10.3.1 Introduction 349 10.3.2 Analysis of Peptide and Protein Primary Structures and post-Translational Structure modifications 34 10.3.3 Tertiary Structure Characterisation by Chemical Modification and Mass Spectrometry 353 10.3.4 Characterisation of Non-Covalent Supramolecular Complexes 354 10.3.5 Mass Spectrometric Proteome Analysis 356 Section V Methods 4: Elemental Analysis 363 X-ray Fluorescence Analysis 365 11.1 Introduction 365 11.2 Basic Principles 367 11.2.1 X-ray Wavelength and Energy Scales 367 11.2.2 Interaction of X-rays with Matter 367 11.2.3 Photoelectric Effect 369 11.2.4 Scattering 371 11.2.5 11.2.6 Selection Rules, Characteristic Lines and X-ray Spectra 3 11.2.7 Figures-of-merit for XRF Spectrometers 376 11.2.7.1 Analytical Sensitivity 376 11.2.7.2 Detection and Determination Limits 377 11.3 Instrumentation 380 11.3.1 X-ray Sources 380 11.3.2 X-ray Detectors 384 11.3.3 Wavelength-dispersive XRF 390 11.3.4 Energy-dispersive XRF 393 11.3.5 Radioisotope XRF 397 11.3.6 Total Reflection XRF 398 Microscopic XRF 399 114 Matrix Effects 40 11.4.1 Thin and Thick Samples 401 11.4.2 Primary and Secondary Absorption, Direct and Third Element Enhancement 403 11.5 Data Treatment 404 11.5.1 Counting Statistics 404 11.5.2 Spectrum Evaluation Techniqu 11.5.2.1 Data Extraction in WDXRF 406 11.5.2.2 Data Extraction in EDXRF: Simple Case, No Peak Overlap 407 11.5.2.3 Data Extraction in EDXRF, Multiple Peak Overlap 408 11.5.3 Quantitative Calibration Procedures 409 11.5.3.1 Single-element Techniques 412 11.5.3. 2 Multiple-element Techniques 413 11.5.4 Error Sources in X-ray Fluorescence Analysis 41510.3.1 Introduction 349 10.3.2 Analysis of Peptide and Protein Primary Structures and Post-Translational Structure Modifications 349 10.3.3 Tertiary Structure Characterisation by Chemical Modification and Mass Spectrometry 353 10.3.4 Characterisation of Non-Covalent Supramolecular Complexes 354 10.3.5 Mass Spectrometric Proteome Analysis 356 Section V Methods 4: Elemental Analysis 363 11 X-ray Fluorescence Analysis 365 11.1 Introduction 365 11.2 Basic Principles 367 11.2.1 X-ray Wavelength and Energy Scales 367 11.2.2 Interaction of X-rays with Matter 367 11.2.3 Photoelectric Effect 369 11.2.4 Scattering 371 11.2.5 Bremsstrahlung 372 11.2.6 Selection Rules, Characteristic Lines and X-ray Spectra 373 11.2.7 Figures-of-merit for XRF Spectrometers 376 11.2.7.1 Analytical Sensitivity 376 11.2.7.2 Detection and Determination Limits 377 11.3 Instrumentation 380 11.3.1 X-ray Sources 380 11.3.2 X-ray Detectors 384 11.3.3 Wavelength-dispersive XRF 390 11.3.4 Energy-dispersive XRF 393 11.3.5 Radioisotope XRF 397 11.3.6 Total Reflection XRF 398 11.3.7 Microscopic XRF 399 11.4 Matrix Effects 401 11.4.1 Thin and Thick Samples 401 11.4.2 Primary and Secondary Absorption, Direct and Third Element Enhancement 403 11.5 Data Treatment 404 11.5.1 Counting Statistics 404 11.5.2 Spectrum Evaluation Techniques 405 11.5.2.1 Data Extraction in WDXRF 406 11.5.2.2 Data Extraction in EDXRF: Simple Case, No Peak Overlap 407 11.5.2.3 Data Extraction in EDXRF, Multiple Peak Overlap 408 11.5.3 Quantitative Calibration Procedures 409 11.5.3.1 Single-element Techniques 412 11.5.3.2 Multiple-element Techniques 413 11.5.4 Error Sources in X-ray Fluorescence Analysis 415 Contents XI