Working with Ion-Selective Electrodes: Chemical Laboratory Practice

ISBN-13: 9783642672781 / Angielski / Miękka / 2011 / 226 str.

K. Cammann; A. H. Schr Der

Opis

The first section introduces the electrochemical nomenclature necessary for under standing the literature on ion-selective electrodes and discusses the general principles behind all electrodes. The second section is concerned with the problems which arise in any accurate elec trode potential measurement in practice. Here the most important reference electrodes are discussed with special reference to their use in conjunction with ion-selective elec trodes. From experience, almost 75% of all problems which arise when working with ion-selective electrodes are on account of the reference electrode. After the reader is aquainted with the basic problems involved, the third section deals with individual ion-selective electrodes; their properties, handling and methods of pre paration. Here the discussion of these electrodes is not arranged according to the spe cies detected, but rather according to the kind of construction, since from this view point characteristic properties are much the same and handling procedures need only be described once for an entire series of similar electrodes. The fourth section discusses amplifiers. Here the problems of high-ohmic EMF meas urements such as noise level, insulation, static charging and ground loops are discussed. The fifth section is devoted to the various evaluation methods. Here a few schemes and examples are provided to indicate optimum practical procedures and the accura cies attainable with the various methods are discussed. The last section describes special set-ups such as clinical flow-thru cells, microelec trodes for measuring intracellular ionic activities, industrial on-line techniques and continuous environmental protection monitors."

Spis treści

1 Fundamentals of Potentiometry.- 1.1 Electrode Processes.- 1.2 The Nernst Equation.- 1.3 Potential-Determining Ions.- 1.4 Ion-Selective Electrode Materials.- 1.5 The Potentiometric Selectivity Coefficient as a Quantitative Indication of the Electrode Selectivity.- 2 Electrode Potential Measurements.- 2.1 Reference Electrodes.- 2.2 The Standard Hydrogen Electrode as a Primary Reference Electrode.- 2.2.1 Preparation.- 2.2.2 Characteristics.- 2.3 The Liquid Junction Potential.- 2.3.1 Origin.- 2.3.2 Calculation.- 2.3.3 Salt Bridge Electrolytes.- 2.3.4 Construction of the Salt Bridge Electrolyte/Sample Solution Contact Zone.- 2.3.5 Cells Without Liquid Junction.- 2.4 Secondary Reference Electrodes.- 2.4.1 Silver/Silver Chloride.- 2.4.1.1 Preparation.- 2.4.1.2 Characteristics.- 2.4.2 Thallium Amalgam/Thallium (I) Chloride (Thalamid®).- 2.4.2.1 Characteristics.- 2.4.3 Mercury/Mercury (I) Chloride (Calomel).- 3 Ion-Selective Electrodes.- 3.1 General Construction Principles.- 3.2 Solid-State Membrane Electrodes.- 3.2.1 Glass Membrane Electrodes For Li+, Na+, K+, Rb+, Cs+, NH4+, NR4+, Ag+, Tl+ Ions.- 3.2.1.1 Construction.- 3.2.1.2 Characteristics.- 3.2.1.3 Handling.- 3.2.1.4 Sample Preparation.- 3.2.2 Homogeneous Solid-State Membrane Electrodes For Ag+, Cd2+, Cu2+, Pb2+, S2-, F-, Cl-, Br-, I-, SCN-, CN- Ions.- 3.2.2.1 Principles.- 3.2.2.2 Construction.- 3.2.2.3 Preparation of Solid-State Membrane Electrodes Based on Ag2S.- 3.2.2.4 Characteristics.- 3.2.2.5 Handling.- 3.2.2.6 Sample Preparation.- 3.2.3 Heterogeneous Solid-State Membrane Electrodes For Ag+, Cl-, Br-, I-,CN-, SCN-, S2- Ions.- 3.2.3.1 Construction.- 3.2.3.2 Preparation.- 3.2.3.3 Characteristics.- 3.2.3.4 Handling.- 3.3 Porous and Nonporous Supported Ion Exchanger and Neutral Carrier Membrane Electrodes.- 3.3.1 Ion-Exchangers For Ca2+, Me2+ Cations and Cl-, ClO4-, NO3-, BF4- Anions.- 3.3.2 Neutral Carrier Compounds For Li+, Na+, K+, Rb+, Cs+, NH4+, NR4+, Ca2+ and Ba2+ Cations.- 3.3.3 Construction.- 3.3.4 Preparation of PVC Membrane Electrodes.- 3.3.5 Characteristics.- 3.3.6 Handling.- 3.3.7 Further Electro-Active Phases.- 3.4 Solid State Electrodes with Electroactive Coatings.- 3.5 Gas Sensors For CO2, NH3, SO2, NO2, HF, H2S, HCN, etc..- 3.5.1 Principles.- 3.5.2 Construction.- 3.5.3 Characteristics of Gas-Sensitive Electrodes.- 3.5.4 Handling.- 3.5.5 Sample Preparation.- 3.6 Bio-Sensors.- 3.6.1 Principles.- 3.6.2 Construction.- 3.6.3 Preparation of Enzyme Electrodes.- 3.6.4 Characteristics of Bio-Sensors.- 3.6.5 Sample Preparation with Bio-Sensors.- 4 Measuring Techniques with Ion-Selective Electrodes.- 4.1 Equivalent Circuit for a Cell with Liquid Junction.- 4.2 Measuring the EMF of an Electrochemical Cell.- 4.3 Choosing an EMF Measuring Device.- 4.4 Characteristics of Electrometer Amplifiers.- 4.4.1 Resolving Power.- 4.4.2 Insulation Problems.- 4.4.3 Charging Phenomena.- 4.4.4 Ground Loops.- 5 Analysis Techniques Using Ion-Selective Electrodes.- 5.1 Calibration Curves.- 5.1.1 Determination of Activity Using an Activity Calibration Curve.- 5.1.2 Determination of Concentration Using a Concentration Calibration Curve.- 5.2 Direct Indication on the pH or plon Scale of an Instrument.- 5.3 Titration Procedures for Determining Concentrations.- 5.3.1 Prerequisites.- 5.3.2 Titration Errors.- 5.3.3 Sample Preparation for Titrations.- 5.3.4 Titration to a Pre-determined EMF Value.- 5.3.4.1 On the Basis of a Titration Curve.- 5.3.4.2 On the Basis of a Concentration Cell Set-Up.- 5.3.5 “Chemically Linearized” Titration Curves (One Point Titration).- 5.4 Concentration Determinations with the Help of a Standard Addition with a Known Electrode Slope S.- 5.4.1 Measuring the Change in EMF upon Addition of a Standard Solution to the Sample Solution.- 5.4.2 Measuring the Change in EMF upon Addition of the Sample Solution to a Standard Solution.- 5.5 Concentration Determinations with the Help of a Standard Addition with an Unknown Electrode Slope S.- 5.5.1 Method of Double Standard Addition.- 5.5.2 Method of Standard Addition with Subsequent Dilution.- 5.6 Practical Example of the Addition Method: Sodium and Potassium Determination in Blood Serum.- 5.7 Concentration Determinations with the Help of a “Mathematically Linearized” Titration Curve.- 5.8 Practical Example of the Gran Extrapolation Method: Determination of Chloride in the ppm Range.- 5.8.1 Principles.- 5.8.2 Preparatory Work.- 5.8.3 Blank Determination.- 5.8.4 Chloride Content Determination of the Sample Solution.- 5.9. Determination of Some Characteristic Electrode Parameters.- 5.9.1 Determination of the Detection Limit.- 5.9.2 Determination of the Selectivity Coefficient.- 6 Applications of Ion-Selective Electrodes.- 6.1 Physiology, Biology, Medicine.- 6.1.1 Measurements in Extracellular Fluids.- 6.1.1.1 In-vitro Measurements.- 6.1.1.1.1 Sample Preparation.- 6.1.1.1.2 The Indicating Electrode.- 6.1.1.1.3 The Reference Electrode.- 6.1.1.2 In-vivo Measurements.- 6.1.2 Measurements of Intracellular Ion Activities.- 6.1.2.1 Preparation of Ion-Selective Microelectrodes.- 6.1.2.2 Guarded Signal Wires for Extremely High Ohmic Electrodes.- 6.1.2.3 Reference Microelectrodes.- 6.1.2.4 Special Amplifiers for Microelectrode Applications.- 6.2 Continuous Measurements in Industry and Environmental Research.- 6.2.1 Flow-thru Cells.- 6.2.1.1 Influence of Grounding.- 6.2.1.2 Influence of Temperature.- 6.2.1.3 Analysis Techniques with Flow-thru Measurements.- 6.2.1.4 Flow-thru Measurements without Reference Electrodes.- 6.2.1.4.1 Direct Potentiometry.- 6.2.1.4.2 Concentration Determination through Standard Solution Addition.- 6.2.1.4.3 Indirect Concentration Determination.- 6.2.1.4.4 The Cyanide Monitor as an Example of Industrial On-Line Measurements.- 6.2.2 Concentration Determination Via a Continuous Titration.- Outlook.- A.1 Concentration, Activity and Activity Coefficient.- A.1.1 Preparing Accurate Activity Calibration Solutions.- A.2 Survey of the Temperature Dependence of Commonly Used Reference Electrodes.- A.3 Table for Evaluation Using Analysis Technique 5.4.1.- A.4 Table for Evaluation Using Analysis Technique 5.4.2.- A.5 Table for Evaluation Using Analysis Technique 5.5.1.- A.6 Table for Evaluation Using Analysis Technique 5.5.2.- A.7 Evaluation Table for Standard Addition + 1:1 Dilution.- A.8 Ion-Selective Electrode Manufacturers and/or Dealers.- Literature.- Index of Symbols Used.