Paul R. Haddad

Ion chromatography : principles and applications

Chapter 1. Introduction. PART I. Ion-Exchange Separation Methods. Chapter 2. An introduction to ion-exchange methods. Chapter 3. Ion-exchange stationary phases for ion chromatography. Chapter 4. Eluents for ion-exchange separations. Chapter 5. Retention models for ion-exchange. PART II. Ion-Interaction, Ion-Exclusion and Miscellaneous Separation Methods. Chapter 6. Ion-interaction chromatography. Chapter 7. Ion-exclusion chromatography. Chapter 8. Miscellaneous separation methods. PART III. Detection Methods. Chapter 9. Conductivity detection. Chapter 10. Electrochemical detection (amperometry, voltammetry and coulometry). Chapter 11. Potentiometric detection. Chapter 12. Spectroscopic detection methods. Chapter 13. Detection by post-column reaction. PART IV. Practical Aspects. Chapter 14. Sample handling in ion chromatography. Chapter 15. Methods development. PART V. Applications of Ion Chromatography. Overview of the applications section. Chapter 16. Environmental applications. Chapter 17. Industrial applications. Chapter 18. Analysis of foods and plants. Chapter 19. Clinical and pharmaceutical applications. Chapter 20. Analysis of metals and metallurgical solutions. Chapter 21. Analysis of treated waters. Chapter 22. Miscellaneous applications. Appendix A. Statistical information on ion chromatography publications. Appendix B. Abbreviations and symbols. Index.

Leaching and recovery of gold using ammoniacal thiosulfate leach liquors (a review)

A review is presented summarising the leaching of gold with ammoniacal thiosulfate solutions, and evaluating the current use and development of ion exchange resins for the recovery of gold and silver from such leach liquors. Comparisons are also made with other recovery processes, including carbon adsorption, solvent extraction, electrowinning and precipitation. Thiosulfate leaching chemistry is compared with cyanide leaching, and the problems associated with obtaining a high yield of recovered gold using the former process are discussed. The present limitations of using Resin-in-Pulp (RIP) and Resin-in-Leach (RIL) systems with thiosulfate liquors are indicated and possible solutions discussed.

Effects of carrier electrolyte composition on separation selectivity in capillary zone electrophoresis of low- molecular-mass anions

Abstract A systematic investigation was carried out on the influence of carrier electrolyte composition on separation selectivity in capillary zone electrophoresis of inorganic anions. Chromate, chloride, sulphate or nitrate was used as the carrier electrolyte, each containing a quaternary ammonium salt to reverse the electro-osmotic flow. The concentration and nature of the carrier electrolyte salt affected the separation order only to a minor degree. Much more pronounced effects could be achieved by adding organic solvents to the carrier electrolyte or by using different quaternary ammonium salts. Chemical modification of the inner wall of the fused-silica capillary did not affect the migration order significantly. There is no indication of retention by effects similar to ion-interaction chromatography as long as capillaries with an inner diameter of 75 μm are used. Nevertheless, such effects might play an important role for capillaries with diameters of 10 μm or less.

Determination of inorganic anions by high-performance liquid chromatography

Chromatographic techniques, and in particular ion-exchange methods, have long been used for the analysis of inorganic ions using diverse monitoring techniques such as conductivity, polarography and spectrophotometry. A major advance in this field occurred in 1975, when Small et al. described a novel system for the chromatographic determination of inorganic ions, in which a specially developed pellicular resin was used to effect the separation and a second ion-exchange column to reduce the background conductivity of the eluent in order to improve the detection limits for the eluted analyte ions. This system, which is described in detail later, illustrated the enormous potential of chromatography for inorganic ion analysis and deservedly received considerable research attention for some years. An important side effect of this development was to stimulate greatly research into alternative chromatographic methods suitable for inorganic ions, and over the past 7 years a considerable volume of material has been published. It is the purpose of this paper to review these alternative methods, and therefore those articles which employ the same or a similar technique to that used by Small et al. will be discussed only briefly in order to provide a basis for comparison with other methods. Further to the above specific restriction, this review will be confined to a discussion of methods that are chiefly applicable to anion analysis, because until very recently these methods have far outnumbered those for cation analysis. The preponderance of research into chromatographic methods for anions strongly reflects the paucity of alternative analytical procedures. This situation does not apply to cations, for which a number of excellent rapid and sensitive spectroscopic techniques (such as atomic-absorption spectrometry and inductively coupled plasma atomic-emission spectrometry) and electrochemical methods (such as polarography and anodic-stripping voltammetry) are available. Moreover, many of these are multi-element techniques and so duplicate one of the chief attractions of chromatography for inorganic cation analysis. Despite this, much of the experience gained from the intensive development of chromatographic approaches to inorganic anion analysis has recently been applied successfully to inorganic cations. At this stage, however, it is fair to say that these chromatographic methods for cations are generally inferior to the existing spectroscopic and electrochemical methods mentioned above. In contrast, the use of chromatography for anion analysis has proved so successful that chromatographic methods are among the best available and have been applied to a wide range of inorganic species. This success can be attributed to concurrent advances in separation technology and detection methods, and in this review these two aspects will be described separately.

Comparison of ion chromatography and capillary electrophoresis for the determination of inorganic ions

The techniques of ion chromatography and capillary electrophoresis are compared as analytical methods for the determination of inorganic anions and cations. Comparison is made in the areas of stage of development, separation efficiency, separation selectivity, analytical performance parameters, method development procedures, applications, strenghts and weaknesses, and future directions. It is shown that the two techniques are complementary rather than competitive, especially with regard to their separation selectivities and the type of applications to which they are most suited.

Indirect photometric detection of anions in capillary electrophoresis

Indirect photometric detection (absorbance and fluorescence) of anions by capillary electrophoresis is reviewed. Factors which influence the displacement process of analyte ions in background electrolytes containing one or more co-ions are discussed and factors which influence detection sensitivity in indirect detection modes are outlined. Procedures are presented for buffering background electrolytes when indirect absorbance detection is to be used in the determination of anions, and approaches to the design and optimization of the composition of background electrolytes for indirect detection of anions are discussed. The application of indirect detection to the separation of major groups of analytes including inorganic anions, organic acids, carbohydrates, phosphates, phosphonates and miscellaneous species is then reviewed. Detailed information on the physical properties of species used as probes for indirect detection of anions is provided.

Online Sample Preconcentration in Capillary Electrophoresis using Analyte Focusing by Micelle Collapse

A dimension for online sample preconcentration in capillary electrophoresis (CE) without modification of current CE commercial instrumentation is introduced. The focusing mechanism is based on the transport, release, and accumulation of molecules bound to micelle carriers that are made to collapse into a liquid phase zone. More than 2 orders of magnitude improvement in detection sensitivity for model steroidal compounds using sodium dodecyl sulfate micelles as carrier is demonstrated.

Separation and sample pre-treatment in bioanalysis using monolithic phases: A review

In order to support drug discovery and development studies within the pharmaceutical industry there has been an increased use of innovative bioanalytical assays and associated analytical technology. Performing quantitative bioanalysis in a variety of biological matrices can also involve the use of sample preparation techniques, complex HLPC column switching and microfluidic systems. Development of assays for diverse therapeutic agents in biomatrices, such as plasma and urine, can be very technically challenging to obtain the sensitivity, speed and specificity required. This challenge focuses on the quantification of drugs and metabolites at very low concentration levels, in an excess of biological matrix and in a high-throughput manner. One area of wide interest is the use and application of monolithic phases where emerging technology has been implemented successfully. This review presents an overview of the application of monolithic phases in a bioanalytical setting, including the bioanalytical challenges that need to be overcome; the synthesis, use and applicability of monolithic phases (with emphasis on polymer-based phases); the currently available bioanalytical techniques and approaches; and future possibilities for these phases.

Developments in sample preparation and separation techniques for the determination of inorganic ions by ion chromatography and capillary electrophoresis

A review is presented of sample preparation and separation techniques for the determination of inorganic ions by ion chromatography (IC) and capillary electrophoresis (CE). Emphasis has been placed on those sample treatment methods which are specific to inorganic analysis, and the developments in separation methods which are discussed are those which enhance the capabilities of IC and CE to handle complex sample matrices. Topics discussed include solid-phase extraction for sample clean-up and preconcentration, dialytic methods, combustion methods, matrix-elimination IC, electrostatic IC, electrically polarised ion-exchange resins, electromigration sample preparation in CE, chromatographic sample preparation for CE, use of high-ionic strength background electrolytes, buffering of background electrolytes in CE, use of capillary electrochromatography for inorganic determinations, and methods for the manipulation of separation selectivity in both IC and CE. Finally, some possible future trends are discussed.

Approaches to enhancing the sensitivity of capillary electrophoresis methods for the determination of inorganic and small organic anions

One of the major problems facing the development of capillary electrophoresis (CE) is the relatively high limits of detection when compared to traditional high‐performance liquid chromatographic (HPLC) methods. While the use of an alternative detector can offer better sensitivity, a more universal approach is sample preconcentration. Numerous on‐line methods have been developed to improve the sensitivity of CE, and are based on electrophoretic principles, chromatographic principles, or a combination of both. This review will discuss all forms of on‐line preconcentration methods for CE, with emphasis given to those that have shown particular merit when applied to inorganic and small organic anions.One of the major problems facing the development of capillary electrophoresis (CE) is the relatively high limits of detection when compared to traditional high-performance liquid chromatographic (HPLC) methods. While the use of an alternative detector can offer better sensitivity, a more universal approach is sample preconcentration. Numerous on-line methods have been developed to improve the sensitivity of CE, and are based on electrophoretic principles, chromatographic principles, or a combination of both. This review will discuss all forms of on-line preconcentration methods for CE, with emphasis given to those that have shown particular merit when applied to inorganic and small organic anions.