Green analytical chemistry metrics: A review

Green analytical chemistry encourages reducing the use of toxic chemicals/reagents, using energy-efficient equipment, and generating minimal waste. The recent trends in analytical method development focus on the miniaturization of the sample preparation devices, the development of solventless or solvent-minimized extraction techniques, and the utilization of less toxic solvents. The twelve principles of GAC serve as a basic guideline for inducing greenness in the analytical procedures. Despite these guidelines, in many conditions, some undesired steps are unavoidable. Therefore, it is important to evaluate the greenness of analytical procedures to assess and, if possible, reduce their impact on the environment and workers. Several metrics have been developed for the evaluation of the greenness of analytical procedures. Analytical Eco-Scale, Green Analytical Procedure Index, and Analytical Greenness Metric are among some important tools for assessing the greenness of analytical procedures. All these metrics take different aspects of the analytical procedure into account to provide the green index of the procedure. This review covered these metrics, their principles, and examples of their application to selected analytical procedures. The advantages and limitations of these metrics with the perspective of common reader/user are presented. We believe that this paper will inspire many new perspectives and developments in this area.