Which of the following substances can achieve true sterilization (i.e., kill all forms of microbial life, including spores and some viruses)? (Select the agent used as a validated sterilant.)

Introduction:
Sterilization is the complete elimination of all microorganisms, including bacterial spores. Many chemicals are disinfectants only. This question distinguishes a true chemical sterilant from common antiseptics/disinfectants.

Given Data / Assumptions:

• “Sterilize” means validated, total kill (including spores) under defined conditions.
• Alcohols and quaternary ammonium compounds are typically high-level disinfectants or antiseptics, not sterilants.
• Ethylene oxide (EtO) gas is used for heat- and moisture-sensitive devices.

Concept / Approach:
EtO alkylates proteins and nucleic acids, penetrating complex device lumens at low temperature to achieve sterility assurance. Other listed agents are mainly for disinfection; chlorine can approach sterilant activity only at high concentrations/contact times uncommon for device processing.

Step-by-Step Solution:
Define sterilization vs disinfection. Match each agent to its validated use level. Identify EtO as the standard low-temperature sterilant. Choose “Ethylene oxide.”

Verification / Alternative check:
Device reprocessing guidelines list EtO among FDA-recognized sterilization modalities.

Why Other Options Are Wrong:

• Alcohol: Rapid disinfection, not sporicidal reliably.
• Cetylpyridinium chloride: Quat; mainly disinfectant/antiseptic.
• Chlorine: Disinfectant; practical sterilization of devices is not standard.

Common Pitfalls:
Assuming “strong disinfectant” equals sterilant; sterilization requires higher assurance levels and validation.

Final Answer:
Ethylene oxide is the chemical sterilant among the options.