Principles of Analytical Chemistry for Toxicology

Abstract

In the first section, a historical summary of analytical chemistry is presented. In ancient history, one function of an analytical chemist was to confirm the identity of noble metals, especially gold. In later times, important inventions and their discoverer were named. Now, in the twenty-first century, analytical chemistry is an interdisciplinary scientific field.

Next, the aim and means of analytical chemistry are discussed. For analytical tasks, the chemist has available over 6,000 experimental procedures (including sub-specifications). The most important procedures are summarized. Moreover analytical problems, such as analyte(s) from complex matrixes, and the necessary purification as well as determination steps are discussed. Quantification measures, such as parts per trillion, are considered. The three analytical phases (pre-analysis, analysis, post-analysis) are presented, and recently developed analytical procedures such as “lab on a chip” and the “omics” sciences are introduced.

In the section “Pre-analysis,” different techniques of sample preparation prior to analytical measurement are described. Apart from classic methods, such as crushing and homogenization, extraction techniques such as solid-phase extraction, liquid-liquid extraction and solid-phase micro-extraction are reviewed.

The analytical section is divided into three parts, plus subparts: (i) separation techniques are presented followed by (ii) atomic spectroscopy and (iii) selective analytical chemistry. Each (sub)part begins with a short historical overview. For separation techniques, first the principles of chromatography are described followed by the principles of electrophoresis and capillary electrophoresis. The chromatographic and atomic spectroscopy classifications and techniques are not presented in isolation, as in many analytical textbooks. They are described along with associated coupled techniques.

Such coupled techniques are liquid chromatography (LC), gas chromatography (GC), thin-layer chromatography, and ion exchange chromatography (IEC). LC is often coupled with mass spectrometry (MS; including different ionization techniques such as thermospray, fast atom bombardment, particle beam). GC is also often coupled with MS. Moreover derivatization techniques and headspace GC are presented.

In the case of atomic spectroscopy, atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) are presented in more detail. In the section “Selective Analytical Chemistry,” sensor techniques with ion-selective electrodes and the principles of immunoassays are described. These techniques are primarily for routine and fast analysis of known components in a sample. In most cases, the sample preparation steps are easy and rapid compared to, say, the sample preparation steps for gas chromatography.

Special types of mass spectrometers such as mass matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and their usage will be described. These mass spectrometers can be coupled with LC.