Rubbing alcohol

Rubbing alcohol

Rubbing alcohol, USP / B.P. is a liquid prepared and used primarily for topical application. It is prepared from a special denaturized alcohol solution and contains 68.5-71.5% by volume of pure, concentrated ethanol (ethyl alcohol). Individual manufacturers can use their own "formulation standards" in which the ethanol content usually ranges from 70-95% v/v.

The term "rubbing alcohol" has become a general non-specific term for either isopropyl alcohol (isopropanol) or ethyl alcohol (ethanol) rubbing-alcohol products. The confusion comes from the greater popularity of isopropyl rubbing alcohol, and as a result, individuals requesting "rubbing alcohol" generally expect and get an isopropyl alcohol product. However, the British Pharmacopoeia and United States Pharmacopeia standards (standards recognized in many countries other than just the UK and USA) define rubbing alcohol as a mixture of ethanol and water of fixed proportions.

Standardization

In the United States, rubbing alcohol, USP and all preparations coming under the classification of Rubbing Alcohols must be manufactured in accordance with the requirements of the US Treasury Department, Bureau of Alcohol, Tobacco, and Firearms, using Formula 23-H (8 parts by volume of acetone, 1.5 parts by volume of methyl isobutyl ketone, and 100 parts by volume of ethyl alcohol). It contains 68.5-71.5% by volume of absolute ethyl alcohol, the remainder consisting of water and the denaturants, with or without color additives, and perfume oils. Rubbing Alcohol contains in each 100 mL not less than 355 mg of sucrose octaacetate or not less than 1.40 mg of denatonium benzoate. The preparation may be colored with one or more color additives. A suitable stabilizer may also be added.

Physical Properties

Rubbing alcohol is a cellular, volatile, and flammable liquid. It is transparent, though it can be coloured as desired. It has an extremely bitter taste and (in the absence of added odorous substances) a characteristic odor. The specific gravity of Formula 23-H is between 0.8691 and 0.8771 at 15.56°.

Isopropyl Rubbing Alcohol

Isopropyl Rubbing Alcohol, USP / B.P. contains 68-99% of isopropanol (isopropyl alcohol) by volume, the remainder consisting of water, with or without color additives, suitable stabilizers, and perfume oils. Isopropyl alcohol is oxidized by the liver into acetone. Symptoms of isopropyl alcohol poisoning include flushing, headache, dizziness, CNS depression, nausea, vomiting, anesthesia, and coma.

Uses

Rubbing alcohol can be applied as a cooling, soothing application for bedridden patients and athletes. It helps soothe deep down cold bones (e.g., shins) if rubbed into skin during winter seasons. It is also widely used for cleansing surgeons' hands and instruments and for the disinfection of skin prior to penetration by a hypodermic needle. As an antiseptic it is good against vegetative bacteria and fair against fungi and viruses, but is ineffective against spores. It is widely believed that 70% ethanol provides the greatest reduction in bacterial count; however, this is incorrect. Other concentrations may be more effective, but their rate of kill is slower . In order to reduce the skin bacterial count to 5% of normal, 70% ethanol must be left on the skin for at least 2 minutes. Rubbing alcohol is also a feeble anesthetic and a mild counterirritant. It is not drinkable, although people have been known to attempt ingestion.

Rubbing alcohol is recognized as a rubefacient because it evaporates quickly and is used to cool and soothe skin. It is, however, more widely used as an antiseptic for sterilizing surfaces or cleaning minor cuts or abrasions.

Isopropyl rubbing alcohol can also be supplied in a 99% concentration. This product can also be used to harden skin, such as in the case of the feet of novice hikers, or the fingertips of guitarists. Care should always be taken, and the label should be read carefully.

It is unsuited as a fuel in alcohol stoves because of the relatively low vapor pressure of isopropyl alcohol, and because the water content will vaporize to steam creating excessive pressure in the stove.

In the UK the equivalent skin preparation is surgical spirit which is always based on an ethyl alcohol-methyl alcohol mixture, and which often has the addition of small quantities of iodoform as a topical bactericide.

A typical modern composition for Surgical Spirit BP is: ethanol, methanol, water, castor oil, methyl salicylate, diethyl phthalate. It has a strong smell of wintergreen due to the presence of the methyl salicylate.

Cautions

Rubbing alcohol should be used in a well-ventilated area. Some cautions go so far as to say protective gloves should be worn while using it. Poisoning can occur from ingestion, inhalation, or consumption of rubbing alcohol.

Isopropyl rubbing alcohol is poisonous and can cause permanent disabling illness or death if consumed.

Mixing rubbing alcohol with pool chlorine can result in a haloform reaction, generating lots of heat and boiling off its products as excess gas. If this chemical reaction is done inside a closed plastic container, the gas can build up until it ruptures violently. This can pose a serious risk of injury as the chemicals (such as bleach) and shrapnel from the container are thrown outward by the explosion.

External links

References

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