Please read the abstract in the section 00front of this documentThesis (PhD (Chemistry))--University of Pretoria, 2005.Chemistryunrestricte

Naidoo, Eliazer Bobby

Thesis (PhD (Chemistry))--University of Pretoria, 2005.Please read the abstract in the section 00front of this documentChemistryunrestricte

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Solid-phase reactors in sequential injection systems by Eliazer Bobby Naidoo Submitted in partial fulfilment of the requirements for the degree PHILOSOPHIAE DOCTOR in the Faculty ofNatural & Agricultural Sciences University ofPretoria Pretoria July 2001 University of Pretoria                                                   © University of Pretoria Solid-Phase reactors in sequential injection systems by Eliazer Bobby Naidoo Promoter: Professor Jacobus F. van Staden Department of Chemistry University of Pretoria Degree : Philosophiae Doctor SYNOPSIS The increasing number ofjournals and reviews published on the development ofprocess analysers signals the importance thereof in the various fields that require analytical measurement to be performed. Analysis need to be done faster, more precise, accurate and economical. Hence the introduction of solid-phase reactors in flow systems. The use ofa solid-phase reactor incorporated into the sequential injection analysis (SlA) manifold is an improvement on the homogeneous methods applied. This represents an achievement for on-line determination ofdifferent substances in clinical, pharmaceutical,    industrial or agricultural fields. Solid-phase reactors has an advantage over homogeneous methods, particularly ifthe reagent is expensive, only slightly soluble or only available in the solid form. Reagent consumption is greatly decreased and the system is simplified with fewer junctions for mixing of reagent, sample and carrier stream. The aim of this research was to investigate the application of the SIA technique as a process analyser, by incorporating super serpentine and solid -phase reactors in its manifold. Super serpentine reactors were investigated for their sensitivity and precision. The solid­phase reactors were used for the determination of manganese, iron, nitrate and nitrite as well as chromium in industrial effiuents, natural waters and pharmaceutical products. For aU these determinations, SIA manifold with a single detector was used. The usefulness, cost-effectiveness and advantages ofthe solid-phase reactor incorporated into the SIA-manifold over the homogeneous system and the flow injection analysis (FIA) system is highlighted during the course of this study. 11    Vastetoestandreaktore in sekwensiiHe-inspuitsisteme deur Eliazer Bobby Naidoo Promotor: Proffesor Jacobus F. van Staden Departement Chemie U niversiteit van Pretoria Graad: Philosophiae Doctor SAMEVATTING Die toenemende aantaljoemaal- en oorsigartikelpublikasies rakende die ontwikkeling van prosesanaliseerders toon die belangrikheid daarvan in die verskeie velde wat vereis dat analitiese meetings uitgevoer moet word. Analises moet vinniger, meer presies, akkuraat en ekonomies uitgevoer word. Dit lei tot inskakeling van vastetoestandreaktore in v loeisisteme. Die gebruik van 'n vastetoestandreaktor, in 'n sekwensiele-inspuitanalise (SIA) reaksiespoel, is 'n verbetering op die homogene metodes. Dit verteenwoordig 'n doelwit III    vir aanlyn bepalings van verskillende stowwe in die kliniese, fannaseutiese, industriele en landbou rigtings. Vastetoestandreaktore het 'n voordeel bo homogene metodes, veral indien die reagense duur is, slegs gedeeltelik oplosbaar is of indien dit alleenlik in die vaste toestand beskikbaar is. Reagens verbruik is grootliks verminder en die sisteem is, deur van minder koppelings vir die vermenging van die reagens-, monster- en draerstroom gebruik te maak. Die doel van hierdie navorsing was om die toepassing van die SIA- tegniek, as 'n prosesanaliseerder, te ondersoek deur superkronkel- en vastetoestandreaktore in die reaksiespoel te inkorporeer. S uperkronkelreaktore is vir sensitiwiteit en presisie ondersoek. Die vastetoestandreaktore is vir die bepaling van mangaan, yster, nitraat, nitriet en chroom in industriele uitvJoeisels, natuurlike water en farmaseutiese produkte aangewend. 'n SIA- reaksiespoel, met ' n enkele detektor, was vir al hierdie bepalings gebruik. Die bruikbaarheid, koste-effektiwiteit en voordele van die vastetoestandreaktor in die SIA­reaksiespoel geihkorporeer, bo die homogene- en vloei-inspuitanalise (VIA) sisteme, word deur die loop van hlerdie studie uitgelig. lV    Acknowledgement To GOD our Creator who knows the destiny of every living being on this earth. It is through His Grace and Love that I am what I am today, tomorrow and forever. To my supervisor ProfJ. F. van Staden, thank you for your guidance and mentorship. I have learned a lot from you, I have acquired much from your supevision and I will always remember you. To Dr Raluca Stefan, you have always been there to help with a smile. You always put me first, then your work later whenever there was some kind of help I needed. Thank you. To my wife, Cbristinah, daughters, Maureen, Valentine, Pearl and Elaine your patience during my absence and your understanding and support were the only things that kept me going to the fulfilment ofmy dream. Elaine, my girl your eagerness to always ask if I needed any help with typing was of great help. Thank you and I dedicate this Thesis especially to you. To the group I found working with Profvan Staden, i.e Adele, EIrisa, Hanneli, Mack, Neels and Vusi, your acceptance of me and assistance to familiarise me with the environment under which I was going to fmd myself working, is appreciated. To those who were always ready to help when I needed any help, thank you. To the University of the North and the Department of Chemistry, I thank you for having allowed me to further my studies. v    Finally I would like to thank, the National Research Foundation and the Irish Government Scholarship for financial assistance. Without your finance I would not have been able to sustain myself while at the University of Pretoria. VI    Table of contents Synopsis 	 1 Samevatting 	 111 Acknowledgement 	 v Table of Contents 	 viii 1. 	 Sequential Injection Analysis(SIA)-homogeneous to heterogeneous systems 1 1.2 	 Introduction 1 1.3 	 Solid-Phase reactors in flow systems 5 1.4 	 Aim ofthis study 8 1.5 	 References 10 Vll    13 2. 	 Sequential Injection Analysis 2.1 	 Introduction 2.2 	 Historical background 2.3 	 Basic principles 2.4 	 Operational parameters 2.5 	 Operational techniques 2.5.1 	 Simple SIA systems 2.5 .2 	 Complexed SIA systems 2.6 	 SJA- Applications 2.7 	 Conclusions 2.8 	 References 3. 	 Super Serpentine reactors in Sequential Injection Analysis Systems 3.1 	 Introduction 3.2 	 Dispersion 3.2.1 	 Transport 3.2.2 	 Theoretical models 3.2.2.1 3.2.2.2 3.2.2.3 3.2.2.4 Taylor' s model Tanks in series model Mixing chamber model General models 3.2.3 	 Practical defmition of dispersion 3.2.3.1 R i ka's disperion coefficient 3.2.4 Influence ofvarious factors on the dispersion 3.2.4.1 3.2.4.2 Sample volume Hydrodynamic factors V111 13 15 19 24 30 30 32 34 41 43 52 52 53 53 55 56 57 57 58 59 60 60 61 62    64 3.2.4.3 Geometric factors 3.2.4.3.1  Straight tubes 64 3.2.4.3.2  Coils 66 3.2.4.3.3  Knotted reactors 67 3.2.4.3.4  Normal packed tubes 67 3.2.4.3.5  Single bead string reactors 68 3.2.4.3.6  Mixing chambers 68 3.3 Super Serpentine reactors 69 3.3.1 Introduction 69 3.3.2 Experimental 70 3.3.2.1 Reagents and solutions 70 3.3.2.1.1 Stock iron 0 11) solution 71 3.3.2. 1.2 Perchloric acid solution 71 3.3.2.1.3 Tiron solution 71 3.3.2.2 Reactor preparation 71 3.3.2.3 Instrumentation 73 3.3 .2.4 Procedure 75 3.3.3 Results and discussion 76 3.3.3.1 Influence of reactor type on sensitivity and precision 77 3.3.3.1.1 50 cm reactors 78 3.3.3.1.2 60 cm reactors 80 3.3.3.1 .3 80 cm reactors 83 3.3.3 .1.4 90 em reactors 85 3.4 Conclusion 88 3.5 References 90 IX    4. SoIid-Phase reactors 92 4.1 Introduction 92 4.2 Reactor type and preparation 93 4.2.1 Derivatising reactors 94 4.2.1.1 Redox reactors 94 4.2.1.1 Complex forming reactors 94 4.2.1.3 Precipitating reactors 95 4.2.1.4 Enzyme reactors 96 4.2.1.5 Immunoassay 97 4.2.2 Non-derivatising reactors 98 4.2.2.1 Adsorptive reactors 98 4.2.2.2 Reagent releaser reactors 99 4.2.2.3 Beads 99 4.3 Modes of immobilization 100 4.3. 1 Natural 100 4.3.2 Adsorption 100 4.3.3 Entrapment 101 4.4 Shape of the reactor/reactor design 102 4.4.1 Tubular 102 4.4.2 Conical 104 4.4.3 Jet ring ce1l!beads 105 4.5 Position of reactor in the system 106 . 4.5.1 Pre-valve position for the reactor 107 4.5.2 Between the injection valve and detector 108 4.5.3 In the injection system 109 4.5.4 In the detector 110 4.6 Application of solid-phase reactors 112 4.6.1 FIA solid-phase reactors 112 x    4.6.2 SIA solid-phase reactors 118 4.7 Conclusion 119 4.8 References 121 5. Determination ofManganese using a solid-phase reactor in an SIA system 129 5.1 Introduction 129 5.2 Properties of manganese 13 1 5.3 Oxidation states ofmanganese 131 5.4 Manganese (II) compounds: Mn 2+ 132 5.5 Industrial uses of manganese 133 5.6 Biological importance of manganese 134 5.7 Choice of analytical method 136 5.8 Manganese determination 138 5.8.1 Experimental 138 5.8.1 .1 Reagents and solutions 138 5.8.1. 1.1 Stock manganese solution 138 5.8.1.1.2 HN03 solution 138 5.8.1.2 Instrumentation 139 5.8.1.3 The solid-phase reactor 140 5.8.1.4 Procedure 142 5.8.2 Method optimization 143 5.8.2.1 Solid-phase reactor (SPR) parameter 143 5.8.2.1 .1 Reactor length 144 5.8.2.1.2 Reactor temperature 145 5.8.2.2 'Chemical parameters 147 5.8.2.2.1 Acid concentration 147 5.8.2.3 Physical parameters 149 Xl    5.8.2.3 .1 Flow rate 	 149 5.8.2.3.2 Tube length 	 151 5.8.2.3.3 Sample volume 	 152 5.8.3 	 Method evaluation 153 5.8.3.1 Linearity 	 154 5.8.3.2 Accuracy 	 155 5.8.3.3 Recovery 	 156 5.8.3.4 Precision 	 156 5.8.3.5 Sample interaction 	 156 5.8.3.6 Detection limit 	 157 5.8.3.7 Interferences 	 158 5.8.3.8 Sampling rate 	 158 5.8.3.9 General problems 	 159 5.9 	 Statistical comparison of techniques used 159 5.10 	 Conclusion 163 5.11 	 References 164 6. 	 Determination of iron as Fe(II) in multi-vitamins, baematinics and natural waters using an SIA system 168 6.1 	 Introduction 168 6.2 	 The biochemistry and biological uses of iron 170 6.3 	 Choice of analytical method 171 6.4 	 Total iron determination 173 6.4.1. Experimental 	 173 6.4.1.1 Reagents and solutions 	 173 6.4.1.1.1 Stock Fe(ID solution 	 173 6.4.1.1.2 Perchloric acid solution 	 174 6.4.1. 1.3 1.10 Phenanthroline solution 174 XlI    174 6.4.1.1.4 Acetic acid solution 6.4.1.2 6.4.1.3 6.4.1.4 6.4.1.5 6.4.1.1.5 6.4.1.1.6 6.4.1.1.7 6.4.1.1.8 Hydroxyl ammonium chloride solution Sodium acetate solution Buffer solution Hydrochloric acid solution Instrumentation Operation of the system The solid-phase reactor preparation Sample preparation 6.4.2 Method optimization 6.4.2.1 Solid-phase reactor 6.4.2.1.1 Reactor length 6.4.2.2 Chemical parameters 6.4.2.2.1 F e(ll) concentration 6.4.2.2.2 Carrier concentration 6.4.2.3 Physical parameters 6.4.2.3.1 Flow rate 6.4.2.3 .2 Sample volume 6.4.2.3.3 Reagent volume 6.4.3 Method evaluation 6.4.3.1 6.4.3.2 6.4.3.3 6.4.3 .4 6.4.3 .5 6.4.3.6 6.4.3.7 Linearity Accuracy Recovery Precision Detection limit Sample interaction Interferences 6.5 Statistical comparisons of techniques used 6.6 Conclusions XlLl 174 174 175 175 175 176 178 179 180 180 180 181 181 183 184 184 185 186 187 187 190 190 190 191 191 192 192 197    198 6.7 References 7. Determination of oxidized nitrogen in water using a solid-phase reactor in an SIA system 201 7.1 Introduction 201 7.2 Choice of analytical method 204 7.3 Determination of total oxidized nitrogen 206 ] 7.3 .1 Experimental 206 7.3.1.1 Reagents and solutions 206 7.3 .1.1. 1 Stock nitrate solution 206 7.3.1. 1.2 Stock nitrite solution 207 7.3.1. 1.3 Buffer solution 207 7.3.1. 1.4 Chromogenic solution 207 7.3.1.2 Instrumentation 208 7.3.1.3 Operation of the system 209 7.3.1.4 The solid-phase reactor 211 7.3.l.5 Sample preparation 2] 2 7.3.2 Method optimization 212 7.3.2.1 Solid-phase reactor parameters 212 7.3 .2. 1.1 Reactor length 2 13 7.3.2.2 Chemical parameters 214 7.3 .2.2.1 Nitrate concentration 214 7.3.2.2.2 Carrier concentration 215 7.3.2.3 Physical parameters 216 7.3.2.3.l 7.3.2.3.2 7.3.2.3 .3 7.3 .2.3.4 Flow rate 216 Sample volume 217 Reagent volume 218 Buffer volume 219 XIV    7.3.3 	 Method evaluation 220 7.3.3.l Linearity 	 220 7.3.3.2 Accuracy 	 220 7.3.3.3 Precision 	 222 7.3.3.4 Detection limit 	 222 7.3.3.5 Recovery 	 222 7.3.3.6 Sample interaction 	 223 7.3.3.7 Interferences 	 223 7.4 	 Statistical comparison of techniques used 224 7.5 	 Conclusions 226 7.6 	 References 228 8. 	 Determination oftotal chromium as chromate in electroplating and natural waters with an SIA system 231 8.1 	 Introduction 23 1 8.2 	 The chemistry of chromium (VI). dO 233 8.3 	 Choice of analytical technique 234 8.4 	 Chromium determination 236 8.4.1 	 Experimental 238 8.4.1.1 Reagents and solutions 	 238 8.4.1.1.1 Stock chromium(IU) solution 238 8.4.1.1.2 Stock dicr.romate solution 	 238 8.4.1. 1.3 Stock chromate solution 	 239 8.4.1.1.4 Ammonium cerium(VI) sulphate solution239 8.4.1.1.5 Sodium nitrite solution 	 239 8.4.1.1.6 Ammonium hydroxide solution 239 8.4.1. 1.7 Sulphuric acid solution 	 239 8.4.1.2 Instrumentation 	 240 xv    8.4.1.3 Solid-phase reactors 8.4.1.4 Sample preparation 8.4.1.5 Operation of the system 8.4.2 Method optimization 8.4.2.1 Chemical parameters 8.4.2.1.1 Chromium (III) concentration 8.4.2.2 Physical parameters 8.4.2.2.1 8.4.2.2.2 8.4.2.2.3 8.4.2.2.4 8.4.3 Method evaluation Reactor length Flow rate Sample volume Base volume 8.4.3.1 8.4.3.2 8.4.3.3 8.4.3.4 8.4.3.5 8.4.3.6 8.4.3.7 Linearity Accuracy Recovery Precision Detection limit General problems Interferences 8.5 Statistical comparison of techniques used 8.6 Conclusions 8.7 References 9. Conclusions Addendum A: Method construction References Addendum B: Publications and presentations XVI 241 242 243 245 245 245 247 247 248 249 250 25 1 251 252 254 255 255 255 255 257 259 261 263 268 280 281    

Solid-phase reactors in sequential injection systems

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Solid-phase reactors in sequential injection systems

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