Electroanalysis最新文献

An ultrasensitive and selective voltammetric microsensor (multiwalled carbon nanotube [MWCNT]/carbon black nanoparticle [nCB])-modified carbon paste microelectrode (mCPµE) with ultra-trace level detection limit is designed for the determination of danofloxacin (DAN) in real samples. The (MWCNT/nCB)-mCPµE consists of a carbon paste cavity microelectrode (MEC) modified with nCBs and MWCNTs. The nanostructure of the different MEC materials are characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Under optimal conditions, a wide linear range (2.5 × 10⁻⁹–2.5 × 10⁻⁷ mol L⁻¹) is obtained. The detection and quantification limits are estimated at 4.3 × 10⁻¹⁰ and 1.43 × 10⁻⁹ mol L⁻¹, respectively. For the measurement of DAN in the presence of many possible interfering chemical molecules, the suggested microsensor demonstrates remarkable selectivity. Analysis of the real samples confirms that the (MWCNT/nCB)-mCPµE is a suitable electrochemical sensor for the determination of DAN in wastewater and urine samples with satisfactory recoveries of 103.5%–104.6% and relative standard deviations less than 4.93%. Finally, in terms of sustainability (availability of materials used), analytical efficiency (precision and very low limit of quantification), and economic considerations (use of a very small quantity of materials), the proposed method outperforms previously reported methods.

Chemical modification of carbonaceous materials is a convenient and reliable approach for the permanent fabrication of functional moieties. Among different linkers, diazirines offer a photogenerated reactive carbene that can insert into X–H (X; O, N) and add to π bonds to tether a variety of moieties on the surface of carbonaceous materials. Explicitly, 3-phenyl-3-(trifluoromethyl)-3H-diazirine is more thermally and chemically stable within the diazirine family. Here, we synthesized 3-(ferrocenylalkyloxy)-3-(trifluoromethyl)-diazirine derivatives and utilized them to covalently modify the surface of glassy carbon (GC). The photogenerated carbene enabled the tethering of the ferrocene (Fc) to the surface of a GC electrode (GCE). The modified surface properties were investigated using different electrochemical techniques, ellipsometry spectroscopy, and scanning electron microscopy. Electrochemical surface responses in KCl and Ru(NH₃)₆³⁺ solutions clearly exhibited ferrocene redox behavior and surface blocking during modification, respectively. Surface analysis results revealed a clear correlation between the thickness and capacitance current of the modified surface. More importantly, the obtained electrochemistry data show substantial chemical stability of the covalently tethered Fc on the GCE surface in both aqueous and nonaqueous media. The presented work offers an approach for the on-demand photochemical formation of carbene from diazirines to add functionality for applications of modified electrodes in electrocatalysis and sensing.

The production of electrochemical devices and systems using additive manufacturing technology, particularly three-dimensional (3D) printing, has proven to be highly promising. This work reports the development of 3D-printed electrochemical sensors for the determination of the antibiotic ciprofloxacin (CIP). To achieve this, a lab-made conductive filament composed of carbon black (CB) and polylactic acid (PLA) was produced and utilized in the fabrication of the sensors. Additionally, an electrochemical cell was constructed using a nonconductive filament, resulting in a miniaturized and entirely additively manufactured platform. The characterization of the proposed CB–PLA sensor was carried out using scanning electron microscopy and electrochemical techniques. The proposed sensor has shown a linear range of 1.0–12.5 µmol L⁻¹, with a sensitivity of 3.77 µA µmol⁻¹ L, and limits of detection and quantification of 0.3 and 0.9 µmol L⁻¹ for CIP, respectively. Regarding the analysis of the samples (tap water and synthetic urine), it was observed recovery values close to 100% for all samples. Thus, the 3D-printed electrochemical device presents itself as a high-potential alternative for CIP drug control, with the possibility of being used in the field and point of care.

This study presents a targeted impedimetric immunosensor for the detection of procalcitonin (PCT), a biomarker associated with SEPSIS. The immunosensor was operated based on the interaction between PCT antibody (anti-PCT) and PCT antigen, utilizing graphene quantum dot (GQD)-modified carbon screen-printed electrode (SPCE). Herein, GQDs, known for their large surface area and excellent electrical conductivity, served as the matrix for immobilizing anti-PCT, thereby enhancing the electrochemical signal. Following the immobilization of anti-PCT onto the GQD@SPCE, the interaction between anti-PCT and with PCT antigen was monitored by using electrochemical impedance spectroscopy. Experimental parameters were optimized, and the analytical characteristics were extensively evaluated. The developed impedimetric PCT immunosensor demonstrated a linear detection range of 0.1–10 ng/mL for PCT, with a detection limit of 0.01 ng/mL and a quantification limit of 0.03 ng/mL. Finally, developed GQD-based impedimetric PCT immunosensor was applied to low- and high-level original control serum samples of the selected kit and very promising recovery values were obtained.

A simple, commercially available, unmodified screen-printed carbon electrode (SPCE) was investigated for the simultaneous voltammetric determination of dopamine (D/A) and uric acid (U/A) in a medium of very low concentration of supporting electrolyte for the first time. The ordinary, simple SPCE from DropSens (DS-SPCE) was found to be able to separate the overlapping peaks of D/A and U/A with a wide peak potential separation of 300 mV in a medium of very low concentration (0.001 M) of NaH₂PO₄ as supporting electrolyte (buffer of low capacity) at pH 8.0. Medium of low concentration of electrolyte made it possible to expose the bare electrode surface for its high catalytic activity which resulted into a high peak current signals, particularly for D/A. The DS-SPCE showed excellent electrocatalytic performance than the other SPCE. The effect of electrolyte concentration and pH on the electrocatalytic behavior of electrode were thoroughly discussed. The DS-SPCE displayed a sensitive results in good linear ranges from 0.1–5 to 6–20 µM for D/A and 0.5–41.5 µM for U/A. The disposable electrode demonstrated better discrimination ability toward the detection of D/A and U/A over ascorbic acid and other potential interfering species. Moreover, the sensor presented sensitive and highly accurate results in human urine samples without preliminary treatment. The DS-SPCE sensor was found to be simple, efficient, fast, low cost, and greener than the other reported modified sensors, while providing better sensitivities to detect D/A and U/A simultaneously. Thus, the bare, unmodified DS-SPCE can be a convenient sensing device for the routine analysis of D/A and U/A, without requiring any complex pretreatment and modification steps of the electrode.

The current study introduces the first voltammetric approach for the quantitation of the recently approved anticancer medication dacomitinib (DCN). The developed method is based on examining the electrode's voltammetric behavior with carbon paste. In this approach, both square wave and cyclic voltammetry were used. To achieve a satisfactory sensitivity, the measuring instrumental parameters were carefully studied using square-wave voltammetry. The limits of detection and quantitation were 6.7 × 10⁻⁷ and 2.0 × 10⁻⁶ M, respectively, indicating the method's high sensitivity. The anodic peak current increased linearly with DCN concentration over the range of 2.3 × 10⁻⁶–1.5 × 10⁻⁵ M upon adjusting the pH at 4 with Britton–Robinson buffer. The electrochemical method was fully validated as per the International Council of Harmonization (ICH) guidelines. The inter- and intra-assay precision relative standard deviation (%RSD) values were ≤1.809. This approach was applied to determine the drug in its pharmaceutical tablets (Vizimpro) with satisfactory %recoveries (98.8–100.9). The statistical results were favorably compared to those provided by a reported spectrofluorimetric method. The greenness and eco-friendliness of the designed approach were demonstrated using the Green Analytical Procedure Index (GAPI) and Analytical GREEnness (AGREE) tools, suggesting its usage as an environmentally friendly alternative for the routine assay of the investigated drug.

This study is aimed at the determination of a new pollutant, fluoroquinolones antibiotics (FQs). Taking ciprofloxacin (CIP) as the research representative, rutin polymer film-modified sensor polyrutin modified glass carbon electrode (PRT/GCE) was prepared by electropolymerization, and a new analytical method for the determination of FQs was established, which is environmentally friendly, simple, efficient, and economical. The topography, elemental composition, and electrochemical behavior of the sensor were investigated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results showed that the linear range of the PRT/GCE sensor used for CIP was 0.8–50 μM, the detection limit was 0.050 μM, and the recovery rate was 94.9%–104%. In addition, when it was used to detect norfloxacin (NOR), enrofloxacin (ENR), pefloxacin (PEF), and rofloxacin (FLE) in FQs, the sensor similarly exhibited a broad linear range; its corresponding detection limits were 0.078, 0.16, 0.088, and 0.12 μM, respectively. The PRT/GCE sensor had a high active area, good catalytic performance for FQs, simple preparation, stable performance, and reusability. It has potential application value for routine determination of fluoroquinolones in real water.

A simple, commercially available, unmodified screen-printed carbon electrode (SPCE) was investigated for the simultaneous voltammetric determination of dopamine (D/A) and uric acid (U/A) in a medium of very low concentration of supporting electrolyte for the first time. The ordinary, simple SPCE from DropSens (DS-SPCE) was found to be able to separate the overlapping peaks of D/A and U/A with a wide peak potential separation of 300 mV in a medium of very low concentration (0.001 M) of NaH₂PO₄ as supporting electrolyte (buffer of low capacity) at pH 8.0. Medium of low concentration of electrolyte made it possible to expose the bare electrode surface for its high catalytic activity which resulted into a high peak current signals, particularly for D/A. The DS-SPCE showed excellent electrocatalytic performance than the other SPCE. The effect of electrolyte concentration and pH on the electrocatalytic behavior of electrode were thoroughly discussed. The DS-SPCE displayed a sensitive results in good linear ranges from 0.1–5 to 6–20 µM for D/A and 0.5–41.5 µM for U/A. The disposable electrode demonstrated better discrimination ability toward the detection of D/A and U/A over ascorbic acid and other potential interfering species. Moreover, the sensor presented sensitive and highly accurate results in human urine samples without preliminary treatment. The DS-SPCE sensor was found to be simple, efficient, fast, low cost, and greener than the other reported modified sensors, while providing better sensitivities to detect D/A and U/A simultaneously. Thus, the bare, unmodified DS-SPCE can be a convenient sensing device for the routine analysis of D/A and U/A, without requiring any complex pretreatment and modification steps of the electrode.

This study is aimed at the determination of a new pollutant, fluoroquinolones antibiotics (FQs). Taking ciprofloxacin (CIP) as the research representative, rutin polymer film-modified sensor polyrutin modified glass carbon electrode (PRT/GCE) was prepared by electropolymerization, and a new analytical method for the determination of FQs was established, which is environmentally friendly, simple, efficient, and economical. The topography, elemental composition, and electrochemical behavior of the sensor were investigated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The results showed that the linear range of the PRT/GCE sensor used for CIP was 0.8–50 μM, the detection limit was 0.050 μM, and the recovery rate was 94.9%–104%. In addition, when it was used to detect norfloxacin (NOR), enrofloxacin (ENR), pefloxacin (PEF), and rofloxacin (FLE) in FQs, the sensor similarly exhibited a broad linear range; its corresponding detection limits were 0.078, 0.16, 0.088, and 0.12 μM, respectively. The PRT/GCE sensor had a high active area, good catalytic performance for FQs, simple preparation, stable performance, and reusability. It has potential application value for routine determination of fluoroquinolones in real water.

The production of electrochemical devices and systems using additive manufacturing technology, particularly three-dimensional (3D) printing, has proven to be highly promising. This work reports the development of 3D-printed electrochemical sensors for the determination of the antibiotic ciprofloxacin (CIP). To achieve this, a lab-made conductive filament composed of carbon black (CB) and polylactic acid (PLA) was produced and utilized in the fabrication of the sensors. Additionally, an electrochemical cell was constructed using a nonconductive filament, resulting in a miniaturized and entirely additively manufactured platform. The characterization of the proposed CB–PLA sensor was carried out using scanning electron microscopy and electrochemical techniques. The proposed sensor has shown a linear range of 1.0–12.5 µmol L⁻¹, with a sensitivity of 3.77 µA µmol⁻¹ L, and limits of detection and quantification of 0.3 and 0.9 µmol L⁻¹ for CIP, respectively. Regarding the analysis of the samples (tap water and synthetic urine), it was observed recovery values close to 100% for all samples. Thus, the 3D-printed electrochemical device presents itself as a high-potential alternative for CIP drug control, with the possibility of being used in the field and point of care.