Application of ionic liquid-based ultrasonic-assisted microextraction coupled with HPLC for determination of citalopram and nortriptyline in human plasma

In this paper, an effective and environmentally friendly method of ultrasound-assisted ionic liquid-based dispersive liquid–liquid microextraction (UA-IL-DLLME) combined with high-performance liquid chromatography (HPLC)–photodiode array detector was applied for extraction and determination of two antidepressant drugs citalopram hydrobromide and nortriptyline hydrochloride from human plasma samples. Several important parameters affect the steps and efficiency of extraction, some of which are sample solution’s pH, type and volume of ionic liquid, ultrasonic time, centrifuging time and rate, and the ionic strength of solution. Optimum conditions were obtained at pH?=?11, 1-octyl-3-methyl imidazolium hexafluorophosphate for ionic liquid, 55?µL for ionic liquid volume, 4?min for ultrasonic time, 5?min and 3,500?rpm for centrifuging time and rotation’s speed, due to ionic strength by the addition of NaCl 1%. Under optimized conditions, the linearity was obtained in the range of 0.02–2,000?µg/L, with correlation coefficients higher than 0.995. The limits of detection were 10?µg/L for citalopram and 6?µg/L for nortriptyline. Preconcentration factors were 920 for citalopram and 800 for nortriptyline. The present method of UA-IL-DLLME combined with HPLC was successfully used for the determination of citalopram and nortriptyline drugs in real samples of human plasma.