Safety
Contamination
The three main contamination categories in a research vial — microbial, endotoxin, particulate — and how each behaves.
- Last updated:
- 2026-07-22
Overview
Contamination in a research vial can be microbial (viable bacteria, fungi, or spores), endotoxin (breakdown products of Gram-negative bacteria), or particulate (glass fragments from vial fracture, rubber particles from stopper coring, undissolved formulation).
The three are independent. A vial can be sterile and endotoxin-laden. It can be endotoxin-free and contain particulate. It can look clear and be all three.
Why it matters
Contamination is invisible until it produces a symptom. Each contamination category produces a different pattern of harm, and each has a different laboratory answer.
Key concepts
Microbial contamination
Introduced during manufacture, fill, storage, or (most commonly) end-user access. Slowed by bacteriostatic diluents; not eliminated. Detected by sterility testing.
Endotoxin contamination
Present when Gram-negative bacteria were involved at any point, even if now dead. Not destroyed by autoclaving. Detected by LAL or rFC assays.
Particulate contamination
Glass, rubber, or undissolved formulation particles visible on inspection. May cause local irritation, injection-site reactions, or embolic events. Reduced by careful vial handling and filter needles where used.
Common misconceptions
- "It looks clear so it's clean." Visual clarity rules out gross particulate; it does not rule out microbial or endotoxin contamination.
- "Refrigeration prevents contamination." Refrigeration slows microbial growth; it does not prevent introduction and it does not remove endotoxin.
- "One contamination test proves the vial is safe." Each contamination category has its own test.
Practical interpretation
The compound page's storage and access guidance is designed to reduce contamination risk. Follow it, and treat any deviation as a reason to discard rather than to salvage.
Limitations
Healthy Mango cannot test individual vials. Contamination risk is a supply-chain and handling risk that a website can describe but cannot verify.