Preparation of a novel sorptive stir bar based on vinylpyrrolidone‐ethylene glycol dimethacrylate monolithic polymer for the simultaneous extraction of diazepam and nordazepam from human plasma

Abstract

A new monolithic coating based on vinylpyrrolidone-ethylene glycol dimethacrylate polymer was introduced for stir bar sorptive extraction. The polymerization step was performed using different contents of monomer, cross-linker and porogenic solvent, and the best formulation was selected. The quality of the prepared vinylpyrrolidone-ethylene glycol dimethacrylate stir bars was satisfactory, demonstrating good repeatability within batch (relative standard deviation < 3.5%) and acceptable reproducibility between batches (relative standard deviation < 6.0%). The prepared stir bar was utilized in combination with ultrasound-assisted liquid desorption, followed by high-performance liquid chromatography with ultraviolet detection for the simultaneous determination of diazepam and nordazepam in human plasma samples. To optimize the extraction step, a three-level, four-factor, three-block Box-Behnken design was applied. Under the optimum conditions, the analytical performance of the proposed method displayed excellent linear dynamic ranges for diazepam (36-1200 ng/mL) and nordazepam (25-1200 ng/mL), with correlation coefficients of 0.9986 and 0.9968 and detection limits of 12 and 10 ng/mL, respectively. The intra- and interday recovery ranged from 93 to 106%, and the relative standard deviations were less than 6%. Finally, the proposed method was successfully applied to the analysis of diazepam and nordazepam at their therapeutic levels in human plasma. The novelty of this study is the improved polarity of the stir bar coating and its application for the simultaneous extraction of diazepam and its active metabolite, nordazepam in human plasma sample. The method was more rapid than previously reported stir bar sorptive extraction techniques based on monolithic coatings, and exhibited lower detection limits in comparison with similar methods for the determination of diazepam and nordazepam in biological fluids.

3‐(2‐Bromoacetamido)‐N‐(9‐ethyl‐9H)‐carbazol fluorescent probe and its application for the determination of thiophenols in rubber products by HPLC with fluorescence detection and atmospheric chemical ionization mass spectrometry identification

“…Rubber products including dactylotheca, nipple, rubber mat, rubber strap, and different colors of rubber gloves were collected in our laboratory or purchased from a local supermarket. To obtain the best extraction efficiency for thiophenol compounds, the ultrasound‐assisted extraction technique was used . The sample (0.5 g) was powdered to approximate powder size and soaked in an appropriate volume of ethanol in a 10 mL centrifuge tube.…”

Covalent organic framework/layered double hydroxide composite–coated poly(ether ether ketone) jacket for stir bar sorptive extraction of Sudan dyes

“…Stir bar sorptive extraction (SBSE) has emerged as an environmentally friendly, miniaturized sample pretreatment technique, initially introduced by Baltussen et al [10]. Offering advantages such as low usage amount of organic solvents, easy-to-operate, high extraction efficacy, and good reproducibility, SBSE has gained widespread acceptance for analyzing trace analytes in complex samples [11][12][13]. Extraction material coated on the stir bar plays a pivotal role in determining its extraction performance for target analytes.…”

Hollow fiber stir bar sorptive extraction for determination of phthalic acid esters in environmental and biological matrices

“…Abbreviations: PAE, phthalic acid ester; DEHP, di-2-ethylhexyl phthalate; SBSE, stir bar sorptive extraction; HF-SBSE, hollow fiber stir bar sorptive extraction; PVDF, polyvinylidene fluoride; PP, polypropylene Stir bar sorptive extraction (SBSE) has attracted growing interest due to its high effectiveness for the extraction of nonpolar and weakly polar compounds from liquid samples or liquid extracts [13]. SBSE has found a wide range of applications in food [14][15][16], environmental [17][18][19], biological [20] analysis, and so on. However, to the best of our knowledge, the common SBSE coatings were mostly organic polymers and modified polymers [21][22][23][24].…”