What alcohol concentration is used to sterilize forceps in the membrane filter test for total coliform?

The correct choice regarding the alcohol concentration used to sterilize forceps in the membrane filter test for total coliform is 70% isopropyl alcohol. This concentration is effective for disinfection and sterilization purposes because it contains a sufficient amount of water to slow down the evaporation rate of alcohol, allowing it to effectively penetrate and denature proteins within microorganisms, ultimately leading to cell death.

In laboratory practices, isopropyl alcohol at 70% concentration is widely recognized as a standard for sterilization due to its optimal balance of efficacy, ease of use, and safety for both the user and the environment. Higher concentrations, such as 95% ethyl alcohol or 100% isopropyl alcohol, tend to evaporate too quickly, reducing their ability to effectively kill bacteria and viruses during contact. A lower concentration like 50% methyl alcohol is usually insufficient for sterilization and may not meet the necessary effectiveness required in labs to ensure safe handling of laboratory equipment.