Manganese oxide based screen-printed sensor for xenoestrogens detection

Chitosan-assisted self-assembly of flower-shaped ε-Fe2O3 nanoparticles on screen-printed carbon electrode for Impedimetric detection of Cd2+, Pb2+, and Hg2+ heavy metal ions in various water samples

The azathioprine (AZA) electrochemical adsorption onto the screen-printed carbon electrodes (SPCE) modified with the reduced graphene oxide (RGO) sheets in the absence and in the presence of polyaniline-emeraldine salt (PANI-ES) is reported in this work. Using cyclic voltammetry (CV), in the case of the SPCE modified with the RGO sheets non-functionalized and functionalized with PANI-ES, respectively, an irreversible process at the electrode/electrolyte interface is highlighted to take place. In the case of the SPCE modified with the non-functionalized RGO sheets (SPCERGO), the oxidation-reduction processes induce an up-shift of the AZA Raman lines from 856 and 1011 cm-1 to 863 and 1020 cm-1, respectively. These variations indicate an AZA adsorption onto the surface of the SPCE modified with the RGO sheets that takes place throught the imidazole and pyrimidine cycles of mercaptopurine, when the generation of the π-π* bonds between the mercaptopurine structure and hexagonal carbon cycles of RGO occurs. The electrochemical functionalization of the RGO sheets with PANI-ES is proved by the appearance of the Raman lines at 1165, 1332-1371, 1496 and 1585 and 1616 cm-1. The oxidation-reduction processes induced at the interface of the SPCE modified with PANI-ES functionalized RGO sheets and the electrolyte consisting into a phosphate buffer (PB) and AZA lead to the generation of new positive charges onto the PANI macromolecular chain and the adsorption of the drug on the working electrode surface that takes place via the π-π* bonds established between the benzene/quinoide rings of PANI and the imidazole/ purine cycles of AZA. These results indicate that the SPCE modified with the PANI-ES functionalized RGO sheets shows potential applications in the field of sensors for AZA detection.

Carbon screen-printed electrode (SPCE), multi-walled carbon nanotubes modified screen-printed electrode (SPCNTE), carbon nanofibers modified screen-printed electrode (SPCNFE), and graphene modified screen-printed electrode (SPGPHE) were in a pioneer way tested as sensors for the simultaneous determination of the two most consumed pain-killers, paracetamol (PA) and ibuprofen (IB), and the stimulant caffeine (CF) in water by differential pulse voltammetry (DPV). Their analytical performances were compared, and the resulting sensitivities (2.50, 0.074, and 0.24 μA V mg−1 L for PA, IB, and CF, respectively), detection limits (0.03, 0.6, and 0.05 mg L−1 for PA, IB, and CF, respectively) and quantification limits (0.09, 2.2, and 0.2 mg L−1 for PA, IB, and CF, respectively) suggested that the SPCNFE was the most suitable carbon-based electrode for the voltammetric determination of the selected analytes in water at trace levels. The methodology was validated using both spiked tap water and hospital wastewater samples. The results were compared to those achieved by liquid chromatography–tandem mass spectrometry (LC-MS/MS), the technique of choice for the determination of the target analytes.

A novel flow injection amperometric sensor based on carbon black and graphene oxide modified screen-printed carbon electrode for highly sensitive determination of uric acid

Modification of electrodes with polymer nanocomposites: Application to the simultaneous determination of Zn(II), Cd(II), and Cu(II) in water samples

Development of disposable amperometric sulfur dioxide biosensors based on screen printed electrodes

Biosensing of catechol via amperometry using laccase immobilized nickel oxide/graphite modified screen-printed electrodes

Magnetic dispersive solid-phase extraction (MDSPE) is combined with electrochemical detection by using a screen-printed carbon electrode modified with gold nanoparticles to determine lead(II). A zeolite-based magnetic composite was used as sorbent during sample preparation, thus combining the unique properties of zeolites as sorbent materials with the remarkable advantages provided by magnetic materials. Three different zeolite-based magnetic composites were initially investigated and characterized. ZSM-5/Fe2O3 treated with HNO3 (ZSM-5/Fe2O3(tr)) was finally selected as sorbent. Lead was extracted from urine samples using ZSM-5/Fe2O3(tr). After extraction, the phases were separated by using an external magnet. Subsequently, the magnetic composite carrying the analyte was directly deposited onto the working electrode of a modified screen-printed carbon electrode for final electrochemical detection. Thereby, the elution and detection of Pb(II) were carried out in a single step. A multivariate approach was employed to optimize the experimental parameters affecting extraction. Under optimized conditions and at a typical working potential of -0.23V (vs. Ag pseudo-reference electrode), response is linear in the 0 to 25μgL-1 Pb(II) concentration range. The empirical limit of detection ranged from 1.0 to 2.0μgL-1. The method was used to analyze Pb(II)-spiked urine samples, and apparent recoveries ranged between 99 and 107%, with coefficients of variation of <20%. Graphical abstractSchematic presentation of the analytical method to determine lead(II) in urine samples. Magnetic dispersive solid-phase extraction using a zeolite-based composite (ZSM-5/Fe2O3(tr)) is directly combined with electrochemical detection by using a screen-printed carbon electrode modified with gold nanoparticles (SPCnAuE).

Screen-printed carbon electrode (SPCE) has been extensively applied in electrochemical (EC) detection due to its excellent characteristics and low cost. However, SPCE is more likely to be contaminated that seriously affects the sensitivity and reproducibility of detection. In this paper, UV-ozone-cleaning process was utilized to solve this problem. Renewal mechanism of UV-ozone-cleaning on contaminated SPCE was firstly investigated in detail, in which the level of SPCE contamination was represented by interfacial impedance. Both scanning electron microscopy and X-ray photoelectron spectroscopy were employed to evaluate the surface morphology and chemical constituents of SPCE respectively. The results indicate that the significant EC enhancement was mainly attributed to the removal of contaminants, the increase of both reaction area and surface oxygen functional groups. To further demonstrate the renewal effect, the determination of nicotinamide adenine dinucleotide was performed. Compared with the contaminated SPCE, the UV-ozone-cleaned SPCE exhibits better EC response that the anodic peak current increased by 6∼28% and the sensitivity increased from 13.31 to 19.11 μA·mM−1. Moreover, the cleaned SPCE shows good reproducibility with the low standard deviation of peak current and oxidation potential.

Screen-printed carbon electrode (SPCE) is one of the most interesting designs to combine a working (from carbon based material), reference, and counter electrode in a single-printed substrate. SPCE has been used in many electrochemical measurements due to its advantages for analysis in microscale. This paper summarises the main information about SPCE fabrication from the material and fabrication technique aspect on the flat substrate based on the work that has been published in the last 30 years. The success of SPCE fabrication is highly dependent on the composition of conductive ink which consists of conductive materials, binder, and solvents; substrate; and fabrication techniques. Among the carbon-based materials, the most widely used for SPCE fabrications are graphite, graphene, and carbon nanotubes. The frequent binder used are polymer-based materials such as polystyrene, polyaniline, poly 3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS), and polyvinyl chloride. The solvents used for SPCE fabrication are varied including water and various organic solvents. The main characteristics of the SPCE substrate should be inert in order to avoid any interferences during electrochemical measurements. The screen printing and inkjet printing technique are preferred for SPCE fabrication due to easy fabrication and the possibility for mass production of SPCE.

A voltammetric method based on the use of screen-printed carbon electrodes (SPCEs) is presented for the simultaneous determination of salbutamol (SAL), sulfamethoxazole (SMX), and trimethoprim (TMP), with high sensitivity, fast response, and excellent repeatability and reproducibility. Under the optimal voltammetric conditions, the simultaneous analysis showed linear ranges of 0.3-2.5 mg L-1, 0.3-11.1 mg L-1, and 0.5-9.0 mg L-1 for SAL, SMX, and TMP, respectively, and detection limits of 83.8 μg L-1, 88.7 μg L-1, and 139.2 μg L-1, respectively. Additionally, the developed method was successfully validated by the analysis of a spiked river water sample with satisfactory recovery values in the range of 97.0-98.8%. The added value of the presented method relays in combining cost-effective disposable SPCEs with rapid analysis (<30 s), providing portable electrochemical tools for the on-site monitoring of pharmaceutical residues, which is critical for addressing contamination linked to anthropogenic activity.

Gold nanoparticle decorated patronite on rGO for the quantification of sulfadiazine at nanomolar levels in contaminated water

Electroactive polypyrrole-molybdenum disulfide nanocomposite for ultrasensitive detection of berberine in rat plasma

Comparative study of screen printed electrodes for ammonia gas sensing in ionic liquids

This article describes a general method for stabilizing microdroplets of mercury on thick‐film screen printed electrodes (SPEs). Electrodes modified with nickel metal powder are compared with amalgam stabilized mercury SPEs. Application of the electrodes to the measurement of organic materials is demonstrated by the electrochemical determination of 2‐furaldehyde, a marker for power transformer condition monitoring. The electrodes were characterized by cyclic voltammetry and subsequently a square‐wave voltammetric method was used to extend the detection limit of the measurement. The resulting cathodic currents for the reduction of 2‐furaldehyde was proportional to the concentration of 2‐furaldehyde. Plots of 2‐furaldehyde concentration against response at a nickel‐modified carbon SPE gave linear regions for concentrations in the range 3.7–14.3 ppm (regression equation; Y = 0.99 + 0.15x,r = 0.999, n = 3), and linear regions at mercury‐coated silver‐modified carbon SPEs in the range 8.9–36.4 ppm (regression equation; Y = 1.71 + 0.14x,r = 0.999, n = 3) and in the range 0.9–8.9 ppm (regression equation; Y = 1.34 + 0.17x,r = 0.980, n = 3), respectively. A particular advantage of using the mercury‐modified SPE rather than the nickel‐modified base card is that the well‐defined electrochemistry of furan derivatives allow them to be individually distinguished. The half‐wave potentials at the mercury SPE for 2‐furaldehyde (E1/2 = −1.15 V vs. Ag/AgCl) and two possible interferents 2‐acetyl‐furan and 5‐methyl‐2‐furaldehyde (E1/2 = −1.2 and −1.31 V vs. Ag/AgCl) are sufficiently well separated to allow the individual components to be resolved whereas at a nickel‐modified SPE a combined signal is observed.