Solid phase extraction with electrospun nanofibers for determination of retinol and α-tocopherol in plasma

A new kind of polystyrene/polyethyleneimine nanofibres coordinated with palladium for fast and efficient extraction of methotrexate and its polyglutamate metabolites in different matrices

Methotrexate (MTX) is a drug that has long been used in high doses as an anti-cancer drug and lately in low doses as a treatment for autoimmune diseases. It is necessary to be determined in various matrices because the drug has a narrow therapeutic range and a high persistence in the environment. Since MTX and its polyglutamate metabolites (MTXPGs) have strong polarity and the potential to be converted during sample processing, rapid and efficient extraction of these targets has provided technical challenges for development of analytical methods for them. A new Pd(ii)/polyethyleneimine (PEI)/polystyrene (PS) nanofibre was prepared and characterized by X-ray diffraction, FTIR spectroscopy, thermal analysis, scanning electron microscopy and transmission electron microscopy, etc. The nanofibre was applied as a sorbent to extract MTX and MTXPGs in whole blood and MTX in urine and water. The extracted analytes were then desorbed by a water solution containing 10% methanol and 20% ammonium hydroxide (v/v) and eventually quantified by high performance liquid chromatography. The peak area of the target substances in the extraction solution and its concentration were linear in the range of 20.0 (∼37.8 to 1000 ng/mL); intraday and interday RSD were 4.6-6.4% and 5.7-14.6%, respectively. The detection limit of this method was 6.0-11.3 ng/mL. The results showed that the method can be used for the determination of MTX and MTXPGs in human whole blood and MTX in urine/water samples.

Evaluating a novel method for vitamin A analysis in an observational study of the UAE's obese population

Vitamin A plays a critical role in various biological functions, including vision, cellular differentiation, and immune regulation. However, accurately assessing its status, particularly in obese individuals, presents challenges due to potential alterations in metabolism and distribution. This study utilized Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) methodology to precisely measure serum vitamin A concentrations in population of UAE. The methodology's reliability and precision, as demonstrated through validation procedures, underscore its potential utility in clinical settings. Employing the Multiple Reaction Monitoring mode of positive ion electrospray ionization, the LC-MS/MS system achieves a limit of detection (LOD) of 0.48 ng/mL in serum, while adhering to FDA-US regulations for accuracy and compliance. A key aspect of this study was the application of LC-MS/MS to assess vitamin A status in an obese population within UAE. By employing a diverse cohort of 452 Emirati participants, including 277 individuals from a randomized controlled trial who were assessed at baseline and at 6th month, and 175 healthy individuals aged 18-82 assessed at baseline, this study explores the relationship between obesity and vitamin A levels, shedding light on potential implications for health and well-being. It was an observational study based on a new vitamin A method and participants were asked to eat vitamin A rich foods. The robust performance of the LC-MS/MS methodology positions it as a valuable tool for clinical research. By accurately quantifying vitamin A levels in human serum, this methodology opens avenues for advancing our understanding of vitamin A physiology and its implications for health, particularly in obese populations. In summary, this LC-MS/MS methodology presents a potent tool for clinical studies, providing reliable, specific, and robust detection of vitamin A in human serum, thus, opening a new frontier for advancing our understanding of vitamin A related physiology and health in the obese population.

Determination of aflatoxin B1 by novel nanofiber-packed solid-phase extraction coupled with a high performance liquid chromatography-fluorescence detector

A novel analytical proposal based on nanofiber-packed solid-phase extraction coupled with high performance liquid chromatography-fluorescence detector (HPLC-FLD) has been successfully developed for determining aflatoxin B1 (AFB1) in foods. Four types of nanofibers, including polystyrene (PS) nanofibers, polypyrrole (PPY) nanofibers, polystyrene-acrylic resin (PS-AR) nanofibers, and polystyrene-polyvinyl pyrrolidone (PS-PVP) nanofibers, were fabricated by electrospinning and utilized to prepare a home-made extraction device. In this study, the factors of different fibers, namely, fiber dosage, pH of extraction solution, type of salt ion, concentration of salt ion, and volume of the eluent were optimized. Under optimized conditions, the method showed good linearity in the range of 0.1-40 ng mL^-1 with a correlation coefficient greater than 0.999 and good inter-day accuracy (90.8-112.7% recovery) and precision (1.8-3.6% intra-day RSDs, 2.6% inter-day RSD), and the limit of detection (LOD) was 0.05 ng mL^-1. Due to its cost-effective, time-saving, environmentally friendly, and simple performance, it has the potential to be utilized to determine aflatoxins in complicated matrices.

Polyaniline-polycaprolactone electrospun nanofibrous mat: new polymeric support with anion exchange characteristic for immobilizing liquid membrane in efficient on-chip electromembrane extraction of polar acidic drugs

The potential of application of an electrospun nanofiber sheet as new polymeric support for immobilizing the liquid membrane, instead of a common commercial polypropylene sheet, in on-chip electromembrane extraction (EME) of some acidic polar drugs followed by HPLC with ultraviolet detection is presented. The nanofiber sheet was prepared by electrospinning a mixture of polycaprolactone and polyaniline. The successful synthesis of the electrospun nanofiber sheet was confirmed by field emission-scanning electron microscopy, energy-dispersive X-ray spectroscopy, elemental mapping, and atomic force microscopy. Several parameters affecting the efficiency of the microextraction method, including pHs of the donor and acceptor phases, applied voltage, sample flow rate, phosphate content of the acceptor phase, and sample volume, were investigated and optimized. After optimization, the linearity range of 0.5-250.0 µg L^-1 and detection limits of 0.2-1.0 µg L^-1 were obtained for the analytes. The extraction recovery values and preconcentration factors were 10.7-55.3% and 16-83, respectively. The presence of polyaniline in the composition of the nanofibers significantly improved the extraction efficiency of the polar acidic drugs due to providing the possibility of various interactions with the target analytes such as hydrogen bonding, π-stacking, and anion exchange. The obtained results demonstrate the excellent efficiency of the synthesized electrospun nanofibrous mat as a novel support membrane for immobilizing 1-octanol and as an interactive substrate for electromembrane extraction of acidic polar drugs. Eventually, the proposed on-chip EME method exhibits acceptable precision (relative standard deviations less than 9.7% (n = 3)) and good accuracy (86-112%) for determining the target analytes in the plasma samples.

The electrospun polyacrylonitrile/covalent organic framework nanofibers for efficient enrichment of trace sulfonamides residues in food samples

In this work, the electrospun polyacrylonitrile/covalent organic frameworks Tp-BD nanofibers (PAN/Tp-BD) were synthesized and applied as an adsorbent for thin film microextraction (TFME) of seven sulfonamides in animal derived food samples. The morphology, structure, porosity, and stability of the prepared nanofibers were investigated. The PAN/Tp-BD nanofibers exhibited good chemical stability, high flexibility, porous fibrous structure, and excellent extraction efficiency. Based on the PAN/Tp-BD nanofibers as the adsorbent, a thin film microextraction-high performance liquid chromatography (TFME-HPLC) method for the determination of seven sulfonamides (SAs) in food samples was developed. Under the optimal conditions, the TFME-HPLC exhibited the low limit of detection (0.10-0.18 ng·mL^-1), the low limit of quantitation (0.33-0.60 ng·mL^-1), the wide linear range (0.5-50 ng·mL^-1) with correlation coefficients between 0.994 and 0.998, and good enrichment factors between 39.7 to 170.1 towards 20 ng/mL SAs solution. The relative standard deviation (RSD) was lower than 11% in the interday and intraday analysis. Furthermore, the applicability of PAN/Tp-BD nanofibers was demonstrated for measuring trace SAs residues in the spiked food samples with recoveries ranging from 85.3% to 115.2%. The results demonstrated that the PAN/Tp-BD nanofibers have great potential for the efficient extraction of sulfonamides from complex food samples.

Screening of extraction properties of nanofibers in a sequential injection analysis system using a 3D printed device

A novel application of the three-dimensional printing technology for the automation of solid phase extraction procedures in a low-pressure sequential injection analysis system is presented. A 3D printed device was used as a housing for nanofiber membranes in solid phase extraction. The applicability of the device is demonstrated with the extraction of substances of various physical-chemical properties. Pharmaceuticals including non-steroidal anti-inflammatory drugs, antihistaminics, and steroidal structures, as well as emerging pollutants such as bisphenols and pesticide metsulfuron methyl were used as model analytes to study the extraction performance of the nanofibers. Six different nanofiber types comprising polyamide, polyethylene, polyvinylidene fluoride, polycaprolactone combined with polyvinylidene fluoride, and polyacrylonitrile, produced by electrospinning were tested in solid phase extraction. The suitability of specific nanofibers for particular analytes is demonstrated.

A Review of the Extraction and Determination Methods of Thirteen Essential Vitamins to the Human Body: An Update from 2010

Vitamins are a class of essential nutrients in the body; thus, they play important roles in human health. The chemicals are involved in many physiological functions and both their lack and excess can put health at risk. Therefore, the establishment of methods for monitoring vitamin concentrations in different matrices is necessary. In this review, an updated overview of the main pretreatments and determination methods that have been used since 2010 is given. Ultrasonic assisted extraction, liquid–liquid extraction, solid phase extraction and dispersive liquid–liquid microextraction are the most common pretreatment methods, while the determination methods involve chromatography methods, electrophoretic methods, microbiological assays, immunoassays, biosensors and several other methods. Different pretreatments and determination methods are discussed.

Polycyclic Aromatic Hydrocarbons: Part II, Urine Markers

There has been increasing demand for simple, rapid, highly sensitive, inexpensive yet reliable method for detecting predisposition to cancer. Human biomonitoring of exposure to the largest class of chemical carcinogen, polycyclic aromatic hydrocarbons (PAHs) that are rapidly transformed into detectable metabolites (eg, 1-hydroxypyrene), can serve as strong pointers to early detection of predisposition to cancer. Given that any exposure to PAH is assumed to pose a certain risk of cancer, several biomarkers have been employed in biomonitoring these ninth most threatening ranked compounds. They include metabolites in urine, urinary thioethers, urinary mutagenicity, genetoxic end points in lymphocytes, hemoglobin adducts of benzo(a)pyrene, PAH-protein adducts, and PAH-DNA adducts among others. In this chapter, the main focus will be on the urine metabolites since urine samples are easily collected and there is a robust analytical instrument for the determination of their metabolites.

Electrospun nanofiber sorbents for the pre-concentration of urinary 1-hydroxypyrene

Background

Synthetic polymers have some qualities that make them good candidates for pre concentration of trace analytes biological fluids because of their great potentials to be functionalized and electrospun into nanofibres.

Methods

In this study, Electrospun nanofiber sorbents fabricated from 11 polymers {poly(styrene-co-methacrylic acid), poly(styrene-co-divinylbenzene) (SDVB), poly(styrene-co-acrylamide), poly(styrene-co-p-sodium styrene sulfonate), polystyrene, poly(vinyl benzyl chloride), cellulose acetate, polyethylene terephthalate (PET), polysulfone, nylon 6} were evaluated for the extraction and pre-concentration of 1-hydroxypyrene from a water sample.

Results

Scanning electron microscopy (SEM) studies revealed the formation of continuous fine bead-free and randomly arrayed fibers with their average diameters ranging from 110 to 650 nm. The percentage recoveries were highest for nylon 6 with 72%, SDVB with 70%, whereas PET achieved the lowest recovery at 34%. Under optimized conditions, the analyte followed a linear relationship for all sorbents in the concentration range of 1 to 1,000 μg/L. The coefficient of determination (r 2) was between 0.9990 to 0.9999, with precision (%relative standard deviation (RSD)) ≤ 9.51% (n = 6) for all the analysis. The %RSD for intra- and inter-day precision at three different concentrations, 10, 25, and 50 μg/L, was ≤7.88% for intraday and ≤8.04% inter-day (3 days), respectively, for all evaluated sorbents. The LOD and LOQ were found to be between 0.054 and 0.16 μg/L and 0.18 and 0.53 μg/L, respectively, using a fluorescent detector.

Conclusions

The study suggested that if packed into cartridges, nylon 6 and SDVB nanofiber sorbents could serve as alternatives to the conventional C-18 sorbents in the pre-concentration and clean-up of the tumorigenic biomarker, 1-hydroxypyrene in human urine. The fabrication of selective nanofibers could also extend and simplify sample preparation for organic and biological analytes.

Adsorption/desorption performance of volatile organic compounds on electrospun nanofibers

Electrospun nanofibers possess the advantages of the certain selectivity, favorable adsorption/desorption efficiency, short adsorption equilibration time and preferable regeneration and can be a potential adsorbent for VOCs.

A nanofiber functionalized with dithizone by co-electrospinning for lead (II) adsorption from aqueous media

An electrospun nanofiber was utilized as a sorbent in packed fiber solid phase extraction (PFSPE) for selective separation and preconcentration of lead (II). The nanofiber had a polystyrene (PS) backbone, which was functionalized with dithizone (DZ) by co-electrospinning of a PS solution containing DZ. The nanofiber exhibited its performance in a cartridge prepared by packing 5mg of nanofiber. The nanofiber was characterized by a scanning electron microscope and IR spectra. The diameter of the nanofiber was less than 400 nm. After being activated by 2.0 mol L(-1) NaOH aqueous solution, the nanofiber quantitatively sorbed lead (II) at pH 8.5, and the metal ion could be desorbed from it by three times of elution with a small volume of 0.1 mol L(-1) HNO(3) aqueous solution. The breakthrough capacity was 16 μg mg(-1). The nanofiber could be used for concentration of lead (II) from water and other aqueous media, such as plasma with stable recovery in a simple and convenient manner.