A voltammetric sensor for simultaneous determination of ascorbic acid, noradrenaline, acetaminophen and tryptophan

Second-order advantage to quantify uric acid and ascorbic acid in blood serum by β-cyclodextrin inclusion complexation

The complexes formed between β-cyclodextrin (β-CD) and uric acid (UA) as well as ascorbic acid (AA) were examined utilizing parallel factor analysis (PFA) as a second-order calibration method (SOCM) for their quantification in blood serum samples. The second-order data were derived from the variations in spectral absorption changes associated with the β-CD complex signals. A three-dimensional dataset was created by stacking the data along the third dimension, which was analyzed by SOCM for determination of UA and AA. Validation of the method was achieved through comparison with HPLC. The findings indicated that the PFA method exhibited remarkable predictive capabilities. Figures of merit were calculated to highlight its potential as a viable alternative for the quantification of UA and AA, even in the presence of unforeseen or untemplated interferents, without necessitating any sample pretreatment.

Electrochemical methods for the determination of acetaminophen in biological matrices: A critical review in the clinical field

BACKGROUND

Paracetamol or acetaminophen (APAP), or acetaminophen, is a widely used medication for pain relief and fever reduction due to its analgesic and antipyretic properties. However, excessive APAP consumption can lead to severe hepatotoxicity and nephrotoxicity, posing overdose risks. Consequently, the development of analytical methods for an accurate and rapid detection of APAP in biological matrices is of great interest in the health-related fields. Electrochemical methods have emerged as efficient, cost-effective, and sensitive tools for APAP detection in biological samples. In the light of the reported insights, this review examines critically diverse electrochemical methods for PAR detection in different biological matrices, including serum, urine, oral fluid, and sweat.

RESULTS

The claimed benefits of chemically-modified electrodes towards the selective determination of paracetamol in such complex sample matrices are discussed. On the other hand, the possible use of unmodified carbon-based electrodes combined with flow methods is highlighted as an alternative that can find relevance in the analysis of biological fluids suspected of PAR overdose occurring in the forensic scenario. Furthermore, the details regarding the distinct techniques and working electrodes for APAP determination are presented, compared and discussed in separate sections for each biological sample (serum, urine, and oral fluid). Another aspect herein debated is the selective determination of APAP in the presence of electroactive drugs naturally found in biological samples, as uric acid, and ascorbic acid, are evaluated. In addition, we have discussed and emphasized the significance of matrix selection to ensure precise results, especially in potential overdose scenarios.

SIGNIFICANCE

This review article provides a critical discussion on the development of electroanalytical methods for biological fluids, with relevance to the fields of clinical analysis and forensics.

Accurate, affordable, and easy electrochemical detection of ascorbic acid in fresh fruit juices and pharmaceutical samples using an electroactive gelatin sulfonamide

In this study, we demonstrated how to design and construct a highly specific and sensitive sensor capable of rapidly and accurately detecting ascorbic acid (AA). A sulfonamide derivative (S) acting as a novel monomer was synthesized through an aldol condensation reaction. Subsequently, a free radical-mediated grafting polymerization approach was used to create a new generation of gelatin (Gel) grafted with poly sulfonamide derivative (Gel-g-PS). The graft percentage (GP%) was 60 ± 0.5% with a conversion rate of 98.3%. Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were utilized to confirm the formation of Gel-g-PS. The developed gelatin sulfonamide modified screen printed electrode (Gel-g-PS/SPE) was employed for the determination of ascorbic acid (AA) in fruit juices and pharmaceutical samples. Gel-g-PS/SPE showed excellent electrochemical catalytic activities toward AA oxidation compared to bare (unmodified) SPE. Ascorbic acid displayed a sensitive oxidation peak at 0.35 V using the differential pulse voltammetry technique. Under optimized experimental conditions, the two linear ranges for AA detection were obtained to be from 0.2-5 ppb and 20-600 ppb, with a limit of detection (LoD) of 0.03 ppb and a limit of quantification (LoQ) of 0.11 ppb. The proposed Gel-g-PS modified SPE surface demonstrated good selectivity, stability, reproducibility, and repeatability as well as a good recovery rate in fresh fruit juices and pharmaceutical samples.

Gold Nanoparticles/Carbon Nanotubes and Gold Nanoporous as Novel Electrochemical Platforms for L-Ascorbic Acid Detection: Comparative Performance and Application

Herein, the effects of nanostructured modifications of a gold electrode surface in the development of electrochemical sensors for L-ascorbic acid detection have been investigated. In particular, a bare gold electrode has been modified by electrodeposition of gold single-walled carbon nanotubes (Au/SWCNTs) and by the formation of a highly nanoporous gold (h-nPG) film. The procedure has been realized by sweeping the potential between +0.8 V and 0 V vs. Ag/AgCl for 25 scans in a suspension containing 5 mg/mL of SWCNTs in 10 mM HAuCl4 and 2.5 M NH4Cl solution for Au/SWCNTs modified gold electrode. A similar procedure was applied for a h-nPG electrode in a 10 mM HAuCl4 solution containing 2.5 M NH4Cl, followed by applying a fixed potential of −4 V vs. Ag/AgCl for 60 s. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the properties of the modified electrodes. The developed sensors showed strong electrocatalytic activity towards ascorbic acid oxidation with enhanced sensitivities of 1.7 × 10−2 μA μM−1cm−2 and 2.5 × 10−2 μA μM−1cm−2 for Au/SWCNTs and h-nPG modified electrode, respectively, compared to bare gold electrode (1.0 × 10−2 μA μM−1cm−2). The detection limits were estimated to be 3.1 and 1.8 μM, respectively. The h-nPG electrode was successfully used to determine ascorbic acid in human urine with no significant interference and with satisfactory recovery levels.

Design of a new electrochemical sensing system based on MoS2–TiO2/reduced graphene oxide nanocomposite for the detection of paracetamol

Synthetic route for the MoS₂–TiO₂/rGO nanocomposite and the electrode reaction for paracetamol.

Broccoli-shaped biosensor hierarchy for electrochemical screening of noradrenaline in living cells

Monitoring and determination of ultra-trace concentrations of monoamine neurotransmitter such as noradrenaline (NA) in living cells with simple, sensitive and selective assays are significantly interesting. We design NA-electrode sensing system based on C-, N-doped NiO broccoli-like hierarchy (CNNB). The spherical broccoli-head umbrella architectures associated with nano-tubular arrangements enabled to tailor NA biosensor design. The homogenous doping and anisotropic dispersion of CN nanospheres along the entire NB head nanotubes lead to creating of abundant electroactive sites in the interior tubular vessels and outer surfaces for ultrasensitive detection of NA in living cells such as PC12. The CNNB biosensor electrodes showed efficient electrocatalytic activity, enhanced kinetics for electrooxidation of NA, and fast electron-transfer between electrode-electrolyte interface surfaces, enabling synergistic enhancement in sensitivity, and selectivity at a low-detectable concentration of ∼ 6nM and reproducibility of broccoli-shaped NA-electrodes. The integrated CNNB biosensor electrodes showed evidence of monitoring and screening of NA released from PC12 cells under K⁺ ion-extracellular stimulation process. The unique features of CNNB in terms of NA-selectivity among multi-competitive components, long-term stability during the detection of NA may open their practical, in-vitro application for extracellular monoamine neurotransmitters detection in living cells.

Rapid Detection of Ascorbic Acid Based on a Dual-Electrode Sensor System Using a Powder Microelectrode Embedded with Carboxyl Multi-Walled Carbon Nanotubes

In this paper, carboxyl groups were introduced by liquid oxidation methods onto multi-walled carbon nanotubes (MWCNTs) to improve the MWCNTs' electrocatalytic properties. A platinum wire microelectrode (ME) was corroded using aqua regia and subsequently embedded with MWCNTs to achieve more active sites, producing a so-called powder microelectrode (PME). Compared with conventional MEs, the PME has a larger specific surface area and more active sites. When PME was used to detect ascorbic acid (AA), the AA oxidation potential shifted negatively and current peak was visibly increased. The calibration curve obtained for AA was in a range of 5.00 × 10-6~9.50 × 10-4 mol·L-1: Ipa(μA) = 3.259 × 10-2+ 1.801 × 10² C (mol·L-1) under the optimum testing conditions. Moreover, the detection and quantitation limits were confirmed at 4.89 × 10-7 mol·L-1 and 1.63 × 10-7 mol·L-1, respectively. When the fabricated PME was practically applied to detect AA, it was shown a recovery rate of 94~107% with relative standard deviation (RSD) <5%. The proposed strategy thus offers a promising, rapid, selective and low-cost approach to effective analysis of AA.