Miniaturized sample preparation techniques using MCM-41-based materials in the analysis of selected non-steroidal anti-inflammatory and anti-depressant drugs

New approaches in miniaturized sample preparation have been investigated involving the use of mesoporous silica materials as adsorbents. Mesoporous silica MCM-41 was successfully synthesized from rice husk ash as an active source of silica and a few mg of the material was enclosed within a cone-shaped membrane for solid phase membrane tip extraction (SPMTE). Four non-steroidal anti-inflammatory drugs (NSAIDs) namely ketoprofen, mefenamic acid, naproxen and diclofenac were selected as target analytes. Under the optimized conditions the proposed MCM-41- SPMTE method provides good limits of detection (LODs) for analytes in human urine samples in the range of 5.7 - 10.6 µg/L and relative analyte recoveries in the range of 81.4 - 108.1% that are comparable with those of conventional solid phase extraction (SPE) method. A simple microextraction technique utilizing a mixed matrix membrane (MMM) as the extraction medium has been successfully demonstrated. Thiol-functionalized MCM-41 adsorbent was immobilized in the cellulose triacetate polymer matrix through dispersion method to form a thiol-MCM- 41-MMM. Three NSAIDs namely diclofenac, mefenamic acid and ibuprofen were used as target analytes. The results showed good relative recoveries (85.9 - 106.7%) with relative standard deviation (RSDs) < 8% (n = 9), and low LODs (0.04 - 0.19 µg/L) for spiked river and tap water samples. The newly developed method is a simple, feasible, and cost effective and showed results that are comparable with conventional SPE. The use of MCM-41 magnetized with iron oxide particles (Fe3O4) in magnetic solid phase extraction (MSPE) method has been investigated. The developed Fe3O4-MCM-41-MSPE method was applied to the extraction of two antidepressant drugs (amitriptyline and chlorpromazine) in human urine and plasma samples prior to gas chromatography–mass spectrometry (GC–MS) analysis. Under the optimized conditions, the results provided good relative recoveries (86.1 - 115.4%), good reproducibility with relative standard deviation (RSDs) < 10% (n = 5) and low LODs for both spiked urine (0.015 - 0.017 µg/L) and plasma (0.020 - 0.028 µg/L) samples. This method proved to be rapid and efficient, for the multi-analysis of the drugs in biological samples. A novel procedure involving sonication-assisted emulsification microextraction (SAEM) followed by Fe3O4-MCM-41-MSPE prior to HPLC-UV has been developed for the analysis of anti-depressant drugs (amitriptyline, chlorpromazine and imipramine) from biological and water samples. In the SAEM procedure, 1-octanol and 3 min were selected as emulsification solvent and extraction time, respectively. Under the most favorable conditions, the method showed good limits of detection (as low as 0.04 µg/L) and reproducibility of extraction (RSDs < 10.6%, n = 3). The proposed methods provide alternative approaches in sample preparation through different microextraction methods to solve analytical problems that are not easily addressed by the individual procedure alone

Electrospun polyacrylonitrile/lignin/poly(Ethylene Glycol)-based porous activated carbon nanofiber for removal of Nickel(II) ion from aqueous solution

The issue of heavy metal contamination has caused a great deal of concern among water quality experts today, as it contributes to water pollution. Activated carbon nanofibers (ACNFs) showed a significant ability in removing heavy metals from the wastewater. In this study, polyacrylonitrile (PAN) was blended and electrospun with an abundant and inexpensive biopolymer, lignin and a water soluble polymer, poly(ethylene glycol) (PEG), by using an electrospinning technique to form nanofibers. The electrospun nanofibers were then investigated as a precursor for the production of porous ACNFs to study the removal of nickel(II) ions by adsorption technique. PEG was added to act as a porogen and to create the porous structure of carbon nanofibers (CNFs). CNFs were prepared by thermal treatment of the electrospun nanofibers and followed by activation of CNFs by thermal and acid treatment on CNFs. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) spectral analysis of the ACNFs showed a strong absorption peak of the C-O functional group, indicating the increase in the oxygenated compound. Field emission scanning electron microscopy (FESEM) images concluded that the ACNFs have more porous and compact fibers with a smaller fiber diameter of 263 ± 11 nm, while the CNFs are less compact and have slightly larger fiber diameter of 323 ± 6 nm. The adsorption study showed that the ACNFs possessed a much higher adsorption capacity of 18.09 mg/g compared with the CNFs, which the amount adsorbed was achieved only at 2.7 mg/g. The optimum adsorption conditions that gave the highest percentage of 60% for nickel(II) ions removal were 50 mg of adsorbent dosage, 100 ppm of nickel(II) solution, pH 3, and a contact time of 60 min. The study demonstrated that the fabrication of ACNFs from PAN/lignin/PEG electrospun nanofibers have potential as adsorbents for the removal of heavy metal contaminants

Electrochemical reduced graphene oxide-poly(eriochrome black T)/gold nanoparticles modified glassy carbon electrode for simultaneous determination of ascorbic acid, dopamine and uric acid

This work reports on the preparation of electrochemically reduced graphene oxide (ERGO)-poly(eriochrome black T) (pEBT) assembled gold nanoparticles for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in PBS pH 6.0. Characterisations of the composite were carried out by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. As a result of the synergistic effect, the modified glassy carbon electrode (GCE) possessed an efficient electrochemical catalytic activity with a high selectivity and sensitivity in oxidising AA-DA and DA-UA as compared to the bare GCE. The peak separations of AA and DA, DA and UA were 183 mV and 150 mV, respectively. The linear response ranges for AA, DA and UA were 10–900 μM, 0.5–20 μM and 2–70 μM with detection limits of 0.53 μM, 0.009 μM and 0.046 μM (S/N = 3), respectively. The sensitivity of ERGO-pEBT/AuNPs was measured as 0.003 µA/μM, 0.164 µA/μM and 0.034 µA/μM for AA, DA, and UA, respectively. The modified electrochemical sensor was used in the determination of AA, DA, and UA in vitamin C tablets and urine sample with good recovery

Magnetic micro-solid-phase extraction based on magnetite-MCM-41 with gas chromatography–mass spectrometry for the determination of antidepressant drugs in biological fluids

A new facile magnetic micro‐solid‐phase extraction coupled to gas chromatography and mass spectrometry detection was developed for the extraction and determination of selected antidepressant drugs in biological fluids using magnetite‐MCM‐41 as adsorbent. The synthesized sorbent was characterized by several spectroscopic techniques. The maximum extraction efficiency for extraction of 500 μg/L antidepressant drugs from aqueous solution was obtained with 15 mg of magnetite‐MCM‐41 at pH 12. The analyte was desorbed using 100 μL of acetonitrile prior to gas chromatography determination. This method was rapid in which the adsorption procedure was completed in 60 s. Under the optimized conditions using 15 mL of antidepressant drugs sample, the calibration curve showed good linearity in the range of 0.05–500 μg/L (r2 = 0.996–0.999). Good limits of detection (0.008–0.010 μg/L) were obtained for the analytes with good relative standard deviations of <8.0% (n = 5) for the determination of 0.1, 5.0, and 500.0 μg/L of antidepressant drugs. This method was successfully applied to the determination of amitriptyline and chlorpromazine in plasma and urine samples. The recoveries of spiked plasma and urine samples were in the range of 86.1–115.4%. Results indicate that magnetite micro‐solid‐phase extraction with gas chromatography and mass spectrometry is a convenient, fast, and economical method for the extraction and determination of amitriptyline and chlorpromazine in biological samples

Introduction to basic concepts of analytical chemistry

Analytical chemistry is an important area, particularly in the industrial sector, agriculture, health and the environment. This book is written with the aim to provide basic concepts in analytical chemistry which involves titration, gravimetry, solvent extraction, chromatography, electrochemical methods, thermal analysis and data analysis. The contents in this book are designed in a simple way with several examples that suitable for students, academicians and researchers

Voltammetric determination of hydroquinone, catechol, and resorcinol by using a glassy carbon electrode modified with electrochemically reduced graphene oxide-poly (Eriochrome Black T) and gold nanoparticles

A nanocomposite consisting of electrochemically reduced graphene oxide, poly(Eriochrome black T) and gold nanoparticles (ERGO-pEBT/AuNPs) was prepared for the simultaneous detection of resorcinol (RC), catechol (CC), and hydroquinone (HQ). The electrochemical oxidation of HQ, CC, and RC was analysed by using cyclic voltammetry and differential pulse voltammetry. Three well-separated potentials were found at 166, 277, and 660 mV (vs. Ag/AgCl) for HQ, CC, and RC, respectively The linear ranges were 0.52–31.4, 1.44–31.2, and 3.8–72.2 μM for HQ, CC, and RC, respectively. The limits of detections (LODs) for both individual and simultaneous detections are negligibly different are (15, 8, and 39 nM, respectively). Graphical abstractVoltammetric determination of hydroquinone, catechol, and resorcinol at ERGO-pEBT/AuNPs resulted in high peak currents and outstanding oxidation potential separation of the analytes

The synthesis and characterisation of porous thioamide-sulfonated-modified poly(acrylonitrile-co-divinylbenzene-80) as a potential sorbent to capture polar analytes

Pharmaceuticals contain biologically active components that can pollute water courses as a result of the excretions from individuals and/or uncontrolled release of residues from chemical plants, and they can pose a hazard to health. Pharmaceutical residues can persist at low concentrations in the environment, and thus may be potentially harmful to aquatic animals and to humans. Controlling and monitoring such residues are therefore a prime interest, for example, a solid-phase extraction uses solid sorbents to purify and preconcentrate the residues prior to their chemical analysis. In the present study, poly (acrylonitrile-co-divinylbenzene-80) sorbents are synthesised by varying the comonomer feed ratios under precipitation polymerisation conditions to deliver a family of porous polymer microspheres. Acrylonitrile confers polar characters onto the sorbents, and the acrylonitrile-derived nitrile groups can be chemically transformed via polymer-analogous reactions into thioamide and sulfonated residues which make the sorbents even more suitable for the capture of polar analytes, including selected pharmaceuticals. The utility of the porous thioamide-sulfonated containing sorbents is demonstrated via the dispersion-solid phase extraction of mefenamic acid from aqueous media; mefenamic acid is an anthranilic acid derivative which is a potent, non-steroidal anti-inflammatory drug which is found in environmental waters at low concentrations

Microextraction of Xenobiotics and Biomolecules from Different Matrices on Nano Structures

Sample preparation is the backbone of any analytical procedure; it involves extraction and pre-concentration of the desired analytes; often at trace levels. The present article describes the applications of nanomaterials (carbon based inorganic and polymeric materials) in miniaturized extraction such as solid phase micro-extraction, stir-bar sorptive extraction, liquid phase micro-extraction, and dispersive liquid phase micro-extraction in the analyses of aqueous samples. The nanoparticles used for micro-extractions are discussed on the basis of their chemical natures. The synthetic route and the preparation of nanomaterials are described along with the optimization strategies for micro-extraction. A comparison between the conventional materials and nanomaterials for micro-extraction is proposed. The key roles of the nanomaterials for the micro-extraction of different analytes such as drugs, pesticides, polycyclic aromatic hydrocarbons, proteins and peptides from aqueous samples are reported. The use of nanomaterials, combined with miniaturized micro-extraction techniques, proved to be highly promising for sample preparation of various matrices with analytes at trace levels

The synthesis and characterisation of porous and monodisperse, chemically modified hypercrosslinked poly(acrylonitrile)-based terpolymer as a sorbent for the adsorption of acidic pharmaceuticals

The synthesis and characterization of porous poly(acrylonitrile(AN)-co-divinylbenzene-80 (DVB-80)-co-vinylbenzylchloride (VBC)) polymers with high specific surface areas and weak anion-exchange character have been successfully researched. The hypercrosslinked (HXL) microspheres were chemically modified with 1,2-ethylenediamine (EDA) to enhance the adsorption selectivity of the HXL materials. The zeta potential of EDA-modified HXL poly(AN-co-DVB-80-co-VBC) revealed that the surface of the modified terpolymer was positively charged. The FT-IR spectra of the chemically modified hypercrosslinked poly(AN-co-DVB-80-co-VBC) showed that the nitrile groups derived from the AN unit were utilised by the presence of diamine groups. The BET-specific surface areas of the EDA-modified hypercrosslinked poly(AN-co-DVB-80-co-VBC) was 503 m2 g-1; meanwhile, the specific surface area of the HXL terpolymer was 983 m2 g-1. The adsorption isotherm data were well fitted by both the Langmuir and Freundlich models, whereas the adsorption kinetics followed the pseudo-second-order kinetic model. This study confirms that the EDA-modified hypercrosslinked poly(AN-co-DVB-80-co-VBC) terpolymer is a potential adsorbent for the adsorption of acidic pharmaceuticals

High-efficiency DNA extraction using poly(4,4′-cyclohexylidene bisphenol oxalate)-modified microcrystalline cellulose magnetite composite

In this study, we studied the DNA extraction capability of poly(4,4-cyclohexylidene bisphenol oxalate) following the surface modification and composite formation with that of microcrystalline cellulose (MCC) and magnetic iron oxide nanoparticles (NPs). The physical characterization techniques like scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray analysis (EDX), and thermogravimetric analysis (TGA) were employed for the poly(bisphenol Z oxalate)-MCC-magnetite composite during different stages of its formation. The results confirmed the successful modification of the polymer surface. On testing in the presence of three types of binding buffers, a high value of 72.4% (out of 10,000 ng/μL) efficiency with a total yield of DNA at ng and absorbance ratio of A260/A280 (1.980) was observed for the 2 M GuHCl/EtOH binding buffer. These results were compared against the other two buffers of phosphate-buffered saline (PBS) and NaCl. The lowest value of DNA extraction efficiency at 8125 ng/μL of 58.845% with absorbance ratios of A260/A280 (1.818) for PBS was also observed. The study has concluded an enhancement in the DNA extraction efficiency when the polymer is in the composite stage along with cellulose and magnetite particles as compared against the bare polymer