A Look at Quats, ‘Low Quats’ … and Loquats?

QUATERNARY AMMONIUM SALTS are sometimes called “quats.” Low concentrations of quats (sometimes called “low quats”) are used in water as disinfecting agents.

When it comes to contamination control, some terminology can be confusing. Let’s clear something up: A “quat” is the abbreviation for a class of chemicals known as quaternary ammonium salts. Low concentrations of quats in water are used as disinfecting agents. These are sometimes casually called “low quats.” A loquat is a tangy fruit originating in China. (NOTE: Low concentrations of quats are not known as “loquats.”)

Quats Vs. “Low Quats”

Disinfecting household wipes containing low concentrations of quats are sold in supermarkets, and they are used in cleaning surfaces household kitchens and bathrooms. Household products like these are not appropriate for the cleanroom.

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Moreover, the wipers marketed for household use do not have the requisite level of cleanliness for cleanroom use. The fabrics sold for household applications present higher particle and fiber levels than are acceptable in cleanrooms. Use of these products is likely to contaminate rather than clean cleanroom surfaces.

Cleanroom wipers, typically laundered knit polyester or hydro-entangled polyester-cellulose, are fully compatible with quat solutions.

Quats And Cleanrooms

But what about quaternary ammonium salts themselves? Do they serve a useful purpose in the cleanroom? Yes and no.

If your cleanroom application is one in the healthcare, biotechnology, pharmaceutical, or biomedical industries then wiping down environmental or production tooling surfaces with quat solutions will provide disinfection against certain classes of bacteria.

If your cleanroom application is not one in which disinfection is a concern (microelectronics manufacturing, for example), then it will not benefit from quat solution wipe-downs. In fact, compared to isopropyl alcohol (IPA) solutions, quat solutions will leave a thin film of non-volatile residue (consisting of the dried quaternary ammonium salts) that can act as a source of contamination through contact transfer.

To remove this residue, one would typically have to wipe the surface with a wiper wetted with an IPA solution. This double-effort wiping adds cost, consumes time, and does not provide a cleaner surface than wiping with an IPA solution alone.