Why 70% IPA is more effective than 100% IPA?

Why 70% IPA is more effective than 100% IPA?

70% Isopropyl Alcohol (IPA) solution is most commonly uses Alcohol in the pharmaceutical Industry. 70% IPA solution is used as disinfection to kills Micro-organism from the surface.

How 100 % IPA work?

As we know Pure Isopropyl Alcohol or 100% IPA Evaporates quickly at room temperature. Like other volatile liquids, it evaporates because the molecules have high kinetic energy at room temperature. Both the gram-positive and Gram-Negative bacteria have the peptidoglycan layer on their cell wall.

When 100 % IPA contact the cell wall, The alcohol will go through the cell wall of the organism in all direction coagulates protein instantly inside the cell wall and there is a ring formation of coagulates protein would then stop the IPA from penetrates further from the cell and no more coagulates take place because absolute IPA has high evaporation capacity and less contact time. At this time cell would become inactive but not dead. Under the favourable conditions, the cell would again reactive and start functioning

Why 70% IPA is more effective than 100% IPA?
Image Credit: Khan Academy

How 70 % Alcohol Works?

We know 70 % IPA contains 70 % Alcohol and 30 % Water. Water is required to denature the proteins of the cell membrane work and acts as a catalyst and It also increases the contact time of Alcohol within the cell wall of the Organism. When it contacts to the cell wall it dissolves the plasma membrane of the cell wall because the presence of water it increases the contact time inside the cell wall of bacteria and it slowly penetrates and does not allow to the formation of Coagulates protein layer it goes further and dissolves all protein and Kills Micro-Organism

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Hence, The 70% IPA  more effective than 100 % IPA because 70% IPA takes more time to evaporate and Water acts as catalyst of reaction to kills germs.

Some Important Tips to Use 70% IPA

  • Isopropyl Alcohol (IPA) should be prepared daily basis (for use inside Laminar Air Flow (LAF) room) and weekly basis for Hand Sanitization and other disinfectant purposes.
  • Freshly Prepared Isopropyl Alcohol should be used in the Production area
  • For the preparation of 70%, Isopropyl Alcohol Purified/Mili Q water should be used
  • While preparation of 70% IPA measuring should be done accurately
  • Isopropyl Alcohol should be validated according to the SOP
  • The Bulk Container use for 70% IPA distribution should properly label with shown in the table

70% Isoproply Alcohol

Date of Preparation:xx-xx-xxxx
Expired Byxx-xx-xxx
Prepared ByYour name and sign
Checked By Manger Name and sign


  1. https://www.pharmaguideline.com/2013/11/why-70-isopropyl-alcohol-is-used-as-disinfectant.html