Many members of plant and fungi kingdoms have toxic alkaloids that are highly poisonous. Chapter One explores how gas chromatography is used to analyse some classes of these alkaloids. In Chapter Two, the effect of surfactants on gas-liquid interfaces by using reverse-flow gas chromatography (RF-GC). Chapter Three describes the application of Solid-Phase Microextraction (SPME) for identifying volatile organic compounds (VOCs), additives and degradation products in industrial plastics, rubber, and packaging materials. And in Chapter Four, the authors discuss sampling procedures for the analysis of volatile and gaseous substances used in daily life and in forensic medicine.