Iranian Journal of Analytical Chemistry
Volume:11 Issue: 2, Summer and Autumn 2024

In this project, in the first part, the Schiff base ligand (3-nitrobenzaldehyde + 2-aminothiophenol = H2L) was prepared. Then a nano-complex with the formula [Zn(HL)2Cl2] was synthesized using sonochemical method. Zn-nano-complex was identified by FT-IR, UV-Vis, 1H-NMR and Emission Scanning Electron Microscope (SEM). The spectroscopic results showed that the H2L ligand was coordinated to the metal through the N atom. The FT-IR spectrum of Zn-nano-complex showed the vibrational banb of the immunity group (C = N) at 1680-1600 cm-1. The studies obtained from the UV-Vis spectrum confirm n → π* and π→π* intra-ligand transitions. FS-DNA (salmon sperm DNA) and Zn-nano-complex were examined using UV-Vis spectroscopy, fluorescence spectroscopy, and gel electrophoresis. The Stern–Volmer equation was used to calculate the binding constant (Kb) and apparent bimolecular quenching constant (kq) for FS-DNA. Van der Waals forces and hydrogen bonds are important in the interaction between the DNA and the Zn (II) complex, according to an analysis of thermodynamic parameters (∆H°, ΔS° and ΔG°). The interaction mechanism was determined to be the groove-binding mode. These results highlight the complex's complicated effects on DNA structure and the need to use a variety of analytical techniques in order to fully investigate metal-DNA interactions.

Phosphomolybdate-hexamine-cobalt (PMA-HMT-Co), a new hybrid prepared by coprecipitation method, was used for coating of titanium dioxide nanoparticles in order to improve photocatalytic activity to visible light. PMA-HMT-Co and TiO2-PMA-HMT-Co were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy. The diffuse reflectance spectroscopy was used to evaluate the band gap variation. The band gap of PMA-HMT-Co decreased and hence, its photocatalytic activity was enhanced under sunlight irradiation. With the incorporation of PMA-HMT-Co, the band gap of titanium dioxide was transferred from UV to visible region successfully. Rhodamine B (RhB) decolorization tests indicated higher photocatalytic activity of TiO2-PMA-HMT-Co under sunlight irradiation. Photodegradation takes place through the excitation of modified titanium dioxide and the creation of holes (h+) and oxidation of dye.

The molecularly imprinted polymer (MIP) sensor for the rapid and immediate detection of carbidopa (CD) has been investigated. Additionally, a voltammetric sensor based on MIP with a glassy carbon electrode (MIP/GCE) has been developed for CD detection. Under optimal conditions, we observed a strong linear correlation between the sensor's peak current and CD concentrations ranging from 1.0 to 1000.0 μM, with a low limit of detection (LOD) of 0.3 μM (S/N = 3). The modified electrode demonstrated satisfactory electrocatalytic properties for CD oxidation, allowing the sensor to selectively detect CD even in the presence of high concentrations of similar compounds. Furthermore, it was confirmed that MIP/GCE effectively detected CD in urine samples.

In this work, copper oxide nano sorbent (CONS) with an average diameter of 30 nm is synthesized by polyvinyl alcohol-based sol-gel method to remove heavy metal ions from an aqueous solution. The produced nanopowder is fully characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS). Various physicochemical parameters such as solution pH, nano-sorbent dosage, solution temperature, contact (mixing) time, initial concentration of lead ion, and the initial volume of lead ion sample are investigated and optimized by the "one at a time" method. Based on the experimental data, the optimum conditions for the full removal of lead ions with an initial concentration of 30 ppm, include pH 6, a sorbent dosage of 1.6 mg ml-1, a solution temperature of 25 ºC, and a contact time of 13 min. The experimental results showed that the adsorption of lead ions by copper oxide nanoparticles has a good fit with Langmuir isotherm and follows the pseudo-second-order kinetics model. The experimental data shows the synthesized CuO nanoparticles are an effective sorbent for the removal of Pb(II), Fe(II), and Cu(II) from water with maximum capacities of 33.7, 20.2, and 18.8 mg g-1, respectively.

A new complex with the formula [Cu(opd)2(H2O)(μ-SCN)Zn(opd)(SCN)3] (a) that opd =ortho-phenylenediamine was synthesized. The complex (a) was characterized using cyclic voltammetry (CV), spectroscopic methods (IR, UV-Vis) and SEM method. FT-IR show the thiocyanate ligand is located in the form of a bridge. The 1-2-phenylenediamine ligand is also bonded to metal ions through the non-bonding electron pairs of nitrogen atoms through bidentate ligand. The studies obtained from the UV-Vis spectrum confirm n → π* and π→π* intra-ligand transitions. The images obtained with the help of scanning electron microscope (SEM) showed that the particles have a uniform morphology. The average size diameter obtained from the Debye-Scherrer equation of nanocrystal complex (a) was approximately 73 nm. Finally, the antibacterial activity of the complex was investigated. The antibacterial activity of complex (a) against gram-negative bacteria is greater than that against gram-positive bacteria.

This study presents an innovative biomimetic sensor leveraging molecularly imprinted polymers (MIPs) for folic acid detection, combining advanced materials and electrochemical design for enhanced performance. The sensor employs methacrylic acid monomers polymerized onto a polymeric surface, integrated with graphite powder and paraffin oil to form a robust carbon paste electrode. Key strengths include its Nernstian response (19.2 mV decade–1) across a wide concentration range (5 × 10−9 to 1 × 10−3 mol L−1) and an impressively low detection limit of 1 × 10−9 mol L−1, surpassing many conventional methods. The design eliminates the need for additional reagents or complex instrumentation, prioritizing cost-effectiveness and simplicity. Novel aspects lie in the MIP-graphite-paraffin oil composite, which enhances stability and selectivity while enabling rapid sensor regeneration through surface polishing. The sensor demonstrates remarkable long-term stability and reproducibility, critical for real-world applications in pharmaceutical samples. Its ability to discern folic acid from interferents, validated in diverse matrices, underscores its practicality for clinical diagnostics and food quality control. By merging MIP specificity with electrochemical transduction, this work advances portable, high-sensitivity sensing platforms for routine analysis.

A simple, rapid, and cost-effective method for the determination of 17-β-estradiol in water samples was developed. The method is based on the extraction of the 17-β-estradiol–β-cyclodextrin complex using a coacervate phase composed of reverse micelles of decanoic acid, followed by high-performance liquid chromatography with ultraviolet detection for quantification. The effects of key parameters, including decanoic acid concentration (50–200 mg in a 30 mL total volume), tetrahydrofuran concentration (1–15% v/v), β-cyclodextrin to 17-β-estradiol molar ratio (1:1–1:4), ionic strength (0–1 M) NaCl, pH (1–4), and extraction time (0–30 min), on recoveries and enrichment factors were studied and optimized. The optimal extraction conditions involved stirring a 20 mL water sample containing 50 mg of decanoic acid with 3 mL of THF, using a 1:1 molar ratio of 17-β-estradiol to β-cyclodextrin complex, for 10 minutes, followed by centrifugation, 10 min at 4000 rpm. Recoveries and enrichment factors of 17-β-estradiol was primarily influenced by the decanoic acid and THF concentrations that form the coacervate phase but remained independent of the ionic strength of the sample solution. The recovery rate, enrichment factor, limit of detection, and relative standard deviation for 17-β-estradiol were 95%, 284, 0.19 μg/L, and 4.34%, respectively. This method was applied to analyze 17-β-estradiol in city water, mineral water, and pastewater samples. No 17-β-estradiol was detected in mineral water, while its concentration in city water and pastewater was found to be 1.9 μg/L and 33.67 μg/L, respectively.

The complexation reactions between Cu2+ and Pd2+ ions with trimethoprim (TMP) and sulfamethoxazole (SMX) in N,N-Dimethylformamide (DMF) were studied by the spectrophotometric methods at [(15, 25, 35 and 45±0.1) °C]. The complexation process was optimized in terms of pH, temperature and time. The stoichiometry of the complexes was found to be 1:2 (metal ion/ligand).  The formation constants of the resulting complexes were determined from computer fitting absorbance-mole ratio data and emphasized by the KINFIT program. The values of the thermodynamic parameters for complexation reactions were obtained from the temperature dependence of the stability constants. In all cases, the complexes were found to be enthalpy stabilized but entropy destabilized. SMX and TMP could be determined by measuring the absorbance of each complex at its specific λmax. The proposed method was successfully applied for the determination of these compounds in their dosage forms.

Amitraz removal was investigated by synthesized TiO2 from an aqueous solution. For this propose, FT-IR, XRD, UV–Vis, SEM and EDS were used to characterize the synthesized nano adsorbents and to determine the removal process. Batch adsorption studies were conducted to investigate the effect of temperature, initial Amitraz concentration, adsorbent count and contact time as important adsorption parameters. The maximum equilibrium time was found to be 15 min with 5 mg adsorbent in 35ºC at pH=7 for TiO2. All the adsorption equilibrium data were well fitted to the Freundlich isotherm model with heterogenous, multilayer, temperature depended, irreversible and spontaneously behavior. The ∆H is -4.2×103 kJ and ∆S is 15 J mol-1K-1.