Analytical Chemistry for Technicians

Analytical Chemistry for TechniciansChapter 1 Introduction to Analytical Science...............................................................................1 1.1 Analytical Science Defined ...............................................................................1 1.2 Classifications of Analysis.................................................................................2 1.3 The Sample........................................................................................................3 1.4 The Analytical Process......................................................................................3 1.5 Analytical Technique and Skills .......................................................................4 1.6 Elementary Statistics.........................................................................................5 1.6.1 Errors....................................................................................................5 1.6.2 Definitions............................................................................................6 1.6.3 Distribution of Measurements..............................................................8 1.6.4 Student’s t ........................................................................................... 10 1.6.5 Rejection of Data................................................................................ 12 1.6.6 Final Comments on Statistics............................................................. 13 1.7 Precision, Accuracy, and Calibration .............................................................. 13 Chapter 2 Sampling and Sample Preparation ............................................................................. 19 2.1 Introduction ..................................................................................................... 19 2.2 Obtaining the Sample...................................................................................... 19 2.3 Statistics of Sampling......................................................................................20 2.4 Sample Handling ............................................................................................. 21 2.4.1 Chain of Custody................................................................................ 21 2.4.2 Maintaining Sample Integrity ............................................................22 2.5 Sample Preparation—Solid Materials.............................................................23 2.5.1 Particle Size Reduction ......................................................................23 2.5.2 Sample Homogenization and Division...............................................23 2.5.3 Solid–Liquid Extraction.....................................................................24 2.5.4 Other Extractions from Solids............................................................24 2.6 Water Purification and Use..............................................................................25 2.6.1 Purifying Water by Distillation..........................................................25 2.6.2 Purifying Water by Deionization .......................................................26 2.7 Total Sample Dissolution and Other Considerations.......................................26 2.7.1 Hydrochloric Acid..............................................................................27 2.7.2 Sulfuric Acid ......................................................................................27 2.7.3 Nitric Acid..........................................................................................28 2.7.4 Hydrofluoric Acid...............................................................................28 2.7.5 Perchloric Acid...................................................................................28 2.7.6 “Aqua Regia”......................................................................................28 2.7.7 Acetic Acid.........................................................................................28 2.7.8 Ammonium Hydroxide ......................................................................29 viii Contents 2.8 Fusion ..............................................................................................................30 2.9 Sample Preparation: Liquid Samples, Extracts, and Solutions of Solids........30 2.9.1 Extraction from Liquid Solutions.......................................................30 2.9.2 Dilution, Concentration, and Solvent Exchange................................. 32 2.9.3 Sample Stability ................................................................................. 32 2.10 Liquid–Liquid Extraction................................................................................ 32 2.10.1 Introduction ........................................................................................ 32 2.10.2 The Separatory Funnel....................................................................... 33 2.10.3 Theory ................................................................................................34 2.10.4 Calculations Involving Equation 2.2.................................................. 35 2.10.5 Calculations Involving Equation 2.3..................................................36 2.10.6 Calculations Involving a Combination of Equations 2.3 (or 2.7) and 2.4 ................................................................................................37 2.10.7 Calculation of Percent Extracted (Equation 2.5) ...............................37 2.10.8 Evaporators.........................................................................................38 2.11 Solid–Liquid Extraction ..................................................................................38 2.12 Distillation of a Mixture of Liquids................................................................39 2.13 Reagents Used in Sample Preparation............................................................. 41 2.14 Labeling and Record Keeping......................................................................... 41 Chapter 3 Gravimetric Analysis .................................................................................................49 3.1 Introduction .....................................................................................................49 3.2 Weight vs. Mass...............................................................................................49 3.3 The Balance.....................................................................................................49 3.4 The Desiccator................................................................................................. 51 3.5 Calibration and Care of Balances.................................................................... 52 3.6 When to Use Which Balance .......................................................................... 52 3.7 Details of Gravimetric Methods...................................................................... 53 3.7.1 Physical Separation Methods and Calculations ................................. 53 3.7.1.1 Loss on Drying ................................................................... 55 3.7.1.2 Loss on Ignition .................................................................. 55 3.7.1.3 Residue on Ignition.............................................................56 3.7.1.4 Insoluble Matter in Reagents..............................................56 3.7.1.5 Solids in Water and Wastewater .........................................56 3.7.1.6 Particle Size by Analytical Sieving .................................... 57 3.7.2 Chemical Alteration/Separation of the Analyte.................................58 3.7.3 Gravimetric Factors............................................................................59 3.7.4 Using Gravimetric Factors................................................................. 61 3.8 Experimental Considerations ..........................................................................63 3.8.1 Weighing Bottles................................................................................63 3.8.2 Weighing by Difference .....................................................................63 3.8.3 Isolating and Weighing Precipitates...................................................64 Chapter 4 Introduction to Titrimetric Analysis ..........................................................................73 4.1 Introduction .....................................................................................................73 4.2 Terminology ....................................................................................................73 4.3 Review of Solution Concentration................................................................... 75 4.3.1 Molarity.............................................................................................. 75 4.3.2 Normality ...........................................................................................77 Contents ix 4.4 Review of Solution Preparation.......................................................................79 4.4.1 Solid Solute and Molarity...................................................................80 4.4.2 Solid Solute and Normality................................................................ 81 4.4.3 Solution Preparation by Dilution........................................................82 4.5 Stoichiometry of Titration Reactions ..............................................................82 4.6 Standardization................................................................................................84 4.6.1 Standardization Using a Standard Solution .......................................84 4.6.2 Standardization Using a Primary Standard .......................................86 4.6.3 Titer ....................................................................................................88 4.7 Percentage Analyte Calculations.....................................................................88 4.8 Volumetric Glassware...................................................................................... 91 4.8.1 Volumetric Flask ................................................................................ 91 4.8.2 Pipet....................................................................................................94 4.8.3 Buret...................................................................................................98 4.8.4 Cleaning and Storing Procedures.....................................................100 4.9 Pipetters, Automatic Titrators, and Other Devices .......................................100 4.9.1 Pipetters............................................................................................100 4.9.2 Bottle-Top Dispensers ...................................................................... 102 4.9.3 Digital Burets and Automatic Titrators............................................ 102 4.10 Calibration of Glassware and Devices .......................................................... 103 4.11 Analytical Technique..................................................................................... 103 Chapter 5 Applications of Titrimetric Analysis........................................................................ 113 5.1 Introduction ................................................................................................... 113 5.2 Acid–Base Titrations and Titration Curves................................................... 113 5.2.1 Titration of Hydrochloric Acid......................................................... 113 5.2.2 Titration of Weak Monoprotic Acids ............................................... 115 5.2.3 Titration of Monobasic Strong and Weak Bases.............................. 116 5.2.4 Equivalence Point Detection ............................................................ 116 5.2.5 Titration of Polyprotic Acids: Sulfuric Acid and Phosphoric Acid........................................................................................... 118 5.2.6 Titration of Potassium Biphthalate................................................... 121 5.2.7 Titration of Tris-(Hydroxymethyl)Amino Methane......................... 122 5.2.8 Titration of Sodium Carbonate......................................................... 122 5.3 Examples of Acid/Base Determinations....................................................... 123 5.3.1 Alkalinity of Water or Wastewater...................................................124 5.3.2 Back Titration Applications .............................................................124 5.3.3 Indirect Titration Applications.........................................................126 5.4 Other Acid/Base Applications....................................................................... 127 5.5 Buffer Solution Applications......................................................................... 127 5.5.1 Conjugate Acids and Bases.............................................................. 128 5.5.2 Henderson–Hasselbalch Equation.................................................... 129 5.6 Complex Ion Formation Reactions................................................................ 133 5.6.1 Introduction ...................................................................................... 133 5.6.2 Complex Ion Terminology................................................................ 133 5.6.3 EDTA and Water Hardness.............................................................. 135 5.6.4 Expressing Concentration Using Parts per Million ......................... 138 5.6.4.1 Solution Preparation ......................................................... 139 5.6.5 Water Hardness Calculations........................................................... 141 5.6.6 Other Uses of EDTA Titrations........................................................ 143 x Contents 5.7 Oxidation–Reduction Reactions.................................................................... 144 5.7.1 Review of Basic Concepts and Terminology ................................... 144 5.7.2 The Ion-Electron Method for Balancing Equations......................... 147 5.7.3 Analytical Calculations.................................................................... 148 5.7.4 Applications...................................................................................... 150 5.7.4.1 Potassium Permanganate .................................................. 150 5.7.4.2 Iodometry: An Indirect Method ....................................... 150 5.7.4.3 Prereduction and Preoxidation ......................................... 152 5.8 Other Examples............................................................................................. 152 Chapter 6 Introduction to Instrumental Analysis ..................................................................... 165 6.1 Review of the Analytical Process.................................................................. 165 6.2 Instrumental Analysis Methods .................................................................... 166 6.3 Basics of Instrumental Measurement ............................................................ 167 6.3.1 Sensors, Signal Processors, Readouts, and Power Supplies............. 168 6.3.2 Calibration of an Analytical Instrument .......................................... 168 6.3.3 Mathematics of Linear Relationships............................................... 170 6.3.4 Method of Least Squares.................................................................. 171 6.3.5 The Correlation Coefficient.............................................................. 172 6.4 Preparation of Standards............................................................................... 172 6.5 Blanks and Controls ...................................................................................... 173 6.5.1 Reagent Blanks................................................................................. 173 6.5.2 Sample Blanks.................................................................................. 174 6.5.3 Controls............................................................................................ 174 6.6 Post-Run Calculations in Instrumental Analysis........................................... 174 6.6.1 Calculation of ppm Analyte in a Solution Given Mass and Volume Data..................................................................................... 175 6.6.2 Calculation of ppm Analyte in a Solid Sample Given Mass Data........ 175 6.6.3 Calculation of the Mass of Analyte Found in an Extract................. 175 6.6.4 Calculation of ppm Analyte in a Liquid or Solid That Was Extracted .......................................................................................... 176 6.6.5 Calculation When a Dilution Is Involved......................................... 176 6.7 Laboratory Data Acquisition and Information Management ........................ 178 6.7.1 Data Acquisition............................................................................... 178 6.7.2 Laboratory Information Management.............................................. 179 Chapter 7 Introduction to Spectrochemical Methods............................................................... 185 7.1 Introduction ................................................................................................... 185 7.2 Characterizing Light...................................................................................... 185 7.2.1 Wavelength, Speed, Frequency, Energy, and Wavenumber ............. 186 7.3 The Electromagnetic Spectrum..................................................................... 189 7.4 Refractometry................................................................................................ 190 7.5 Absorption and Emission of Light................................................................. 193 7.5.1 Brief Summary................................................................................. 193 7.5.2 Atoms vs. Molecules and Complex Ions.......................................... 196 7.5.3 Absorption Spectra........................................................................... 197 7.5.4 Light Emission ................................................................................. 201 7.6 Absorbance, Transmittance, and Beer’s Law................................................202 7.7 Effect of Concentration on Spectra ...............................................................207 Contents xi Chapter 8 UV-Vis and IR Molecular Spectrometry.................................................................. 215 8.1 Review ........................................................................................................... 215 8.2 UV-Vis Instrumentation ................................................................................ 215 8.2.1 Sources............................................................................................. 215 8.2.1.1 Tungsten Filament Lamp .................................................. 215 8.2.1.2 Deuterium Lamp............................................................... 216 8.2.1.3 Xenon Arc Lamp .............................................................. 216 8.2.2 Wavelength Selection ....................................................................... 216 8.2.2.1 Absorption Filters............................................................. 217 8.2.2.2 Monochromators............................................................... 217 8.2.3 Sample Compartment.......................................................................220 8.2.3.1 Single-Beam Spectrophotometer......................................220 8.2.3.2 Beam Splitting and Chopping .......................................... 221 8.2.3.3 Double-Beam Designs......................................................222 8.2.3.4 Diode Array Design..........................................................223 8.2.3.5 Summary ..........................................................................225 8.2.4 Detectors ..........................................................................................226 8.2.4.1 Photomultiplier Tube ........................................................226 8.2.4.2 Photodiodes.......................................................................228 8.3 Cuvette Selection and Handling....................................................................228 8.4 Interferences, Deviations, Maintenance, and Troubleshooting.....................229 8.4.1 Interferences.....................................................................................229 8.4.2 Deviations.........................................................................................229 8.4.3 Maintenance .....................................................................................230 8.4.4 Troubleshooting................................................................................230 8.5 Fluorometry................................................................................................... 231 8.6 Introduction to IR Spectrometry ................................................................... 233 8.7 IR Instrumentation ........................................................................................234 8.8 Sampling........................................................................................................ 235 8.8.1 Liquid Sampling............................................................................... 235 8.9 Solid Sampling ..............................................................................................240 8.9.1 Solution Prepared and Placed in a Liquid Sampling Cell................240 8.9.2 Thin Film Formed by Solvent Evaporation......................................240 8.9.3 KBr Pellet.........................................................................................240 8.9.4 Nujol Mull ........................................................................................242 8.9.5 Reflectance Methods........................................................................242 8.9.5.1 Specular Reflectance ........................................................242 8.9.5.2 Internal Reflectance..........................................................242 8.9.5.3 Diffuse Reflectance ..........................................................244 8.9.6 Gas Sampling ...................................................................................244 8.10 Basic IR Spectra Interpretation .....................................................................244 8.11 Quantitative Analysis ....................................................................................247 Chapter 9 Atomic Spectroscopy ...............................................................................................259 9.1 Review and Comparisons..............................................................................259 9.2 Brief Summary of Techniques and Instrument Designs...............................260 9.3 Flame Atomic Absorption.............................................................................262 9.3.1 Flames and Flame Processes ...........................................................262 9.3.2 Spectral Line Sources ......................................................................263 xii Contents 9.3.2.1 Hollow Cathode Lamp......................................................264 9.3.2.2 Electrodeless Discharge Lamp .........................................265 9.3.3 Premix Burner..................................................................................265 9.3.4 Optical Path...................................................................................... 267 9.3.5 Practical Matters and Applications..................................................268 9.3.5.1 Slits and Spectral Lines....................................................268 9.3.5.2 Linear and Nonlinear Standard Curves............................269 9.3.5.3 Hollow Cathode Lamp Current ........................................ 271 9.3.5.4 Lamp Alignment............................................................... 271 9.3.5.5 Aspiration Rate ................................................................. 271 9.3.5.6 Burner Head Position........................................................ 271 9.3.5.7 Fuel and Oxidant Sources and Flow Rates....................... 271 9.3.6 Interferences..................................................................................... 271 9.3.6.1 Chemical Interferences..................................................... 272 9.3.6.2 Spectral Interferences....................................................... 273 9.3.7 Safety and Maintenance ................................................................... 274 9.4 Graphite Furnace Atomic Absorption........................................................... 275 9.4.1 General Description ......................................................................... 275 9.4.2 Advantages and Disadvantages........................................................277 9.5 Inductively Coupled Plasma .......................................................................... 278 9.6 Miscellaneous Atomic Techniques................................................................ 281 9.6.1 Flame Photometry............................................................................ 281 9.6.2 Cold Vapor Mercury.........................................................................282 9.6.3 Hydride Generation ..........................................................................282 9.6.4 Spark Emission.................................................................................282 9.6.5 Atomic Fluorescence........................................................................282 9.7 Summary of Atomic Techniques...................................................................282 Chapter 10 Introduction to Chromatography.............................................................................. 291 10.1 Introduction ................................................................................................... 291 10.2 Chromatography............................................................................................ 291 10.3 “Types” of Chromatography..........................................................................292 10.3.1 Partition Chromatography................................................................292 10.3.2 Adsorption Chromatography............................................................293 10.3.3 Ion-Exchange Chromatography .......................................................294 10.3.4 Size Exclusion Chromatography ......................................................295 10.4 Chromatography Configurations...................................................................295 10.4.1 Paper and Thin-Layer Chromatography ..........................................296 10.4.2 Classical Open-Column Chromatography .......................................298 10.4.3 Instrumental Chromatography ......................................................... 301 10.4.4 Instrumental Chromatogram............................................................ 301 10.4.5 Quantitative Analysis with GC and HPLC ......................................305 10.5 Electrophoresis..............................................................................................306 Chapter 11 Gas Chromatography ............................................................................................... 311 11.1 Overview ....................................................................................................... 311 11.2 Vapor Pressure and Solubility ....................................................................... 311 11.3 Instrument Components ................................................................................ 312 11.4 Sample Injection............................................................................................ 314 Contents xiii 11.5 Column Details.............................................................................................. 316 11.5.1 Instrument Logistics......................................................................... 316 11.5.2 Packed, Open Tubular, and Preparative Columns............................ 317 11.5.3 The Nature and Selection of the Stationary Phase........................... 318 11.5.4 Column Temperature........................................................................ 319 11.5.5 Carrier Gas Flow Rate .....................................................................320 11.6 Detectors........................................................................................................ 321 11.6.1 Flame Ionization Detector (FID) ..................................................... 321 11.6.2 Thermal Conductivity Detector (TCD)............................................ 322 11.6.3 Electron Capture Detector (ECD).................................................... 323 11.6.4 Nitrogen/Phosphorus Detector (NPD) .............................................324 11.6.5 Flame Photometric Detector (FPD) .................................................324 11.6.6 Electrolytic Conductivity (Hall Detector)........................................324 11.6.7 Gas Chromatography–Mass Spectrometry (GC-MS)......................324 11.6.8 Photoionization Detector (PID)........................................................ 325 11.7 Qualitative Analysis...................................................................................... 325 11.8 Quantitative Analysis .................................................................................... 326 11.8.1 Quantitation Methods....................................................................... 326 11.8.2 Response Factor Method.................................................................. 326 11.8.3 Internal Standard Method ................................................................ 327 11.8.4 Standard Additions Method ............................................................. 328 11.9 Troubleshooting............................................................................................. 329 11.9.1 Diminished Peak Size ...................................................................... 329 11.9.2 Unsymmetrical Peak Shapes............................................................ 329 11.9.3 Altered Retention Times .................................................................. 330 11.9.4 Baseline Drift................................................................................... 330 11.9.5 Baseline Perturbations...................................................................... 330 11.9.6 Appearance of Unexpected Peaks.................................................... 330 Chapter 12 High-Performance Liquid Chromatography and Electrophoresis ........................... 341 12.1 Introduction ................................................................................................... 341 12.1.1 Summary of Method ........................................................................ 341 12.1.2 Comparisons with GC...................................................................... 341 12.2 Mobile Phase Considerations ........................................................................ 342 12.3 Solvent Delivery ............................................................................................344 12.3.1 Pumps...............................................................................................344 12.3.2 Gradient vs. Isocratic Elution........................................................... 345 12.4 Sample Injection............................................................................................346 12.5 Column Selection ..........................................................................................348 12.5.1 Normal Phase Columns....................................................................348 12.5.2 Reverse-Phase Columns...................................................................348 12.5.3 Adsorption Columns ........................................................................349 12.5.4 Ion Exchange and Size Exclusion Columns.....................................349 12.5.5 The Size of the Stationary Phase Particles.......................................349 12.5.6 Column Selection .............................................................................349 12.6 Detectors........................................................................................................ 350 12.6.1 UV Absorption................................................................................. 350 12.6.2 Diode Array...................................................................................... 351 12.6.3 Fluorescence..................................................................................... 351 12.6.4 Refractive Index ............................................................................... 353 xiv Contents 12.6.5 Electrochemical................................................................................ 354 12.6.5.1 Conductivity...................................................................... 354 12.6.5.2 Amperometric................................................................... 354 12.7 Qualitative and Quantitative Analysis........................................................... 355 12.8 Troubleshooting............................................................................................. 356 12.8.1 Unusually High Pressure.................................................................. 356 12.8.2 Unusually Low Pressure................................................................... 356 12.8.2.1 System Leaks.................................................................... 356 12.8.2.2 Air Bubbles....................................................................... 357 12.8.2.3 Column “Channeling” ...................................................... 357 12.8.2.4 Decreased Retention Time................................................ 357 12.8.2.5 Baseline Drift ................................................................... 357 12.9 Electrophoresis.............................................................................................. 357 12.9.1 Introduction ...................................................................................... 357 12.9.2 Capillary Electrophoresis................................................................. 359 12.9.2.1 Electroosmotic Flow......................................................... 361 12.9.2.2 Sample Introduction.......................................................... 361 12.9.2.3 Analyte Detection............................................................. 361 Chapter 13 Mass Spectrometry................................................................................................... 371 13.1 Basic Principles............................................................................................. 371 13.2 Sample Inlet Systems and Ion Sources.......................................................... 372 13.3 Mass Analyzers............................................................................................. 373 13.4 The Ion Detector............................................................................................ 376 13.5 Mass Spectra.................................................................................................. 377 13.6 ICP-MS.......................................................................................................... 378 13.7 GC-MS .......................................................................................................... 378 13.8 LC-MS...........................................................................................................380 13.9 Tandem Mass Spectrometry.......................................................................... 381 Chapter 14 Electroanalytical Methods .......................................................................................387 14.1 Introduction ...................................................................................................387 14.2 Transfer Tendencies: Standard Reduction Potentials.................................... 391 14.3 Determination of Overall Redox Reaction Tendency: Ecell ° ........................... 393 14.4 The Nernst Equation......................................................................................394 14.5 Potentiometry ................................................................................................396 14.5.1 Reference Electrodes........................................................................396 14.5.1.1 The Saturated Calomel Reference Electrode (SCE).........396 14.5.1.2 The Silver–Silver Chloride Electrode............................... 398 14.5.2 Indicator Electrodes .........................................................................399 14.5.2.1 The pH Electrode..............................................................399 14.5.3 Combination Electrodes...................................................................400 14.5.3.1 The Combination pH Electrode........................................400 14.5.3.2 Ion-Selective Electrodes................................................... 401 14.5.4 Other Details of Electrode Design ...................................................403 14.5.5 Care and Maintenance of Electrodes...............................................403 14.5.6 Potentiometric Titrations..................................................................404 14.6 Voltammetry and Amperometry ...................................................................405 14.6.1 Voltammetry.....................................................................................405 Contents xv 14.6.2 Amperometry ...................................................................................406 14.7 Karl Fischer Titration ....................................................................................406 14.7.1 End Point Detection..........................................................................406 14.7.2 Elimination of Extraneous Water.....................................................407 14.7.3 The Volumetric Method ...................................................................407 14.7.4 The Coulometric Method .................................................................409 Chapter 15 Miscellaneous Instrumental Techniques.................................................................. 417 15.1 X-Ray Methods.............................................................................................. 417 15.1.1 Introduction ...................................................................................... 417 15.1.2 X-Ray Diffraction Spectroscopy...................................................... 418 15.1.3 X-Ray Fluorescence Spectroscopy................................................... 421 15.1.4 Applications...................................................................................... 421 15.1.5 Safety Issues Concerning X-Rays.................................................... 422 15.2 Nuclear Magnetic Resonance Spectroscopy ................................................. 422 15.2.1 Introduction ...................................................................................... 422 15.2.2 Instrumentation ................................................................................ 423 15.2.3 The NMR Spectrum......................................................................... 425 15.2.3.1 Chemical Shifts ................................................................ 425 15.2.3.2 Peak Splitting and Integration .......................................... 427 15.2.4 Solvents and Solution Concentration................................................ 428 15.2.5 Analytical Uses ................................................................................ 428 15.3 Viscosity ........................................................................................................ 428 15.3.1 Introduction ...................................................................................... 428 15.3.2 Definitions........................................................................................ 429 15.3.3 Temperature Dependence................................................................. 430 15.3.4 Capillary Viscometry....................................................................... 430 15.3.5 Rotational Viscometry ..................................................................... 433 15.4 Thermal Analysis.......................................................................................... 434 15.4.1 Introduction ...................................................................................... 434 15.4.2 DTA and DSC .................................................................................. 434 15.4.3 DSC Instrumentation........................................................................ 436 15.4.4 Applications of DSC......................................................................... 437 15.5 Optical Rotation ............................................................................................ 437 Appendix 1: Formulas for Solution Concentration and Preparation Calculations...............443 Appendix 2: The Language of Quality Assurance and Good Laboratory Practice (GLP) Laws: A Glossary .......................................................................................447 Appendix 3: Significant Figure Rules........................................................................................ 451 Appendix 4: Answers to Questions and Problems.................................................................... 453 xvii List of Experiments Experiment 1: Assuring the Quality of Weight Measurements.....................................................14 Experiment 2: Weight Uniformity of Dosing Units......................................................................15 Experiment 3: A Study of the Dissolving Properties of Water, Some Common Organic Liquids, and Laboratory Acids..............................................................................42 Experiment 4: Loss on Drying......................................................................................................64 Experiment 5: Particle Sizing .......................................................................................................65 Experiment 6: The Determination of Salt in a Salt–Sand Mixture...............................................65 Experiment 7: The Gravimetric Determination of Sulfate in a Commercial Unknown ...............65 Experiment 8: High-Precision Glassware: A Calibration Experiment .......................................104 Experiment 9: Preparation and Standardization of HCl and NaOH Solutions...........................106 Experiment 10: Titrimetric Analysis of a Commercial Soda Ash Unknown for Sodium Carbonate ............................................................................................................152 Experiment 11: Titrimetric Analysis of a Commercial KHP Unknown for KHP.........................152 Experiment 12: EDTA Titrations..................................................................................................153 Experiment 13: Plotting a Standard Curve Using Excel Spreadsheet Software (Version 2010).......179 Experiment 14: Percentage of Sugar in Soft Drinks by Refractometry........................................207 Experiment 15: Colorimetric Analysis of Prepared and/or Real Water Samples for Iron ............207 Experiment 16: Design an Experiment: A Study of the Effect of pH on the Analysis of Water Samples for Iron .......................................................................................208 Experiment 17: Design an Experiment: Determining the Concentration at Which a Beer’s Law Plot Becomes Nonlinear..............................................................................208 Experiment 18: The Determination of Phosphorus in Environmental Water ...............................208 Experiment 19: Spectrophotometric Analysis of a Prepared Sample for Toluene........................248 Experiment 20: Extraction of Iodine with Cyclohexane...............................................................248 Experiment 21: Determination of Nitrate in Drinking Water by UV Spectrophotometry............249 Experiment 22: Fluorometric Analysis of a Prepared Sample for Riboflavin ..............................249 Experiment 23: Design an Experiment: Determination of Riboflavin in a Vitamin Tablet Using Fluorometry ..............................................................................................250 Experiment 24: Quantitative Infrared Analysis of Isopropyl Alcohol in Toluene ........................250 Experiment 25: Quantitative Flame Atomic Absorption Analysis of a Prepared Sample ............284 Experiment 26: The Analysis of Soil Samples for Iron Using Atomic Absorption ......................284 Experiment 27: Design an Experiment: A Study to Determine the Optimum pH for the Extraction Solution for Experiment 26 ...............................................................285 Experiment 28: The Determination of Sodium in Soda Pop ........................................................285 Experiment 29: Design an Experiment: Sodium in Soda Pop by the Standard Additions Method ................................................................................................................286 Experiment 30: Design an Experiment: Analysis of Fertilizer for Potassium..............................286 Experiment 31: Thin-Layer Chromatography Analysis of Cough Syrups for Dyes.....................306 Experiment 32: Thin-Layer Chromatography Analysis of Jelly Beans for Food Coloring..........307 Experiment 33: A Qualitative Gas Chromatography Analysis of a Prepared Sample .................. 330 Experiment 34: The Quantitative Gas Chromatography Analysis of a Prepared Sample for Toluene by the Internal Standard Method ..................................................... 331 Experiment 35: The Determination of Ethanol in Wine by Gas Chromatography and the Internal Standard Method....................................................................................332 xviii List of Experiments Experiment 36: Design an Experiment: Determination of Ethanol in Cough Medicine or Other Pharmaceutical Preparation.......................................................................333 Experiment 37: A Study of the Effect of the Changing of GC Instrument Parameters on Resolution............................................................................................................333 Experiment 38: The Quantitative Determination of Methyl Paraben in a Prepared Sample by HPLC...................................................................................................................362 Experiment 39: HPLC Determination of Caffeine in Soda Pop ...................................................363 Experiment 40: Design an Experiment: Dependence of Caffeine Analysis on the pH of the Mobile Phase.......................................................................................................364 Experiment 41: The Analysis of Mouthwash by HPLC: A Research Experiment .......................364 Experiment 42: The Determination of 4-Hydroxyacetophenone by Capillary Electrophoresis...365 Experiment 43: The Quantitative GC-MS Analysis of a Prepared Sample for Chlorobenzene by the Internal Standard Method.........................................................................382 Experiment 44: GC-MS Determination of Ethylbenzene in Gasoline by Combined Internal Standard and Standard Additions Methods.........................................................382 Experiment 45: Determination of the pH of Soil Samples...........................................................409 Experiment 46: Analysis of a Prepared Unknown for Fluoride Using an Ion-Selective Electrode..............................................................................................................409 Experiment 47: Design an Experiment: Determination of Fluoride in Toothpaste Using an Ion-Selective Electrode .......................................................................................410 Experiment 48: Operation of Metrohm Model 701 Karl Fischer Titrator (for Liquid Samples)..............................................................................................................410 xix © 2010 Taylor & Francis Group, LLC Preface The primary purpose of this text continues to be as a training manual for chemistry-based laboratory technicians. It is designed to emphasize the practical rather than the theorical. The practical begins with classical quantitative analysis, because this is what instills the mindset of analytical skill and technique into the students’ psyche, and very practicing scientists should agree that this is a very important part of a technician’s training. But equally important is what follows this in the book: a very practical approach to the complex world of the sophisticated electronic instrumentation that a technician will find in common use in the real-world laboratory. My hope is that laboratory supervisors will find that technicians who have utilized this textbook will have an analytical mindset and a basic understanding of the analytical instrumentation needed for success on the job. It has been 10 years since the publication of the third edition of Analytical Chemistry for Technicians. I have taught the sequence of courses that use this text over 20 times since then. Each time I teach these courses, it seems I have fresh ideas and new developments to discuss with my students. These have resulted in new drawings for my PowerPoint slides and new (and I hope better) explanations of what can be complex instrument designs and functions. It is true that my students have a limited background in chemistry when they come to me, and so I strive to write, draw, and speak with this in mind. And now the time has come for the fourth edition. What is new and what has changed? Following is the list: • Over 150 new photographs and either new or reworked drawings spanning every chapter to assist the visual learner. • A new chapter on mass spectrometry. • Thirteen new laboratory experiments, including nine “design an experiment” exercises. • An “Introduction to Laboratory Work” section before Chapter 1 to give students a preview of general laboratory considerations, safety, laboratory notebooks, and instrumental analysis. • “Application Notes” in each chapter. A few of these are carryovers of the “Workplace Scenes” in the third edition, but most are new. The intent is to give students a larger hint of how specific techniques may be routinely used in the laboratory. • Calculation summary tables in Chapters 3 and 4. • Relevant section headings in the end-of-chapter Questions and Problems section to help better organize the material for students. • An appendix providing a glossary of quality assurance and good laboratory practice (GLP) terms. • More end-of-chapter problems in Chapters 1, 2, 3, 6, and 14 covering statistics, liquid–liquid extraction, gravimetric analysis, post-run instrumental analysis, and electrode potential. • More examples of calculations covering liquid–liquid extraction theory and post-run instrumental analysis in Chapters 2 and 6. • The topic of refractometry has been moved to Chapter 7 from Chapter 15 since it represents a basic technique involving light. • The topics of liquid–liquid extraction, solid–liquid extraction, and distillation–deionization have been moved to Chapter 2 from Chapter 11 as sample and solution preparation techniques rather than analytical separation techniques. Chapter 11 has become Chapter 10 and is now dedicated to chromatography, and this is reflected in the chapter title “Introduction to Chromatography