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 us ed for sample clean-up before the chromatographic determination of per phenazine (PPZ) in serum. The method comprises the trapping of PPZ fro m 2 mt of serum by 100 mg of silica gel with polymeric C-18 phase, fol lowed by rinsing of the endogenous compounds with water and acetonitri le. The drug is eluted with 0.7 mt of methanol and the eluate is evapo rated to dryness under stream of air. The residue is dissolved in 100 mu L of methanol and 20-mu L aliquot is injected onto an HPLC column p acked with silica gel modified with cyanopropyl groups. To control the retention and separation of PPZ from the other compounds, ammonium ac etate 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-liqui d 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.