Solid-Phase Extraction of Perphenazine from Blood Serum for High Performance Liquid Chromatographic Analysis

A solid-phase extraction (SPE) process has been developed with the aim of replacing multistage liquid-liquid extraction that is currently used for sample clean-up before the chromatographic determination of perphenazine (PPZ) in serum. The method comprises the trapping of PPZ from 2 mL of serum by 100 mg of silica gel with polymeric C18 phase, followed by rinsing of the endogenous compounds with water and acetonitrile. The drug is eluted with 0.7 mL of methanol and the eluate is evaporated to dryness under stream of air. The residue is dissolved in 100 μL of methanol and 20–μ aliquot is injected onto an HPLC column packed with silica gel modified with cyanopropyl groups. To control the retention and separation of PPZ from the other compounds, ammonium acetate concentration in the mobile phase consisting of 90% v/v methanol has been varied from 10 to 40 mmol/L. The SPE method enabled 86.2+5.0% of PPZ to be recovered which is 12% to 22% more than by liquid-liquid extraction procedure. The repeatability of 5.7% (rel.) and the limit of detection (S/N=3) of 1.3 ng/mL have been attained. The method has been verified on serum samples from patients medicated with PPZ.