Analytical chemistry is the branch of chemistry that deals with the identification, separation, and quantification of matter. The techniques used in analytical chemistry can be broadly classified into two categories – classical techniques and instrumental techniques.
Classical qualitative methods involve the use of separation techniques such as distillation, precipitation, and extraction. Instrumental methods involve the use of specialized instruments to identify and quantify analytes. Common examples of instrumental methods in analytical chemistry include mass spectrometry, spectroscopy, thermal analysis, and electrochemical analysis. Some important instrumental analysis methods in the field of analytical chemistry are provided in this article.
Mass spectrometry is an instrumental method in the field of analytical chemistry that involves the measurement of the charge-to-mass ratios in molecules. The charge-to-mass ratio is usually measured with the help of magnetic fields or electric fields. Many ionization methods are employed in mass spectrometry. Some common methods that are used to ionize molecules in this instrumental method are:
- Ionization through electron impact
- Ionization through chemical ionization
- Ionization through electrospray
- Ionization through fast atom bombardment
- Ionization through matrix-assisted laser desorption ionization
It is important to note that mass spectrometry is often categorized by the approaches of mass analyzers. Some common examples of such mass analyzers include the quadrupole mass analyzer, the quadrupole ion trap, the magnetic sector, the time of flight, and the Fourier transform ion cyclotron resonance.
In the field of analytical chemistry, electrochemical analysis involves the use of methods that measure the electric potential (usually in volts) or the electric current (usually in amperes) in a given electrochemical cell that contains the analyte (which is the substance that must be analyzed). The methods used in the electrochemical analysis can be further classified on the basis of the controlled aspects of the electrochemical cell and the measured aspects of the electrochemical cell. The four primary categories of methods used in electrochemical analysis processes are listed below.
- Potentiometry – a class of techniques in the electrochemical analysis of analytes that involve the measurement of the potential difference in the electrochemical cell.
- Coulometry – a class of techniques in the electrochemical analysis of analytes that involve the measurement of the electric charge (usually in Coulombs) in the electrochemical cell.
- Amperometry – a class of techniques in the electrochemical analysis of analytes that involve the measurement of the magnitude of the electric current (usually in Amperes) in the electrochemical cell.
- Voltammetry – a class of techniques in the electrochemical analysis of analytes that involve the measurement of the current while altering the cell potential of the electrochemical cell.
In the field of analytical chemistry, the term ‘spectroscopy’ is used to denote the measurement or the study of the interactions between matter and electromagnetic radiation. Several important types of spectroscopy exist. Some common examples of the different types of spectroscopy include infrared spectroscopy, NMR spectroscopy (which is an abbreviation of ‘Nuclear magnetic resonance spectroscopy’), X-ray spectroscopy, fluorescence spectroscopy, photoemission spectroscopy, atomic emission spectroscopy, atomic absorption spectroscopy, and Raman spectroscopy.