Novel extraction method based on the dispersion of the extractionsolvent for extraction of letrozole from biological fluids

Abstract

The analysis of drugs in various biological fluids is an important criterion for the determination of the physiological performance of a drug. Dispersive liquid–liquid microextraction (DLLME) technique was successfully used as a simple, rapid and sensitive sample preparation method for the determination of letrozole in biological fluids and water samples. Chloroform at microlitre volume level and acetone were used as extraction and disperser solvents, respectively. The influence of several variables (e.g. type and volume of disperser and extraction solvents, ionic strength, etc.) on the performance of the sample preparation step was carefully evaluated. Under the optimum conditions, a preconcentration factor of 120 was obtained from only 10.0 mL of a water sample. The calibration graph was linear in the range of 1–500 μg L⁻¹ with a detection limit of 0.3 μg L⁻¹. The relative standard deviation (RSD) for five replicate measurements of letrozole was 3.2%. The calibration graphs were linear in the range of 2.5–500 μg L⁻¹ and 5.0–500 μg L⁻¹ with detection limits of 0.7 μg L⁻¹ and 1.5 μg L⁻¹ in urine and plasma samples, respectively. The relative recoveries of letrozole in plasma, urine and tap water samples at spiking levels of 50 μg L⁻¹, 30 μg L⁻¹ and 5 μg L⁻¹ were 87.4%, 92.0% and 96.0%, respectively. DLLME combined with HPLC-UV is a fast, simple and efficient method for the determination of letrozole in biological fluids and water samples.