Determination of Lorazepam and Diazepam Using Modified Nanocrystalline Cellulose for Ultrasonic-Assisted Dispersive Solid Phase Microextraction (UA-DSPME) and Gas Chromatography-Mass Spectrometry (GC-MS).

A rapid and effective method utilizing ultrasonic assisted-dispersive solid-phase microextraction coupled with gas chromatography/mass spectrometry (GC/MS) was developed for the determination of lorazepam and diazepam in biological and aqueous samples. A modified nanocrystalline cellulose-based sorbent was prepared and applied for the microextraction of the analytes. The extraction efficiency of the sorbents prepared using self-assembled N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, including cellulose nanostructure and modified nanocrystalline cellulose, was compared. The modified cellulose nanostructure was characterized using thermogravimetric analysis (TGA), energy dispersive X-ray (EDX), and Fourier transform infrared spectroscopy (FTIR). Additionally, the study investigated the effects of relevant factors on the extraction/desorption performance, including extraction time, ionic strength, and the type and volume of the desorption solvent. The method achieved limits of detection of 1 ng mL−1 and 3 ng mL−1 and quantification limits of 4 ng mL−1 and 10 ng mL−1 for lorazepam and diazepam, respectively. Furthermore, the developed method demonstrated good repeatability with relative standard deviations of 4% and 6% (n = 5) for the spiked analyte aqueous solutions at 50 ng mL−1. The method also exhibited high linearity (R > 0.9996) in the range from 10 to 1000 ng mL−1. [ABSTRACT FROM AUTHOR]