Development and validation of an EI-GC/MS method for the determination of sertraline and its major metabolite desmethyl-sertraline in blood

A sensitive and specific GC/MS method for the determination of sertraline and its main metabolite desmethyl-sertraline in whole blood has been developed, optimized and validated. Sample preparation included solid-phase extraction of both analytes and their derivatization with heptafluorobutyric anhydride (HFBA). Protriptyline was used as internal standard for the determination of both analytes. Limits of detection and quantification for both sertraline and desmethyl-sertraline were 0.30 and 1.00 μg/L, respectively. The calibration curves were linear within the dynamic range of each analyte (1.00–500.0 μg/L) with a correlation coefficient (R2) exceeding 0.991. Extraction efficiency ranged from 90.1(±5.8)% to 95.4(±3.0)% for sertraline, and from 84.9(±8.2)% to 107.7(±4.4)% for desmethyl-sertraline. The precision for sertraline and desmethyl-sertraline was between 3.6–5.5% and 4.7–7.2%, respectively, while the accuracy was in the range of −6.67% to 2.20% and −6.33% to 2.88% for sertraline and desmethyl-sertraline, respectively. The method was applied to real blood samples obtained from patients that follow sertraline treatment and also in cases of forensic interest. The developed method can be used in routine every day analysis by clinical and forensic laboratories, for pharmacokinetic studies, for therapeutic sertraline monitoring or for the investigation of forensic cases where sertraline is involved.