Methods Used in Analytical Chemistry

The methods used to determine the identity and the quantity of the analytes in the field of analytical chemistry can be broadly divided into classical and instrumental methods.

1. Classical Methods

• There exist many classical methods of checking for the presence or absence of a particular compound in a given analyte. One such example is the acid test for gold.
• Another example of a classical method for qualitative analysis is the Kastle-Meyer test which employs phenolphthalein as an indicator to check for the presence of haemoglobin in the given analyte.
• Flame tests can be used to check for the presence of specific elements in an analyte by exposing it to a flame and observing the change in the colour of the flame.
• Gravimetric analysis is a classical method of quantitative analysis, which can be used in analytical chemistry to determine the amount of water in a hydrate by heating it and calculating the weight of the water lost.
• One of the better known classical methods of quantitative analysis is volumetric analysis (also known as titration). In the titration method, a reactant is added to the analyte till an equivalence point is obtained.

2. Instrumental Methods

• Spectroscopy involves the measurement of the interaction between electromagnetic radiation and the atoms or molecules belonging to a sample.
• With the help of electric fields and magnetic fields, the method of mass spectroscopy is used to measure the ratio of the mass of the molecule to its charge.
• A common instrumental method used in the field of analytical chemistry is electrochemical analysis. In this method, the analyte is placed in an electrochemical cell and the voltage or the current flowing through it is measured.
• The interaction between the analyte and energy in the form of heat is studied in the discipline of analytical chemistry known as calorimetry. A calorimeter is an instrument that is used to measure the heat of a chemical reaction.

It can be noted that even biological measurements are made with the help of this branch of chemistry, and this field is known as bio analytical chemistry.