High-Level Instrument Disinfectants: A Buyer's Guide for Clinics & Labs
Choosing a high-level disinfectant (HLD) comes down to three questions: what you are reprocessing, how long the solution stays usable, and how you will verify it is still strong enough to work. If you reprocess semi-critical instruments — items that touch mucous membranes or non-intact skin, such as endoscopes, laryngoscope blades, or vaginal specula — you need an FDA-cleared high-level disinfectant, not a general surface cleaner. This guide compares the glutaraldehyde and OPA (ortho-phthalaldehyde) options we stock through our McKesson authorized-dealer line so you can match chemistry, reuse life, and contact time to your workflow.
First, confirm you actually need a high-level disinfectant
Infection-control practice follows the Spaulding classification, which sorts devices by infection risk. It is the framework behind CDC disinfection and sterilization guidance:
- Critical — enters sterile tissue or the vascular system (surgical instruments, implants). Requires sterilization.
- Semi-critical — contacts mucous membranes or non-intact skin (endoscopes, respiratory equipment, specula). Requires high-level disinfection at minimum.
- Noncritical — contacts intact skin only (blood-pressure cuffs, bed rails). Needs low- or intermediate-level surface disinfection.
If your instruments fall in the semi-critical bucket, an HLD is the right category. For surfaces, noncritical items, and safe chemical storage, see our chemical storage and handling guide.
The chemistries we stock
Every option below is an FDA-cleared liquid chemical sterilant / high-level disinfectant. The right one depends on reuse life, contact time, odor, and material compatibility.
| Product | Active ingredient | Reuse life | Notes |
|---|---|---|---|
| MetriCide 28 | 2.5% glutaraldehyde | Up to 28 days | Activation required; contains a surfactant; economical, widely used |
| McKesson 28-Day Glutaraldehyde | 2.5% glutaraldehyde | Up to 28 days | Activation required; corrosion inhibitor; not for lensed scopes (film risk) |
| REGIMEN | 3.4% glutaraldehyde | Up to 28 days | Higher concentration; no dilution; broad kill claims |
| Rapicide OPA/28 | 0.3% OPA | Up to 14 days (in AER) | Faster contact time; low odor; stains proteins and skin — wear PPE |
Glutaraldehyde (2.5%–3.4%)
The long-standing workhorse. Economical, broadly compatible, and available in 14- and 28-day formulations. Trade-offs: it usually must be activated before first use, has a recognizable pungent odor, and requires good ventilation and PPE. The 3.4% REGIMEN formula skips the dilution step; the 2.5% MetriCide 28 and McKesson 28-Day options are the value choice for routine reprocessing.
OPA (ortho-phthalaldehyde)
Chemically related to glutaraldehyde but with a faster contact time and much lower odor, which is why many endoscopy suites prefer it. It does stain proteins, skin, and clothing gray, so gloves and eye protection are essential. Verify strength with the matched Rapicide OPA/28 test strips before each cycle.
Do not skip the test strips
Every reusable HLD has a minimum effective concentration (MEC). As the solution is used, the active ingredient dilutes and degrades — so you must test the concentration with a product-specific strip before each use and discard the solution if it drops below its MEC, even if the labeled reuse date has not passed. This is both a performance and a compliance requirement. Match the strip to the disinfectant: OPA strips for OPA, glutaraldehyde strips for glutaraldehyde.
Clean before you disinfect
High-level disinfection only works on a clean instrument — organic soil such as blood, protein, and lipids shields microbes and inactivates the chemistry. Pre-clean with an enzymatic instrument detergent immediately after use so debris does not dry on. Cleaning always precedes disinfection.
Safety and handling
Glutaraldehyde and OPA are potent sensitizers. Follow OSHA guidance for exposure control: use closed containers with tight-fitting lids, ensure adequate ventilation, and wear appropriate gloves and eye protection. Keep the product-specific Safety Data Sheet accessible. Our lab PPE requirements guide covers glove and eye-protection selection for chemical handling.
Shop the full range of McKesson high-level disinfectants and instrument-reprocessing supplies, shipped from US inventory as an authorized McKesson dealer.
Why buy your HLDs from LabSupplies.com
As an authorized McKesson dealer, we ship these products directly from US inventory with manufacturer support behind them. You get the McKesson private-label line alongside the major brands — MetriCide, Rapicide, and REGIMEN — in one place, with fast fulfillment and technical help by phone.
Frequently asked questions
What is the difference between a high-level disinfectant and a sterilant?
A high-level disinfectant eliminates all microorganisms except large numbers of bacterial spores. A sterilant, typically the same chemistry used at a longer contact time, eliminates all microbial life including spores. Many products carry both claims at different contact times.
Glutaraldehyde or OPA — which should I choose?
OPA offers a faster contact time and lower odor, which suits high-throughput endoscopy. Glutaraldehyde is more economical and broadly compatible. Base the decision on throughput, ventilation, and device compatibility.
How long can I reuse an HLD solution?
Up to its labeled reuse life — commonly 14 or 28 days — but only while it stays above its minimum effective concentration. Test before each use and discard early if it fails, regardless of the date.
Do I really need test strips?
Yes. Verifying concentration with a product-matched strip before each use is required by FDA labeling and infection-control guidance. It is the only way to confirm the solution still works.
Can I use these on endoscopes?
Many are cleared for immersible, heat-sensitive scopes, but some glutaraldehyde formulas are not recommended for lensed instruments because of film risk. Always follow the device and disinfectant instructions for use.
By the LabSupplies.com Technical Team
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