Electrochemical study and flow injection analysis of paracetamol in pharmaceutical formulations based on screen-printed electrodes and carbon nanotubes

Enhanced Acetaminophen Electrochemical Sensing Based on Nitrogen-Doped Graphene

Because of the widespread acetaminophen usage and the danger of harmful overdosing effects, developing appropriate procedures for its quantitative and qualitative assay has always been an intriguing and fascinating problem. A quick, inexpensive, and environmentally friendly approach based on direct voltage anodic graphite rod exfoliation in the presence of inorganic salt aqueous solution ((NH₄)₂SO₄-0.3 M) has been established for the preparation of nitrogen-doped graphene (exf-NGr). The XRD analysis shows that the working material appears as a mixture of few (76.43%) and multi-layers (23.57%) of N-doped graphenes. From XPS, the C/O ratio was calculated to be 0.39, indicating a significant number of structural defects and the existence of multiple oxygen-containing groups at the surface of graphene sheets caused by heteroatom doping. Furthermore, the electrochemical performances of glassy carbon electrodes (GCEs) modified with exf-NGr for acetaminophen (AMP) detection and quantification have been assessed. The exf-NGr/GCE-modified electrode shows excellent reproducibility, stability, and anti-interfering characteristics with improved electrocatalytic activity over a wide detection range (0.1-100 µM), with a low limit for AMP detection (LOD = 3.03 nM). In addition, the developed sensor has been successfully applied in real sample analysis for the AMP quantification from different commercially available pharmaceutical formulations.

Voltammetric Determination of Active Pharmaceutical Ingredients Using Screen-Printed Electrodes

A simple, fast, sensitive and low-cost voltammetric method using a screen-printed carbon electrode (SPCE) is presented in this work for the simultaneous determination of ascorbic acid (AA), paracetamol (PA), dextromethorphan (DX) and caffeine (CF) in both pharmaceutical formulations and samples of environmental interest. The oxidative peak current displayed linear dependence on concentration within the range 1.7–60.5, 0.6–40.0, 0.9–8.4 (1st linear part) and 1.8–22.0 mg L−1 for AA, PA, DX and CF, respectively; and detection limits of 0.5, 0.2, 0.3 and 0.5 mg L−1, respectively. The developed differential pulse voltammetric (DPV) method was validated using both a pharmaceutical product and a spiked well water sample. A very good agreement between the determined and the theoretical label drug content and recoveries in the range of 99.5–100.8% were obtained for pharmaceutical product and well water samples, respectively.

Screen-Printed Technologies Combined with Flow Analysis Techniques: Moving from Benchtop to Everywhere

Screen-printed electrodes (SPEs) coupled with flow systems have been reported in recent decades for an ever-growing number of applications in modern electroanalysis, aiming for portable methodologies. The information acquired through this combination can be attractive for future users with basic knowledge, especially due to the increased measurement throughput, reduction in reagent consumption and minimal waste generation. The trends and possibilities of this set rely on the synergistic behavior that maximizes both SPE and flow analyses characteristics, allowing mass production and automation. This overview addresses an in-depth update about the scope of samples, target analytes, and analytical throughput (injections per hour, limits of detection, linear range, etc.) obtained by coupling injection techniques (FIA, SIA, and BIA) with SPE-based electrochemical detection.

Conductive Metal-Organic Frameworks for Amperometric Sensing of Paracetamol

An electrochemical sensor for paracetamol is executed by using conductive MOF (NiCu-CAT), which is synthesized by 2, 3, 6, 7, 10, 11-hexahydroxytriphenylene (HHTP) ligand. The utility of this 2D NiCu-CAT is measured by the detection of paracetamol, p-stacking within the MOF layers is essential to achieve high electrical conductivity, redox activity, and catalytic activity. In particular, NiCu-CAT demonstrated detection Limit of determination near 5μM for paracetamol through a wide concentration range (5-190 μM). The NiCu-CAT/GCE exhibits excellent reproducibility, stability, and interference for paracetamol.

Chemically modified carbon-based electrodes for the determination of paracetamol in drugs and biological samples

Paracetamol is a non-steroidal, anti-inflammatory drug widely used in pharmaceutical applications for its sturdy, antipyretic and analgesic action. However, an overdose of paracetamol can cause fulminant hepatic necrosis and other toxic effects. Thus, the development of advantageous analytical tools to detect and determine paracetamol is required. Due to simplicity, higher sensitivity and selectivity as well as costefficiency, electrochemical sensors were fully investigated in last decades. This review describes the advancements made in the development of electrochemical sensors for the paracetamol detection and quantification in pharmaceutical and biological samples. The progress made in electrochemical sensors for the selective detection of paracetamol in the last 10 years was examined, with a special focus on highly innovative features introduced by nanotechnology. As the literature is rather extensive, we tried to simplify this work by summarizing and grouping electrochemical sensors according to the by which manner their substrates were chemically modified and the analytical performances obtained.

Disposable Nafion-Coated Single-Walled Carbon Nanotube Test Strip for Electrochemical Quantitative Determination of Acetaminophen in a Finger-Prick Whole Blood Sample

A disposable electrochemical test strip for the quantitative point-of-care (POC) determination of acetaminophen (paracetamol) in plasma and finger-prick whole blood was fabricated. The industrially scalable dry transfer process of single-walled carbon nanotubes (SWCNTs) and screen printing of silver were combined to produce integrated electrochemical test strips. Nafion coating stabilized the potential of the Ag reference electrode and enabled the selective detection in spiked plasma as well as in whole blood samples. The test strips were able to detect acetaminophen in small 40 μL samples with a detection limit of 0.8 μM and a wide linear range from 1 μM to 2 mM, well within the required clinical range. After a simple 1:1 dilution of plasma and whole blood, a quantitative detection with good recoveries of 79% in plasma and 74% in whole blood was achieved. These results strongly indicate that these electrodes can be used directly to determine the unbound acetaminophen fraction without the need for any additional steps. The developed test strip shows promise as a rapid and simple POC quantitative acetaminophen assay.

New Electrochemical Flow-Cell Configuration Integrated into a Three-Dimensional Microfluidic Platform: Improving Analytical Application in the Presence of Air Bubbles

A newly configured electrochemical flow cell to be used for (end-channel) amperometric detection in a microfluidic device is presented. The design was assembled to place the reference electrode in a separated compartment, isolated from the flow in the microchannel, while the working and counter electrodes remain in direct contact with both compartments. Moreover, a three-dimensional coil-shaped microfluidic device was fabricated using a nonconventional protocol. Both devices working in association enabled us to solve the drawback caused by the discrete injection when the automatic micropipette was used. The high performance of the proposed electrochemical flow cell was demonstrated after in situ modifying the surface of the platinum working electrode with surfactant (e.g., using Tween 20 at 0.10%). As the reference electrode remained out of contact with the flowing solution, there was no trouble by air bubble formation (generated by accidental insertion or by presence of surfactants) throughout the measurements. This device was characterized regarding its analytical performance by evaluating the amperometric detection of acetaminophen, enabling determination from 6.60 to 66.0 μmol L^-1. This issue is important since at high concentration (e.g., as assessed in clinical analysis) the acetaminophen is known to passivate the working electrode surfaces by electrogenerated products, impairing the accuracy of the electrochemical measurements.

Taking advantage of CTAB micelles for the simultaneous electrochemical quantification of diclofenac and acetaminophen in aqueous media

Cetyltrimethylammonium bromide hemimicelles, formed on the surfaces of a carbon paste electrode, selectively adsorbed diclofenac molecules from a neutral aqueous solution containing acetaminophen, allowing simultaneous quantification of both drugs.

Single Drop Electroanalysis and Interfacial Interactions: Sensitivity versus Limit of Detection†

We report single drop electroanalytical measurements of pharmaceutically and biologically relevant compounds using screen printed electrodes (SPEs) modified with carboxylated multiwalled carbon nanotubes (MWCNT-COOH) as the sensor surface. Acetaminophen, nicotine, ascorbic acid, and nicotinamide adenine dinucleotide reduced form (NADH) were detected in a single drop of solution. We show that combined polar and nonpolar interactions of analytes with -COOH functional groups and large surface area of MWCNT, respectively, allow highly sensitive analyte detection with wide dynamic range. Smaller analytes can bind to a significantly greater number of sensor sites than the bulkier analytes and offer better detection sensitivity. Results suggest that sensitivity is controlled by predominant nonpolar interactions that an analyte can undergo with the MWCNT-COOH SPE sensor surface, whereas limit of detection is controlled by the extent of polar interactions between an analyte and the sensor surface, facilitating interfacial charge transport and an electrochemical signal output. Furthermore, a combination of polar and nonpolar analyte interactions with the sensor surface shows a synergistic effect on sensitivity and detection limit. This could be a likely reason for why sensitivity does not need to always correlate with lower detection limits as variations in the interfacial interactions are critical. Application of the designed single drop method to real samples was validated by estimating the amounts of acetaminophen, nicotine, ascorbic acid, and NADH in commercially available pharmaceuticals with excellent recovery.

Electrochemical properties of the acetaminophen on the screen printed carbon electrode towards the high performance practical sensor applications

Acetaminophen is a non-steroidal anti-inflammatory drug used as an antipyretic agent for the alternative to aspirin. Conversely, the overdoses of acetaminophen can cause hepatic toxicity and kidney damage. Hence, the determination of acetaminophen receives much more attention in biological samples and also in pharmaceutical formulations. Here, we report a rapid and sensitive detection of the acetaminophen based on the bare (unmodified) screen printed carbon electrode (BSPCE) and its electrochemistry was studied in various pHs. From the observed results, the mechanism of the electro-oxidation of acetaminophen was derived for various pHs. The acetaminophen is not stable in strong acidic and strong alkaline media, which is hydrolyzed and hydroxylated. However, it is stable in intermediate pHs due to the dimerization of acetaminophen. The kinetics of the acetaminophen oxidation was briefly studied and documented in the schemes. In addition, the surface morphology and disorders of BSPCE was probed by scanning electron microscope (SEM) and Raman spectroscopy. Moreover, the BSPCE determined the acetaminophen with the linear concentration ranging from 0.05 to 190μM and the lower detection limit of 0.013μM. Besides that it reveals the good recoveries towards the pharmaceutical samples and shows the excellent selectivity, sensitivity and stability. To the best of our knowledge, this is the better performance compare to the previously reported unmodified acetaminophen sensors.

A Novel One-Step Fabricated, Droplet-Based Electrochemical Sensor for Facile Biochemical Assays

A simple, novel concept for the one-step fabrication of a low-cost, easy-to-use droplet-based electrochemical (EC) sensor is described, in which the EC reagents are contained in a droplet and the droplet assay is operated on a simple planar surface instead of in a complicated closed channel/chamber. In combination with an elegant carbon electrode configuration, screen-printed on a widely available polyethylene terephthalate (PET) substrate, the developed sensor exhibits a stable solution-restriction capacity and acceptable EC response, and thus can be used directly for the detection of different analytes (including ascorbic acid (AA), copper ions (Cu(2+)), 2'-deoxyguanosine 5'-triphosphate (dGTP) and ferulic acid (FA)), without any pretreatment. The obtained, acceptable linear ranges/detection limits for AA, Cu(2+), dGTP and FA are 0.5-10/0.415 mM, (0.0157-0.1574 and 0.1574-1.5736)/0.011 mM, 0.01-0.1/0.008 mM and 0.0257-0.515/0.024 mM, respectively. Finally, the utility of the droplet-based EC sensor was demonstrated for the determination of AA in two commercial beverages, and of Cu(2+) in two water samples, with reliable recovery and good stability. The applicability of the droplet-based sensor demonstrates that the proposed EC strategy is potentially a cost-effective solution for a series of biochemical sensing applications in public health, environmental monitoring, and the developing world.

A composite material based on nanoparticles of yttrium (III) oxide for the selective and sensitive electrochemical determination of acetaminophen

An electrochemical sensor was prepared by modifying a glassy carbon electrode (GCE) with a composite of yttrium (III) oxide nanoparticles (Y2O3NPs) and carbon nanotubes (CNTs) for the determination of acetaminophen (ACT). Compared with a bare GCE and CNTs/GCE, the Y2O3NPs/CNTs/GCE exhibited a well-defined redox couple for ACT and highly enhanced the current response. The separations in the anodic and cathodic peak potentials (ΔEp) for ACT were 552mV, 24mV and 10mV at ba4re GCE, CNTs/GCE and Y2O3NPs/CNTs/GCE, respectively. The observation of only 10mV of ΔEp for ACT at Y2O3NPs/CNTs/GCE was a clear indication of a great acceleration of the electrode process compared to bare GCE and GCE modified with CNTs. Also, l-ascorbic acid (l-AA) and l-tyrosine (l-TRY) did not interfere with the selective determination of ACT. Square wave voltammetry (SWV) was performed for the quantification of ACT. A linear plot was obtained for current responses versus the concentrations of ACT over the range from 1.0×10(-10) to 1.8×10(-8)M with a detection limit of 3.0×10(-11)M (based on 3Sb/m). The proposed composite material provided high electrocatalytic activity, improved voltammetric behavior, good selectivity and good reproducibility. The accurate quantification of ACT makes the proposed electrode of great interest for the public health.

Nickel oxide nanoparticles/ionic liquid crystal modified carbon composite electrode for determination of neurotransmitters and paracetamol

Ionic liquid crystals mimic the natural bio-based ionic liquid crystals such as cell membrane structures in their interactions with drugs.

Carbon nanotubes and graphene modified screen-printed carbon electrodes as sensitive sensors for the determination of phytochelatins in plants using liquid chromatography with amperometric detection

Nanomaterials are of great interest for the development of electrochemical sensors. Multi-walled carbon nanotubes and graphene were used to modify the working electrode surface of different screen-printed carbon electrodes (SPCE) with the aim of improving the sensitivity of the SPCE and comparing it with the conventional glassy carbon electrode. To assay the usability of these sensors, a HPLC methodology with amperometric detection was developed to analyze several phytochelatins in plants of Hordeum vulgare and Glycine max treated with Hg(II) or Cd(II) giving detection limits in the low μmolL(-1) range. Phytochelatins are low molecular weight peptides with the general structure γ-(Glu-Cys)n-Gly (n=2-5) which are synthesized in plants in the presence of heavy metal ions. These compounds can chelate heavy metal ions by the formation of complexes which, are transported to the vacuoles, where the toxicity is not threatening. For this reason phytochelatins are essential in the detoxification of heavy metal ions in plants. The developed HPLC method uses a mobile phase of 1% of formic acid in water with KNO3 or NaCl (pH=2.00) and 1% of formic acid in acetonitrile. Electrochemical detection at different carbon-based electrodes was used. Among the sensors tested, the conventional glassy carbon electrode offers the best sensitivity although modification improves the sensitivity of the SPCE. Glutathione and several isoforms of phytochelatin two were found in plant extracts of both studied species.

Multi-walled Carbon Nanotubes/Graphite Nanosheets Modified Glassy Carbon Electrode for the Simultaneous Determination of Acetaminophen and Dopamine

Graphite nanosheets prepared by thermal expansion and successive sonication were utilized for the construction of a multi-walled carbon nanotubes/graphite nanosheets based amperometric sensing platform to simultaneously determine acetaminophen and dopamine in the presence of ascorbic acid in physiological conditions. The synergistic effect of multi-walled carbon nanotubes and graphite nanosheets catalyzed the electrooxidation of acetaminophen and dopamine, leading to a remarkable potential difference up to 200 mV. The as-prepared modified electrode exhibited linear responses to acetaminophen and dopamine in the concentration ranges of 2.0 × 10(-6) - 2.4 × 10(-4) M (R = 0.999) and 2.0 × 10(-6) - 2.0 × 10(-4) M (R = 0.998), respectively. The detection limits were down to 2.3 × 10(-7) M for acetaminophen and 3.5 × 10(-7) M for dopamine (S/N = 3). Based on the simple preparation and prominent electrochemical properties, the obtained multi-walled carbon nanotubes/graphite nanosheets modified electrode would be a good candidate for the determination of acetaminophen and dopamine without the interference of ascorbic acid.

Facile and novel electrochemical preparation of a graphene-transition metal oxide nanocomposite for ultrasensitive electrochemical sensing of acetaminophen and phenacetin

A facile and novel preparation strategy based on electrochemical techniques for the fabrication of electrodeposited graphene (EGR) and zinc oxide (ZnO) nanocomposite was developed. The morphology and structure of the EGR-based nanocomposite were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (XPS) and Raman spectroscopy. Meanwhile, the electrochemical performance of the nanocomposite was demonstrated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Due to the synergistic effect of EGR and ZnO nanoparticles, an ultrasensitive electrochemical sensor for acetaminophen (AC) and phenacetin (PCT) was successfully fabricated. The linearity ranged from 0.02 to 10 μM for AC and 0.06 to 10 μM for PCT with high sensitivities of 54,295.82 μA mM(-1) cm(2) for AC and 21,344.66 μA mM(-1) cm(2) for PCT, respectively. Moreover, the practical applicability was validated to be reliable and desirable in pharmaceutical detections. The excellent results showed the promise of the proposed preparation strategy of EGR-transition metal oxide nanocomposite in the field of electroanalytical chemistry.

New approaches for carbon nanotubes-based biosensors and their application to cell culture monitoring

Amperometric biosensors are complex systems and they require a combination of technologies for their development. The aim of the present work is to propose a new approach in order to develop nanostructured biosensors for the real-time detection of multiple metabolites in cell culture flasks. The fabrication of five Au working electrodes onto silicon substrate is achieved with CMOS compatible microtechnology. Each working electrode presents an area of 0.25 mm², so structuration with carbon nanotubes and specific functionalization are carried out by using spotting technology, originally developed for microarrays and DNA printing. The electrodes are characterized by cyclic voltammetry and compared with commercially available screen-printed electrodes. Measurements are carried out under flow conditions, so a simple fluidic system is developed to guarantee a continuous flow next to the electrodes. The working electrodes are functionalized with different enzymes and calibrated for the real-time detection of glucose, lactate, and glutamate. Finally, some tests are performed on surnatant conditioned medium sampled from neuroblastoma cells (NG-108 cell line) to detect glucose and lactate concentration after 72 hours of cultivation. The developed biosensor for real-time and online detection of multiple metabolites shows very promising results towards circuits and systems for cell culture monitoring.