Automated solid-phase extraction method for the determination of piperaquine in capillary blood applied onto sampling paper by liquid chromatography

A bioanalytical method for the determination of piperaquine in 100 μL blood applied onto sampling paper, by solid-phase extraction and liquid chromatography, has been developed and validated. Blood spots were cut into small pieces prior to addition of 0.3 M perchloric acid, acetonitrile and phosphate buffer containing an internal standard. The liquid phase was loaded onto a mixed phase cation-exchange (MPC) solid-phase extraction column. Piperaquine and the internal standard were analysed by liquid chromatography and separated on a Chromolith Performance (100 mm × 4.6 mm) column with acetonitrile:phosphate buffer pH 2.5, I = 0.1 (8:92, v/v) at the flow of 3.5 mL/min. The UV detection was performed at 345 nm. The intra-assay precision was 12.0% at 0.150 μM, 7.3% at 1.25 μM and 7.3% at 2.25 μM. The inter-assay precision was 1.8% at 0.150 μM, 5.2% at 1.25 μM and 2.8% at 2.25 μM. The lower limit of quantification (LLOQ) was determined to 0.050 μM where the precision was 14.7%.