Solid phase extraction of antidepressant drugs amitriptyline and nortriptyline from plasma samples using core-shell nanoparticles of the type Fe3O4@ZrO2@N- cetylpyridinium, and their subsequent determination by HPLC with UV detection

The solid phase extraction (SPE) is described for preconcentration of the antidepressant drugs amitriptyline and nortriptyline prior to their determination by HPLC with UV detection. It is based on the use of water-dispersible core-shell nanoparticles (NPs) of the Fe3O4@ZrO2@N-cetylpyridinium type. The positively charged surfactant N-cetylpyridinium forms mixed aggregates with the drugs on the surface of the core-shell and thereby improves the adsorption of amitriptyline and nortriptyline through hydrophobic and/or ionic interactions. Their extraction depends on the type and amount of surfactant, sample pH, extraction time, desorption conditions, sample volume and amount of NPs that were optimized by application of experimental design. The enrichment factors are 220 and 250, respectively, for amitriptyline and nortriptyline, and the detection limits are 0.04 and 0.08 ng center dot mLaEuro3/4(1). This protocol enables accurate and precise quantification of the two drugs in complex and low content samples. It was applied to the determination of the two drugs in plasma samples with relative recoveries in the range from 89 to 105 % and RSDs less than 4 %.