ICP Mass and Optical Emission Spectrometry of Ore Samples Containing Rare Earth Elements
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Al-Azhar University Faculty of Science Physics Department ICP Mass and Optical Emission Spectrometry of Ore Samples Containing Rare Earth Elements Thesis Submitted for partial fulfillment of the requirements for the degree of Master of Science in Solid state physics By Abd-Elwahhab Mohammed Abd-Elhady Mohammed Central Laboratory for Elemental and Isotopic Analysis, Nuclear Research Center, Atomic Energy Authority (B. Sc. physics 2004) Supervised by Prof. Dr. Mohammed. M.El-Okr Prof. Dr. Abd-Elfattah. I. Helal Physics Department Nuclear Research Center Faculty of Science Atomic Energy Authority Al-Azhar University Dr. Mahmoud. I. Mohammed Dr. Ashraf. A. Abd-Allateef Physics Department Nuclear Research Center Faculty of Science Atomic Energy Authority Al-Azhar University 2013 ACKNOWLEDGMENT ACKNOWLEDGMENT I am grateful to many people who have shared their time and experience with me to make the completion of this dissertation possible. At this time, I would like to acknowledge who helped me during the course of this work. First of all I would like to express my gratitude and appreciation to Prof. Dr. A. I. Helal Nuclear Research Center, Atomic Energy Authority for his sincere advice, helpful guidance and valuable discussions throughout this work. I wish to express my deepest thanks to Prof. Dr. M. El-Okr Prof. of solid-state physics faculty of science, Al-Azhr University for his continuous support, encouragement and constructive discussions. Special thanks also expressed to Prof. Dr. Hisham F. Aly Atomic Energy Authority, for providing the geological samples and his valuable advices. Many thanks are also to my colleagues in the Central Lab. for Elemental and Isotopic Analysis, Nuclear Research Center, Atomic Energy Authority for their help and collaboration specially Dr. M. Amr, Dr. A. Lateef, Dr. H. Mansour, Dr. S. Abd-Elaal and geo. A. Attia. I wish also to thank head and the staff of the accelerators and ion sources department for their great help. I would like to express my deepest thanks to Eng. Gad El-Okl and Dr. A. El-Hanafy for their continuous support during these years. I CONTENTS Chapters Subjects Pages Acknowledgments....................................................... I Contents....................................................................... II List of tables................................................................ VI List of figures.............................................................. VII Abstract…………………………………………… X Chapter (1) Introduction 1.1. Rare Earth Elements .................................................... 1 1.1.1. Introduction to Rare Earth Elements (REEs) .............. 1 1.1.2. Uses of REEs ............................................................... 2 1.1.3. Biological Effects of REEs ......................................... 4 1.1.4. Abundance and Occurrence of Rare Earth Elements .. 4 1.1.5. Determination of REEs ............................................... 5 1.1.5.1. Historical review ......................................................... 5 1.1.5.2. Preconcentration and Separation of REEs ................... 7 1.2. Ion Exchange Resins ................................................... 8 1.2.1. Amberlite IR-120......................................................... 8 1.3. The Use of the Inductively Coupled Plasma in Analytical Chemistry ................................................... 9 1.4. Matrix Interferences in ICP–AES ............................... 9 1.4.1. Spectral Interference in ICP–AES ............................... 10 1.4.2. Non-plasma-related Matrix Effects in ICP–AES ........ 11 1.4.3. Plasma-related Matrix Effects in ICP–AES ................ 12 1.5 Brief Literature Review of Plasma-related Matrix Effects .......................................................................... 13 1.4. Aim of the Work …………………………………….. 18 Chapter (2) Theoretical Considerations 2.1. Plasma Atomic Emission Spectrometry ...................... 20 II 2.1.1. Origins of Atomic Spectra ........................................... 20 2.1.2. Spectral Line Intensity ................................................ 21 2.1.3. Spectral Line Broadening ............................................ 23 2.1.4. Robustness of ICP-OES .............................................. 25 2.2. Plasma Mass Spectrometry ......................................... 28 2.2.1. Ionization Theory ....................................................... 28 2.3. Inductively Coupled Plasma as an Excitation and ionization Source ........................................................ 29 2.3.1. The ICP Discharge ..................................................... 29 2.3.2. Dispersion and detection of atomic emission ............ 33 2.3.2.1. Gratings ...................................................................... 33 2.3.2.2. The Photomultiplier Tube .......................................... 37 2.3.2.3. Array Detectors .......................................................... 41 2.3.3. Simultaneous Versus Sequential Detection ................ 43 2.3.4. Ion separation and detection in mass spectrometry .... 43 2.3.4.1. Ion extraction ............................................................... 43 2.3.4.2. Mass analyzers ............................................................ 44 2.3.4.3. Double-focusing sector field mass spectrometer ........ 44 2.3.4.3.1. Action of the Magnetic Field ..................................... 44 2.3.4.3.2. Electrostatic Field ..................................................... 45 2.3.4.3.3. Dispersion and Resolution ......................................... 46 2.3.4.3.4. Double Focusing of Energy ....................................... 46 2.3.4.4. Ion detection ............................................................. 46 2.3.4.5. Electron multiplier .................................................... 47 2.3.4.6. Resolution of ICP-MS .............................................. 48 2.4. Detection limit........................................................... 49 2.5. Accuracy, precision and reproducibility..................... 50 2.6. Interferences of ICP-MS............................................. 50 2.6.1. Isobaric Overlap ......................................................... 50 2.6.2. Polyatomic Ions........................................................... 51 2.6.3. Refractory Oxides....................................................... 52 2.6.4. Doubly Charged Ions.................................................... 53 III Chapter (3) APPARATUS AND EXPERIMENTAL CONDITIONS 54 3.1. Prodigy High Dispersion ICP-OES............................. 54 3.1.1. SAMPLE INTRODUCTION..................................... 55 3.1.2. The Concentric Nebulizer............................................ 55 3.1.3. The Cyclonic Spray Chamber...................................... 55 3.1.4. ICP Torch .................................................................... 56 3.2. JMS-PLASMAX2 Mass Spectrometer........................ 56 3.3. X-ray fluorescence(XRF)............................................. 56 3.3.1. Characteristic radiation................................................. 57 3.3.2. Primary radiation.......................................................... 57 3.3.3. Detection...................................................................... 58 3.3.4. X-ray intensity.............................................................. 58 3.3.5. XRF in chemical analysis............................................. 59 Chapter (4) Experimental Results and Discussion 60 4.1. Robustness of ICP-OES............................................... 60 4.2. Optimization of the operational parameters of ICP- OES.............................................................................. 60 4.3. Matrix interferences studies......................................... 62 4.3.1 Matrix Solution Preparation......................................... 62 4.3.2. Procedures of the experiment....................................... 63 4.3.3. Results of Matrix interferences studies........................ 63 4.3.3.1. Primary Factor of Matrix Effect................................. 63 4.3.3.2. Identification of the Secondary Factor for the Matrix Effect............................................................................ 66 4.3.3.3. Atomic Partition Function of Doubly Charged Matrix Ion as an Identified Secondary Factor for Matrix Effects........................................................................... 66 IV 4.3.3.4. Third Ionization Potential of the Matrix....................... 67 4.3.3.5. First Ionization Potential of the Matrix........................ 69 4.3.3.6. Partition Function Ratio of M2+ to M+ of the Matrix 69 4.3.3.7. Metal-oxide Bond Energy of the Matrix...................... 70 4.3.3.8. Atomic Partition Function of the Singly Charged Matrix Ion..................................................................... 73 4.3.3.9. Averaged Excitation Energy of the Singly Charged Matrix Ion..................................................................... 75 4.3.4. Excitation Mechanisms in the ICP............................... 76 4.3.5. Proposed Matrix-Effect Mechanism............................ 78 4.4. Results of REEs Separation......................................... 82 4.4.1. Quantitative Analysis.................................................. 82 4.4.2. Optimization for Performance of the Amberlite IR- 120 in Pre-concentration of Rare Earth Element Species........................................................................ 82 4.4.3.