Analytical Chemistry

KEY POINTS:

• Analytical Chemistry involves the separation, identification and quantification of matter. From identifying hydrogen gas through the squeaky pop test, to the sequencing of DNA by gel electrophoresis, analytical chemistry is at the forefront of research and development in numerous fields.
• Qualitative analysis involves the identification of unknowns. Whilst the vast majority of high school students will recall the methods for identifying H₂, O₂, CO₂, NH₃ and Cl₂, as well as numerous precipitation reactions for cations and anions, more powerful complex instrumental methods are available.
• Atomic absorption and emissions spectroscopy both build on the fundamentals of what occurs at an atomic level in flame tests. Mass spectrometry is able to identify through relative abundances of isotopes and fragmentation patterns, Infrared spectroscopy can provide the functional groups of compounds and Nuclear Magnetic Resonance spectroscopy can provide full structures of complex molecules in a matter of seconds.
• Quantitative analysis involves the measuring of how much of a substance is present. Whilst titrations are the mainstay of all good analytical chemists, other methods of quantification utilise the absorbance of ultraviolet or visible light by molecules to construct calibration curves and determine amounts with a great deal of precision and accuracy. Gravimetric analysis uses mass changes during chemical reaction to quantify reactants or products.
• In order for any substance to be identified or quantified, it must first be separated if found in a mixture of materials. This may involve liquid or gas chromatography, electrophoresis or field flow fractionation.