How to tell if a vial has gone bad: signs of contamination and degradation

Discard timelines (like the 28-day window for opened bacteriostatic water) are useful defaults, but they're not the only signal that matters. A vial can go bad before its stated window closes, and recognizing the visual signs is a basic laboratory skill worth having regardless of what the calendar says.

Cloudiness or haze

A solution that was clear when reconstituted or opened and has since become cloudy or hazy should be discarded immediately. This is one of the most reliable visual indicators of contamination or compound degradation.

Visible particulates

Small floating particles, flakes, or sediment at the bottom of a vial are a discard signal, even if the surrounding liquid still looks clear.

Discoloration

Any shift away from the solution's original color — including a color that's simply "off" compared to a freshly reconstituted reference — is worth treating as a discard signal rather than something to monitor further.

Unusual odor

Most laboratory-grade water and reconstituted solutions are effectively odorless or have a very mild, consistent scent. A new or unusual odor is a sign something has changed in the vial.

When in doubt, discard

None of these signs require lab equipment to detect — they're all things you can and should check by eye (and, where appropriate, smell) before every draw. When any of them appear, the safest and simplest response is to discard the vial rather than attempt to determine exactly what went wrong.

This article is for laboratory research reference only. Products discussed are for in vitro laboratory research use only and are not evaluated or approved for human or veterinary use.