiment … 14 CHAPTER 2 Study of Electrode Reaction 1 Cyclic Voltammetry Cyclic voltammetry is the most widely used techniques for acquiring qualitative information about electrochemical reactions. The power of cyclic voltammetry results … 1.1 Data Interpretation The cyclic voltammogram is characterized by several important parameters. Four of these observables, two … 1.11 Reversible Systems The peak current for a reversible couple (at 25oC), is given by Randles-Sevcik equation : 2.11 Irreversible and Quasi-Reversible Systems For irreversible processes (those with sluggish electron exchange), the individual peaks are reduced in … 2.1 Study of Reaction Mechanisms One of the most important applications of cyclic voltammetry is for qualitative diagnosis of chemical reactions that precede or succeed the … 3.1 Study of Adsorption Processes Cyclic voltammetry can also be used for evaluating the interfacial behavior of electroactive … 4.1 Quantitative Applications Cyclic voltammetry can also be useful for quantitative purposes, based on measurements of peak current (equation 2-1). Such … 2 Spectroelectrochemistry The coupling of optical and electrochemical methods spectroelectrochemistry has been employed for over … 15 1.2 Experimental Arangement Optically transparent electrodes (OTEs), which enable light to be passed through … 2.2 Principles and Applications The primary advantage of spectroelectrochemistry is the cross-correlation of information from the simultaneous electrochemical and optical … 3.2 Other Spectroelectrochemical and Spectroscopic Techniques In addition to UV-visible absorption measurements, other spectroscopic techniques can be used for monitoring the dynamics … 3 Scanning Probe Microscopy The recently developed scanning probe microscopies (SPM) promise to revolutionize the understanding of electrode … 1.3 Scanning Tunneling Microscopy Scanning tunneling microscopy (STM) has revolutionized the field … Figure 2 STM image of an electrochemically activated glassy carbon surface 16 2.3 Atomic Force Microscopy Atomic force microscopy (AFM) has become a standard technique for high resolution imaging … Figure 3 Design of a system for in-situ electrochemical scanning tunneling microscopy 3.3 Scanning Electrochemical Microscopy The scanning tunneling microscope (STM) has led to several other variants … 4 Electrochemical Quartz Crystal Microbalance The electrochemical quartz crystal microbalance (EQCM) is a powerful tool for elucidating interfacial … 5 References R.S.Nicholson and I.Shain … 6 Examples Examples 2-1 The reversible oxidation of dopamine (DA) … 7 Questions Explain and demonstrate clearly how spectroelectrochemistry can provide useful … 17 CHAPTER 3 Controlled Potential Techniques The basis of all controlled potential techniques is the measurement of the current response … 1 Chronoamperometry Chronoamperometry involves stepping the potential of the working electrode from a value … 2 Polarography Polarography is a subclass of voltammetry in which the working electrode is the dropping mercury electrode (DME). Because … Table 2 Functional Groups Reducible at the Dropping Mercury Electrode 3 Pulse Voltammetry Pulse voltammetry techniques, introduced by Baker and Jenkin (3), are aimed at lowering the detection limits … 1.3 Normal Pulse Voltammetry Normal pulse voltammetry consists of a series of pulses of increasing amplitude applied … 18 2.3 Differential Pulse Voltammetry Differential pulse voltammetry is an extremely useful technique for measuring trace levels of organic and … 3.3 Square Wave Voltammetry Square wave voltammetry is a large amplitude differential technique in which a waveform composed of a symmetrical … 4.3 Staircase Voltammetry Staircase voltammetry has been proposed as a useful tool for rejecting the background charging current. The potential time … 4 AC Voltammetry Alternating current (AC) voltammetry is a frequency domain technique that involves the superimposition of a small amplitude … 5 Stripping Analysis Stripping analysis is an extremely sensitive electrochemical technique for measuring trace … 1.5 Anodic Stripping Voltammetry Anodic stripping voltammetry (ASV) is the most widely used form of stripping analysis. In the case, the metals … 2.5 Potentiometric Stripping Analysis Potentiometric stripping analysis (PSA), known also as stripping potentiometry, differs from ASV in methods used … 3.5 Adsorptive Stripping Voltammetry and Potentiometry Adsorptive stripping analysis greatly enhances the scope of stripping measurements toward numerous trace … 4.5 Cathodic Stripping Voltammetry Cathodic stripping voltametry (CSV) is the “mirror image” of ASV. It involves anodic depotition of the … 19 5.5 Applications The remarkable sensitively, broad scope, and low cost of stripping analysis have led to … 6 Flow Analysis An electrochemical detector uses the electrochemical properties of target analytes for their determination … Table 3 Reprentative Application of Stripping Analysis 1.6 Principles Electrochemical detection is usually performed by controlling the potential of the working electrode at a … 2.6 Cell Design A wide range of cell designs have been used for electrochemical monitoring of flowing streams. The cell design must … 20 3.6 Mass Transport and Current Response Well defined hydrodynamic conditions, with high rate of mass transport, are essential for successful … 4.6 Detection Modes The simplest, and by far the most common, detection scheme is the measurement of the ... 7 References D.Ilkovic, … 8 Examples Examples 3-1 Voltammogram (a) … 9 Questions Describes clearly the principle and operation of … 21 CHAPTER 4 Practical Consideration The basic instrumentation required for controlled potential experiments is relatively inexpensive … 1 Electrochemical Cells Three electrode cells (e.g., Figure 4-1) are commonly used in controlled potential … 2 Solvents and Supporting Electrolytes Electrochemical measurements are commonly carried out in a medium that consists of solvent … 3 Oxygen Removal The electrochemical reduction of oxygen usually proceeds via two well separated two electron … 4 Instrumentation Rapid advences in microelectronics, and in particular the introduction of operational amplifiers, have … 5 Working Electrodes The performance of the voltammetric procedure is strongly influenced by the material of the working … 1.5 Mercury Electrodes Mercury is a very attractive choice of electrode material because it has a high hydrogen overvoltage that … 22 Figure 4 The Dropping Mercury Electrode 2.5 Solid Electrodes The limited anodic potential range of mercury electrodes has precluded their utility for monitoring … 1.52 Rotating Disk and Ring Disk Electrodes The rotating disk electrode (RDE) is vertically mounted in the shaft of a synchronous controllable … 2.52 Carbon Electrodes Solid electrodes based on carbon are currently in widespread use in electroanalysis, primarily because of their broad … 1.522 Glassy Carbon Electrodes 23 Glassy (or”vitreous”) carbon has been very popular because its excellent mechanical … 2.522 Carbon Paste Electrodes Carbon paste electrodes, which use graphite powder mixed with various water immiscible organic … 3.522 Carbon Fiber Electrodes The growing interest in ultramicroelectrodes (section … 3.52 Metal Electrodes While a wide choice of noble metals is available, platinum and gold are the most widely used metallic electrodes. Such … 3.5 Chemically Modified Electrodes Chemically modified electrodes (CMEs) represent a modern approach to electrode systems. These … 1.53 Self Assembled Monolayers Spontaneously adsorbed monolayers of n-alkanethiols … 2.53 Sol Gel Encapsulation of Reactive Species Another new and attractive route for tailoring electrode surfaces involves the low temperature encapsulation … 3.53 Electrocatalytic Modified Electrodes Often the desired redox reaction at the bare electrode involves slow electron transfer kinetics … 4.53 Pre concentrating Electrodes Preconcentrating CMEs, with surfaces designed for reacting and binding of target analytes, hold … 5.53 Permselective Coatings Permselective coatings offer to bring higher selectivity and stability to electrochemical devices. This … 24 6.53 Conducting Polymers Electronically conducting polymers (such as polypyrrole, poly thiophene, and polyaniline) have … Table 4 Commonly Used Membrane Barriers 4.5 Microelectrodes Miniaturization is a growing trend in the field of analytical chemistry. The miniaturization of working … 1.54 Diffusion at Microelectrodes The total diffution limited current is composed of the planar flux diffusion components : 2.54 Configuration of Microelectrodes Electrodes of different materials have been miniaturized in many geometrical shapes … 3.54 Composite Electrodes Composite electrodes couple the advantages of single microelectrode systems with significantly … 6 References T.P.De Angelis, R.E.Bond, … 25 7 Examples Examples 4-1 A rotating ring … 8 Questions What are the advantages of … 26 CHAPTER 5 Potentiometry 1 Principles of Potentiometric Measurements In potentiometry information on the compotition of a sample is obtained through the … 2 Ion Selective Electrodes The discussion of section … 1.2 Glass Electrodes Glass electrodes are … 1.21 pH Electrodes the most common potentiometric devices is the pH electrode. This electrode has been widely … 2.21 Glass Electrodes for Other Cations From the early days of galss pH electrodes, it was noticed that alkaline solutions display … 2.2 Liquid Membrane Electrodes Liquid membrane types ISEs, based on water immiscible liquid substances impregnated in a … 1.22 Ion Exchanger Electrodes One of the most successful liquid membrane electrodes is selective toward calcium. Such an electrode relies on the ability … 2.22 Neutral Carrier Electrodes In addition to charged liquid ion exchangers, liquid membrane electrodes often rely … 27 3.2 Solid State Electrodes Considerable work has been devoted to the development of solid membranes that are selective primarily … 4.2 Coated Wire Electrodes Coated wire electrodes (CWEs), introduced by Freiser in the mid 1970s, are prepared by coating … Figure 5 Coated Wire Ion Selective Electrode 3 Online and in Vivo Potentiometric Measurements Various online monitoring systems can benefit from the inherent specificity, wide scope, dynamic … 28 4 References J.Koryta, … 5 Examples Examples 5-1 Calculate the … 6 Questions Discuss clearly the … 29 CHAPTER 6 Electrochemical Sensors A chemical sensor is a small device that can be used for direct measurement of the … 1 Electrochemical Biosensors Electrochemical biosensors combine the analytical power of electrochemical techniques with … 1.1 Enzyme Based Electrodes Enzymes are proteins that catalyze chemical reactions in living systems. Such catalysts are not … 1.11 Impractical and Theoretical Considerations The operation of an enzyme electrode is illustrated in … 2.11 Enzyme Electrodes of Analytical Significance 1.112 Glucose sensors The determination of glucose in blood plays a crucal role in the diagnosis and therapy … 2.112 Ethanol Electrodes The reliable sensing of ethanol is of great significance in various disciplines. The enzymatic … 3.112 Urea Electrodes The physiologically important substrate urea can be sensed based on the following … 4.112 Toxin (Enzyme Inhibition) Biosensors Enzyme affectors (inhibitors and activators) that influence the rate of biocatalytic reactions can also be measured. Sensing … 30 3.11 Tissues and Bacteria Electrodes The limited stability of isolated enzymes, and the fact that some enzymes are expensive or even … Table 5 Some Common Enzyme Electrode 2.1 Affinity Biosensors Affinity sensors exploit selective binding of certain biomolecules (e.g. antibodies … 1.12 Immunosensors Most reported affinity biosensors are based on immunological reactions involving the shape … 2.12 DNA Hybridization Biosensors Nucletic acid recognition layers can be combined with electrochemical tranducers to form new and important types of … 3.12 Receptor Based Sensors Another new and promising avenue of sensing is the use of chemoreceptors as biological recognition … 2 Gas Sensors Real time monitoring of gases, such as carbon dioxide, oxygen, and ammonia, is of great … 31 1.2 Carbon Dioxide Sensors Carbon dioxide devices were originally developed by Severinghaus and Bralley … 2.2 Oxygen Electrodes While most gas sensors rely on potentiometric detection, the important oxygen probe … 3 Solid State Devices The integration of chemically sensitivemembranes with solid state electronics has led to the evolution … 1.3 Microfabrication of Solid State Sensor Assemblies Other miniaturized solid state sensors can be … 2.3 Microfabrication Techniques Microfabrication technology has made a considerable impact on the miniaturization of electrochemical sensors and … 4 Sensor Arrays So far we have discussed the one sensor/one analyte approach. However, arrays of independent … 5 References G.Sittamplam and … 6 Examples Example 6-1 Chronoamperogram a … 7 Questions Describe different … 32 INDEX Absorbance, … 33 34
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