Determination of diuretics in human urine using HPLC coupled with magnetic solid phase extraction based on a metal-organic framework.

: Magnetic solid-phase extraction (MSPE) employing a metal-organic framework (Fe3 O4 @UiO-66-OH) combined with high-performance liquid chromatography was developed for the determination of trace diuretics in urine. The structure and properties of Fe3 O4 @UiO-66-OH were investigated using X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and vibrating sample magnetometry. Magnetic solid-phase extraction conditions, such as adsorbent amount and solution pH were optimised using response surface methodology. Under the optimal conditions, the method resulted in excellent linearity with a high correlation coefficient (r> 0.99), satisfactory intraday repeatability (1.78%-2.99%), low limits of detection (0.08-0.23 ng mL-1 ), and good recoveries in urine samples (between 93.5% and 103%). Fe3 O4 @UiO-66-OH based on MSPE is a novel pretreatment technique for the detection of trace diuretics in urine.