Background: Developing a simple analysis method for quantification of drug concentration
is one of the essential issues in pharmacokinetic and therapeutic drug monitoring studies.
Objective: A fast and reliable dispersive liquid-liquid microextraction procedure was employed for preconcentration
of verapamil in exhaled breath condensate (EBC) samples and this was followed by the
determination with high-performance liquid chromatography-ultraviolet detection.
Methods: A reverse-phase high-performance liquid chromatography (RP-HPLC) combined with a
dispersive liquid-liquid microextraction method (DLLME) was applied for quantification of verapamil
in the EBC samples. The developed method was validated according to FDA guidelines.
Results: Under the optimum conditions, the method provided a linear range between 0.07 and 0.8
µg.mL-1 with a coefficient of determination of 0.998. The intra- and inter-day relative standard deviation
and relative error values of the method were below 15%, which indicated good precision and accuracy.
The proposed method was successfully applied for the analysis of verapamil in two real samples
with concentrations of 0.07 and 0.09 µg.mL-1.
Conclusion: The established HPLC-UV-DLLME method could be applied for the analysis of verapamil
in human EBC samples.