USP - the gold standard
The gold standard for compound quality is “pharmaceutical-grade”: meeting the standards set by the US Pharmacopeia (USP) or other regional pharmacopeias for chemical purity. If you are injecting novel pharmaceutical compounds, why would you risk your research by flushing them in with solutions of unknown quality? Heparin in particular has a notoriously “twisted” supply chain, starting with pig farms in China. Contaminated heparin harmed hundreds of patients in 2008, leading the FDA to require improved testing to receive the USP designation. And yet non-pharmaceutical-grade heparin remains readily available from Fisher Scientific and other suppliers.
AAALAC International states that using pharmaceutical-grade compounds is preferred in some situations and required in others, if available. If you are using non-pharmaceutical-grade flush or lock solutions, your IACUC should require a justification.
Sterility is critical
In addition to the chemical purity, you must be certain that your flush and lock solutions are sterile. Non-sterile solutions can cause patency problems at a minimum, or worse infections which could compromise your research and the health of your animals. Sterile USP solutions will have been prepared according to the USP <797> standard for compounding sterile pharmaceutical preparations. If you are preparing solutions in your lab starting with sterile components, you must follow careful procedures to make sure they remain sterile until they are injected. For example, syringes with tips that are not sealed will not maintain sterility.