Green analytical chemistry metrics for evaluation of microextraction methods: Fascinating or essential tools in real-world applications?

The twelve principles of Green Analytical Chemistry serve as a guideline for introducing greenness in the analytical methods. Microextraction-based sample preparation has been developed as a greener alternative to large-scale liquid-liquid extraction and solid-phase extraction, minimizing the amount of solvents, eliminating toxic substances, reducing sample size, and generating less waste. However, the establishment of microextraction as the standard method in routine analysis is still limited, although they are becoming increasingly available. Therefore, this review aims to emphasize the features of microextractions and their evaluation using greenness metrics. The greenness metrics, such as NEMI, AES, GAPI, AGREE, their modified versions, and the new SPMS, are discussed along with their application to microextractions. The analysis involves comparing their scores and highlighting factors that influence their greenness. In summary, microextraction techniques could be a preferred choice in future to replace large-scale extraction and be used as standard methods for routine laboratories.