Here we report a sensitive LC-MS/MS method capable of quantifying n-Butylphthalide (NBP) down to 0.5 ng/mL in rat and human hepatic microsome incubating solutions.The method was validated over linear range of 0.5-4 000 ng/mL using diazepam as the internal standard.Compound was simply prepared by protein precipitation method and analyzed on the LC-MS/MS,which was an API-4000 system equipped with ESI interface and a Symmetry C18 column.The between-day and within-day precision and accuracy of quality control samples were ≤9.3% RSD% and ≤3.3% RE%.Sample stability (Stock solution,freeze/thaw,bench-top,short-term and long-term stability) were also investigated.This method has been applied to drug-drug interaction study of NBP in rat and human hepatic microsome incubating solutions.
