Analytical and Bioanalytical Chemistry Research
Volume:11 Issue: 4, Autumn 2024

Metal-organic frameworks (MOFs), formed by the self-assembly of metal centers or clusters and organic linkers, possess many key structural and chemical features. MOFs are generally synthesized by employing a modular synthesis, where crystals are slowly grown from a hot solution by nucleation and growth mechanism to form porous structures. The advantages and applications of many MOFs are ultimately limited by their stability under harsh conditions. The factors that affect MOF stability under certain chemical environments are introduced to guide the design of robust structures. Therefore, stable MOFs are formed by using different techniques including modulated synthesis (spray drying, electrochemical, microwave-assisted, mechanochemical synthesis, microfluidic synthesis method). In particular, their high porosity, large surface area, tunable chemical composition, high degree of crystallinity, and potential for post-synthetic modification for molecular recognition make stable MOFs promising candidates for many implicated in the industry such as photocatalysis, hydrogen storage, adsorption, carbon capture, energy storage, biomedical application (drug delivery, antibacterial, biocatalysis and biological imaging) and sensing (fluorescent and electrochemical). Overall, this review is expected to guide the design of stable MOFs by providing insights into existing structures, which could lead to the discovery and development of more advanced functional materials for different applications.

In this research, for the first time, a novel electrochemical sensor was proposed for detection of Gefitinib (Gefi) as an anticancer drug based on a molecularly imprinted polymer (MIP) on the glassy carbon electrode (GCE) surface. The present research aimed to introduce a selective electrochemical sensor through electropolymerization of o-aminophenol (o-AP) as monomer on the GCE surface for the determination of Gefi as a template molecule. Afterwards, the proposed sensor was assayed by scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and electrochemical methods including electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and cyclic voltammetry (CV). The introduced sensor illustrated a good linear range of 5 to 1000 µM and limit of detection of 1.6 µM for Gefi detection. Moreover, the modified electrode to determine Gefi in the blood serum sample was successfully employed. The recoveries were from 98.8 to 100.5% and the RSD was less than 2.7% which illustrated the applicability of proposed sensor in the real sample.

A novel highly sensitive and selective electrochemical sensor with low limit of detection and wide linear ranges for elecotrooxidation of adrenaline (Adr) and tryptophan (Trp) were utilized by immobilization of curcumin nanoparticles, AgNPs on MWCNTs on glassy carbon electrode. The SEM and XRD analysis were applied for characterization of fabricated sensor surface. The diameter of synthesized nanoparticles was obtained 39 to 64 nanometers using SEM analysis. The CV peak currents of Adr and Trp were linear in range 1.0-1150 µmol L-1 and 0.5-1200 µmol L-1 respectively. The detection limit was found 0.058 µmol L-1 and 0.032 µmol L-1, for Adr and Trp, respectively. The fabricated nanocomposite was successfully employed to determine Adr in an adrenaline injection solution as well as Adr and Trp in a human urine sample. The calculated recovery values confirmed that electrochemical was appropriate for the precise and accurate simultaneous determination of target Adr and Trp in complex mixtures with recovery in the range of 98–103%.

In this research, a modified carbon paste electrode (CPE) has been constructed for the electrochemical determination of clonazepam (CLZP) in different real samples. Different modifiers including multi-wall carbon nanotube (MWCNT) molecularly imprinted polymer (MIP) as magnetic and non-magnetic modifiers are used for the surface modification. The characterization of the as-synthesized MIP was carried out using Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), simultaneous thermal analysis (STA), and Brunauer-Emmett-Teller (BET). It was found that the MIP was found to be a selective modifier to design a CLZP sensor, in an electrocatalytic process. To investigate the electrochemical behavior of the sensor and determination of CLZP, the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were applied, respectively. The effect of some parameters on sensor response such as pH, MIP percentage, and scan rate was studied and optimized. Under optimum conditions (pH=7, scan rate of 50 mV.s-1), a linear range from 1.64 to 72.3 μM, a detection limit of 0.26 μM (3Sb/m; N=5), and quantification limit (LOQ) of 0.87 μM was obtained. Besides, compared to the non-imprinted polymer sample (NIP), MIP modified-CPE (MIP/CPE) showed good sensitivity toward the CLZP drug. The prepared sensor was used to determine the CLZP drug in different real samples such as drinking water, urine, blood, and tablets.

A highly sensitive, fast and convenient colorimetric assay for acetylcholinesterase (AChE) activity was developed. To do this, phosalone was used to aggregate citrate-coated gold nanoparticles which caused its color to be changed from wine-red to blue. This aggregation was significantly hindered with AChE, due to its preferential reaction with phosalone, and the corresponding color change was probed spectrophotometrically as a function of AChE activity. The ratio of the measured absorbances at the wavelengths of 520 and 650 nm (A520/A650) was found to be linear with the activity of AChE from 0.050 to 1.0 U mL−1 (R2 = 0.9912). A limit of 0.030 U mL−1 for detection of AChE was achieved based on signal to noise ratio of 3. The procedure was successfully applied for determination of AChE in real samples as well as quantitation of phosalone in diverse fields such as food and agricultural industries as well as pharmaceutical, healthcare and environmental affairs.

In this study, a solvent-based method to the microextraction of Hg(II) ions is described, relying on the use of a synthesized/characterized imidazolium-based ionic liquid (IL), specifically 1-methyl-2-hexylthioimidazolium chloride ([C1C6Sim][Cl]), as a task-specific ionic liquid (TSIL) or a functionalized ionic liquid (FIL). The synthesized TSIL underwent characterization through 1HNMR and FTIR analyses. The TSIL, chelated with Hg(II) ions in the aqueous phase to form a hydrophilic Hg-TSIL complex, which was subsequently converted into a hydrophobic Hg-TSIL complex through anion exchange reactions using sodium tetrafluoroborate. To assess the microextraction method capability in analyzing real samples with complex matrices containing Hg(II) ions, the experimental conditions need to determined, followed by the determination the Hg(II) concentration values using cold-vapor flame atomic absorption spectrometry (CV-FAAS). Based on the obtained results, the limit of detection (LOD) and limit of quantification (LOQ) were determined to be 0.015 ng ml-1 and 0.078 ng ml-1, respectively. The precision, expressed as relative standard deviations (RSD%) for intra-day and inter-day measurements over seven replicates, was found to be 1.7% and 1.9%, respectively. Furthermore, a linear dynamic range (LDR) of 0.1–80 ng ml-1 was achieved. The optimized conditions facilitated evaluating the method validity. Ultimately, the method validity was confirmed through its successful utilization in determining of Hg(II) ions in various real water and wastewater samples.

The goal of this pilot work was to find out suitable experimental conditions which enable to reliably determine the species origin of blood by proteomic analysis using Matrix-Assisted Laser Desorption/Ionization – Time of Flight Mass Spectrometry. Easy and quick determination of the presence of blood and its animal species determination is useful, for example, for uncovering incorrectly marked or adulterated meat in the food industry, fighting against illegal hunting, and for the analysis of art objects. The main advantage of the proteomic approach over DNA analysis is the long-term durability of proteins and usually their greater quantity in the sample. The tested conditions included searching for the most suitable time duration of trypsin cleavage of blood proteins, monitoring the effect of removal of blood lipids on trypsin cleavage, and the determination of a suitable solution for trypsin cleavage (isopropanol at various concentrations or 50 mM NH4HCO3). Obtained mass spectra were processed by Principal Component Analysis and m/z values specific for humans and six other selected animal species (cat, chicken, cow, dog, goose, human, and pig) were found. It was possible to divide blood samples of all analysed avian and mammalian species into separate clusters and to identify the species origin of an unknown sample using Principal Component Analysis. The animal species origin of the unknown sample was confirmed by the species-specific m/z values and Partial Least Squares – Discrimination Analysis.

Pesticides serve a crucial function in contemporary farming practices, safeguarding agricultural crops against pest infestations and boosting production outputs. However, indiscriminate use has caused environmental and human health damage. The aim of this study was to develop and validate a gas chromatography-flame ionization detection (GC-FID) methodology for the direct and routine analysis of spiromesifen residues in soil, leaves and tomato fruits. The proposed method prioritizes simplicity by avoiding derivatization steps, offering advantages over existing approaches that utilize lengthy multi-step extraction or derivatization prior to GC analysis. A key novelty of this work is the development of a QuEChERS extraction coupled directly to GC-FID without further clean-up or chemical treatment steps, rendering the method more convenient and accessible for routine monitoring applications. Factors evaluated included: sample solvent; inlet and column temperature profiles; inlet type; sample volume; and injection technique. Recovery and matrix effect studies were conducted by fortifying tomato, leaf, and soil matrices at three different concentrations (0.5, 1, and 10 µg/mL). Quadruplicate analyses (n=4) yielded mean recoveries of 98.74% (fruits), 93.92% (leaves), and 94.18% (soil), confirming efficient extraction. Matrix effects were negligible at -7.9%, -7.8% and -5.3%, respectively. Chromatographic linearity of developed GC-FID method was excellent over the 0.002-20 µg/mL range with R2 > 0.9979. The method demonstrated good precision, with inter- and intra-day RSD% ranging from 0.06-1.8%, below the 3% limit. GC-MS analysis confirmed spiromesifen identification. Under greenhouse conditions, residual levels were 1.39 mg/kg in soil, 8.24 mg/kg in tomato, and 3.39 mg/kg in leaves.

Tributyltin is well recognized as an environmental endocrine disruptor and is listed as a priority substance that requires extended monitoring by the European Water Framework Directive (2000/60/EC). At the same time, due to their high pathogenicity, producing hormonal, immune, metabolic and reproductive dysfunctions, other butyltin species (e.g. monobutyltin, dibutyltin and tetrabutyltin) are consistently monitored in marine and freshwater aquatic ecosystems; the European Chemicals Agency classified these butyltin species as potential carcinogens and toxic substances for the human reproduction. Several analytical techniques, including gas chromatography and high-performance liquid chromatography, have been used to determine organotin species in aquatic ecosystems. Because of their chemical properties, organotin compounds result poorly stable upon temperature and are thus unsuited for direct analysis through capillary gas chromatography, which is usually performed after a derivatization step. The procedure described in this paper allowed the detection of underivatized chlorinated organotin compounds through gas chromatography-triple quadrupole mass spectrometry. Importantly, the obtained spectra of chlorinated monobutyltin and dibutyltin are herein presented and the fragmentation patterns are identified for the first time. The method was successfully applied to evaluate organotin compounds in sediments, providing the speciation of organotin species. Taking advantage of a simplified procedure of sample treatment, this study provided an innovative protocol for the gas chromatography/mass spectrometry of phenyl and butyl-substituted organotin compounds in contaminated sediments, capable of improving the efficiency of the conventional analysis of organotin compounds.

In this study, an optimized QuEChERS method combined with ultra-high-performance liquid chromatography (UHPLC) was employed to quantify residue levels. The amount of diazinon pesticide in peach and cherry samples at days after use with the permitted dose of 25 g was 1.66 mg/kg for peach samples and 1.82 mg/kg for cherry samples. The first-order kinetic model describes the loss patterns in all products, with half-lives of 1.8 days for the peach samples and 1.9 days for the cherry samples. Method validation was achieved based on the recovery percentage values obtained from the samples for inter-day repeatability RSDs% (n=21) for peach samples 13.2% and cherry samples 15.6%. The method validation was obtained recovery values from the samples for intera-day repeatability RSDs% (n=7) was achieved based on the 92.5–106.2% recovery for the peach samples with RSD ≤7.1%, and was achieved based on the 92.0–102.0% recovery for cherry samples with RSD ≤5.2%. The proposed UHPLC method could selectively separate diazinon pesticides from peach, and cherry samples. Furthermore, the method in this research employed can be adapted for studying other pesticide compounds with low concentrations in fruits, water, and soil, highlighting the versatility of the method employed.