Instability of 7-aminoclonazepam in frozen storage conditions.

Drug monitoring of benzodiazepines is often performed in toxicology and pain management settings. During the validation of a laboratory-developed multiplex UPLC-MS/MS assay for quantifying benzodiazepines in human urine, we observed notable instability (greater than 20% nominal) in 7-aminoclonazepam (7AC) during prolonged freezing conditions by performing method comparisons and a conventional analyte stability study. These findings highlight the importance of proper calibrator storage and also the essential need to perform method comparison and analyte stability studies. It is recommended that clinical laboratories testing for urine 7AC carefully validate its stability if subjected to freezing conditions.