What are the chemicals used in disinfection and sterilization?

September 29, 2025 •

4 min read

According to the Centers for Disease Control and Prevention (CDC), effective disinfection and sterilization protocols are critical for preventing the spread of infection. A wide range of chemical agents is employed for this purpose, with different strengths and applications depending on the required level of microbe elimination. Knowing what are the chemicals used in disinfection and sterilization is essential for maintaining a clean and safe environment.

Quick Summary

Diverse chemical agents are used for disinfection and sterilization, including alcohols, halogens like chlorine compounds, aldehydes such as glutaraldehyde, and peroxygens like hydrogen peroxide, each with distinct killing mechanisms and suitable applications for different surfaces and items.

Key Points

Alcohols are fast disinfectants: Ethanol and isopropanol (60-90%) kill most bacteria and viruses rapidly by denaturing proteins, but they evaporate quickly and are not sporicidal.
Chlorine compounds are potent and inexpensive: Sodium hypochlorite (bleach) is a powerful, broad-spectrum oxidant that kills spores but is corrosive and inactivated by organic matter.
Aldehydes offer high-level disinfection: Glutaraldehyde and OPA are used for sterilizing heat-sensitive medical devices, though they require careful handling due to toxicity or staining properties.
Peroxygens are eco-friendly alternatives: Hydrogen peroxide and peracetic acid decompose into safe byproducts and are effective against a wide range of microbes, including spores, at appropriate concentrations.
Quats are for general sanitation: Quaternary Ammonium Compounds are common, low-level disinfectants for everyday cleaning, but they are ineffective against spores and certain viruses.
Contact time and concentration are crucial: The effectiveness of any chemical agent depends heavily on the concentration used and the duration of contact with the surface or instrument.
Sterilization is more thorough than disinfection: Sterilization kills all microbial life, including spores, while disinfection only eliminates most pathogens.

Disinfection vs. Sterilization: Understanding the Difference

Before exploring the specific chemicals, it's vital to differentiate between disinfection and sterilization. Disinfection eliminates most pathogenic microorganisms but does not necessarily kill bacterial spores. Sterilization is a more rigorous process that destroys all forms of microbial life, including highly resistant bacterial spores. This is a crucial distinction that dictates which chemical agent is appropriate for a given task.

Alcohols: Rapid-Acting Agents

Alcohols, primarily ethyl alcohol (ethanol) and isopropyl alcohol (isopropanol), are widely used as disinfectants and antiseptics. They exhibit rapid broad-spectrum activity against vegetative bacteria, fungi, and lipid-enveloped viruses, though they are not effective against bacterial spores. Their antimicrobial action comes from denaturing proteins and disrupting cell membranes. The ideal concentration is typically 60–90% aqueous solution, as pure alcohol is less effective because it evaporates too quickly. A key limitation is that they evaporate rapidly, which can reduce their contact time on surfaces.

Halogens: Potent Oxidizing Agents

Halogen-based chemicals are highly effective oxidizing agents that disrupt the cellular activity of microorganisms. They include:

Chlorine Compounds: Most commonly used as household bleach (sodium hypochlorite), these are inexpensive, fast-acting, and effective against a broad spectrum of microorganisms, including viruses, bacteria, and spores. However, their activity is significantly reduced by organic matter and they can be corrosive to metals. Solutions should be freshly prepared and handled with care due to their irritant and corrosive properties.
Iodophors: These are complexes of iodine and a carrier, offering a sustained release of free iodine. While widely used as antiseptics (e.g., povidone-iodine), they are also used as disinfectants in some healthcare settings. They are bactericidal, fungicidal, and virucidal, though typically not sporicidal.

Aldehydes: High-Level Disinfectants and Sterilants

Aldehydes are potent chemical agents used for high-level disinfection and, with longer exposure times, for sterilization, especially for heat-sensitive medical equipment like endoscopes.

Glutaraldehyde: A high-level disinfectant and chemical sterilant that is effective against bacteria, viruses, fungi, and spores. It is non-corrosive to plastics and metal, making it suitable for delicate instruments. However, it can be irritating and toxic, requiring proper ventilation and handling precautions.
Ortho-phthalaldehyde (OPA): Often used as a glutaraldehyde alternative, OPA is a high-level disinfectant with superior mycobactericidal activity. It is more stable and has a less noxious odor, though it can stain skin and equipment that is not properly cleaned and rinsed.

Peroxygens: Environmentally-Friendly Choices

Peroxygens are oxidizing agents that break down into water and oxygen, making them more environmentally friendly options. They are effective against a wide range of microorganisms, including spores.

Hydrogen Peroxide: Used in various concentrations for disinfection and sterilization. It produces hydroxyl free radicals that attack cell components. Higher concentrations and longer contact times are required for sporicidal activity.
Peracetic Acid: A rapid-acting agent that is sporicidal even at low temperatures and in the presence of organic matter. It is often used in automated endoscope reprocessors.
Combined Hydrogen Peroxide and Peracetic Acid: Synergistic formulations are used to boost effectiveness, particularly against glutaraldehyde-resistant mycobacteria.

Quaternary Ammonium Compounds (Quats): Everyday Cleaners

Quaternary Ammonium Compounds (QACs) are cationic detergents widely used for general environmental sanitation, such as on floors and furniture. They are effective against many bacteria and some enveloped viruses but are not effective against spores or non-enveloped viruses. Their antimicrobial activity can be reduced by hard water and organic matter. Products with QACs, such as disinfectant wipes, are commonplace for daily cleaning.

Comparison of Common Chemical Agents


Agent	Primary Use	Spectrum	Notes	Effectiveness vs. Spores	Material Compatibility
Alcohols	Disinfecting hard surfaces, skin antisepsis	Bacteria, fungi, enveloped viruses	Rapid evaporation, flammable; optimal concentration is 60-90%	No	Good (but can harden rubber/plastics)
Chlorine Compounds	Surface disinfection, water treatment	Broad-spectrum, including spores	Corrosive to metal, inactivated by organic material, requires fresh dilution	Yes (at high concentrations)	Poor on metal
Glutaraldehyde	High-level disinfection/sterilization of instruments	Broad-spectrum, including spores	Toxic, requires PPE and ventilation; effective on heat-sensitive items	Yes	Good (non-corrosive)
Ortho-phthalaldehyde (OPA)	High-level disinfection of endoscopes	Superior mycobactericidal; some sporicidal activity	Stains skin/equipment, less toxic fumes than glutaraldehyde	Moderate	Good (non-corrosive)
Hydrogen Peroxide	Disinfection, sterilization	Broad-spectrum, including spores (at higher concentrations)	Environmentally friendly, can be corrosive at high concentrations	Yes (at high concentrations)	Variable (can corrode metal)
Peracetic Acid	High-level disinfection/sterilization, automated systems	Broad-spectrum, including spores	Rapid action, environmentally friendly by-products; corrosive to some metals	Yes	Variable (can corrode some metals)
Quaternary Ammonium Compounds	General cleaning/sanitation of surfaces	Bacteria, some fungi, enveloped viruses	Inactivated by organic matter and hard water; low toxicity	No	Good

Conclusion: Choosing the Right Chemical for the Job

Selecting the correct chemical agent for disinfection or sterilization is a critical decision based on the specific application, surface type, and required level of microbial kill. While common household cleaners like chlorine and alcohols are suitable for many tasks, high-level disinfection and sterilization in clinical or laboratory settings require more potent and specialized agents like glutaraldehyde or peracetic acid. Understanding the strengths, weaknesses, and safe handling procedures for each chemical is essential to ensure a clean and safe environment for both personal and public health. For more detailed guidance, always refer to product labels and authoritative sources like the CDC.

Visit the CDC for official guidelines on disinfection and sterilization

Frequently Asked Questions

A disinfectant eliminates most pathogenic microorganisms but does not kill bacterial spores, while a sterilant is a chemical agent that is capable of destroying all forms of microbial life, including spores, under specific conditions.

A 70% aqueous alcohol solution is more effective because the water aids in the denaturation of proteins, a primary mechanism by which alcohol kills microbes. In contrast, 100% alcohol can cause proteins to coagulate on the surface, creating a protective layer that prevents deeper penetration.

At the high concentrations needed for sporicidal activity, household bleach (sodium hypochlorite) can function as a sterilant. However, for most applications, it is used as a disinfectant. It is highly corrosive and its effectiveness decreases in the presence of organic matter, so it must be used on pre-cleaned surfaces and diluted fresh.

Yes, ortho-phthalaldehyde (OPA) is a commonly used alternative that is more stable, has a less pungent odor, and is highly effective. Peracetic acid is another option, often used in automated reprocessing systems.

Quats are low-level disinfectants widely used for general sanitation on surfaces like floors, walls, and furniture. They are effective against many common bacteria and some enveloped viruses, and are found in many household cleaning wipes and sprays.

Peracetic acid is an oxidizing agent that disrupts the cell walls and denatures proteins and enzymes within microorganisms. It is known for its rapid action and effectiveness against spores, even at low temperatures, making it suitable for heat-sensitive instruments.

Chemicals like glutaraldehyde and chlorine can release toxic or irritating fumes. Proper ventilation, and wearing personal protective equipment (PPE), is crucial to minimize inhalation exposure and prevent skin or respiratory irritation for users and others in the vicinity.