Abstract
A novel diatomite-supported zeolitic imidazolate framework-8 sorbent (ZIF-8@Dt-COOH) was in situ fabricated and developed for solid-phase extraction of three benzodiazepines (triazolam, midazolam and diazepam) in urine followed by high-performance liquid chromatography. ZIF-8@Dt-COOH was easily prepared by coating ZIF-8 on the surface of Dt-COOH and characterized by Fourier transform infrared spectra, X-ray powder diffractometry and scanning electron microscopy. Compared with bare Dt-COOH, the extraction efficiency of ZIF-8@Dt-COOH for the target was significantly increased from 20.1–39.0% to 100%. Main extraction parameters, including ionic strength and pH of solution, loading volume, washing solution, elution solvent and elution volume, were optimized in detail. Under optimum conditions, the developed method gave linearity of three BZDs in 2–500 ng/mL (r ≥ 0.9995). Limits of detection (S/N = 3), and limits of quantification (S/N = 10) were 0.3–0.4 ng/mL and 1.0–1.3 ng/mL, respectively. In addition, the average recoveries at three spiked levels (5, 10 and 20 ng/mL) varied from 80.0% to 98.7%, with the intra-day and inter-day precisions of 1.4–5.2% and 1.5–8.2%, respectively. The proposed method provided an effective purification performance and gave the enrichment factors of 24.0–29.6. The proposed method was successfully employed for the accurate and sensitive determination of benzodiazepines in urine.
Highlights
Benzodiazepines (BZDs, Figure 1), as a class of psychoactive drugs, are extensively prescribed in the therapy of insomnia, anxiety and convulsive attacks due to their hypnotic, anxiolytic, anticonvulsant and muscle-relaxant properties [1]
The ZIF-8 nanocrystals grown on Dt-COOH surface provide the interaction sites, and their density dominates the adsorption efficiency for the target compounds
Zn2+ is fixed at 0.04 mmol/mL, almost no growth of ZIF-8 crystals is found on the surface of both Dt-COOH(1×) and Dt-COOH(2×)
Summary
Benzodiazepines (BZDs, Figure 1), as a class of psychoactive drugs, are extensively prescribed in the therapy of insomnia, anxiety and convulsive attacks due to their hypnotic, anxiolytic, anticonvulsant and muscle-relaxant properties [1]. Long-term use of BZDs leads to the risk of dependence, memory loss, fainting and cognitive disturbance [2,3]. BZDs with alcohol and other drugs (sedatives, antidepressants and neuroleptics) may result in illicit drug abuse and even drug-facilitated assault cases and robbery [4,5]. The accurate and sensitive monitoring of BZDs in pharmaceutical preparations, clinical or criminal examinations is of particular importance. Sample pretreatment is an important process to isolate desired components and remove matrix interferences from complex matrices [6]. Numerous sample pretreatment techniques have been developed for the determination of BZDs in biofluids, such as liquid–liquid extraction [7], solid-phase microextraction (SPME) [8], magnetic solid-phase extraction (MSPE) [9] and solid-phase extraction (SPE) [10,11]
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