CONTRIBUTORS Roman Brukh, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102 Zafar Iqbal, Department of Chemistry and Environmental Science, New Jersey Institute of Tecl Mahesh Karwa, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ07102 Barbara B. Kebbekus, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ0710 Dawen Kou, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102 Somenath Mitra, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102 Sharmila M. Mukhopadhyay, Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH 45435 Bhama Parimoo, Department of Pharmaceutical Chemistry, Rutgers University College of Pharmacy, Piscataway, NJ 08854 Satish Parimoo. Aderans Research Institute. Inc.. 3701 Market Street Philadelphia, PA 19104 Gregory C Slack, Department of Chemistry, Clarkson University, Potsdam. NY 13676 Nicholas H. Snow, Department of Chemistry and Biochemistry, Seton Hall University, South Orange, NJ 07079 Martha J M. Wells, Center for the Management, Utilization and Protection of Water Resources and Department of Chemistry, Tennessee Technological University, Cookeville, TN 38505
CONTRIBUTORS Roman Brukh, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102 Zafar Iqbal, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102 Mahesh Karwa, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102 Barbara B. Kebbekus, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102 Dawen Kou, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102 Somenath Mitra, Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ 07102 Sharmila M. Mukhopadhyay, Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH 45435 Bhama Parimoo, Department of Pharmaceutical Chemistry, Rutgers University College of Pharmacy, Piscataway, NJ 08854 Satish Parimoo, Aderans Research Institute, Inc., 3701 Market Street, Philadelphia, PA 19104 Gregory C. Slack, Department of Chemistry, Clarkson University, Potsdam, NY 13676 Nicholas H. Snow, Department of Chemistry and Biochemistry, Seton Hall University, South Orange, NJ 07079 Martha J. M. Wells, Center for the Management, Utilization and Protection of Water Resources and Department of Chemistry, Tennessee Technological University, Cookeville, TN 38505 xvii
PREFACE There has been unprecedented growth in measurement techniques over the last few decades. Instrumentation, such as chromatography, spectroscopy and microscopy, as well as sensors and microdevices, have undergone phe nomenal developments. Despite the sophisticated arsenal of analytica tools, complete noninvasive measurements are still not possible in most cases. More often than not, one or more pretreatment steps are necessary. These are referred to as sample preparation, whose goal is enrichment, cleanup, and signal enhancement Sample preparation is often the bottleneck in a measurement process, as they tend to be slow and labor-intensive. De- spite this reality, it did not receive much attention until quite recently However, the last two decades have seen rapid evolution and an explosive growth of this industry. This was particularly driven by the needs of the environmental and the pharmaceutical industries, which analyze large num- ber of samples requiring significant efforts in sample preparation Sample preparation is important in all aspects of chemical, biological materials, and surface analysis. Notable among recent developments are faster, greener extraction methods and microextraction techniques. Spe cialized sample preparations, such as self-assembly of analytes on nano- particles for surface enhancement, have also evolved. Developments in high throughput workstations for faster preparation-analysis of a large number of samples are impressive. These use 96-well plates(moving toward 384 wells) and robotics to process hundreds of samples per day, and have revolu- ionized research in the pharmaceutical industry. Advanced microfabrica tion techniques have resulted in the development of miniaturized chemical analysis systems that include microscale sample preparation on a chip Considering all these, sample preparation has evolved to be a separate dis- cipline within the analytical/measurement sciences The objective of this book is to provide an overview of a variety of sam- ple preparation techniques and to bring the diverse methods under a com- mon banner. Knowing fully well that it is impossible to cover all aspects in a single text, this book attempts to cover some of the more important and widely used techniques. The first chapter outlines the fundamental issues relating to sample preparation and the associated quality control. The
PREFACE There has been unprecedented growth in measurement techniques over the last few decades. Instrumentation, such as chromatography, spectroscopy and microscopy, as well as sensors and microdevices, have undergone phenomenal developments. Despite the sophisticated arsenal of analytical tools, complete noninvasive measurements are still not possible in most cases. More often than not, one or more pretreatment steps are necessary. These are referred to as sample preparation, whose goal is enrichment, cleanup, and signal enhancement. Sample preparation is often the bottleneck in a measurement process, as they tend to be slow and labor-intensive. Despite this reality, it did not receive much attention until quite recently. However, the last two decades have seen rapid evolution and an explosive growth of this industry. This was particularly driven by the needs of the environmental and the pharmaceutical industries, which analyze large number of samples requiring significant e¤orts in sample preparation. Sample preparation is important in all aspects of chemical, biological, materials, and surface analysis. Notable among recent developments are faster, greener extraction methods and microextraction techniques. Specialized sample preparations, such as self-assembly of analytes on nanoparticles for surface enhancement, have also evolved. Developments in highthroughput workstations for faster preparation–analysis of a large number of samples are impressive. These use 96-well plates (moving toward 384 wells) and robotics to process hundreds of samples per day, and have revolutionized research in the pharmaceutical industry. Advanced microfabrication techniques have resulted in the development of miniaturized chemical analysis systems that include microscale sample preparation on a chip. Considering all these, sample preparation has evolved to be a separate discipline within the analytical/measurement sciences. The objective of this book is to provide an overview of a variety of sample preparation techniques and to bring the diverse methods under a common banner. Knowing fully well that it is impossible to cover all aspects in a single text, this book attempts to cover some of the more important and widely used techniques. The first chapter outlines the fundamental issues relating to sample preparation and the associated quality control. The xix
PREFACE remainder of the book is divided into three sections In the first we describe various extraction and enrichment approaches. Fundamentals of extraction along with specific details on the preparation of organic and metal analytes, are presented. Classical methods such as Soxhlett and liquid-liquid extra tion are described, along with recent developments in widely accepted methods such as SPE, SPME, stir-bar microextraction, microwave extrac tion, supercritical extraction, accelerated solvent extraction, purge and trap, headspace, and membrane extraction The second section is dedicated to the preparation for nucleic acid analy is. Specific examples of DNA and RNA analyses are presented, along with he description of techniques used in these procedures. Sections on high hroughput workstations and microfabricated devices are included. The third section deals with sample preparation techniques used in microscopy, spectroscopy, and surface-enhanced Raman The book is intended to be a reference book for scientists who use sample preparation in the chemical, biological, pharmaceutical, environmental, and material sciences. The other objective is to serve as a text for advanced undergraduate and graduate students. e I am grateful to the New Jersey Institute of Technology for granting me a baical leave to compile this book. My sincere thanks to my graduate students Dawen Kou, Roman Brukh, and Mahesh Karwa, who got going when the going got tough; each contributed to one or more chapte New Jersey Institute of Technology SOMENATH MITRA Newark. Nj
remainder of the book is divided into three sections. In the first we describe various extraction and enrichment approaches. Fundamentals of extraction, along with specific details on the preparation of organic and metal analytes, are presented. Classical methods such as Soxhlett and liquid–liquid extraction are described, along with recent developments in widely accepted methods such as SPE, SPME, stir-bar microextraction, microwave extraction, supercritical extraction, accelerated solvent extraction, purge and trap, headspace, and membrane extraction. The second section is dedicated to the preparation for nucleic acid analysis. Specific examples of DNA and RNA analyses are presented, along with the description of techniques used in these procedures. Sections on highthroughput workstations and microfabricated devices are included. The third section deals with sample preparation techniques used in microscopy, spectroscopy, and surface-enhanced Raman. The book is intended to be a reference book for scientists who use sample preparation in the chemical, biological, pharmaceutical, environmental, and material sciences. The other objective is to serve as a text for advanced undergraduate and graduate students. I am grateful to the New Jersey Institute of Technology for granting me a sabbatical leave to compile this book. My sincere thanks to my graduate students Dawen Kou, Roman Brukh, and Mahesh Karwa, who got going when the going got tough; each contributed to one or more chapters. New Jersey Institute of Technology Newark, NJ Somenath Mitra xx preface
CHAPTER SAMPLE PREPARATION: AN ANALYTICAL PERSPECTIVE SOMENATH MITRA AND ROMAN BRUKH Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 1.1. THE MEASUREMENT PROCESS The purpose of an analytical study is to obtain information about some object or substance. The substance could be a solid, a liquid, a gas, or a biological material. The information to be obtained can be varied. It could be the chemical or physical composition, structural or surface properties or a sequence of proteins in genetic material. Despite the sophisticated arse- nal of analytical techniques available, it is not possible to find every bit of information of even a very small number of samples. For the most part, the state of current instrumentation has not evolved to the point where we take an instrument to an object and get all the necessary information Although there is much interest in such noninvasive devices, most analysis is still done by taking a part (or portion of the object under study (referred to as the sample) and analyzing it in the laboratory(or at the site). Some com- mon steps involved in the process are shown in Figure l. The first step is sampling, where the sample is obtained from the object to be analyzed. This is collected such that it represents the original object Sampling is done with variability within the object in mind. For example while collecting samples for determination of Ca+ in a lake, it should be kept in mind that its concentrations can vary depending on the location, the depth, and the time of year. The next step is sample preservation. This is an important step, because there is usually a delay between sample collection and analysis. Sample preservation ensures that the sample retains its physical and chemical char acteristics so that the analysis truly represents the object under study. Once ISBN 0-471-32845-6 Copyright O 2003 John Wiley Sons.i. by Somenath Mitra
CHAPTER 1 SAMPLE PREPARATION: AN ANALYTICAL PERSPECTIVE SOMENATH MITRA AND ROMAN BRUKH Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 1.1. THE MEASUREMENT PROCESS The purpose of an analytical study is to obtain information about some object or substance. The substance could be a solid, a liquid, a gas, or a biological material. The information to be obtained can be varied. It could be the chemical or physical composition, structural or surface properties, or a sequence of proteins in genetic material. Despite the sophisticated arsenal of analytical techniques available, it is not possible to find every bit of information of even a very small number of samples. For the most part, the state of current instrumentation has not evolved to the point where we can take an instrument to an object and get all the necessary information. Although there is much interest in such noninvasive devices, most analysis is still done by taking a part (or portion) of the object under study (referred to as the sample) and analyzing it in the laboratory (or at the site). Some common steps involved in the process are shown in Figure 1.1. The first step is sampling, where the sample is obtained from the object to be analyzed. This is collected such that it represents the original object. Sampling is done with variability within the object in mind. For example, while collecting samples for determination of Ca2þ in a lake, it should be kept in mind that its concentrations can vary depending on the location, the depth, and the time of year. The next step is sample preservation. This is an important step, because there is usually a delay between sample collection and analysis. Sample preservation ensures that the sample retains its physical and chemical characteristics so that the analysis truly represents the object under study. Once 1 Sample Preparation Techniques in Analytical Chemistry, Edited by Somenath Mitra ISBN 0-471-32845-6 Copyright 6 2003 John Wiley & Sons, Inc
2 SAMPLE PREP ARATION: AN ANALYTICAL PERSPECTIVE Sample preparation igure l.l. Steps in a measurement proces the sample is ready for analysis, sample preparation is the next step. Most samples are not ready for direct introduction into instruments. For exam ple, in the analysis of pesticides in fish liver, it is not possible to analyze the liver directly. The pesticides have to be extracted into a solution, which can be analyzed by an instrument. There might be several processes within sample preparation itself. Some steps commonly encountered are shown in Figure 1. 2. However, they depend on the sample, the matrix, and the con centration level at which the analysis needs to be carried out. For instance, trace analysis requires more stringent sample preparation than major com- ponent analysis Once the sample preparation is complete, the analysis is carried out by an instrument of choice. A variety of instruments are used for different types of analysis, depending on the information to be acquired: for example, chro- matography for organic analysis, atomic spectroscopy for metal analysis, capillary electrophoresis for DNA sequencing, and electron microscopy for small structures. Common analytical instrumentation and the sample prep- aration associated with them are listed in Table 1. 1. The sample preparation depends on the analytical techniques to be employed and their capabilities For instance, only a few microliters can be injected into a gas chromato- graph. So in the example of the analysis of pesticides in fish liver, the ulti- mate product is a solution of a few microliters that can be injected into a gas chromatograph Sampling, sample preservation, and sample preparation are
the sample is ready for analysis, sample preparation is the next step. Most samples are not ready for direct introduction into instruments. For example, in the analysis of pesticides in fish liver, it is not possible to analyze the liver directly. The pesticides have to be extracted into a solution, which can be analyzed by an instrument. There might be several processes within sample preparation itself. Some steps commonly encountered are shown in Figure 1.2. However, they depend on the sample, the matrix, and the concentration level at which the analysis needs to be carried out. For instance, trace analysis requires more stringent sample preparation than major component analysis. Once the sample preparation is complete, the analysis is carried out by an instrument of choice. A variety of instruments are used for di¤erent types of analysis, depending on the information to be acquired: for example, chromatography for organic analysis, atomic spectroscopy for metal analysis, capillary electrophoresis for DNA sequencing, and electron microscopy for small structures. Common analytical instrumentation and the sample preparation associated with them are listed in Table 1.1. The sample preparation depends on the analytical techniques to be employed and their capabilities. For instance, only a few microliters can be injected into a gas chromatograph. So in the example of the analysis of pesticides in fish liver, the ultimate product is a solution of a few microliters that can be injected into a gas chromatograph. Sampling, sample preservation, and sample preparation are Sampling Sample preservation Sample preparation Analysis Figure 1.1. Steps in a measurement process. 2 sample preparation: an analytical perspective