Emphasis is on the use of mass selective detectors (MSDs) with gas chromatography, although several other detectors (flame ionization, thermal conductivity, electron capture, and nitrogen-phosphorus) are also described.
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The fundamental principles of paper chromatography, thin-layer chromatography (TLC), column chromatography (CC), ion-exchange chromatography (IEC), high-performance liquid chromatography (HPLC), and gas chromatography (GC) are discussed. This chapter is designed to provide a basic survey of the concepts and principles of organic chemistry reactions will be limited to applications in forensics and structural analysis will concentrate on the basic recognition of functional groups.Ĭhromatography and mass spectrometry are introduced as analytical methods used to identify drugs and controlled substances. Arguably the most complex and mysterious of the specialized areas of chemistry, organic chemistry often requires years of both practical and theoretical study to master. Organic chemistry is the study of the properties, structure, and function of compounds containing carbon. It is now possible to synthesize and manipulate organic molecules in a laboratory environment, and with this knowledge has come a modern definition of organic chemistry. The complex chemical behavior exhibited by organic compounds is now explained in terms of reaction mechanisms, structural analysis, and thermodynamics. In today’s world of science, advancements in research and technology have laid the mythical “life force” to rest. It was once believed that the unexplained differences between organic compounds, those from living organisms, and inorganic compounds, those from mineral sources, were attributed to an unknown “life force” within the organic compounds. Historically, organic chemistry was once defined as the study of the structure and function of molecules originating from living organisms.
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This convenient language will be used to study bonding and structural properties in this chapter. Characterizing chemical bonds as ionic or covalent is a common, reliable practice that is universally accepted. For example, a bond that contains a higher percentage of ionic character is termed ionic however, this does not mean that the bond contains no covalent character. The vast majority of chemical bonds contain both ionic and covalent character and classification is based on the type present in the highest percentage. It is important to note that pure ionic and pure covalent represent the extremes of chemical bonding and rarely exist. Compounds are electrically neutral and divided into two broad classes based on the type of chemical bond present: ionic bonds form ionic compounds and covalent bonds form covalent compounds. For example, H2O is the chemical formula for water, a compound containing one atom of oxygen bound to two atoms of hydrogen. The symbol without a subscript is used to represent the presence of a single atom in the formula. Subscripts are used only when two or more atoms of the same element appear in the formula. Symbols from the periodic table are used to identify atoms, and the relative number of each atom present is indicated using a subscript attached to the symbol. The number and identity of each atom present in the compound are given by the chemical formula.
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Compounds are formed through the combination of two or more elements held together by chemical bonds.