Organic solvents mouth contact

Often the easiest way to set the initial water activity of components of the reaction mixture is by pre-equilibration with a saturated salt solution. The relative humidity or water activity is fixed above a saturated solution of a given salt at a known temperature. As water equilibrates in or out of the solution, solid salt will tend to dissolve or crystallize to maintain saturation and hence the fixed water activity in the headspace. Any other material placed in contact with the headspace will eventually equilibrate to the same water activity. The reaction mixture component can simply be placed inside a closed vessel together with the salt solution, such that water can transfer between the two via the vapour phase. Wide-mouth screw cap jars are convenient, with salt solution over the base and an open vial containing the sample (Fig. 8-3). The rate of equilibration depends on the surface areas exposed and the amount of water that must be transferred. Typically 1-2 days is sufficient for either solid biocatalyst preparations or liquid phases based on relatively non-polar organic solvents. The rate of equilibration may be checked by weighing or Karl Fischer analysis respectively. 

Isophorone can enter your body if you breathe its vapor, have skin contact with it, drink contaminated water, or eat contaminated food. If isophorone is present at a waste site near homes that use local wells as a source of water, the well water could be contaminated with isophorone. Experiments in animals show that after doses by mouth, isophorone enters easily and spreads to many organs of the body, but most of it leaves the body within 24 hours in the breath and in urine. Isophorone may enter the lungs of workers exposed to isophorone where it is used indoors as a solvent. Isophorone disappears quickly from outside air, so the chance of breathing outdoor air contaminated with isophorone is small. If isophorone is spilled at a waste site and evaporates, however, a person nearby may breathe isophorone before it disappears from the air. In addition, soil around waste sites may contain isophorone, and a person, such as a child playing in the dirt, may eat or have skin contact with the contaminated soil. How much isophorone enters the body through the skin is not known. More information on how isophorone can enter and leave the body can be found in Chapter 2. 

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