Silica supported metal organic framework 808 composites as adsorbent for solid-phase extraction of benzodiazepines in urine sample

A novel silica supported metal organic framework 808 core-shell adsorbent (MOF-808@SiO2 ) was fabricated via the controllable in-situ growth for the solid-phase extraction of benzodiazepines (bromazepam, triazolam and diazepam) in urine samples. The prepared sorbent was characterized by scanning electron microscopy, X-ray powder diffractometry and nitrogen adsorption experiment. Compared with the bare silica particles, the MOF808@SiO2 sorbent gave enhanced surface area and improved extraction efficiency for benzodiazepines. It was developed as solid-phase extraction sorbent and combined with high-performance liquid chromatography for the determination of three benzodiazepines in urine samples. The parameters influencing the loading and eluting processes were investigated in detail. Under the optimized conditions, the proposed method provided the linear range of 2.0-200 ng/mL for bromazepam, 1.7-170 ng/mL for triazolam and 1.5-150 ng/mL for diazepam (r = 0.999). The method detection limits (S/N = 3) and the limits of quantification (S/N = 10) ranged from 0.4 to 0.6 ng/mL and 1.5 to 2.0 ng/mL, respectively. Besides, the enhancement factors of 16.2-19.2 were achieved and the recoveries for spiked urine samples with three levels were in the range of 81.2-95.9%. The developed method was successfully applied for the determination of benzodiazepines in urine samples.