Specific Chemicals with Incompatibles

Acetylene, monosubstituted acetylenes Ammonia, anhydrous and aqueous 

Alkali and alkaline earth Carbides Hydrides Hydroxides Metals 

Halogenated organic compounds Halogenating agents Oxidizing agents 

Heavy metals and their salts Oxidizing agents Acids/Strong bases Acetylene 

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After this list is reviewed for incompatibilities, individual fume hoods need to be assigned for use with specific chemical classes. A hidden aspect to this situation is the administrative controls which the project leader must enforce in order to keep incompatibles separate. 

If chemical-specific information is not available, the consequences may be able to be predicted by methods using compatibility groups, or chemicals with similar chemical structures that are expected to have similar chemical reactivity characteristics. One computerized tool that uses this approach is the Chemical Reactivity Worksheet made available by the U.S. National Oceanic and Atmospheric Administration (NOAA 2002). This program has over 6000 chemicals, mixtures, and solutions included in its database. It also predicts chemical reaction consequences of combining two materials at a time (e.g., "Heat generation by chemical reaction, may cause pressurization"). Examples from the Chemical Reactivity Worksheet are shown in Section 4.2. It is critical that all chemicals be positively identified to have a complete evaluation of all potential incompatibilities. 

The following chemicals react, sometimes violently (indicated by italics), in certain chemical environments. " Incompatibilities may cause fires, explosions, or the release of toxic gases. Extreme care must be taken when working with these materials. This list is not inclusive, and the reader is urged to consult multiple sources for more specific information. 

Based on experiments conducted up to the boiling points of the liquids listed. Absence of a specific chemical does not mean that it is incompatible with TEFLON resins. 

The process of formulation for any of the above is generically the same, beginning with some form of product specification and ending with one or more formulations that meet the requirements. Correct choice of additives or excipients is paramount in the provision of efficacy, stability, and safety. For instance, the excipients may be chemically or physically incompatible with the drug or they may exhibit batchwise variability to such an extent that at the extremes of their specification they may cause failure in achieving the desired drug release profile. In addition, some excipients, especially those that are hydroscopic, may be contraindicated if the formulation is to be manufactured in tropical countries. Flence formulators must work in a design space that is multidimensional in nature and virtually impossible to conceptualize. 

A major challenge in providing electrical power for implantable devices is the isolation of toxic or bio-incompatible materials. As the size of the device decreases to a centimeter or millimeter scale, the parts responsible for isolation, such as canisters and seals, begin to determine the size of the device. An alternative is to design an electrochemical system that is compatible with the physiological environment and can take advantage of chemical species available in that environment, specifically the... 

Lacking actual test results, the next best option is to check chemical-specific safety data such as MSDSs or International Chemical Safety Cards (ICSCs) for the particular compounds and concentrations involved. Section 10 (Stability and Reactivity) of standard MSDSs should contain information on Incompatibilities with Other Materials. Similar information should be in the Chemical Dangers section of ICSCs. However, these are rarely more than lists of incompatible materials, and do not indicate what consequences can be expected. The listed incompatibilities should be considered as only applying to ambient conditions. 

We are specifically interested in the system in which a liquid-solid interface reaction has taken place. An example of this type of reaction is the chemical grafting of a rubber with a monomer at the interface. The function of the grafted rubber as an adhesive has been postulated (II, 29, 46, 64) but has never been proved. Since the grafted rubber is the key to bridging two incompatible polymers together, we devoted a major portion of our experimental work to the characterization of the grafted polymer as an adhesive at the interface. 

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