contents
PRELIMINARY OPERATIONSOF ANALYSIS
1.1
1.1 SAMPLING 1.2
1.1.1 Handling the Sample in the Laboratory 1.2
1.1.2 Sampling Methodology 1.3
1.2 MIXING AND REDUCTION OF SAMPLE VOLUME 1.6
1.2.1 Introduction 1.6
1.2.2 Coning and Quartering 1.6
Figure 1.1 Coning Samples 1.7
Figure 1.2 Quartering Samples 1.7
1.2.3 Riffles 1.7
1.3 CRUSHING AND GRINDING 1.8
1.3.1 Introduction 1.8
1.3.2 Pulverizing and Blending 1.8
Table 1.1 Sample Reduction Equipment 1.9
Table 1.2 Properties of Grinding Surfaces 1.10
1.3.3 Precautions in Grinding Operations 1.11
1.4 SCREENING AND BLENDING 1.11
Table 1.3 U.S. Standard Sieve Series 1.12
1.5 MOISTURE AND DRYING 1.12
1.5.1 Forms of Water in Solids 1.13
1.5.2 Drying Samples 1.14
Table 1.4 Drying Agents 1.14
Table 1.5 Solutions for Maintaining Constant Humidity 1.15
1.5.3 Drying Collected Crystals 1.15
Table 1.6 Concentrations of Solutions of H2SO4, NaOH, and CaCl2 Giving
Specified Vapor Pressures and Percent Humidities at 25°C 1.16
1.5.4 Drying Organic Solvents 1.16
Table 1.7 Relative Humidity from Wet- and Dry-Bulb Thermometer Readings 1.17
Table 1.8 Relative Humidity from Dew-Point Readings 1.18
1.5.5 Freeze-Drying 1.19
1.5.6 Hygroscopic lon-Exchange Membrane 1.19
1.5.7 Microwave Drying 1.19
Table 1.9 Chemical Resistance of a Hygroscopic lon-Exchange Membrane 1.20
1.5.8 Critical-Point Drying 1.20
Table 1.10 Transitional and Intermediate Fluids for Critical-Point Drying 1.21
1.5.9 Karl Fischer Method for Moisture Measurement 1.21
1.6 THE ANALYTICAL BALANCE AND WEIGHTS 1.22
1.6.1 Introduction 1.22
Table 1.11 Classification of Balances by Weighing Range 1.23
1.6.2 General-Purpose Laboratory Balances 1.23
Table 1.12 Specifications of Balances 1.23
1.6.3 Mechanical Analytical Balances 1.24
1.6.4 Electronic Balances 1.24
1.6.5 The Weighing Station 1.26
1.6.6 Air Buoyancy 1.27
1.6.7 Analytical Weights 1.27
Table 1.13 Tolerances for Analytical Weights 1.27
1.7 METHODS FOR DISSOLVING THE SAMPLE 1.28
1.7.1 Introduction 1.28
1.7.2 Decomposition of Inorganic Samples 1.29
Table 1.14 Acid Digestion Bomb-Loading Limits 1.31
Table 1.15 The Common Fluxes 1.33
Table 1.16 Fusion Decompositions with Borates in Pt or Graphite Crucibles 1.34
1.7.3 Decomposition of Organic Compounds 1.34
Table 1.17 Maximum Amounts of Combustible Material Recommended
for Various Bombs 1.36
Table 1.18 Combustion Aids for Accelerators 1.36
1.7.4 Microwave Technology 1.38
Table 1.19 Typical Operating Parameters for Microwave Ovens 1.39
1.7.5 Other Dissolution Methods 1.41
Table 1.20 Dissolution with Complexing Agents 1.41
Table 1.21 Dissolution with Cation Exchangers (H Form) 1.42
Table 1.22 Solvents for Polymers 1.42
1.8 FILTRATION 1.42
1.8.1 Introduction 1.42
1.8.2 Filter Media 1.43
Table 1.23 General Properties of Filter Papers and Glass Microfibers 1.44
Table 1.24 Membrane Filters 1.47
Table 1.25 Membrane Selection Guide 1.47
Table 1.26 Hollow-Fiber Ultrafiltration Cartridge Selection Guide 1.48
Table 1.27 Porosities of Fritted Glassware 1.49
Table 1.28 Cleaning Solutions for Fritted Glassware 1.49
1.8.3 Filtering Accessories 1.49
1.8.4 Manipulations Associated with the Filtration Process 1.50
1.8.5 Vacuum Filtration 1.51
1.9 SPECIFICATIONS FOR VOLUMETRIC WARE 1.52
1.9.1 Volumetric Flasks 1.52
Table 1.29 Tolerances of Volumetric Flasks 1.52
1.9.2 Volumetric Pipettes 1.52
Table 1.30 Pipette Capacity Tolerances 1.53
1.9.3 Micropipettes 1.53
Table 1.31 Tolerances of Micropipettes (Eppendorf) 1.53
1.9.4 Burettes 1.54
Table 1.32 Burette Accuracy Tolerances 1.54
SECTION 2
PRELIMINARY SEPARATION
METHODS
2.1 COMPLEX FORMATION, MASKING, AND DEMASKING REACTIONS 2.3
2.1.1 Complex Equilibria Involving Metals 2.3
Table 2.1 Overall Formation Constants for Metal Complexes
with Organic Ligands 2.6
Table 2.2 Overall Formation Constants for Metal Complexes
with Inorganic Ligands 2.9
2.1.2 Masking 2.11
Table 2.3 Masking Agents for Ions of Various Elements 2.12
Table 2.4 Masking Agents for Anions and Neutral Molecules 2.14
2.1.3 Demasking 2.15
Table 2.5 Common Demasking Agents 2.16
2.2 EXTRACTION METHODS 2.17
2.2.1 Solvent Extraction Systems 2.17
2.2.2 Extraction of Formally Neutral Species 2.20
Table 2.6 Properties of Selected Solvents 2.21
Figure 2.1 Log D vs. pH for a Weak Acid (RCOOH Type) with
KHA 6.7 109 and Kd 720 2.22
Table 2.7 Extraction of Systems Having Simple, Nonpolar Species
in Both the Organic Solvent and Aqueous Phase 2.23
Table 2.8 Percentage Extraction of Metals as Chlorides with
Oxygen-Type Solvents 2.24
Table 2.9 Percent Extraction of Elements as Thiocyanates with
Diethyl Ether from 0.5M HCl Solutions 2.26
2.2.3 Metal-Chelate Systems 2.26
Table 2.10 Percentage Extraction of Metals into Tributyl Phosphate
from HCl Solutions 2.27
Table 2.11 Percent Extraction of Elements from Nitric Acid by
Tributyl Phosphate 2.28
Table 2.12 Percentage Extraction of Metals from HCl Solution by
a 5% Solution of Trioctylphosphine Oxide in Toluene 2.29
Table 2.13 Percent Extraction of Elements by 5% Trioctylphosphine Oxide
(in Toluene) from Nitric Acid Solution 2.29
Table 2.14 Percentage Extraction of Metals from HCl Solution with
Di-(2-Ethylhexyl)phosphoric Acid (50% in Toluene) 2.30
Table 2.15 Extraction of Elements from Nitric Acid Solution
with Di-(2-Ethylhexyl)phosphoric Acid 2.31
Figure 2.2 Distribution of Zinc as a Function of Aqueous Hydrogen-Ion
Concentration for Three Stated Concentrations of Chelating
Agent in CCl4 2.32
Table 2.16 Extraction of Metal 8-Hydroxyquinolates (Oxines) with CHCl3 2.33
Table 2.17 pH Ranges for Extractability of Diethyldithiocarbamates
with Carbon Tetrachloride 2.34
Table 2.18 Chelate Solvent Extraction Systems for the Separation
of Elements 2.35
2.2.4 Ion-Association Systems 2.36
Table 2.19 Percent Extraction of Tetraphenylarsonium Anions with CHCl3 2.37
Table 2.20 Percentage Extraction of Metals from HCl Solution with 0.11M
Triisooctylamine in Xylene 2.38
2.2.5 Chelation and Ion Association 2.39
2.2.6 Summary of Extraction Methods for the Elements 2.40
2.2.7 Laboratory Manipulations 2.40
2.2.8 Continuous Liquid–Liquid Extractions 2.40
Table 2.21 Extraction Procedures for the Elements 2.41
Table 2.22 Recoveries by Solvent Extraction under Various Conditions 2.53
Figure 2.3 High-Density Liquid Extractor 2.53
Figure 2.4 Low-Density Liquid Extractor 2.54
2.2.9 Extraction of a Solid Phase 2.54
Figure 2.5 Soxhlet Extractor 2.55
Figure 2.6 Extraction of Solids with the Soxtec® System 2.56
Table 2.23 Solid-Phase Extraction Packings and Polarity Classification 2.56
2.2.10 Supercritical-Fluid Extraction 2.57
Table 2.24 Characteristics of Selected Supercritical Fluids 2.57
2.3 ION-EXCHANGE METHODS (NORMAL PRESSURE, COLUMNAR) 2.59
2.3.1 Chemical Structure of Ion-Exchange Resins 2.59
Table 2.25 Guide to Ion-Exchange Resins 2.61
Table 2.26 Conversion of Ion-Exchange Resins 2.64
Table 2.27 Gel Filtration Media 2.65
2.3.2 Functional Groups 2.66
2.3.3 Exchange Equilibrium 2.66
Table 2.28 Relative Selectivity of Various Counter Cations 2.67
Table 2.29 Relative Selectivity of Various Counter Anions 2.68
2.3.4 Applications 2.70
Table 2.30 Distribution Coefficients (Dg) of Metal Ions on
AG 50W-8X Resin in HCl Solutions 2.72
Table 2.31 Distribution Coefficients (Dg) of Metal Ions on
AG 50W-X8 Resin in Perchloric Acid Solutions 2.73
Table 2.32 Distribution Coefficients (Dg) of Metal Ions on
AG 50W-X8 Resin in Nitric Acid Solutions 2.74
Table 2.33 Distribution Coefficients (Dg) of Metal Ions on
AG 50W-X8 Resin in H2SO4Solutions 2.75
Table 2.34 Distribution Coefficients (Dg) of Metal Ions on
AG 50W-X8 Resin in 0.2N Acid Solutions 2.76
Table 2.35 Distribution Coefficients (Dv) of Metal Ions on
AG 1-10X in HCl Solutions 2.78
2.4 DISTILLATION OR VAPORIZATION METHODS 2.78
Table 2.36 Distribution Coefficients (Dg) of Metal Ions on
AG 1-8X in H2SO4Solutions 2.79
2.4.1 Simple Batch Distillation 2.79
Table 2.37 Metal Separations on Ion Exchangers 2.80
Table 2.38 Selected Applications of Ion Exchange for the Separation
of a Particular Element from Other Elements or Ions 2.82
Table 2.39 Separations by Ligand-Exchange Chromatography 2.90
2.4.2 Inorganic Applications 2.90
Table 2.40 Approximate Percentage of Element Volatilized from
20- to 100-mg Portions at 200 to 220 C by Distillation
with Various Acids 2.91
2.4.3 Distillation of a Mixture of Two Liquids 2.95
2.4.4 Fractional Distillation 2.95
Table 2.41 Theoretical Plates Required for Separation in Terms of
Boiling-Point Difference and 2.97
Table 2.42 Distillation Behavior of Binary Mixtures of Organic Compounds 2.98
Table 2.43 Azeotropic Data 2.104
Table 2.44 Vapor-Pressure Ratios of Binary Mixtures 2.109
2.4.5 Azeotropic Distillation 2.111
2.4.6 Column Designs 2.112
Figure 2.7 Packings for Fractionating Columns 2.113
Figure 2.8 Teflon Spinning Band Column 2.114
2.4.7 Total-Reflux Partial Takeoff Heads 2.114
2.4.8 Vacuum Distillation 2.114
Figure 2.9 Total-Reflux Partial-Takeoff Still Head 2.115
2.4.9 Steam Distillation 2.115
2.4.10 Molecular Distillation 2.116
2.4.11 Sublimation 2.117
2.5 CARRIER COPRECIPITATION AND CHEMICAL REDUCTION METHODS 2.117
2.5.1 Coprecipitation and Gathering 2.117
2.5.2 Reduction to the Metal 2.118
Table 2.45 Preconcentration by Coprecipitation and Gathering 2.119
3.1 INTRODUCTION 3.1
3.1.1 Errors in Quantitative Analysis 3.2
3.1.2 Representation of Sets of Data 3.2
3.2 THE NORMAL DISTRIBUTION OF MEASUREMENTS 3.3
Figure 3.1 The Normal Distribution Curve 3.3
Table 3.1a Ordinates (Y) of the Normal Distribution Curve at Values of z 3.5
3.3 STANDARD DEVIATION AS A MEASURE OF DISPERSION 3.5
Table 3.1b Areas Under the Normal Distribution Curve from 0 to z 3.6
3.4 THEORETICAL DISTRIBUTIONS AND TESTS OF SIGNIFICANCE 3.7
3.4.1 Student’s Distribution or t Test 3.7
Table 3.2 Percentile Values for Student t Distribution 3.9
3.4.2 Hypotheses About Means 3.10
3.4.3 The Chi-Square (c2) Distribution 3.12
Table 3.3 Percentile Values for the c2 Distribution 3.13
3.4.4 The F Statistic 3.13
Table 3.4 F Distribution 3.14
3.5 CURVE FITTING 3.16
3.5.1 The Least Squares or Best-Fit Line 3.17
3.5.2 Errors in the Slope and Intercept of the Best-Fit Line 3.19
3.6 CONTROL CHARTS 3.21
3.7 CONCEPTS OF QUALITY ASSURANCE AND QUALITY CONTROL PROGRAMS 3.22
3.7.1 Quality Assurance Plans 3.22
3.7.2 Quality Control 3.22
3.8 METHOD DETECTION LIMIT (MDL) 3.24
Bibliography 3.24
4.1 INORGANIC GRAVIMETRIC ANALYSIS 4.2
Table 4.1 Ionic Product Constant of Water 4.2
Table 4.2 Solubility Products 4.3
Table 4.3 Elements Precipitated by General Analytical Reagents 4.9
Table 4.4 Summary of the Principal Methods for the Separation
and Gravimetric Determinations of the Elements 4.11
Table 4.5 Heating Temperatures, Composition of Weighing Forms,
and Gravimetric Factors 4.22
Table 4.6 Metal 8-Hydroxyquinolates 4.24
4.2 ACID–BASE TITRATIONS IN AQUEOUS MEDIA 4.26
4.2.1 Primary Standards 4.26
Table 4.7 Compositions of Constant-Boiling Hydrochloric Acid Solutions 4.26
Table 4.8 Densities and Compositions of Hydrochloric Acid Solutions 4.27
Table 4.9 Primary Standards for Aqueous Acid–Base Titrations 4.28
4.2.2. Indicators 4.29
Table 4.10 Indicators for Aqueous Acid–Base Titrations and pH Determinations 4.29
Table 4.11 Mixed Indicators for Acid–Base Titrations 4.32
Table 4.12 Fluorescent Indicators for Acid–Base Titrations 4.33
4.2.3 Equilibrium Constants of Acids 4.35
Figure 4.1 Range of pKa Values of Dissociating Groups 4.35
Table 4.13 Selected Equilibrium Constants in Aqueous Solutions
at Various Temperatures 4.36
4.2.4 Titration Curves and Precision in Aqueous Acid–Base Titrations 4.42
4.2.5 Calculation of the Approximate pH Value of Solutions 4.47
4.2.6 Calculation of Concentrations of Species Present at a Given pH 4.47
4.2.7 Volumetric Factors for Acid–Base Titrations 4.47
4.3 ACID–BASE TITRATIONS IN NONAQUEOUS MEDIA 4.47
Table 4.14 Volumetric (Titrimetric) Factors for Acid–Base Titrations 4.48
4.3.1 Solvents 4.50
Table 4.15 Properties of Common Acid–Base Solvents 4.51
Figure 4.2 Approximate Potential Ranges in Nonaqueous Solvents 4.52
Figure 4.3 Schematic Representation of Autoprotolysis Ranges of Selected
Solvents, in Relation to the Intrinsic Strength of Certain Index Acids 4.52
4.3.2 Preparation and Standardization of Reagents 4.54
4.3.3 Acidities and Basicities of Acids and Bases in Nonaqueous Solvents 4.55
Table 4.16 pKa Values for Various Acids and Indicators in Nonaqueous Systems 4.56
4.3.4 Titration Curves in Nonaqueous Acid–Base Systems 4.57
Table 4.17 Selected Titration Methods in Nonaqueous Media 4.58
4.4 PRECIPITATION TITRATIONS 4.60
4.4.1 Titration Curves and Precision in Precipitation Titrations 4.60
Figure 4.4 Titration Curves for the Precipitation Titration X R XR 4.61
Table 4.18 Standard Solutions for Precipitation Titrations 4.62
4.4.2 Applications 4.63
4.5 OXIDATION–REDUCTION TITRATIONS 4.63
4.5.1 Titration Curves and Precision in Redox Titrations 4.63
Table 4.19 Indicators for Precipitation Titrations 4.64
Table 4.20 Titration Methods Based on Precipitation 4.66
Table 4.21 Potentials of Selected Half-Reactions at 25°C 4.68
4.1