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Compatibility with materials is a key characteristic of disinfectants, along with efficacy and safety. Microchem tests for compatibility using soak tests and customized mechanical abrasion tests.
Active ingredients, surfactants and solvents present in household and medical disinfectants can damage surfaces and textiles over the course of time. For example, bleach destroys pigments present in certain textiles and acidic household disinfectants can corrode metals or dissolve unsealed granite.
When a disinfectant is incompatible with the substrate to which it is applied, outcomes range from minor aesthetic modifications to loss of surface or textile functionality. In some cases, damage may appear rapidly. In other instances, damage may manifest over time.
In order to determine use instructions and mitigate the risk that a disinfectant will damage surfaces, manufacturers engage laboratories to conduct materials compatibility tests. Materials compatibility tests are required by FDA for disinfectants which are used to disinfect critical medical devices. The tests are not mandated by EPA for ordinary disinfectants, but are advisable nonetheless.
Few standardized procedures for materials compatibility testing have been developed, so testing is most often customized based on the anticipated use of the disinfectant. Relevant factors include use type (immersion, spray, or wipe), and exposure or dwell time. Sophisticated companies also account for the effect of product evaporation, since the process of evaporation can temporarily concentrate the active ingredient or cause it to precipitate.
Microchem tests disinfectants for compatibility with surfaces and textiles using three methods:
- Soak Test (materials soaked in disinfectant over time)
- Mechanical Abrasion test (materials exposed to disinfectant and scrubbed by a machine)
- Customized Compatibility test (some combination of soaking and mechanical abrasion)
The most common type of materials compatibility test is a simple soak test, where a broad array of test materials are soaked in the disinfectant for a period of time equivalent to the dwell time of the product multiplied by the number of desired use cycles. The end result of materials compatibility testing is a concise data summary defining the total number of product exposures that can be considered "safe" for each material that was tested.
The second most common test is a mechanical abrasion test. This is most applicable do disinfectant towelettes. The towelettes are loaded onto a standarized abrasion-testing machine, saturated with disinfectant, then scrubbed repeatedly over the surface at a set abrasion pressure and speed.
Some of Microchem's clients want to be extra-certain that their disinfectants will not damage surfaces over time. Those companies often benefit from a hybrid abrasion/soak test, which we call a customized compatibility test. It provides a "worst-case" scenario that is capable of detecting even minor incompatibilities.
The majority of disinfectants are compatible with most materials, but when incompatibility is evident, the damage is often obvious and companies benefit. For instance, a recent study at Microchem found that two different disinfectants damaged the delicate screen of a particular electronic device. By comparing ingredients in the damaging formulations and contrasting with screen-compatible formulations, the product formulator was able to identify the responsible ingredient - valuable information for any company in the era of electronics.