Extraction of ultratrace amounts of nelfinavir from biological samples and pharmaceutical formulations using surfactant-modified magnetite nanoparticles followed by spectrophotometric determination

• A micellar magnetic solid phase extraction method was developed for nelfinavir.
• The spectrophotometry method was used for determination of nelfinavir.
• Nelfinavir was determined in pharmaceutical formulations and biological samples.
• The proposed method is so fast, economic, precise, and sensitive.

A new sensitive, selective, rapid, and simple magnetic solid phase extraction (MSPE)/spectrophotometry method was proposed for extraction and determination of nelfinavir in biological samples and pharmaceutical formulations using tetradecyltrimethylammonium bromide (TTAB)-coated Fe3O4 nanoparticles (Fe3O4 NPs) as an efficient adsorbent. The synthesized Fe3O4 NPs were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Fourier transform infrared (FT-IR) spectrometry was used for confirmation of TTAB-coated Fe3O4 NPs. The influence of various parameters affecting the extraction of nelfinavir has been investigated. The maximum extraction efficiency for extraction of 100.0 μg nelfinavir from aqueous solution was obtained with 18.6 mg Fe3O4 NPs and 9 mg TTAB at pH = 9. The analyte was desorbed by 2.5 mL acetonitrile (AN) prior to the absorbance measurement. Under optimized conditions, quantitative extraction recoveries of nelfinavir were observed with the sample volumes up to 600 mL and hence an enrichment factor of 240 was obtained. This method was so rapid and complete recovery was obtained in 5 s. By applying this method for determination of nelfinavir in sample volume of 600 mL, the calibration curve was linear in the range of 15.4–500 μg L− 1 (r2 = 0.994) and the detection limit was obtained 0.83 μg L− 1. Also, the relative standard deviations (RSD) for determination of 100.0 and 300.0 μg L− 1 of nelfinavir were 1.20% and 2.4% (n = 7), respectively. This method was successfully applied for determination of nelfinavir in serum samples, urine samples, and pharmaceutical formulations. The recoveries of spiked serum and urine samples were between 98.7% and 102.4%. All the obtained results are indicative of a convenient, fast, and economic method for extraction and determination of nelfinavir from biological samples and pharmaceutical formulations.