An analytical methodology can be divided into four sequential steps: technique, method, procedure, and protocol. A technique is a scientific principle that rationalizes a specific phenomenon through chemical measurements. Adapting a technique for analyzing a sample of interest is termed a method. The procedure outlines the directions for performing the analysis via an analytical method. The protocol is the detailed guidelines on the procedure, which should be strictly followed to obtain the desired results.

Analytical methods can be categorized into classical and instrumental methods. Classical analytical methods use wet chemical processes, such as precipitation, extraction, or distillation, to separate the component of interest (analyte) from the rest of the materials (matrix) in a sample. Instrumental analytical methods use instruments to measure the physical properties of an analyte, such as conductivity, electrode potential, mass-to-charge ratio, and absorption or emission of light. An analytical method is chosen based on the required accuracy, precision, sensitivity, selectivity, robustness, ruggedness, scale of operation, analysis time, availability of the equipment, and cost.