Fluoxetine is a clinically used antidepressant, due to its slimming effect, unscrupulous elements will add it to slimming products. The aim of this study was to establish an optimized derivatization method for fluoxetine and norfluoxetine to be analized by a gas chromatography-tandem mass spectrometry (GC-MS/MS) and apply it to real case.

Hair samples were washed and cut into approximately 2mm, and 50mg was added to the internal standard and hydrolyzed with 1% sodium hydroxide solution. Add 3mL ethyl acetate, vortex and centrifuge; urine samples were taken as 1mL and then added to the internal standard and 3mL ethyl acetate, then submitted to vortex and centrifugation. The supernatant was evaporated to dryness under a nitrogen gas stream and then derivatized by adding 25μL ethyl acetate and 25μL HFBA at 70°C for 45minutes and later analyzed by GC-MS/MS. The derivatisation procedure for the remaining derivatisation reagents TFAA, FPPA, MSTFA and 99% BSTFA+1% TMCS was the same as above.

Fluoxetine and norfluoxetine were analyzed by GC-MS/MS and the validation data were satisfactory. The derivatization reagent HFBA was the most effective for the modification of fluoxetine and norfluoxetine. The concentrations of fluoxetine in hair and urine extracts were 40.9ng/mg and 10.8ng/mL, respectively; the concentrations of norfluoxetine were 4.94ng/mg and 7.57ng/mL, respectively.

A method for the determination of fluoxetine and norfluoxetine in human hair and urine by GC-MS/MS was developed and applied to real cases. Furthermore, the chemical modification effects of five derivatization reagents on fluoxetine and norfluoxetine were compared, and the best effect was obtained by HFBA at 70°C for 45min.