Limiting specific volatile substance

Since the introduction of Gas-Liquid-Chromatography (GLC) (see Part V, Chapter 29) as an essential analytical tool, it has been judiciously exploited as an useful alternative means for not only determining water content in pharmaceutical chemicals but also limiting specific volatile substances present in them. It may be expatiated with the help of the following examples ... 

Dickey (113) has discussed in detail the preparation of specific silicas by precipitating the silica in the presence of the specific compound. Of the various procedures described by Dickey, the hydrochloric acid preparation seems to give best results. The procedure of Polyakov for preparing specific silicas is based on drying the silica in an atmosphere of the specific compound (108,115). The specificity of these adsorbents appears to be less pronounced than in the case of adsorbents prepared by Dickey s procedure, and Polyakov s technique is limited to volatile specific compounds. The Dickey procedure cannot be applied to compounds which are not water soluble, but for such substances the procedure of Patrikeev and Sholin (109) can be used After precipitation of the silica without added specific compound, the adsorbent is washed with methanol and allowed to finish gelling in the presence of a methanol solution of the specific compound. The preparation of specific aluminas (722) and silica-aluminas (114) has also been described. 

Keeping in mind advantages and limitations ENs do not allow to replace human panels or analytical techniques, as long as their ability to smelUng odors rather than detecting and quantifying specific volatiles is still far from required standards. In spite, they can be used in parallel to those techniques, or even considered as valuable alternatives, to perform quick go-no go product tests or occasionally replace human panels when non-odorous, irritant or potentially toxic volatile substances need to be detected. 

Several sets of wide-reaching regulations also directly affect laboratory operations. The Clean Air Act (42 USC 7401 et seq.) regulates emissions into the air and sets specific limits on the disposal of volatiles through the fume hood system. To protect both the community and the emergency response personnel that may be put at risk by a laboratory accident, the Superfund Amendments and Reauthorization Act (SARA 42 USC 9601 et seq., 11000 et seq.) requires that inventories of hazardous chemicals be maintained and made available to the public. The Toxic Substances Control Act (TSCA 15 USC 4601 et seq.) is concerned with the manufacture, distribution, and processing of new chemicals that are unusually dangerous to health and/or the environment. 

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