Magnetic C18-modified mesoporous silica as an efficient adsorbent for dispersive solid phase microextraction of cardiac glycosides in human plasma

A magnetic mesoporous silica (SBA-15)-based dispersive solid phase microextraction was first proposed and introduced for simultaneous analysis of four cardiac glycosides (including deslanoside, lanatoside C, digoxin, and digitoxin) in human plasma coupled with HPLC-UV. In this study, magnetic C 18 -modified SBA-15 (SBA-15/C 18 /Fe 3 O 4 ) was used as the extractant, which was prepared and characterized using a suite of techniques including Fourier transform infrared spectroscopy, transmission electron microscopy, N 2 adsorption-desorption, vibrating sample magnetometer, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The influencing parameters of the extraction were investigated and optimized. The adsorption process of SBA-15/C 18 /Fe 3 O 4 followed the Langmuir isotherm and pseudo-second-order kinetic models. The adsorbent also exhibited excellent thermal and chemical stability, alongside good reusability. Under the optimum experimental conditions, the proposed method demonstrated satisfactory performance with good linearity (8-3200 ng/mL for deslanoside and 1.6-640 ng/mL for lanatoside C, digoxin and digitoxin with the correlation coefficients no less than 0.9987), high precision (0.8%