Determination of rivastigmine in serum using solid phase extraction and high perfomance liquid chromatography coupled to UV detection technique for routine medical analysis

Aim: A novel high performance liquid chromatography(hplc)assay for the purification of rivastigmine from serum, its detection and estimation has been developed and validated. Methods: A solid phase extraction using Oasis HLB-columns(Waters Ltd,Ger)was optimized to purify rivastigmine from serum followed by HPLC separation with UV detection. Chromatographic analyses were performed on a Dionex system with a Phenomenex Luna Phenyl-Hexyl analytical column. The mobile phase constituted of 0,02mol/l K2HPO4/acetonitrile(80/20)and the flow rate was kept at 0,4ml/min. The detection wavelength was kept at 210nm. Results: The retention time was 10,5min for rivastigmine. Our method recovered >92% of rivastigmine from the serum samples. The calibration curve was linear (r=0,9999, n=9) over rivastigmine concentrations ranging from 5 to 640ng/ml. No endogenous compounds were found to interfere with the analyte. The method had an accuracy of >90%. Intra- and interday precision were <5% and <3%, resp., at three different concentrations of 5, 80 and 640ng/ml. The limit of quantification(LOQ) was found to be 2,5ng/ml. The accuracy and precision at the LOQ level are in agreement with the guidelines of GTFCh(Society of Tox. and Forensic Chemistry) in consideration of ISO 5725(International Organization for Standardization). The method reported here is simple, reliable, precise, and accurate and has the capacity to be used for detection of rivastigmine in serum samples in routine analysis.