Extraction and Determination of Three Steroid Molecules in Milk Using Functionalized Magnetic Carbon Nanotube-Based Solid Phase Extraction Coupled with HPLC

A new magnetic carbon nanotube-based strontium-titanium (Fe/CNT-SrTiO3) adsorbent was synthesized to extract two steroid hormones (17-estradiol and progesterone) and a synthetic derivative of estradiol (ethinyl estradiol) from milk in an optimized MSPE-HPLC method. The proposed adsorbent was characterized using FT-IR, BET, FESEM, TEM, and XRD techniques. Under optimized extraction parameters (effects of strontium-titanium dosage, desorbing solvent, adsorbent amount, solvent and sample volumes, adsorption and desorption times, salt percentage, and pH value) and matrix-matched calibration, a decent linear dynamic range was obtained 1-1000ngmL(-1) for all three hormones with acceptable relative standard deviation percentages of 1.49-2.31. The limits of detection (S/N=3, n=3) and quantitation (S/N=10, n=3) for the analytes were respectively in the range of 0.033-0.34 and 0.11-1.14ngmL(-1). The proposed method provided acceptable precision based on intra-day (RSD range of 1.47-2.31%, n=3) and inter-day (RSD range of 1.75-4.54%, n=9) experiments. Real sample analysis was conducted using the same method to determine the concentration of hormones in three milk samples with related recovery percentages of 60.2-113.49. The results showed that the novel adsorbent could be used as an alternative material for hormone extraction in different biological fluids.