Assignment #4: Laboratory Reagent
MLT 2191 Histotechniques I
November 12, 2017
1) What is the nature of your selected reagent?
Toluene, also known as toluol and methylbenzene, is a clear water-insoluble colorless liquid with a peculiar aromatic odor of paint thinners. It is flammable (class B2), non-corrosive, very toxic, and it can acquire static charges. It can float on water and spread fires. It cannot be stored in confined spaces. This reagent occurs naturally in crude oil and in the tolu tree. It is produced when making gasoline and other crude fuels. Toluene is used to make paints, fingernail polish, lacquers, adhesives, rubber, benzene, nylon and plastics. “Toluene is a federal hazard air pollutant. In April of 1993, it was identified as an air contaminant.” (PubChem) “The physical properties of toluene are as follow: it has a molecular weight of 92.13, a boiling point of 110.7 C, a melting point of -95 C, a flash point of 40 F, a vapor density of 3.2 (air = 1), a vapor pressure of 36.7 mm Hg at 30 C, a density/specific gravity of 0.866 at 20/4 C (water = 1), a log octanol/water partition coefficient of 2.69 and a conversion factor of 1 ppm= 3.77 mg/m3.” (PubChem) Toluene has a chemical formula of C6H5CH3. Toluene is also a single methyl group. One interesting thing about Toluene is that is it used for gasoline aviation and a solvent for paint, gum, and resins. The source of toluene are many which includes tobacco smoke, petroleum, chemical intermediates, and styrene production. It was also registered as a pesticide but is no longer used as such. Toluene exists in the atmosphere as a gas.
2) Explain the purpose of using this reagent in the histology lab.
Toluene, is used in the histology laboratory as a clearing agent. This reagent works better than xylene and it does not over-harden tissue like xylene. “Toluene is better at preserving tissue structure and is more tolerant of small amounts of water left behind in the tissues than xylene.” (National Diagnostics) The reason why it is not used in some laboratories is because it is three times more expensive than xylene. As mentioned, this reagent is first used in the clearing process. This is the process in which toluene clears all of the alcohols of the tissue being processed and prepares the tissue to be infiltrated by paraffin. Since clearing agents frequently have identical refractive indexes as proteins, the term clearing is often used. When a tissue is completely submerged in the clearing solution, the tissue becomes see through. The appearance will often determine if the agent was fully effective as well as show if the clearing process has completed. Toluene can also be used in H&E staining, cytology, frozen section stainer, IHC, and special staining. It can be used to aid in the cover slipping of the slides.
3) Explain the hazard associated with the selected reagent, and include the recommended disposal methods of this reagent.
Toluene affects the central nervous system, eyes, skin,...