High-Level Disinfectant Chemistry Compared: Glutaraldehyde, OPA, Peracetic Acid, Chlorine Dioxide and Hydrogen Peroxide

A sealed sterilization pouch with a blue external chemical indicator stripe, labelled Class 4 dual indicator
A sealed sterilization pouch with a blue external chemical indicator stripe, labelled Class 4 dual indicator

Five chemistries do most of the high-level disinfection and chemical sterilization work in health care: glutaraldehyde, ortho-phthalaldehyde (OPA), peracetic acid, chlorine dioxide and hydrogen peroxide. They differ in the strength they need, the time and temperature they need to work, the materials they corrode, the ventilation and protection they demand, how long a working solution lasts, how they must be rinsed, and — the column that is most often overlooked — what their actual authorization status is. This article compares all five across eight parameters from the published Canadian guidance, and separates two things that are routinely treated as one: what a product claims it kills, and what its licence record says it may be used for.

Quick facts

  • The high-level disinfectants named in Canadian provincial guidance include 2% glutaraldehyde, 6% hydrogen peroxide, 0.2% peracetic acid, 2–7% enhanced action formulation hydrogen peroxide, and 0.55% ortho-phthalaldehyde; pasteurization also achieves high-level disinfection.
  • High-level disinfection is the minimum for semicritical devices, and it is not a sterilant claim. Sterility from the same chemistry requires a much longer immersion — for example, the published guidance notes glutaraldehyde sterilizing in about 10 hours at 20°C and peracetic acid in 12 minutes at 50–56°C.
  • Every disinfectant used on medical equipment or devices has to carry a Drug Identification Number (DIN) from Health Canada; the DIN is a separate record from the product's efficacy wording.
  • The in-use solution has to be concentration-tested with a chemical strip, daily if used daily, because a working solution loses strength through use and dilution.
  • Ventilation is a requirement, not a preference: the vapour concentration of the disinfectant used may not exceed the allowable limit, cited as 0.05 ppm for glutaraldehyde.

What counts as a high-level disinfectant

A high-level disinfectant is defined by what it kills and where it may be used. High-level disinfection eliminates vegetative bacteria, enveloped viruses, fungi, mycobacteria (such as tuberculosis) and non-enveloped viruses; it does not reliably kill high numbers of bacterial spores. It is the level applied to semicritical devices, and when the same chemistry is used with a much longer immersion it becomes a liquid chemical sterilant for critical devices.

Two things follow from that definition. First, the label wording matters more than the bottle: the same active chemistry can be sold as a surface disinfectant, as a high-level disinfectant, or as a sterilant, and the lawful use is set by the product's own authorization, not by the family name. Second, a claim and a clearance are recorded in different places, which is the point developed later in this article.

Table 1 — The five chemistries at a glance

Chemistry Active ingredient, as named in guidance Typical in-use strength Where it is aimed
Glutaraldehyde 2% solution for high-level disinfection; 2.5–3.5% for the dialdehyde sterilant products 2% for high-level disinfection Semicritical devices, including heat-sensitive items; also a liquid sterilant at long immersion
Ortho-phthalaldehyde (OPA) 0.55% solution 0.55% Semicritical devices, including flexible endoscopes
Peracetic acid 0.2% solution 0.2% Heat-sensitive immersible devices; automated endoscope reprocessing
Chlorine dioxide Oxidising chlorine dioxide solutions Product-specific Surface and device oxidiser, depending on the product's authorization
Hydrogen peroxide 6% solution and 2–7% enhanced action formulations; 6–25% liquid sterilant products 6% for high-level disinfection Semicritical devices; hydrogen peroxide liquid as a chemical sterilant at extended immersion

Which parameters matter when you compare them

The comparison that matters at the bench is not the kill claim but the operating envelope: what strength, what time, what temperature, what it damages, what protection it needs, how long it lasts once in use, what is left behind, and what the licence says it is for.

Table 2 — Five chemistries across eight parameters

Parameter Glutaraldehyde OPA Peracetic acid Chlorine dioxide Hydrogen peroxide
Effective-concentration criterion A 2% in-use solution; concentration verified with a test strip, tested at least daily A 0.55% in-use solution; concentration verified with a test strip A 0.2% in-use solution; concentration verified with a test strip Product-specific oxidiser strength; verified against the product's own criteria 6% high-level solution; concentration verified with a test kit for each load
Contact time and temperature 2% solution at 20 minutes and 20°C for high-level disinfection; sterilizing products about 10 hours at 20°C Per the product label for the strength in use Sterilizing at 12 minutes and 50–56°C in an automated cycle Per the product label 6 hours for the 6–25% liquid sterilant; enhanced action formulations run from 20 minutes to 6 hours at 20°C
Material compatibility Metals, plastics and rubber, including lens cement; does not coagulate protein Per the device and product instruction Corrosive; incompatible with some materials such as aluminium; immersible instruments only Oxidiser with material-specific effects; follow the product instruction Liquid product contraindicated for copper, zinc, brass and aluminium; vapour processes limit lumen length
Ventilation and PPE Toxic and sensitising irritant; ceiling limit cited at 0.05 ppm; closed containers required Aldehyde handling and ventilation controls as for the product label Vapour is volatile, has a pungent odour, is toxic, and is a fire and explosion hazard Oxidising gas and solutions; containment and ventilation per the product label Vapour processes are non-toxic but require special wraps and trays; liquid handling per the safety data sheet
Reusable life Working life up to 14 days once mixed; concentration drops on reuse and dilution Per the product label, which bounds reuse Unstable, particularly when diluted; reuse bounded by the cycle and the label Per the product label Concentration must be monitored; reuse bounded by the label
Residual and rinse Requires copious rinsing with sterile water to remove residual chemical Requires rinsing and channel flushing per the label Leaves no residue; still requires the rinse step the label states Requires rinsing per the label Rinse and dry per the label; vapour processes carry their own limitations
Licence status field DIN on the disinfectant product; device-level sterilant status separate DIN on the disinfectant product; device-level status separate DIN on the disinfectant product where sold as such DIN on the disinfectant product where sold as such DIN on the disinfectant product where sold as such
Waste disposal Disposal per the safety data sheet and local requirements Disposal per the safety data sheet and local requirements Disposal per the safety data sheet; diluted product is unstable Disposal per the safety data sheet and local requirements Disposal per the safety data sheet and local requirements
A Class 5 steam chemical integrator card with a yellow moving front between the reject and accept zones

Which materials does each chemistry affect, and how is it rinsed?

The published advantages-and-disadvantages tables in Canadian guidance show how differently the five behave with materials. Glutaraldehyde is noted as compatible with metals, plastics and rubber, including equipment with lens cement, and it does not coagulate protein. The liquid hydrogen peroxide sterilant is contraindicated for copper, zinc, brass and aluminium, and hydrogen peroxide vapour processes carry restrictions on the length and width of the lumens they can reach. Peracetic acid is explicitly corrosive and incompatible with materials such as aluminium, and the chlorine dioxide product's compatibility is read from its own instructions.

The rinse step is the parameter that turns a chemical's material profile into a workflow. Because these chemistries are applied by immersion, whatever is left on the device after the process is a residue. Glutaraldehyde is noted as requiring copious rinsing with sterile water to remove residual chemical; peracetic acid is noted as leaving no residue but is still rinsed according to its label; and for endoscopes the guidance sets out the rinse and channel flushing that follows disinfection, with filtered or sterile water preferred. Rinsing is not cosmetic — it is the step that removes the chemical the patient would otherwise contact.

What ventilation and protection does each chemistry require?

None of the five chemistries is a nuisance vapour. The reprocessing area has to have a ventilation system that removes the vapours these products emit, with the vapour concentration of the disinfectant not permitted to exceed the allowable limit, cited as 0.05 ppm in the example for glutaraldehyde. In-use solutions are maintained in closed, covered and labelled containers at all times.

The protection a person wears is set by the product's safety data sheet and its hazard classification under WHMIS and the globally harmonised system, not by habit. Because aldehydes are irritants and sensitisers, glutaraldehyde carries a specific occupational-health profile in health care: it is toxic and a sensitising irritant, exposure is associated with respiratory symptoms in workers who handle it, and the controls that reduce exposure follow the standard hierarchy of containment, ventilation and personal protective equipment. Peracetic acid adds a second hazard dimension — its vapour is volatile and is a fire and explosion hazard — so containment and the product label govern its handling as much as the kill chemistry does.

How long can a high-level disinfectant solution be used?

A high-level disinfectant is a perishable supply. The in-use solution is concentration-tested with a chemical strip before processing and daily if used daily, and each new package of strips is checked with positive and negative controls so that a passing strip means something. Reuse life is then bounded by the label: glutaraldehyde working life is cited as up to 14 days once mixed, peracetic acid is unstable particularly when diluted, and a hydrogen peroxide solution's concentration has to be monitored because it can fall on reuse.

Residue and disposal follow from the same chemistry. Products that leave no residue still require the rinse the label states; products that are corrosive are disposed of as hazardous waste under the safety data sheet and local rules; and no test strip result extends a solution beyond its stated life. The medical waste stream is a separate obligation, and a chemistry that is spent is not a chemistry that can be poured away without reference to its safety data sheet.

Is a kill claim the same as a licence?

The comparison that most often misleads a purchaser is not on the bottle. It is the gap between the efficacy wording — the spectrum a product claims and the contact time it prints — and the product's authorization record.

In Canada, a disinfectant used on medical equipment or devices has to carry a Drug Identification Number from Health Canada, and the authorization listing records the product's active ingredient, its form and the use sites it is authorized for. In the United States, the split is by jurisdiction: the Environmental Protection Agency regulates sanitizers, disinfectants and sterilants under the pesticide law, but liquid chemical sterilant products intended for critical or semi-critical devices are no longer regulated as pesticides and instead fall to the Food and Drug Administration as medical devices. The consequence is the same on both sides of the border: the marketing wording and the authorization field live in different records.

Table 3 — What a claim records against what a licence records

Question The claim wording The authorization record
What it states The spectrum the product asserts and the contact time it prints Whether the product may be sold and for which uses
Where it sits The label, the product page, the data sheet The DIN listing in Canada; the device clearance in the United States
What it does not do It does not authorize a use on its own It does not replace the label's temperature and contact-time instructions
How to read it As an efficacy claim to be matched to the use As the field that governs lawful use on equipment and devices
Why it matters here A sporicidal claim is not a clearance to reprocess a device A DIN on the surface list is not a clearance to reprocess an instrument

Read together, the two columns explain a common failure. A facility can hold a broad-spectrum product that is authorized for surfaces and assume it may be used to reprocess an instrument, or it can hold an instrument-grade product and ignore the temperature and contact-time conditions the label sets for the strength in use. The first mistake is a licensing mistake; the second is a process mistake. Neither is caught by reading the claim alone.

For teams that reprocess and monitor on the same bench, the sterilization compliance hub gathers the standards and monitoring material, the Spaulding classification explainer sets out which devices fall to which level, and the high-level disinfection endoscopy guide covers the workflow side. The sterilization monitoring collection groups the indicators and readers that support the record, and facilities building the pack-level side often start from the Class 4 dual-indicator pouches and the Class 5 chemical integrators, can begin a monitoring programme with the biological indicator 5-pack trial, and order at case level through a wholesale account. Reselling? become a distributor.

CliniEco Medical supplies biological indicators, incubators and sterilization monitoring consumables for Canadian care settings (MDEL #35334).

Match the record to the chemistry. A high-level disinfection record is a chemistry-specific page: the active ingredient, its in-use strength, the concentration test result, the temperature and the contact time all belong on the same sheet as the device and the operator. The printable sterilization log sheet prints a blank sheet built on the four record groups and 20 fields that follow the record-keeping sections of the RCDSO IPAC Self Audit Review Form (v2), and the load log and label generators produce a dated page you can print or export without an account.

Have a question about your own facility? Send it in and you will get a written answer specific to your setup, with the regulation or standard it is based on cited. Ask your compliance question.

This article describes standards and guidance published by third parties and is not a substitute for the standard of practice that governs your setting, the product manufacturer's validated instructions, or the requirements of your provincial regulator.

Related reading

Frequently Asked Questions

What are the five high-level disinfectant chemistries compared here?

Glutaraldehyde, ortho-phthalaldehyde (OPA), peracetic acid, chlorine dioxide and hydrogen peroxide. The high-level disinfectants named in Canadian provincial guidance include 2% glutaraldehyde, 0.55% OPA, 0.2% peracetic acid, 6% hydrogen peroxide and 2–7% enhanced action hydrogen peroxide, and pasteurization also achieves high-level disinfection.

Is a high-level disinfectant the same as a sterilant?

No. High-level disinfection does not reliably kill high numbers of bacterial spores and is the level applied to semicritical devices. A liquid chemical sterilant kills spores and is used for critical devices, reached by using the same chemistry with a much longer immersion — the published guidance gives glutaraldehyde sterilizing in about 10 hours at 20°C and peracetic acid in 12 minutes at 50–56°C.

Does a broad-spectrum claim mean a product can reprocess instruments?

No. What a product claims it kills and what its authorization record permits are two different things. In Canada a disinfectant used on medical equipment or devices has to carry a Drug Identification Number from Health Canada, and a broad-spectrum claim is not a substitute for that authorization or for the label's temperature and contact-time conditions.

Which of these chemistries corrode instruments?

Peracetic acid is noted as corrosive and incompatible with some materials such as aluminium, and the liquid hydrogen peroxide sterilant is contraindicated for copper, zinc, brass and aluminium. Glutaraldehyde is noted as compatible with metals, plastics and rubber, including equipment with lens cement. Compatibility is always confirmed against the device and product instructions, not the family name.

Why must a high-level disinfectant solution be concentration-tested?

Because a working solution loses strength through use and dilution, so the strength on the day of use is not the strength on the day it was mixed. The in-use solution is tested with a chemical strip before processing and daily if used daily, and each new package of strips is checked with positive and negative controls before it is relied on.

Why is ventilation a requirement for these chemistries?

Because the vapours are workplace hazards. The reprocessing area needs ventilation that removes the vapours, with the vapour concentration of the disinfectant not permitted to exceed the allowable limit — cited as 0.05 ppm in the glutaraldehyde example — and in-use solutions are kept in closed, covered and labelled containers. Peracetic acid vapour is additionally a fire and explosion hazard.

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