5.A INTRODUCTION

This chapter organizes the discussion of managing laboratory chemicals into six main topics: reducing and eliminating the use and generation of hazardous substances (green chemistry); acquisition; inventory and tracking; storage in stockrooms and laboratories; recycling of chemicals and laboratory materials; and transfer, transport, and shipment of chemicals. As Chapter 1 makes clear, prudence in these areas requires knowledge of the hazards posed by laboratory chemicals and the formulation of reasonable measures to control and minimize the risks associated with their handling and disposal. Not all risk can be eliminated, but through informed risk assessment and careful risk management, laboratory safety is greatly enhanced.

Trained laboratory personnel, laboratory supervisors, and individuals who handle chemicals will find essential information in this chapter. Each person has an important role to play in a chemical’s life cycle at an institution, and each one of them should be aware that the wise management of that life cycle not only minimizes risks to humans and to the environment but also decreases costs. Acknowledging this role and giving it due consideration is one element of the culture of safety within a laboratory.

5.B GREEN CHEMISTRY FOR EVERY LABORATORY

Green chemistry is the philosophy of designing products and processes that reduce or eliminate the use and generation of hazardous substances, which fts well with the overall goals of a culture of safety. The 12 principles of green chemistry (Anastas and Warner, 1998) can be applied in the laboratory as guidelines for prudent experimental design and execution. Some of the principles are explained in more detail below, with examples of their broader application. A wealth of green chemistry resources exists online in the form of reports, databases, and other Web applications and tools. These resources assist the development of green synthetic methods by providing information about the redesign of processes at the molecular level, the reduction or elimination of the use of hazardous materials, and the modification of chemical substances to make them safer.

5.B.1 Prevent Waste

Prudent laboratory chemical management begins with adopting the first green chemistry principle of waste prevention, which is considered before the ordering of the chemicals. When experiments have been carefully planned, trained laboratory personnel can be confident that they have chosen procedures that minimize the quantities of chemicals to be used and minimize the disposal of hazardous materials.

Experiment planning in the culture of laboratory safety includes minimization of the material used at each step of an experiment. Consider two simple examples: (1) Transferring a liquid reaction mixture or other solution from one flask to another container usually requires the use of a solvent to rinse out the flask. During this procedure, laboratory personnel should use the smallest amount of solvent possible that enables a complete transfer. (2) Celite is often used during filtrations to keep the pores of filter papers or filter frits from becoming clogged. When positioning the Celite, carefully determine the minimum amount needed to be effective. Other examples of such strategies include

   considering how a reaction product will be used and making only the amount needed for that use;

   appreciating the cost of making and storing unneeded material;

   thinking about minimization of material used in each step of an experiment;

   searching for ways to reduce the number of steps in an experiment;

   improving yields;

   recycling and reusing materials when possible;

   coordinating work with co-workers who may be using some of the same chemicals (section 5.D.2);

   considering the amount of reagents, solvents, and hazardous materials used by automated laboratory equipment when purchasing a new system;

   isolating nonhazardous waste from hazardous waste; and

   using a column purification system for recycling of used solvent (section 5.D.3)

These steps are increasingly important because of the changing requirements and economics of laboratory management.

5.B.2 Microscale Work and Wet Chemistry Elimination

One successful method of reducing hazards is to carry out chemical reactions and other laboratory procedures on a smaller scale (i.e., microscale) when feasible. In microscale chemistry the amounts of materials used are reduced to 25 to 100 mg for solids and 100 to 200 µL for liquids, compared with the usual 10 to 50 g for solids or 100 to 500 mL for liquids. Smaller scale synthetic methods save money because they require less reagent and result in less waste. Of course, not all laboratory procedures can be scaled down. Multigram laboratory preparation is often required to provide



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