Safe Laboratory Techniques

It is also necessary to use a safe method for storing contaminated pipets until they can be washed. They should be placed horizontally in a pan containing enough suitable decontaminant solution to allow their complete immersion (209), rather than being dropped vertically into a cylinder. There are several reasons for avoiding the use of vertical cylinders. First, hydraulic pressure will force an aerosol of residual liquids and contaminants from the bore of the pipet out through its upper end as it is dropped into the cylinder. Second, flat trays can be placed directly in the autoclave, thus 

Never pipet by mouth. Always use some type 8. of pipetting aid. 

If working with infectious or toxic fluid, pipetting operations should be confined to a 9. safety cabinet or hood. 

Pipets used for the pipetting of infectious or toxic materials always should be plugged with cotton. This avoids collecting aerosols of the pipetted solution within the mechanical pipet- 10. ting device. 

No infectious material should be prepared by bubbling expiratory air through a liquid with a pipet. 

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For small-scale laboratory transfers, recommended personal protective equipment includes a minimum of a full face shield and fire retardant lab coat. A recent tragic occurrence which resulted in the death of a university laboratory student (35) while handling tert-butyllithium would likely not have happened had the person been wearing proper personal protective equipment. A detailed discussion of techniques for safe laboratory transfers of metal alkyls is available (36). 

There are many kinds of familiar hazards, such as mechanical, electrical, and fire hazards, that are found in all laboratories. These kinds of hazards often are overlooked simply because they are so familiar and common, so that workers do not exercise the necessary degree of caution in proportion to the risk involved, because familiarity breeds contempt. The purpose of Part 4 is to identify these common physical hazards (which are normally covered by occupational safety programs), to discuss these hazards in terms of safe laboratory practices, and to describe techniques for controlling them. 

One of the main drawbacks to the development of the chemistry of many of the boron hydrides has been the absence of synthetic procedures for producing these materials in reasonable yields and quantities by relatively safe and simple techniques. Classical approaches are heavily dependent upon pyrolytic procedures. Although they have been developed to a "fine art," they require a high degree of skill in order to be employed safely in ordinary laboratory environments. Other important classical methods are dependent upon controlled protolysis reactions, frequently giving mixtures of materials which are difficult to separate. 

The major characteristic of technetium is that it is the only element within the 29 transition metal-to-nonmetal elements that is artificially produced as a uranium-fission product in nuclear power plants. It is also the tightest (in atomic weight) of all elements with no stable isotopes. Since all of technetiums isotopes emit harmful radiation, they are stored for some time before being processed by solvent extraction and ion-exchange techniques. The two long-lived radioactive isotopes, Tc-98 and Tc-99, are relatively safe to handle in a well-equipped laboratory. 

Laboratory procedures may need to be evaluated against the sampling techniques and materials involved in the toll. There may be new laboratory chemicals and hazards to be considered. This work may have been identified in the evaluation of special analytical techniques required for the process. A good practice is to ensure that the lab technicians have the necessary guidance and types of equipment on hand to monitor the process and waste streams accurately and safely. 

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