A syringe can retain its original drug concentration even when a separate question about sterility remains unanswered. Anderson and MacKay tested chemical stability for several medications stored individually in polypropylene syringes.
The researchers used liquid chromatography with diode-array detection to measure concentrations initially, around day 50 and at day 100. Both tested midazolam preparations, 0.4 mg/mL in 5% dextrose and 5 mg/mL, retained more than 95% of their initial concentration at day 100 under the study conditions. Visual inspection was also recorded.
A concentration assay measures the drug remaining in the tested sample. It does not establish microbial sterility or the condition of a different syringe stored or prepared another way. The authors explicitly limited their result to stability. A review of an actual syringe should keep chemical potency, preparation history and sterility evidence separate.