A new and efficient design of dual solvent-stir bar microextraction for the simultaneous determination of two drugs with various acceptor phases from human plasma by high-performance liquid chromatography

A new dual solvent stir bar microextraction (DSSBME) was developed for simultaneous extraction of clozapine and lorazepam in human plasma with different acceptor phases and analyzed by HPLC – UV. The solvent bars fixed to staple pin which was applied as the magnetic stirrer and also rotates separately them in the sample solution without any encounter with each other. In this process, the target analytes were extracted simultaneously from a sample solution into their respective solvent bar selectively. The extraction parameters such as type of organic phase, pH of the sample solution, the concentration of acceptor phases, ionic strength, stirring rate, extraction time, and temperature were optimized to achieve the highest extraction efficiency. Under the optimum conditions, extraction recovery and enrichment factor for clozapine were 95.4% and 343 and for lorazepam 74.3% and 263, respectively. Finally, the introduced method was successfully applied for the simultaneous determination and quantification of clozapine and lorazepam in human plasma sample.

Keywords:

clozapine , lorazepam , human plasma , dual solvent-stir bar microextraction , high-performance liquid chromatography