6 9 The significant role of trace elements present at the Jlgfg (10- gig), ngfg (10- gig) 12 and pgfg (10- gig) levels in geological, biological, environmental and industrial materials has increasingly been recognized in science and technology. To detect and determine trace elements, we usually use modern optical, electrochemical and nuclear analytical techniques. Althouih most of them are highly sensitive and selective, preliminary enrichment techniques are required to extend the detection limits, improve precision and accuracy of analytical results, and to widen the scope of the determina tion techniques. About two decades ago, I wrote a chapter "Separations and Pre concentrations" in "Trace Analysis: Physical Methods" edited by Prof. G. H. Morrison (Wiley-Interscience, New York, 1965). Since then, the progress in this field has been remarkable. This 'monograph is intended as a laboratory book directly applicable to the practice, but is not a so-called "cookbook" which offers detailed laboratory instruc is useful for all analysts solving problems in inorganic trace tions. I hope this book analysis and appreciating the applicability and limitations of enrichment techniques combined with instrumental determination techniques. In three introductory chapters, general aspects and control of contamination and loss are discussed. The following eight chapters deal with enrichment techniques based on volatilization, liquid-liquid extraction, selective dissolution, precipitation, electrochemical deposition and dissolution, sorption, ion exchange, liquid chromato graphy, flotation, freezing and zone melting. The final two chapters are devoted to special enrichment techniques used in trace analyses of natural waters and gaseous samples.

1 Introduction

1.1 Inorganic Trace Analysis in Science and Technology
1.2 The Role of Enrichment Techniques in Inorganic Trace Analysis
2 General Aspects of Enrichment Techniques
2.1 Trace Recovery
2.2 Enrichment Factor
2.3 Contamination
2.4 Simplicity and Rapidity
2.5 Sample Size
3 Control of Contamination and Loss
3.1 Airborne Contamination
3.2 Contamination and Loss Due to Apparatus
3.3 Contamination Due to Reagents
3.4 Other Sources of Contamination and Loss
4 Volatilization
4.1 Volatilization from Solutions
4.2 Volatilization from Solid and Molten States
5 Liquid-Liquid Extraction
5.1 General Procedures
5.2 Extraction of Metal Chelates
5.3 Extraction of Ion Pairs
5.4 Special Extractions
6 Selective Dissolution
6.1 Selective Dissolution of the Matrix
6.2 Selective Dissolution of Trace Elements
7 Precipitation
7.1 Precipitation of Matrix Elements
7.2 Precipitation of Trace Elements
8 Electrochemical Deposition and Dissolution
8.1 Electrodeposition on Solid Electrodes
8.2 Electrodeposition on Mercury Cathodes
8.3 Spontaneous Electrochemical Deposition
8.4 Anodic Dissolution
9 Sorption, Ion Exchange and Liquid Chromatography
9.1 General Procedures
9.2 Separation with Ion Exchange Resins
9.3 Separation with Cellulosic Exchangers
9.4 Separation with Polyurethane Foams
9.5 Separation with Miscellaneous Organic Sorbents
9.6 Separation with Activated Carbon
9.7 Inorganic Ion Exchangers
10 Flotation
10.1 General Procedures
10.2 Carrier Precipitation Followed by Flotation
10.3 Ion Flotation
11 Freezing and Zone Melting
11.1 Freeze Concentration of Dilute Aqueous Solutions
11.2 Enrichment of Impurities in Solids by Zone Melting
12 Enrichment Techniques in Water Analysis
12.1 Separation Based on the Particle Size and Density
12.2 Separation Based on Chemical Reactivity
13 Enrichment Techniques in Gas Analysis
13.1 Separation of Particles
13.2 Separation of Gaseous Trace Constituents
Literature
A.1 Solvents
A.2 Masking Agents
A.3 Ion Exchange Data
Index of Abbreviations and Symbols.