pH Measurement and Control

The article contains sections titled: 1 Introduction and Theory 1.1 Importance of pH Measurements 1.2 pH Definition and pH Buffers 1.3 Activities 1.4 Self-Dissociation 2 pH Measurement and Technologies 2.1 Electrochemical Methods 2.2 The Hydrogen Electrode in pH Measurements 2.3 Optical pH Measurement Technology 2.4 pH Standard Solutions and Traceability 2.4.1 Primary pH Standards 2.4.2 Secondary pH Standards 3 Electrode Cell and Electrode Architecture 3.1 Principal Types of pH Electrodes 3.2 Glass Electrodes 3.3 Reference Electrodes 3.4 Liquid Junction 3.5 Combined Electrodes 3.6 Testing Glass Electrodes 3.7 Alternative pH Electrodes 4 pH Signal Processing 4.1 Potential Input Amplifier 4.2 pH Calculation and Correction Functions 4.3 pH meters and Transmitters: Data Visualization and Output 4.4 Testing and Input Calibration of pH Meters and Transmitters 4.5 Digitalization of pH Sensors and Sensor Self-diagnostics 5 pH Measurement Requirements in Different Industries 5.1 pH Measurement in the Pharmaceutical Industry 5.2 pH Measurement in the Food and Beverage Industry 5.3 pH Measurements in the Chemical Industry 5.3.1 pH Measurement in Concentrated Solutions 5.3.2 Suspension Effects 5.3.3 pH Measurement in Nonaqueous Solvents 5.3.4 Extreme Temperature 5.3.5 Interfering Compounds 6 Good Practices in Laboratory pH Measurement 6.1 Evaluation and Selection 6.1.1 Selection of a pH Meter 6.1.2 Selection of a pH Electrode 6.1.3 Selection of pH Buffer Solutions 6.1.4 Selection of PC Software and Additional Accessories 6.2 Installation and Qualification 6.3 Routine Operation 6.3.1 Sensor Calibration and Verification 6.3.2 Sensor Care and Maintenance 6.3.3 Buffer Quality 6.3.4 Meter Settings 6.4 Product Retirement 7 Process pH Measurement 7.1 Off-Line, At-Line, and Inline Measurements 7.2 Inline pH Sensor Calibration under Process Conditions 8 Inline Installations 8.1 Immersion Assemblies 8.2 Built-In Static Assemblies 8.3 Retractable Assemblies 8.4 Flow-Through Assemblies 9 pH Signal Integration 9.1 Analog Signal Integration 9.2 Digital Signal Integration 10 pH Control References