Construction and characterization of nano iron complex ionophore for electrochemical determination of Fe(III) in pure and various real water samples

Comparison of selectivity and sensitivity of various ferric selective electrodes prepared using N-((bis(dimethyl amino)methylene)carbamothioyl)benzamide

N-((Bis(dimethyl amino)methylene)carbamothioyl)benzamide (NBMCB) was synthesized, characterized, and used as an ionophore for producing three novel ion-selective potentiometric sensors for Fe(III) determination. Firstly, using the molecular mechanic-based MMFF94 method, the most stable NBMCB's conformer and its isosteric complexes with various cations were determined. According to the Gibbs free energy results of the reaction, the thermodynamic complexation reactivity of Fe(III) and the ligand was acceptable. These results were obtained using the B3LYP approach and the 6-31G(d,p) basis set that was substituted for heavy metals by the LanL2DZ basis set. We used UV-visible spectrophotometry to confirm the tendency of NBMCB to react with Fe(III). Generally, three diverse liquid membrane ferric selective electrodes were obtained by the use of the specified ligand: classic with a liquid internal electrolyte-ferric selective electrode (LIE-FSE), solid state-FSE (SS-FSE), and coated wire-FSE (CW-FSE). The reactions exhibited Nernstian behavior across all electrodes. The limit of detection was enhanced for the SS-FSE (3 × 10-9 M) and the CW-FSE (3 × 10-7 M) in comparison with that of the LIE-FSE (7 × 10-7 M). The lifetime of the LIE-FSE was 8 weeks, while it was 10 weeks for the SS-FSE and the CW-FSE. Elimination of the internal solution reduced the limit of detection and prolonged the lifespan of the sensors. Also, the three electrodes all had a short response time of around 5-7 s. The sensors were utilized as indicator electrodes during the potentiometric titration of Fe(III) using ethylenediaminetetraacetic acid.

The New Ion-Selective Electrodes Developed for Ferric Cations Determination, Modified with Synthesized Al and Fe-Based Nanoparticles

The solid-state ion-selective electrodes presented here are based on the FePO₄:Ag₂S:polytetrafluoroethylene (PTFE) = 1:1:2 with an addition of (0.25-1)% microwave-synthesized hematite (α-Fe₂O₃), magnetite (Fe₃O₄), boehmite [γ-AlO(OH)], and alumina (Al₂O₃) nanoparticles (NPs) in order to establish ideal membrane composition for iron(III) cations determination. Synthesized NPs are characterized with Fourier-Transform Infrared (FTIR) spectroscopy, Powder X-Ray Diffraction (PXRD), and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). The iron oxides NPs, more specifically, magnetite and hematite, showed a more positive effect on the sensing properties than boehmite and alumina NPs. The hematite NPs had the most significant effect on the linear range for the determination of ferric cations. The membrane containing 0.25% hematite NPs showed a slope of -19.75 mV per decade in the linear range from 1.2∙10^-6 to 10^-2 mol L^-1, with a correlation factor of 0.9925. The recoveries for the determination of ferric cations in standard solutions were 99.4, 106.7, 93.6, and 101.1% for different concentrations.

Development of Chromium(III) Selective Potentiometric Sensors for Its Determination in Petroleum Water Samples Using Synthesized Nano Schiff Base Complex as an Ionophore

BACKGROUND

Many analytical techniques, such as X-ray fluorescence spectrometry, inductively coupled plasma atomic emission spectrometry (ICP-AES), and even traditional spectroscopic and fluorimetric methods, are used for the measurement of Cr(III) ions. These methods are sophisticated and very expensive. So, the chipset and the low cost ion selective electrodes were used.

OBJECTIVE

The quantification of Cr(III) ions in various samples of petroleum water using ion selective electrodes was suggested. Nano chromium modified carbon paste sensor (MCPE) and nano chromium modified screen printed sensor (MSPE) based on Schiff base Cr(III) complex are developed.

METHOD

The developed nano Cr(III) Schiff base chelate was characterized utilizing elemental, spectroscopic, and thermal analysis techniques. The proposed nano Cr(III) has a good properties for antibacterial and antifungal activity. The modified carbon paste and screen-printed sensors were fabricated for determination of Cr(III) ion.

RESULT

The proposed MCPE (sensor I) and MSPE (sensor II) obeys Nernstian equation upon incorporating nono Cr(III) ionophore in the paste at 25 °C with a trivalent cationic slope of 18.8 ± 0.2 and 20.0 ± 0.4 mV/decade. They have showed fast response time around 8 and 5 s, and they may be utilized for at least 98 and 240 days without significant changes in MCPE and MSPE potential, respectively. The sensors I and II showed good selectivity for Cr(III) ion toward a wide variety of metal ions or anions as confirmed by potentiometric selectivity coefficients values. The detection and quantification limits were defined alongside the other process validation parameters. The results have been compared well to those obtained by atomic absorption spectrometry (AAS) and the data of F- and t-test indicated no significant difference between the proposed and AAS methods.

CONCLUSION

These sensors have been utilized to determine Cr(III) ions in genuine spiked different petroleum well water samples with satisfactory percentage recoveries, low standard and relative standard deviation values using direct potentiometric and standard addition methods. The proposed method of producing nano Cr(III) complex as a sensor material possesses the distinct advantages of being simple, easily reproducible, appropriate for operation, and highly selective and sensitive.

HIGHLIGHTS

Modified carbon paste and screen-printed electrodes were fabricated based on nano Cr(III) complex as ionophore. The electrodes follow Nernstian behavior and they optimized according to IUPAC recommendation. They showed a high selectivity for Cr(III) ion over many bi or trivalent metal ions and anions. The results obtained compared well with those obtained using atomic absorption spectrometry (AAS). They successfully applied for determination of Cr(III) in petroleum water samples.

Potentiometric Response of Solid-State Sensors Based on Ferric Phosphate for Iron(III) Determination

A novel ion-selective electrode with membranes based on iron(III) phosphate and silver sulfide integrated into a completely new electrode body design has been developed for the determination of iron(III) cations. The best response characteristics with linear potential change were found in the iron(III) concentration range from 3.97 × 10⁻⁵ to 10⁻² mol L⁻¹. The detection limit was found to be 2.41 × 10⁻⁵ mol L⁻¹ with a slope of −20.53 ± 0.63 and regression coefficient of 0.9925, while the quantification limit was 3.97 × 10⁻⁵ M. The potential change per concentration decade ranged from −13.59 ± 0.54 to −20.53 ± 1.56 for Electrode Body 1 (EB1) and from −17.28 ± 1.04 to −24 ± 1.87 for Electrode Body 2 (EB2), which is presented for the first time in this work. The prepared electrode has a long lifetime and the ability to detect changes in the concentration of iron cations within 20 s. Membrane M1 showed high recoveries in the determination of iron cations in iron(III) standard solutions (98.2–101.2%) as well as in two different pharmaceuticals (98.6–106.5%). This proves that this type of sensor is applicable in the determination of ferric cations in unknown samples, and the fact that all sensor parts are completely manufactured in our laboratory proves the simplicity of the method.