Studies on Determination of the New Drug Venlafaxine in Human Plasma by HPLC with Fluorimetric Detection

Objective:A RP-HPLC method was developed for the determination of venlafaxine in human plasma.Method:Required components were extracted with 1% triethylamine-ether by solid phase extraction(SPE)technology.The plasma sample was analyzed on an ODS column and with a fluorimetric detector(λ Ex 276 nm,λ Em 598 nm).The mobile phase was a mixture of acetonitrile-phosphate buffer solution-triethylamine(30∶70∶1),pH was adjusted to 2 8 by phosphoric acid.The internal standard was maprotiline.Results:The linear range of venlafaxine was 10～800 ng·mL -1 .The lowest detectable limit was 3 ng and the lowest detectable plasma concentration was 6 ng·mL -1 ( S/N 3).The extraction recovery and method recovery of venlafaxine over plasma concentration 10,50,100,500 ng·mL -1 were 98 4%～102 0% and 98 2%～105 7% respectively.The RSD of within-day and between-day were less than 6% and 9% respectively( n=5 ).The extraction recovery of maprotiline was 81 7%.Conclusion:The method is sensitive,simple,accurate and reproducible.It can be applied to the pharmacokinetic study and therapeutic drug monitoring.