The use of hydrophilic lipophilic balanced (HLB) copolymer SPE cartridges for the extraction of diclofenac from small volume paediatric plasma samples

The extraction of diclofenac from spiked aqueous and plasma samples by liquid-liquid extraction (LLE) and solid phase extraction (SPE) methods is compared. The SPE methodology utilised a hydrophilic lipophilic balanced (HLB) copolymer as the extraction phase. Using a literature HPLC method, a calibration curve for diclofenac was constructed in the range 1.0-50.0 microg/ml. Diclofenac spiked samples (aqueous and plasma) were extracted by LLE and SPE methodologies. The SPE resulted in higher extraction efficiencies (mean 94.9%) than the LLE (mean 78.9%) with %R.S.D.s similar in both methods (3.2 vs. 2.1%, respectively). The SPE method was suitable for the extraction of diclofenac from small volume paediatric plasma samples.