Magnetic separation as a new method for the extraction of small molecules from biological fluids of humans

A new version of extraction is proposed for the extraction of doping substances from urine. It is based on magnetic separation using ferromagnetic microparticles with the surface modified with C₁₈ groups. A procedure is developed on its basis for the quantification of selective modulators of androgen receptors and peroxisome proliferator-activated delta-receptor agonists using high-performance liquid chromatography coupled with tandem mass spectrometry. Using the proposed approach, the recovery of doping substances from human biological fluids approximates 100%, while the negative effect of the matrix components on the ionization of target compounds is reduced to a minimum. In contrast to solid phase extraction and liquid-liquid extraction, the method of magnetic separation appears to be more rapid and simple. The time of pretreatment for a sample intended for HPLC coupled to tandem mass spectrometry makes 5 min; the detection limit makes 0.25–5 ng/mL.