*3.8. Environmental Impact of the Analysis*

While developing an analytical procedure, attention is being shifted more and more to its ecological acceptability. Several methods can assess the green aspects of an analytical procedure in which the green analytical procedure index (GAPI) (Scheme 3A) and Analytical GREEnness metric approach and software (AGREE) (Scheme 3B) are used. While GPAI is the most comprehensive and has the advantages of graphically describing all relevant factors-quantification; sample collection, preservation, transport and storage; sample preparation; reagents and compounds used and instrumentation, AGREE enables straightforward interpretation, since the level of greenness is expressed numerically on a scale from

0 to 1, with 1 being the greenest. Furthermore, AGREE contains all the relevant data about the analytical procedure and is easy to generate thanks to a free software downloadable from https://mostwiedzy.pl/AGREE (accessed on 7 June 2022) [59]. For GAPI, each aspect is presented with a pentagon further divided into segments that stand for specific demands that make a procedure green (amounts of solutions used, purification, energy consumption, generated waste, etc.). The colors of the segments depict the low, medium or high impact of the method on the environment, moving from green through yellow to red, and each of them has to fulfil certain conditions to be considered green [60].

**Scheme 3.** (**A**) GAPI and (**B**) AGREE pictograms for the estimation of the greenness of the analytical procedure.

In Scheme 3, we can see that the analysis performed with the proposed sensing platform is quantitative and can be performed at-line. Thus, no sample preservation, transport or storage is needed. Furthermore, the cell culture matrix can be used directly or dissolved in water or biological buffer without any prior purification or sample preparation. This minimizes the energy consumption and the amount of generated waste, while the minimum volume needed for the analysis is 5 mL. Overall, this analytical procedure can be considered green, direct and robust and it can easily be further miniaturized for commercial application.
