Effective mass yield is defined as the percentage of the mass of the desired product relative to the mass of all non-benign materials used in its synthesis. Hudlicky et al. suggests the following equation:
Effective mass yield (%) = mass of products × 100 / mass of non-benign reagents
This metric requires further definition of a benign substance. Hudlicky defines it as “those by-products, reagents or solvents that have no environmental risk associated with them, for example, water, low-concentration saline, dilute ethanol, autoclaved cell mass, etc.”. This definition leaves the metric open to criticism, as nothing is non-benign (which is a subjective term) and the substances listed in the definition have some environmental impact associated with them. The formula also fails to address the level of toxicity associated with a process. Until all toxicology data is available for all chemicals and a term dealing with these levels of “non-benign” reagents is written into the formula the effective mass yield is not the best metric for chemistry.
Read more about this topic: Green Chemistry Metrics
Famous quotes containing the words effective, mass and/or yield:
“Basically, I have no place in organized politics. By coming to the British Parliament, I’ve allowed the people to sacrifice me at the top and let go the more effective job I should be doing at the bottom.”
—Bernadette Devlin (b. 1947)
“No atomic physicist has to worry, people will always want to kill other people on a mass scale. Sure, he’s got the fridge full of sausages and spring water.”
—William Burroughs (b. 1914)
“I believe that there is a subtle magnetism in Nature, which, if we unconsciously yield to it, will direct us aright. It is not indifferent to us which way we walk.”
—Henry David Thoreau (1817–1862)