Preface

Sampling and sample preparation are major parts of every chemical analysis. These steps are the most time-consuming and challenging of any analysis procedure. In addition, most errors are likely to occur at these steps. This is why the sample preparation step is known as the "bottleneck" of any analysis; therefore, the overall success of analysis depends on advances in sample preparation methods.

For many years, sample preparation techniques were based on low-tech approaches including non-automated and labor techniques such as dilution, filtration, deproteinization, derivatization, centrifugation, purification, and extractions such as liquid-liquid extraction and liquid-solid extraction (i.e., Soxhlet extractor). These techniques are hazardous to both the environment and operator and require a high volume of samples and extracting organic solvent. This book is divided into three sections that discuss a variety of sample preparation techniques and their applications.

Chapter 1, "Introductory Chapter: Evolution of Sample Preparation", reviews the development of sample preparation techniques away from hazardous methods toward modern and more environmentally friendly approaches. Evolving rules of green analytical chemistry have forced analytical chemists to find new, "greener" sample preparation and extraction techniques. This has resulted in two major advances in sample preparation in the past three decades. First is the introduction of solid-phase extraction (SPE), and the second is the invention of solidphase microextraction (SPME). Both approaches were themselves revolutionized with the introduction of nanomaterials as sorbents. While SPE is an exhaustive method of separation, SPME is a non-exhaustive method of extraction based on equilibrium. SPME tries to address solvent-free needs. Both SPE and SPME can be fully automated, and by changing the type of their solid or pseudo-solid extracting phase, they can be used for many varieties of analytical needs. Chapter 2, "Modern Sample Preparation Techniques: A Brief Introduction," details the history and different modes of extraction techniques, derived mainly from SPE and SPME. Together, Chapters 1 and 2 introduce readers to the basic concepts in sampling and describe in detail the major techniques. They also discuss automation, miniaturization, advantages, and some applications of the presented techniques.

The second section of the book presents the latest advances in sample preparation techniques for surface spectroscopy analysis. Both theoretical aspects of sample preparation and practical recipes for successful surface analysis are discussed.

Finally, the third section of the book discusses sample preparation for particle, tissue, and cellular separation in two chapters: "Preparation of Tissues and Heterogeneous Cellular Samples for Single-Cell Analysis" and "Particle and Cell Separation."

Although this book does not provide a comprehensive review of all techniques of sample preparation, it does present the latest information to keep readers abreast of new areas of research in this field.

I am grateful to all the contributing authors for their time and efforts in preparing the chapters of this book.

## **Massoud Kaykhaii**

Chemistry Department, University of Sistan and Baluchestan, Zahedan, Iran Section 1
