Magnetic solid-phase extraction of high molecular weight peptides using stearic acid-functionalized magnetic hydroxyapatite nanocomposite: Determination of some hypothalamic agents in biological samples

Peptide drugs have an essential effect on human health, so it is momentous to quantify and detect their low levels in biological samples for treatment and diagnostic purposes. In this work, an efficientmagnetic solid-phase extraction (MSPE) method was developed based on stearic acid-functionalizedmagnetic hydroxyapatite nanocomposite (MHAP/SA) as a novel and cost-effective sorbent forextraction of five peptide drugs (goserelin, octreotide, triptorelin, somatostatin, and cetrorelix) frombiological samples. To characterize the morphology and physicochemical properties of MHAP/SA,Fourier transform infrared spectroscopy (FT-IR), field emission scanning microscopy (FE-SEM),and vibrating sample magnetometry (VSM) were applied. Under optimum conditions, the proposedmethod (MSPE-HPLC-UV) represented favorable linearity with R۲ ≥ ۰.۹۹۸۷, suitable intra- andinter-day precisions (RSD ≤ ۶.۹%, and RSD ≤ ۸.۱%, respectively, n = ۳), and limits of detection andquantification in the range of ۰.۷۵-۱.۱۲ ng mL-۱ and ۲.۵-۳.۷۵ ng mL-۱, respectively. Eventually, theproposed method was used for the extraction and quantification of target therapeutic peptides inplasma and urine samples, and satisfactory relative recoveries were achieved in the range of ۹۰.۶-۱۱۰.۳%.

Keywords:

Magnetic solid-phase extraction , Hydroxyapatite , Stearic acid , Peptide drugs , Biological samples