Ionic Liquid Carbon Paste Electrode Research Articles

A novel sandwich electrochemical immunosensor utilizing customized template and phosphotungstate catalytic amplification for CD44 detection

A sandwich-type electrochemical immunosensor was proposed for the ultra-sensitive detection of CD44, a potential biomarker for breast cancer. In this design, a customized template-based ionic liquid (1-butyl-2,3-dimethylimidazolium tetrafluoroborate) carbon paste electrode (CILE) served as the sensing platform, and thionine/Au nanoparticles/covalent-organic frameworks (THI/Au/COF) were used as the signal label. Moreover, an enzyme-free signal amplification strategy was introduced by involving H2O2 and phosphotungstate (PW12) with peroxidase-like activity. Under optimized conditions, the linear range is as wide as six orders of magnitude, and the detection limit is as low as 0.71 pg mL−1 (estimated based on S/N = 3). Average recoveries range from 98.16 %-100.1 %, with a relative standard deviation (RSD) of 1.42–8.27 % in mouse serum, and from 98.44 %-99.06 %, with an RSD of 1.14–4.84 % (n = 3) in artificial saliva. Furthermore, the immunosensor exhibits excellent specificity toward CD44, good stability, and low cost, indicating great potential for application in clinical trials.

Voltammetric determination of organic UV filters by carbon paste electrodes modified with pyridinium-based ionic liquids

The rapid and sensitive voltammetric determination of organic UV filters benzophenone-3 (BP-3) and avobenzone (AVO) was performed by an ionic liquid carbon paste electrode (IL-CPE). Namely, the synthesized pyridinium-based ILs, 1-butyl-3-methylpyridinium chloride ([N–C4–3C1Py]Cl) and 1-ethoxyethyl-3-methylpyridinium chloride ([N–C2OC2–3C1Py]Cl) were compared as bulk CPE modifiers for BP-3 determination. [N–C4–3C1Py]Cl-CPE showed more favorable interactions with the target analyte, and it was tested for AVO determination, too. Cyclic voltammetric (CV) studies suggested that the irreversible electrode reaction is adsorption controlled in the case of both UV filters. Also, the square-wave adsorptive stripping voltammetric (SW-AdSV) method was optimized for quantifying selected UV filters. In the model solutions, the linear calibration curve was obtained by the SW-AdSV method in the concentration range from 0.05 to 0.89 μg mL−1 at pH 3.0 for BP-3 (Eacc = −0.7 V, tacc = 100 s), and from 0.05 to 1.77 μg mL−1 at pH 11.98 for AVO (Eacc = 0.2 V, tacc = 100 s). The evaluated limit of detection (LOD) was 0.015 μg mL−1 in both cases, while the relative standard deviation (RSD) was lower than 1.5%. The affordable IL-based voltammetric sensor fulfills the main requirements for application in real samples due to an adequate selectivity towards selected analytes in the presence of interferents usually found in swimming pool water. Therefore, the BP-3 and AVO were quantified in a swimming pool water matrix with good repeatability and recovery. The obtained results demonstrate an excellent potential of the IL-CPEs, especially of the [N–C4–3C1Py]Cl-CPE, for determining selected UV filters in various real samples.

Development of a highly sensitive voltammetric sensor for the detection of folic acid by using MoS2 and ionic liquid-modified carbon paste electrode.

Sensitive analytical determination of folic acid is important in clinical laboratories due to its versatile biological functions. A simple folic acid sensor was successfully fabricated based on two-dimensional transition metal dichalcogenide MoS2 modified carbon ionic liquid paste electrode (MoS2-CILPE). The electrochemical properties of the fabricated electrode were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry. The fabricated sensor displayed excellent electroactivity towards folic acid using CV. Under optimal conditions (0.1 M PBS (pH 7.0)), the DPV oxidation peak current was proportional to folic acid concentration in the range from 5.0 μM to 100.0 μM with an estimated limit of detection of 1.0 μM and limit of quantification of 5.0 μM. The ability of the sensor for routine analyses was demonstrated by the detection of folic acid present in folic acid tablets and urine samples with appreciable recovery values.

Performance comparison of simultaneo us detection Heavy-Metal ions based on carbon materials electrochemical sensor

In this study, oak biomass carbon (BC) and BC-Au composite materials were synthesized by the pyrolysis method to construct BC-Au electrode and ionic liquid carbon paste electrode (CILE) composed of BC, graphite and 1-octyl-3-methylimidazolium hexafluorophosphate(IL) for simultaneous detection of Cd2+, Pb2+ and Hg2+. The obtained materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectrum (Raman). The electrochemical performance of two sensors was studied using square wave voltammetry (SWV), cyclic voltammetry (CV), electrochemical impedance methods (EIS) and linear sweep voltammetry (LSV). The obtained results show that the detection performance of CILE was clearly better than BC-Au in terms of wide linear range(0.5 µM to 6.0 µM for Cd2+, Pb2+ and Hg2+) and high sensitivity(the detection limit toward Cd2+, Pb2+ and Hg2+ is 0.09 µM, 0.366 µM and 0.489 µM, respectively). In addition, a portable electrochemical sensing device matched with one-off CILE was constructed, which would enhance the ability for multiple electrochemical detection situations and show prospective applications for the detection of Cd2+, Pb2+ and Hg2+ in real lakes and cucumber samples.

A Carbon Ionic Liquid Paste Sensor Modified with Lanthanum Nanorods /MWCNTs/Nafion Hybrid Composite for Carbamazepine Screening in Biological and Pharmaceutical Media

AbstractIn this original paper, a new electrochemical sensor for carbamazepine (CBZ) was developed. First, lanthanum nanorods (LaNRs) were synthesized by a simple microemulsion method. Then, a nanocomposite consist of lanthanum nanorods, multiwalled carbon nanotubes (MWCNTs), and nafion (LaNRs/MWCNTs/Nafion) was prepared and deposited at the surface of the carbon ionic liquid paste electrode (CILPE). X‐ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersion spectroscopy (EDS), and scanning electron microscopy (SEM) were used to characterize the structure of synthesized LaNRs and the surface morphology of the modified electrode. Also, electrochemical methods such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) were utilized to investigate the performance of the proposed electrode. Under the optimal conditions, a linear relationship of the electrical signal versus the concentration of CBZ was obtained in the range from 0.06 μM to 20 μM with a detection limit (LOD) of 0.006 μM and quantification limit (LOQ) of 0.02 μM. Eventually, the fabricated sensor was satisfactorily applied for rapid and accurate determination of CBZ in real samples.

A rapid voltammetric strategy for determination of ferulic acid using electrochemical nanostructure tool in food samples

In this project, we performed an electrochemical investigation using a reduced graphene (rG) decorated CdO nanocomposite/1-methyl-3-octylimidazolium tetrafluoroborate ionic liquid (MOITF) carbon paste electrode (rG-CdO/MOITF/CPE) for determination of ferulic acid in food samples. In preparation of rG-CdO/MOITF/CPE, 6% w/w rG-CdO nanocomposite and 20% v/v room temperature ionic liquid were used to modify the bare CPE. SEM (Scanning Electron Microscopy) and XRD (X-Ray Diffraction) methods were applied to characterize the structure of the synthesized rG-CdO nanocomposite. At all the stages of this research, phosphate buffer solution (PBS) with the pH of 5.0, as an optimized pH condition, was used. The electron transfer coefficient (α) was obtained ⁓0.68 by recorded data from cyclic voltammogram of rG-CdO/MOITF/CPE in the presence of ferulic acid. In addition, using the chronoamperometric technique, the diffusion coefficient (D) of ferulic acid at rG-CdO/MOITF/CPE was calculated 5.4 × 10−5 cm2/s. Using the square wave voltammetry method, the linear dynamic range (LDR) was calculated to be from 0.02 to 400 μM, and the limitation of detection (LOD) was obtained as 8.0 nM. Eventually, the rG-CdO/MOITF/CPE was utilized to determine the amount of ferulic acid in food samples, and statistical calculations confirmed the sensitivity, selectivity, and precision of rG-CdO/MOITF/CPE, which is an electroanalytical tool.

A Sensitive SiO2@Fe3O4/GO Nanocomposite Modified Ionic Liquid Carbon Paste Electrode for the Determination of Cabergoline

In this study, the initial report on determining cabergoline via nanostructure-adjusted ionic liquid carbon paste electrode with aqueous solutions is described. For this purpose, an original adjusted carbon paste electrode that uses SiO2@Fe3O4/GO nanocomposite and 1-methyl-3-butylimidazolium bromide as a binder (SiO2@Fe3O4/GO/CPILE) was designed. Cabergoline oxidation peak at SiO2@Fe3O4/GO/CPILE surface was 500 mV that was approximately 200 mV less compared to the oxidation potential pertaining to the CPE surface subjected to a similar state. Moreover, there was an increase in the peak current of approximately 3.0 times greater at SiO2@Fe3O4/GO/CPILE surface in comparison to that of the CPE. The relevant linear response range and detection limit were determined as 0.07–500.0 and 0.01 μM, correspondingly. The adjusted electrode was successful in determining cabergoline within real specimens entailing adequate results.

Voltammetric Mixture Analysis of 6-thioguanine and Folic Acid Using Ionic Liquid-Carbon Paste Electrode Modified by Nano Petal-Like MoWS2 and N-(ferrocenylmethylidene)fluoren-2-amine

Here, a simple voltammetric method has been reported for the simultaneous determination of 6-thioguanine (6-TG) and folic acid (FA) using MoWS2 nanocomposit and N-(ferrocenylmethylidene)fluoren-2-amine modified ionic liquid-carbon paste electrode (MoWS2/NFMF2A/IL-CPE). X-ray diffraction (XRD), energy dispersive X-ray (EDX), and field emission scanning electron microscopy (FESEM) were used to characterize the structure of synthesized MoWS2 nanopetals. Also, different electrochemical methods were used to investigate the performance of the proposed electrode. The oxidation peak current of 6-TG at the surface of MoWS2/NFMF2A/IL-CPE was increased dramatically against CPE. The DPV method was employed for the determination of 6-TG in the presence of FA. The effects of modifier amount, pH and scan rate as some important parameters on the electrochemical response of 6-TG oxidation, were investigated. The diffusion coefficient, D, for the oxidation of 6-TG at the surface of MoWS2/NFMF2A/IL-CPE was also estimated. Under the optimized conditions, 6-TG give linear response over the range of 0.8–600.0 μM. The detection limit was found to be 0.09 μM (S/N = 3). The practical application of the MoWS2/NFMF2A/IL-CPE was confirmed by measuring the concentration of the intended drugs in real samples through the standard addition method.

Simple and sensitive detection of acrylamide based on hemoglobin immobilization in carbon ionic liquid paste electrode

A simple and sensitive electrochemical biosensor for acrylamide (AA) detection based on hemoglobin (Hb) entrapped in ionic liquid-carbon paste was constructed. The Hb-carbon ionic liquid paste electrode (Hb/CILPE) was studied and characterized by scanning electron microscopy (SEM) and electrochemical method. The surface passivation of the Hb/CILPE could be achieved by the addition of acrylamide molecule, which caused the lower current response value owing to the adduct formed by acrylamide and Hb as a result of the reaction between the α-NH2 group and the N-terminal valine of Hb. The experimental conditions such as pH value of supporting electrolyte, pulse increment and concentrated time of AA was examined. Under the optimum conditions, the differential pulse voltammetry (DPV) responses of Hb/CILPE toward AA was evaluated in a good linear range from 1.0 × 10−11 to 1.0 × 10−5 M, with a detection limit of 5.0 × 10−12 M at S/N = 3. This biosensor can be successfully applied to the determination of AA in a real sample without complex pretreatment. Compared with other electrochemical methods for detecting AA, the prepared electrochemical biosensor exhibited advantages of simple preparation, easy surface renewal, better reproducibility and satisfactory stability.

3D reduced graphene oxide/FeNi3-ionic liquid nanocomposite modified sensor; an electrical synergic effect for development of tert-butylhydroquinone and folic acid sensor

This paper reports an electroanalytical sensor developed based on reduced graphene oxide/FeNi3 (FeNi3/rGO)-ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate (HMPF6) carbon paste electrode (CPE) for determining the antioxidant additive tertbutylhydroquinone (TBHQ) in the presence of folic acid. The FeNi3/rGO synthesized by hydrothermal strategy and characterized by X-ray diffraction (XRD) and FESEM methods. The electrochemical response were found to be linearly symmetrical to TBHQ and folic acid concentrations in the range from 0.05 to 900 μM and 0.6–1100 μM with detection limits of 10.0 nM and 0.1 μM, respectively. The FeNi3/rGO/HMPF6/CPE showed high-quality for determination of TBHQ in the presence of folic acid in the real samples with the separation potential ∼600 mV.

Application of antibody–nanogold–ionic liquid–carbon paste electrode for sensitive electrochemical immunoassay of thyroid-stimulating hormone

A novel electrochemical immunosensor based on carbon paste electrode (CPE) composed of ionic liquid (IL) and graphite was constructed. It demonstrated good efficiency for quick (each test in 30 s) determination of thyroid stimulating hormone (TSH). Electrode surface was modified by gold nanoparticles in order to immobilize of the thyroid stimulating hormone antibody (anti-TSH) on the CPE. The immunoassay structure was established by sandwiching the antigen (TSH) between the thyroid stimulating hormone antibody on the CPE surface modified with gold nanoparticles and the secondary antibody, polyclonal anti-human-TSH labeled with horseradish peroxidase (HRP-labeled anti-TSH). The signal of differential pulse voltammetry (DPV) was used as a basis for the determination of TSH concentration. This signal is generated by the reaction between O-aminophenol (OAP) and H2O2 catalyzed by HRP. The proposed immunosensor is able to measure the concentration of TSH in a linear range between 0.2 and 90.0 ng/mL with a detection limit 0.1 ± 0.02 ng/mL. In addition, high sensitivity and acceptable stability were achieved by this immunosensor which is promising in the clinical assay of TSH.

A novel electrochemical sensor fabricated by embedding ZnO nano particles on MWCNT for morphine detection

Sol-gel method was used to synthesize ZnO-MWCNT ionic liquid carbon paste electrode (ZnO/MWCNTs/IL/CPE) taking 1-methyl-3-butylimidazolium bromide as appropriate binder in carbon paste matrix for detection of morphine. X-ray diffraction (XRD), Transmission electron microscopic (TEM), Scanning electron microscopic (SEM) and Energy-Dispersive X-ray spectroscopic (EDS) techniques were used to characterize the nanocomposite. The results obtained by electrochemical oxidation of morphine on ZnO/MWCNTs/IL/CPE shows the detection of morphine in the linear range of 0.1 to 700 μmol L−1 and in the detection limit of 0.06 μmol L−1 (3σ). The simple fabrication method, high sensitivity, stability and low cost of the modified electrode were the main features of the prepared electrochemical sensor.

Nanomolar simultaneous determination of tryptophan and melatonin by a new ionic liquid carbon paste electrode modified with SnO2-Co3O4@rGO nanocomposite

This work describes the development of a new sensor for simultaneous determination of tryptophan and melatonin. The proposed sensor was an ionic liquid carbon paste electrode modified with reduced graphene oxides decorated with SnO2-Co3O4 nanoparticles. The voltammetric oxidation of the analytes by the proposed sensor confirmed that the electrooxidation process undergoes a two-electron/one-proton reaction for melatonin and a two-electron/two-proton reaction for tryptophan in diffusion-controlled processes. Moreover, based on the excellent electrochemical properties of the modified electrode, a sensitive voltammetric method was used for individual and simultaneous determination of melatonin and tryptophan in the aqueous solutions. Under the optimized experimental conditions, a linear response obtained in the range of 0.02 to 6.00μmolL−1 with detection limits of 4.1 and 3.2nmolL−1 for melatonin and tryptophan, respectively. The prepared sensor possessed accurate and rapid response toward melatonin and tryptophan with a good sensitivity, selectivity, stability, and repeatability. Finally, the applicability of the proposed sensor was verified by evaluation of melatonin and tryptophan in various real samples including human serum and tablet samples.

Highly sensitive nanostructure voltammetric sensor employing Pt/CNTs and 1-butyl-3-methylimidazolium hexafluoro phosphate for determination of tryptophan in food and pharmaceutical samples

A novel, sensitive, selective and simple method for the direct and quantitative determination of l-tryptophan (Trp) was proposed in this work. Pt/CNTs nanocompoite made by polyol technique, were used to modify ionic liquid carbon paste electrode (CPE) without any treatment to study the electrochemical behaviors of the Trp using cyclic voltammetry (CV) and chronoamperometry (CA) and square wave voltammetry (SWV) methods. The results demonstrated that the 1-butyl-3-methylimidazolium hexafluoro phosphate (([C4mim]-[PF6])) Pt/CNTs modified carbon paste electrode ([C4mim]-[PF6]/Pt/CNTs/CPE) exhibited high catalytic activity and analytical performance towards the electro-oxidation of Trp. The linear oxidation response range and limit of detection were found to be 0.1–400μM and 0.04μM, respectively. The [C4mim]-[PF6]/Pt/CNTs/CPE was successfully applied for the voltammetric determination of Trp in food and pharmaceutical samples.

Synthesis of CdO nanoparticles using direct chemical precipitation method: Fabrication of novel voltammetric sensor for square wave voltammetry determination of chlorpromazine in pharmaceutical samples

ABSTRACTA chemically modified electrode was constructed and applied to the electrooxidation of the chlorpromazine (CPZ). The oxidation peak potential of the CPZ at a surface of CdO/nanoparticles (NPs) ionic liquid carbon paste electrode (CdO/NPs/IL/CPE) appeared at 695 mV. The CdO/NPs were characterized with different methods such as transmission electron microscope and X-ray diffraction. Under optimized (pH 7.0), linear calibration curves were obtained in the range of 0.1–350 µM for CPZ, which shows adequate for the quantification in real samples. The proposed method was successfully applied to the determination of CPZ in both pharmaceutical and urine samples.

Silica gel/gold nanoparticles/(NS)2 ligand nanoporous platform-modified ionic liquid carbon paste electrode for potentiometric ultratrace assessment of Ag(I)

A novel ionic liquid carbon paste electrode has been developed using sol–gel/Au nanoparticle (SGAN) involving (NS)2 compound of N,N′-di-(cyclopentadienecarbaldehyde)-1, 2-di (o-aminophenylthio) ethane (CCAE) as an appropriate neutral ion-carrier for ultrahigh-sensitive potentiometric determination of Ag(I). Colloidal gold nanoparticles (AuNPs) also well dispersed self-assembly into the 3-(mercaptopropyl)-trimethoxysilane (MPTS)-derived sol–gel network through Au–S covalent bond engendering continuous and super-conductive nanoporous three-dimensional array. The room-temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMIM.PF6), was applied as a super-conductive pasting agent (binder). The SGAN/CCAE/IL-CPE exhibited a significantly enhanced sensitivity and preferential selectivity toward Ag(I) over a wide concentration range of 2.4 × 10−9 to 2.2 × 10−2 mol L−1 (R 2 = 0.9996) with a lower limit of detection of 7.9 × 10−10 M and a Nernstian slope of 58.5 (±0.3) mV decade−1. The electrode has a short response time of ∼5 s and long-time durability of about 2 months without any considerable divergence in potentials. Moreover, the potentiometric examinations could be carried out within the wide pH range of 3.5–9.5. Eventually, the practical utility of the proposed Ag(I)-sensor was evaluated by volumetric titration of AgNO3 solution by sodium chloride and recovery of silver content in some real samples using flame atomic absorption spectroscopy as a confident reference.

Highly sensitive determination of promazine in pharmaceutical and biological samples using a ZnO nanoparticle-modified ionic liquid carbon paste electrode

Abstract In this work we describe the first report for the determination of promazine using a nanostructure-modified ionic liquid carbon paste electrode in aqueous solutions. To achieve this goal, a novel modified carbon paste electrode using ZnO nanoparticles and 1-methyl-3-butylimidazolium bromide as a binder (ZnO/NPs/ILs/CPE) was fabricated. The oxidation peak potential of promazine at the surface of the ZnO/NPs/ILs/CPE appeared at 685 mV, which was about 65 mV lower than the oxidation potential at the surface of CPE under similar conditions. Also, the peak current was increased to about 4.0 times higher at the surface of ZnO/NPs/ILs/CPE compared to that of CPE. The linear response range and detection limit were found to be 0.08–450 and 0.04 μmol/L, respectively. The modified electrode was successfully used for the determination of promazine in real samples with satisfactory results.

Electrochemical determination of carbamazepin in the presence of paracetamol using a carbon ionic liquid paste electrode modified with a three-dimensional graphene/MWCNT hybrid composite film

In this research work, a carbon ionic liquid paste electrode (CILPE) based on butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([bmim] NTF2) was fabricated and further modified with graphene/multiwall carbon nanotube (GR/MWCNT) hybrid composite. The modified electrode (GR/MWCNT/CILPE) was used for measurement of carbamazepine (CBZ) in the presence of paracetamol (PA) with an excellent electrochemical catalytic behavior. The application of the electrode was investigated by cyclic voltammetry and differential pulse voltammetry. The oxidation peak currents of CBZ and PA were linear at the ranges of 1–60μM and 2–80μM, respectively. Also, the detection limits for CBZ and PA were 0.233μM and 0.262μM, respectively. The proposed sensor was successfully applied for the determination of CBZ and PA in tablet and urine samples.

Bisphenol A Analysis in Food Samples Using Modified Nanostructure Carbon Paste Electrode as a Sensor

The electrochemical oxidation of bisphenol A has been studied by CdO nanoparticle ionic liquid carbon paste electrode. Cyclic voltammetry, square wave voltammetry, and chronoamperometry were used to investigate the suitability of new sensor for the electrooxidation of bisphenol A in aqueous solution. The electrooxidation of bisphenol A occurs at a potential about 50 mV less positive than with the unmodified carbon paste electrode at pH 7.0. The square wave voltammetry (SWV) peak currents of the electrode increased linearly with the corresponding bisphenol A concentration in the range of 0.3–650 μM with a detection limit of 0.1 μM. The influence of pH value and potential interfering substances on the determination of bisphenol A were studied. Finally, the proposed novel sensor was also examined as a sensitive, high selective, simple, and precise electrochemical sensor for the determination of bisphenol A in food samples.

A highly selective voltammetric sensor for nanomolar detection of mercury ions using a carbon ionic liquid paste electrode impregnated with novel ion imprinted polymeric nanobeads.

This work reports the preparation of a voltammetric sensor for selective recognition and sensitive determination of mercury ions using a carbon ionic liquid paste electrode (CILE) impregnated with novel Hg(2+)-ion imprinted polymeric nanobeads (IIP) based on dithizone, as a suitable ligand for complex formation with Hg(2+) ions. The differential pulse anodic stripping voltammetric technique was employed to investigate the performance of the prepared IIP-CILE for determination of hazardous mercury ions. The designed modified electrode revealed linear responses in the ranges of 0.5nM-10nM and 0.08μM-2μM with a limit of detection of 0.1nM (S/N=3). It was found that the peak currents of the modified electrode for Hg(2+) ions were at a maximum value in phosphate buffer of pH4.5. The optimized preconcentration potential and accumulation time were to be -0.9V and 35s, respectively. The applicability of the proposed sensor to mercury determination in waste water samples is reported.