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Antiseptic Compounds

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Natural Pharmaceuticals
Medicines from plants and organisms
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Antiseptic Compounds
Phenol, iodine, alcohol preparations

The organic-chemistry carrier lists four antiseptics: ethanol at 60-80%, which kills most bacteria and loses effect above 90%; phenol at 2-5% in water; thymol from thyme; and iodine tincture at 2-7% in alcohol. Phenol and iodine are strong and can harm tissue and the body, so they are best kept for intact skin and instruments, with open wounds irrigated with clean boiled water. Dilute stock to the stated strength by calculation and label it.

Part of Organic Chemistry

Chemical agents that reduce microbes on skin, wounds and tools, with their strengths and the harm each can do.

The Carrier’s Four, And What Each Costs

  • Ethanol. The carrier gives 60-80% as the working range and says that above 90% it is less effective because it evaporates before killing bacteria, and below 50% it does not kill reliably.
  • Phenol (carbolic acid). The carrier says to dilute to 2-5% in water for wound cleaning and that higher concentrations burn tissue. It is made from tar (see Creosote for the related wood-tar phenols).
  • Thymol, steam-distilled from thyme (Steam Distillation). The carrier calls it excellent and less toxic than phenol.
  • Tincture of iodine, iodine dissolved in alcohol at 2-7%, which the carrier calls one of the most effective broad-spectrum antiseptics. The source of iodine is in Iodine Sources.

The Corpus Disagrees On Alcohol And Wounds; Take The Safer Reading

Three corpus pages say different things about alcohol. The carrier gives 60-80% and a reason for the upper limit (evaporation). Wound Antiseptic gives 60-70% as the effective window and a different reason (stronger alcohol coagulates surface protein and shields the bacteria beneath). Antiseptic Sources says to irrigate a wound with cooled boiled water and a layer of honey, and that alcohol belongs on tools, not wounds. The mechanism is argued two ways here and this article does not settle it. The conservative reading that fits all three: use alcohol at 60-70% on intact skin and instruments, and irrigate open wounds with clean boiled water first. No figure from any of the three pages has been altered.

Why Phenol And Strong Iodine Are Not For Large Open Wounds

The carrier warns that higher phenol concentrations burn tissue. The mechanism is worth stating: phenol is corrosive and also absorbed through skin and raw tissue into the blood, where it is toxic to the nervous system and kidneys; it numbs the area, so damage can be painless. A larger raw area absorbs more. Iodine is irritating to tissue and absorbed through broken skin as well. These are general toxicology points, not corpus figures. The safer use of both is on intact skin, small areas and instruments, at the lower end of the carrier’s range.

What You Need

  • Spirit of known strength from a grain or sugar wash (see Methanol Hazards).
  • Clean water, boiled and cooled.
  • Graduated measure and scale.
  • Dark glass bottles for iodine and phenol solutions, labelled with contents, strength, date and POISON.

Method: Making 70% Ethanol From Stronger Spirit

Step 1: Measure the strength of the stock spirit.

Step 2: Calculate the spirit and water volumes with C1 × V1 = C2 × V2.

Step 3: Mix, top up to the mark with water, and label.

Worked Example: Dilution And Iodine Mass

To make 1 litre at 70% from 90% stock: V1 = 70 × 1,000 ÷ 90 = 778 mL of stock, and 1,000 − 778 = 222 mL of water. Check: 778 × 0.90 = 700 mL of pure alcohol in 1,000 mL, which is 70%.

For iodine tincture at a weight-to-volume strength of 2%, each 100 mL carries 2 g of iodine, so 1 litre carries 2 × 10 = 20 g; at 7% it is 7 × 10 = 70 g. The weights follow from the definition of per cent weight per volume and are not corpus figures.

Common Mistakes

  • Using alcohol above 90% on skin and assuming stronger is better.
  • Pouring a burning antiseptic over a large wound.
  • Storing phenol or iodine in an unlabelled or food container.
  • Skipping irrigation, the step most likely to remove contamination.

Safety

Antiseptics are poisons used in small amounts

Phenol burns and is absorbed into the body; iodine is toxic if swallowed in quantity; strong alcohol is flammable and, if a fruit distillate, may carry methanol. Keep all of them in labelled bottles away from children, use the lowest strength that works, and never swallow them. See Antiseptic Technique for the wider practice.

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