Drug screening in human plasma by cloud-point extraction and HPLC

Abstract

Cloud-point extraction (CPE) with RP-HPLC/DAD detection was used to develop a screen for six model basic drugs (paracetamol, promazine, amitriptyline, nortriptyline, clomipramine and chlorpromazine) in human plasma. These drugs’ varied hydrophobicities entail different affinities for the micelle-rich phase and CPE extraction efficiencies. Extraction recovery (except paracetamol) was above 80% and reproducibility (RSD%) ranged from 2.88 to 10.26 intraday and from 3.12 to 12.33 interday. The limits of detection were: 0.125 µg mL−1 (promazine and chlorpromazine), 0.25 µg mL−1 (amitriptyline and nortriptyline) and 0.5 µg mL−1 (paracetamol and clomipramine). The method was linear over the ranges: 0.125–1.0 µg mL−1 (promazine and chlorpromazine), 0.25–1.0 µg mL−1 (amitriptyline and nortriptyline), 0.5–1.0 µg mL−1 (clomipramine) and 0.5–10 µg mL−1 (paracetamol). The procedure is a good alternative to the SPE or LLE sample preparation usually used.