Organic solvents for liquid-liquid extraction or chromatography can often be replaced by other solvents with significant benefit. Benzene, once a widely used solvent, is now recognized as a human carcinogen and must be handled accordingly. Toluene can often serve as a satisfactory substitute. Diethyl ether is a flammable solvent whose handling must take into account its tendency to form explosive peroxides. Methyl t-butyl ether (MTBE) offers only slight advantages over diethyl ether with respect to flammability, but its greatly reduced tendency to form peroxides eliminates the need to monitor peroxide formation during handling and storage.
The technology for handling supercritical fluids has developed rapidly in recent years. Supercritical carbon dioxide can replace organic solvents for high-performance chromatography and is beginning to find use as a reaction solvent. While supercritical solvents require specialized equipment for handling, they offer the potential benefit of large reductions in organic solvent waste.
Because handling and disposal of multihazardous waste require special waste management, it is especially prudent to develop strategies to minimize its generation. Chapter 7, section 7.C.1.1, provides information on eliminating or minimizing the components of waste that are radioactive or biological hazards. The strategies discussed include substituting nonradioactive materials for radioactive materials, substituting radioisotopes having shorter decay times (e.g., using iodine-131, with a half-life of 8 days, instead of iodine-125, with a half-life of 60 days, in thyroid research), and carrying out procedures with smaller amounts of materials.
Before purchasing a chemical, several questions should be asked:
Is the material already available from another laboratory within the institution or from a surplus-chemical stockroom? If so, waste is reduced, and the purchase price is saved. The tendency to require the use of new chemicals because of their purity should be scrutinized and that requirement should be carefully justified to ensure that materials already on hand are used whenever possible.
What is the minimum quantity that will suffice for the current use? Chemical purchases should not be determined by the cheaper unit price basis of large quantities, but rather by the amount needed for the experiment. The cost of disposing of the excess is likely to exceed any potential savings gained in a bulk purchase (i.e., in the present economic climate, the cost of getting rid of a chemical may exceed its acquisition cost). If a quantity smaller than the minimum offered by a supplier is needed, the supplier should be contacted and repackaging requested. Compressed gas cylinders, including lecture bottles, should normally be purchased only from suppliers who will accept return of empty cylinders.
What is the maximum size container allowed in the areas where the material will be used and stored? Fire codes and institutional policies regulate quantities of certain chemicals, most notably flammables and combustibles. For these materials, a maximum allowable quantity for laboratory storage has been established (see also sections 4.E.3, 4.E.4, and 4.E.5).
Can the chemical be managed safely when it arrives? Does it require special storage, such as in a dry box or freezer? Do receiving personnel need to be notified of the order and given special instructions for receipt? Will the equipment necessary to use the chemical be ready when it arrives? An effort should be made to order chemicals for just-in-time delivery, by purchasing all necessary materials from the same supplier with a request for delivery all together at the best time for performing an experiment.
Is the chemical unstable? Inherently unstable materials may have very short storage times and should be purchased just before use to avoid losing a reagent and creating an unnecessary waste of material and time. Some materials may require express or overnight delivery and will not tolerate being held in transit over a weekend or holiday.
Can the waste be managed satisfactorily? A chemical that will produce a new category of waste may cause a great deal of trouble for the waste management program. An appropriate waste disposal mechanism should be identified before the chemical is ordered.
More detail on all of these questions should be reviewed as necessary to arrive at satisfactory answers. Only when these issues have been identified and resolved can ordering proceed.
Authority to place orders for chemicals may be cen-