To develop even greener syntheses, we attempted to perform the synthesis in lower grade water. Using deionised water did not lead to reproducible results. High purity water, more costly to obtain, can therefore be a drawback in the long term to develop an optimally green synthesis of Au NPs. It is however known that high purity water is almost a pre-requisite for the successful synthesis of Au namomaterial. In this respect, the successful use of crude glycerol to obtain Au NPs can be an interesting option since it is a byproduct of other industries. The question whether bio-ethanol could be used for the synthesis of Au NPs following the general approach presented remains open. Finally, and although this is not the focus of the present research, it is important to stress that several reports highlight the opportunity to recycle the gold precursor. Recycling is very complementary to the inherent challenges of large parametric screenings that by nature generate waste, although the use of smaller volumes here minimizes this drawback.