Gel electro-membrane extraction of propranolol and atenolol from blood serum samples: Effect of graphene-based nanomaterials on extraction efficiency of gel membrane

SPE of gallic acid and ascorbic acid in fruits using polymerized deep eutectic solvent-modified substrate

Aim: Novel substrates were synthesized by porous and nonporous polymerization of deep eutectic solvents on magnetic silica nanoparticles and introduced for dispersive solid-phase extraction of two analytes. Materials & methods: The prepared substrates were characterized, and an extraction procedure was implemented to select the best substrates and eluent. The central composite design acted to optimize the effects of parameters that influenced the extraction efficiencies. Results: For gallic and ascorbic acids, the limits of detection were obtained at 0.136 and 0.165 μM, respectively, with linear ranges of 0.6-125.2 and 0.5-106.8 μM, respectively. Conclusion: The substrate produced good extractions even after being used three-times and was successfully applied for the analysis of real samples.

In-tube gel electromembrane extraction: A green strategy for the extraction of narcotic drugs from biological samples

The development of green and miniature extraction methods is always a major and controversial challenge in the field of sample preparation. In this work, in-tube gel electromembrane extraction (IT-G-EME) was developed as a miniaturized extraction device for the extraction of six narcotic drugs (codeine, oxycodone, hydrocodone, tramadol, thebaine, and noscapine) from biological samples. A transparent capillary tube (∼6 cm) was used as a microextraction unit. The middle part of the tube was filled with a narrow plug (∼3 mm) of the agarose gel (3.0% w/v) as a membrane and the other sides were filled with aqueous extractant solution (pH 2.0, 20 µL) and sample solution (pH 5.0, 200 µL). By applying electrical potential (400 V), the target drugs with positive charge were migrated from sample solution toward the extractant solution through gel membrane during short extraction time (5 min). Then, the enriched analytes in extractant solution was analyzed by HPLC-UV. Under the optimized conditions, the calibration curves were linear within the permissible range of 10.0-1500 ng/mL (r² ≥ 0.991). Limits of detection and extraction recoveries were in the range of 3.0-4.5 ng/mL and 61.9-86.9%, respectively. On the basis of four replications, the repeatability of the method was also evaluated in terms of intra- and inter-day RSDs (%), which did not exceed from 6.6 and 7.9%, respectively in aqueous media. The figures of merit were also assessed in biological samples. Eventually, the developed method was profitably used for simultaneous determination of narcotic drugs in the real urine and plasma samples.

Green bioanalysis: an innovative and eco-friendly approach for analyzing drugs in biological matrices

Green bioanalytical techniques aim to reduce or eliminate the hazardous waste produced by bioanalytical technologies. A well-organized and practical approach towards bioanalytical method development has an enormous contribution to the green analysis. The selection of the appropriate sample extraction process, organic mobile phase components and separation technique makes the bioanalytical method green. UHPLC-MS is the best option, whereas supercritical fluid chromatography is one of the most effective green bioanalytical procedures. Nevertheless, there remains excellent scope for further research on green bioanalytical methods. This review details the various sample preparation techniques that follow green analytical chemistry principles. Furthermore, it presents green solvents as a replacement for conventional organic solvents and highlights the strategies to convert modern analytical techniques to green methods.

Electromembrane extraction of polar substances - Status and perspectives

In this article, the scientific literature on electromembrane extraction (EME) of polar substances (log P < 2) is reviewed. EME is an extraction technique based on electrokinetic migration of analyte ions from an aqueous sample, across an organic supported liquid membrane (SLM), and into an aqueous acceptor solution. Because extraction is based on voltage-assisted partitioning, EME is fundamentally suitable for extraction of polar and ionizable substances that are challenging in many other extraction techniques. The article provides an exhaustive overview of papers on EME of polar substances. From this, different strategies to improve the mass transfer of polar substances are reviewed and critically discussed. These strategies include different SLM chemistries, modification of supporting membranes, sorbent additives, aqueous solution chemistry, and voltage/current related strategies. Finally, the future applicability of EME for polar substances is discussed. We expect EME in the coming years to be developed towards both very selective targeted analysis, as well as untargeted analysis of polar substances in biomedical applications such as metabolomics and peptidomics.

Self-supported 3D reduced graphene oxide for solid-phase extraction: An efficient and low-cost sorbent for environmental contaminants in aqueous solution

A 3D reduced graphene oxide (3D-rGO), a self-supported, efficient, and low-cost sorbent, was synthesised and employed in a solid-phase extraction (SPE) cartridge. As a proof of concept, it was applied to remove diclofenac from aqueous solution. After applying statistical methods to systematically investigate key parameters for optimizing the 3D-rGO cartridge performance, it reached removal and elution efficiencies of 100 % and 90 %, respectively. This SPE cartridge presented advantages compared to traditional ones as the smaller amount of material into the cartridge (mass twenty times smaller), in addition to the ability of eliminating sorbent preconditioning, reducing the use of solvents, and making the process environmentally friendly with a faster operation. Also, it presented improved reproducibility after several cycles of reuse, and finally a lower cost of production unveiled by a cost-benefit analysis. Analysis with scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, Raman, and Fourier transform infrared spectroscopy in attenuated total reflectance mode suggested that the 3D framework morphology with a high content of carbon at the surface and some residual oxygen-containing groups are the protagonists in this performance. Therefore, 3D-rGO has the potential to be a highly efficient sorbent in analytical procedures using SPE for environmental contaminants in water and effluent samples.

The Effect of Flow-Induced Vibration on Heat and Mass Transfer Performance of Hollow Fiber Membranes in the Humidification/Dehumidification Process

Cross-flow hollow fiber membranes are commonly applied in humidification/dehumidification. Hollow fiber membranes vibrate and deform under the impinging force of incoming air and the gravity of liquid in the inner tube. In this study, fiber deformation was caused by the pulsating flow of air. With varied pulsating amplitudes and frequencies, single-fiber deformation was investigated numerically using the fluid–structure interaction technique and verified with experimental data testing with a laser vibrometer. Then, the effect of pulsating amplitude and frequency on heat and mass transfer performance of the hollow fiber membrane was analyzed. The maximum fiber deformation along the airflow direction was far larger than that perpendicular to the flow direction. Compared with the case where the fiber did not vibrate, increasing the pulsation amplitude could strengthen Nu by 14–87%. Flow-induced fiber vibration could raise the heat transfer enhancement index from 13.8% to 80%. The pulsating frequency could also enhance the heat transfer of hollow fiber membranes due to the continuously weakened thermal boundary layer. With the increase in pulsating amplitude or frequency, the Sh number or E_m under vibrating conditions can reach about twice its value under non-vibrating conditions.

A low-voltage electro-membrane extraction for quantification of imatinib and sunitinib in biological fluids

Aim: Hollow-fiber-based supported liquid membrane was modified utilizing nanostructures such as graphite, graphene oxide or nitrogen-doped graphene oxide, for electro-membrane extraction (EME) of imatinib and sunitinib from biological fluids. By applying these conductive nanostructures, a low-voltage EME device (6.0 V) was fabricated. Materials & methods: A response surface methodology through central composite design was used to evaluate and optimize effects of various essential factors that influence on normalized recovery. Results: Optimal extraction conditions were set as, 1-octanol with 0.01 % (w/v) graphene oxide functioning as the supported liquid membrane, an extraction time of 17.0 min, pH of the acceptor and the donor phase of 2.8 and 7.9, respectively. Conclusion: The method was successfully applied to quantify imatinib and sunitinib in biological fluids.