Quantitative analysis is a technique for measuring the amount of specific constituents in a sample. When the sample's composition is unknown, qualitative analysis is performed first to identify its components, which ensures that the correct substances are measured during the quantitative phase.

In quantitative analysis, two key measurements are made: the sample quantity and a property proportional to the amount of the analyte (the substance being analyzed). This forms the basis of the method and ensures accuracy in determining the amount of the analyte's concentration.

Quantitative analysis can be classified into two main types: classical methods and instrumental methods. Classical methods involve measuring the mass or volume of the analyte or its chemically derived form. For example, gravimetric analysis measures the mass of a precipitate formed from a chemical reaction with the analyte to determine its concentration. Another classical method is titration, where the volume of a reactant needed to react completely with the analyte is measured.

Instrumental methods assess the interaction between the analyte and physical forces like electromagnetic radiation.For instance, in spectrophotometry, the analyte's concentration is determined by measuring the amount of light absorbed by the sample. Another example is atomic absorption spectroscopy, where the amount of light absorbed by atoms in the sample provides information about the analyte's concentration.

Calibration curves play a pivotal role in quantitative analysis. Detectors and instruments must be calibrated using known concentrations of the analyte, typically placed in cuvettes. These known values are used to generate a calibration plot. This crucial tool ensures the accuracy of the analysis by helping to determine the concentration of the unknown analyte in the sample.

In summary, quantitative analysis is a vital scientific process. It involves several key steps: identifying the analyte, measuring the sample and analyte properties, and classifying the method used. The process ensures accuracy through calibration curves, a crucial tool in determining the concentration of the unknown analyte in the sample.