Application of micelle-mediated extraction in preparation of body fluids for HPLC-DAD screening of acidic and neutral drugs

Experimental conditions of cloud-point extraction (CPE) for the selected five acidic and neutral medicaments (salicylic acid, opipramol, carbamazepine, lorazepam, and alprazolam) in human plasma were studied and optimized. Separation and detection of the tested drugs were performed by the high-performance liquid chromatography with diode array detection (HPLC-DAD) method in an appropriate gradient mode using a column Nucleosil C8. Under the optimized conditions, main validation parameters were determined for all the compounds. The extraction yields (%) ranged from 54.12 to 82.17 with intra- and interday repeatability (RSD, %) 5.70–9.92 and 5.79–10.19, respectively. The detection limit was 0.5 μg mL-1 for all the tested drugs with exception of salicylic acid (LOD = 2.5 μg mL-1). The linearity of the proposed method was examined for the four drugs: opipramol, carbamazepine, lorazepam, and alprazolam in the concentration range of 0.5–2.0 μg mL-1 (correlation coefficient r2 = 0.995–0.999) and for salicylic acid in the concentration range of 2.5–10.0 μg mL-1 (correlation coefficient r2 = 0.993). The analytical parameters for the medicaments tested in whole blood were unsatisfactory, especially in terms of extraction recovery and repeatability, and application of the developed procedure for this biological matrix requires further study.