Differential Pulse Voltammetric Method Research Articles

Voltammetric Assessment of Paracetamol on a CuONPs – MWCNTs Modified Glassy Carbon Electrode

In this work, an electrochemical sensor using differential pulse voltammetric method for the assessment of antipyretic and analgesic drug, paracetamol was developed. The CuO nanoparticles were synthesized and characterized. A glassy carbon electrode (GCE) fabricated with the suspension of CuO nanoparticles (CuONPs) and multi-walled carbon nanotubes (MWCNTs) were used. The fabricated electrode was characterized using Potassium ferricyanide as a redox probe, which showed increase in the electro active area in the modified electrode. The modified electrode showed improved anodic peak current enhancement in phosphate buffer solution. The consequence of pH of supporting electrolyte and amount of nanoparticles suspension were investigated at a physiological pH of 7.4. Using differential pulse voltammetry, the fabricated electrode showed linear dynamic range from 9 to 160 nM of paracetamol concentration. From the calibration plot, the computed detection limit was 5.06nM and quantification limit was16.88 nM. The developed method was checked for its reproducibility and assay during a day and intraday as well and the results were good with permitted range of errors. The developed process was fruitfully applied to detect paracetamol in pharmaceutical formulations.

Electrochemical sensor based on mesoporous g-C3N4/N-CNO/gold nanoparticles for measuring oxycodone

Oxycodone, often used as an analgesic, is a potent opioid. While its effectiveness has been proven in the control of moderate to acute pain, excessive use of oxycodone imposes heart failure, heart palpitations, reduction of red blood cells, bone pain, and even death. Therefore, monitoring the oxycodone concentration in blood is vital for emergency care. For this purpose, a novel electrochemical sensor was designed based on a glassy carbon electrode modified with mesoporous g-C3N4 (M-C3N4), carbon nano-onions doped with nitrogen (N-CNO), and gold nanoparticles. At first, the SEM and XRD techniques were employed to characterize prepared M-C3N4 and N-CNO samples. The electro-oxidation behavior of the oxycodone was evaluated by cyclic and differential pulse voltammetric methods. Based on the influence of the potential scanning rate and solution pH on the voltammetric response of oxycodone oxidation, a redox mechanism was proposed. A 16 nM detection limit was acquired for the oxycodone analysis with a linear response in the 0.05–150 µM range. This sensor showed a remarkable ability for oxycodone detection in plasma samples. The long-term stability, superior selectivity, and reproducibility of this sensor prove its ability to measure oxycodone accurately and precisely in authentic spices.

Solid Bismuth Drop Electrode – A New Tool for Voltammetric Determination of Electrochemically Reducible Organic Compounds

Solid bismuth drop electrode (SBiDE) is a new working electrode commercially available on the Czech market from 2020 by the company Metrohm. The aim of this work was to verify the applicability of the SBiDE in the voltammetric determination of a model organic substance. According to the available information, this is the very first published work on this topic. Metronidazole (an antibiotic used to treat diseases caused by both Gram-positive and Gram-negative anaerobic bacteria) was chosen in this study as a model drug representing electrochemically reducible biologically active compounds. Under optimum conditions (Britton-Robinson buffer of pH 12.0 used as the supporting electrolyte and no electrochemical regeneration of the working electrode surface), a linear calibration dependence of metronidazole was recorded in the concentration range from 1 to 600 μmol L–1, with the limits of detection (LOD) and quantification (LOQ) of 0.41 μmol L–1 and 1.4 μmol L–1, respectively. The newly developed differential pulse voltammetric (DPV) method has also been successfully applied in the determination of metronidazole in various dosage forms.

A new generation of fully-printed electrochemical sensors based on biochar/ethylcellulose-modified carbon electrodes: Fabrication, characterization and practical applications

Biochar is a material prepared by biomass pyrolysis, representing a more sustainable and efficient alternative to commonly used conventional carbon materials in electroanalysis. The aim of this paper is to point out that it can also show significant potential in the mass screen-printing production of miniaturized, low-cost, disposable and sensitive electrochemical sensors. Herein, a new generation of fully screen-printed electrochemical sensors is introduced, based on biochar/ethylcellulose-modified carbon working electrodes. The optimization in the sensor fabrication, involving the variability in the concentration of a binder and rheology modifier (ethylcellulose) and its impact on biochar inks from the viewpoint of viscoelasticity, printability and thermal stability, was performed to obtain the carbon-based electrochemical sensors with favourable robustness. The viability of these electrochemical sensors was demonstrated by the development and full validation of a new and sensitive differential pulse voltammetric method for the fast and reliable determination of paracetamol in pharmaceutical formulations. Within the method development, all necessary aspects, such as a study of the effect of ethylcellulose concentration, pH study of supporting electrolyte, selection of pulse parameters and analytical performance, were investigated. The obtained results allow us to predict the production and subsequent use of new, printable, cheap and environmentally friendly sensor platforms, which will exhibit convenient analytical performance with the possibility of commercialization.

Voltammetric behavior of solifenacin succinate on gold, glassy carbon and boron-doped diamond electrodes: Stability testing and determination

The anticholinergic drug, solifenacin, is frequently used for the treatment of the urological tract for urinary incontinence, and urinary frequency. The development of reliable and effective solifenacin electrochemical sensors is of great importance for the pharmaceutical industry and clinical practice. In this work, the electrochemical behavior of solifenacin succinate (SOL) was studied using three different working electrodes: gold (Au), glassy carbon (GCE) and boron-doped diamond electrode (BDDE). The cyclic voltammetric (CV) measurements performed in 0.05 M NaHCO3 indicated that the SOL oxidation process is irreversible and diffusion-controlled at all investigated working electrodes. Afterwards, the testing of SOL electrochemical stability and the possibility of its electrochemical degradation was performed at the Au electrode by the cycling of the potential during 3 h and continuously to 6 h. It was shown that the SOL was electrochemically transformed into another electroactive species and its degradation was excluded. For electroanalytical application, the anodically pretreated BDDE (+2.0 V; 30 s) was selected. Various experimental parameters were optimized, including the pH of the aqueous Britton-Robinson (B-R) buffer as a supporting electrolyte (from pH 2.0 to 11.98) and the most intensive peak of the target analyte was at pH 11.0, so this pH value was chosen as the optimum for further measurements. Based on the correlation of the SOL peak intensity and different concentrations, the developed differential pulse voltammetric (DPV) method was characterized by a linear concentration range from 0.041 to 2.50 µM, with a correlation coefficient of 0.999, and a relative standard deviation of 0.3 %. Taking into account the sensitivity of the developed DPV method towards the electrochemical oxidation of SOL, a very low detection limit of 0.012 µM in the model system was achieved. The BDDE showed adequate selectivity for SOL in the presence of the investigated interferents. The obtained results indicate that the BDDE with an optimized DPV method could be applied for the trace-level electroanalytical determination of SOL in human urine sample with excellent recovery and reproducibility.

Triangle-Shaped Cerium Tungstate Nanoparticles Used to Modify Carbon Paste Electrode for Sensitive Hydroquinone Detection in Water Samples.

In this study, we propose an eco-friendly method for synthesizing cerium tungstate nanoparticles using hydrothermal techniques. We used scanning, transmission electron microscopy, and X-ray diffraction to analyze the morphology of the synthesized nanoparticles. The results showed that the synthesized nanoparticles were uniform and highly crystalline, with a particle size of about 50 nm. The electrocatalytic properties of the nanoparticles were then investigated using cyclic voltammetry and electrochemical impedance spectroscopy. We further used the synthesized nanoparticles to develop an electrochemical sensor based on a carbon paste electrode that can detect hydroquinone. By optimizing the differential pulse voltammetric method, a wide linearity range of 0.4 to 45 µM and a low detection limit of 0.06 µM were obtained. The developed sensor also expressed excellent repeatability (RSD up to 3.8%) and reproducibility (RSD below 5%). Interferences had an insignificant impact on the determination of analytes, making it possible to use this method for monitoring hydroquinone concentrations in tap water. This study introduces a new approach to the chemistry of materials and the environment and demonstrates that a careful selection of components can lead to new horizons in analytical chemistry.

Gold particle-modified glassy carbon electrode: an advanced electrochemical sensor for dipyrone monitoring

This study presents the development and optimization of a gold particle-modified glassy carbon electrode (Au/GCE) as an advanced electrochemical sensor for monitoring dipyrone (DIP), a commonly used pharmaceutical compound. The objective of this study was to enhance the sensitivity and accuracy of DIP quantification through efficient experimental planning and the incorporation of gold particles onto the surface of the GCE. The electrodeposition of gold particles onto the GCE significantly improved the response of DIP in a 0.5 mol L−1 H2SO4 solution. By employing a design of experiments (DoE) approach, we optimized the differential pulse voltammetric (DPV) method, resulting in enhanced performance, including the achievement of a remarkably low limit of detection (0.15 µmol L−1). To assess the accuracy of the electroanalytical method, we conducted extensive recovery tests, which yielded recovery values ranging from 98.9% to 104% for DIP concentration in pharmaceutical formulations. These results emphasize the selectivity and robustness of the developed electroanalytical method, positioning it as a reliable tool for monitoring DIP. The comprehensive account of experimental procedures, optimization strategies, and analytical validation presented in this study establish the efficacy and potential applications of the developed sensor in pharmaceutical analysis. Overall, this research contributes valuable insights into the field of electrochemical sensing and offers promising prospects for its application in various pharmaceutical and clinical settings.

An innovative nanoparticle-modified carbon paste sensor for ultrasensitive detection of lignocaine and its extremely carcinogenic metabolite residues in bovine food samples: Application of NEMI, ESA, AGREE, ComplexGAPI, and RGB12 algorithms.

Nowadays, veterinary medicine residues have been viewed as a major threat to food safety worldwide, especially when dealing with carcinogenic residues. Herein, we present the first differential pulse voltammetric method for the quantification of lignocaine and its carcinogenic metabolite 2,6-xylidine residues in bovine food samples, aided by five greenness and whiteness assessment tools, including NEMI, ESA, ComplexGAPI, AGREE, and RGB12. The method depends on the electrochemical oxidation after modification of the carbon paste sensor with recycled Al2O3-NPs functionalized multi-walled carbon nanoparticles. The produced sensor (Al2O3-NPs/MWCNTs/CPE) was characterized using XRD, FT-IR, EDX, SEM, and TEM. As expected, the active surface area and electron transfer processes were accelerated by the modification, resulting in ultra-sensitive quantification with detection limits of 19.00 and 13.94nM for lignocaine and 2,6-xylidine, respectively. In terms of greenness, whiteness, sustainability, analytical effectiveness, and economic and practical considerations, the proposed method outperforms the reported methods.

Electrochemical Sensor Based on N–Doped Carbon Nanodots Derived from the Agro-Waste Cotton Boll Peel Extracts for Nano Molar Determination of an Anti-Cancer Drug, Pemetrexed

A green and facile one-step synthetic route was proposed for the synthesis of nitrogen-doped carbon nanodots (N-CDs) from agro-waste cotton boll peel extract as a natural carbon source and glycine as a nitrogen source. The prepared N-CDs were utilized further in the fabrication of an electrochemical sensor for the nanomolar determination of an anti-cancer drug, pemetrexed (PMT). The electrode material was characterized by XRD, FTIR, TEM, Raman, EDX, UV–vis, fluorescence, cyclic voltammetric and electrochemical impedance spectroscopic studies. The N-CDs drop-casted on the surface of glassy carbon electrode (GCE) served as a good sensing material and exhibited electrocatalytic activity as evident from ∼20-fold enhancement in the oxidation peak current of PMT at N-CDs/GCE with 130 mV lesser positive oxidation peak potential than that at bare GCE. This was attributed to excellent conductivity, higher electroactive surface area, graphitic cores of N-CDs besides the interactions between PMT and N-CDs via hydrogen bonding and π–π stacking. The sensing performance of the demonstrated electrode was optimized by varying the peak current dependant parameters and also by investigating the influence of interfering substances in the determination of PMT. The electrochemical behaviour of PMT at different pH revealed the adsorption controlled electrode process with the involvement of protons. Under optimized conditions, differential pulse voltammetric (DPV), square wave voltammetric (SWV) and adsorptive differential pulse voltammetric (AdSDPV) methods were developed for sensitive determination of PMT at nano molar level. Further, these developed analytical methods were applied successfully for the determination of PMT in analyte fortified human urine samples and pharmaceutical formulations.

Fabrication of NiSe2 decorated graphene oxide nanocomposite modified electrode as a high performance electrochemical sensor for carbamazepine

AbstractRecently, semiconductor nanomaterials have gained interest amongst researchers because of their good electrocatalytic properties. Two dimensional (2D) transition metal dichalcogenide materials, NiSe2 have good physical, chemical, and transport properties for sensing applications. The present work demonstrates the fabrication of NiSe2‐graphene oxide (NiSe2−GO) modified glassy carbon electrode for the determination of carbamazepine (CBZ). The prepared nanocomposite was characterized by XRD, SEM and FT‐IR spectral methods. CBZ exhibited an irreversible oxidation peak at 0.85 V on NiSe2−GO/GCE in phosphate buffer of pH 7.0. A 54‐fold enhancement in oxidation peak current was observed at NiSe2−GO/GCE when compared to that at bare GCE. Sensing performance of NiSe2−GO/GCE was optimized by varying peak current dependent parameters. Linear relationship between the peak current and concentration of CBZ was observed in the range of 4.50×10−8–3.22×10−5 mol L−1 for differential pulse voltammetric method and 2.32×10−8–4.79×10−5 mol L−1 for square wave voltammetric method. The practical utility of the proposed sensor, was demonstrated by determining CBZ in pharmaceutical formulations and spiked urine samples.

Molten salt Cu(I) intercalation into the poly(triazine imide) for the electrochemical sensing of nitrite

AbstractSlight modification of the molten salt synthesis of poly(triazine imide) (PTI) with introduction of copper (I) chloride yielded a novel copper modified material. Energy‐dispersive x‐ray spectroscopy together with electron microscopy confirmed homogenous distribution of the copper within PTI lattice. X‐ray photoelectron spectroscopy suggests the copper to coordinate randomly at bridging nitrogen atoms. Thus obtained material exhibited excellent sensitivity to nitrite anions together with low limits of detection. Under previously optimized experimental conditions and pH 4 of supporting electrolyte, differential pulse voltammetric detection method showed linear response in wide range from 5 to 2200 μM with detection limit of 1.3 μM. Practical applicability for the developed method was scrutinized in wastewater and pipe water samples. Developed method of metal ion intercalation open doors to widespread introduction of metal ions in the PTI structure for practical utilization.

A simple voltammetric method to evaluate the firing distance through determination of nitrocellulose

Nitrocellulose (NC) is the main component of propellants for small firearm ammunitions. Even though NC particles are ejected from gun barrels together with bullets and they are often recovered on close-to-muzzle targets, quantitative analysis of nitrocellulose for forensic purposes has been neglected so far. Moreover, although the presence of the nitroester groups makes nitrocellulose electroactive, its electrochemical determination has been poorly considered in literature. In this paper, a quantitative differential pulse voltammetric method for the analysis of nitrocellulose in targets is suggested, with the aim of estimating its concentration decay on targets with increasing the shooting distance. The presented method works in acetonitrile/ethanol/lithium perchlorate, has a LOQ of 4 mg L−1 and linearity up to 2000 mg L−1. Ammunitions loaded with a nitrocellulose/nitroglycerine-based gunpowder were discharged to draw a calibration curve for shooting distance determination in the range from 5 cm to 120 cm. The effect of possible interfering substances (water, nitroglycerine, nitroguanidine, nitrites) was evaluated, and results are compared with literature methods.

Voltammetric determination of sulfamethoxazole using commercial screen-printed carbon electrodes

A differential pulse voltammetric (DPV) method using commercial screen-printed carbon electrodes (SPCE) is developed for a fast and cost-effective determination of the antibiotic sulfamethoxazole (SMX). Optimal measurements are carried out at pH 5.5 in acetate buffer and yield a detection limit of 15 µg/L and a linearity range of 50 – 600 µg/L with good repeatability (1.1%) and reproducibility (2.5%). The method is successfully applied to the analysis of a spiked tap water sample with very high reproducibility (0.4%) and good trueness (Recovery 95.2%).Additional considerations are made about the irreversible electrochemical oxidation of SMX, which is notoriously pH-dependent according to a process involving 2e- and 2H+, in agreement with several reported mechanisms in the literature. Besides, the analysis of other sulfonamide antibiotics is discussed, showing the key role of the free terminal amino group in oxidation, which makes almost undistinguishable voltammetric signals from different molecules sharing this moiety. In contrast, the acetylation of the mentioned group (e.g., in sulfonamide metabolites) drastically reduces the sensitivity of voltammetric measurements.

An electrochemical sensor based on graphene nanoribbon nano-catalyst for determination of etoposide as an approved drug in lung cancer

Monitoring of anticancer drugs is an important strategy in clinical investigation. Determining the level of these drugs in chemotherapy processes provides useful information about the treatment process. The etoposide is one of the important drugs approved to lung cancer with many side effects. Therefore, monitoring of it is so important in clinical process and specially chemotherapy processes. The presence study focused on design of a new, simple, electrical-based, safe and fast response sensor to trace level monitoring of etoposide in biological fluids and pharmaceutical samples. The sensor successfully determined etoposide in nano-level concentration that is very important to investigation role of this anticancer drug in biological fluids. To this goal, the graphene nanoribbon nano-catalyst (GNR) was synthesized and characterized by MAP and SEM methods. The electrochemical catalytic activity of it was investigated by electrochemical impedance spectroscopy method. In continuous, glassy carbon electrode (GCE) modified with GNR was fabricated and ability of sensor to sensing of etoposide was investigated by differential pulse voltammetric (DPV) method. The GNR/GCE monitored etoposide in the concentration range 0.4–150 µM with detection limit 0.1 µM by DPV methods. At biological condition (pH = 7.4), the GNR/GCE was successfully used to monitoring of etoposide in urine, serum and injection samples and data confirmed with HPLC method and Statistical tests.

Voltammetric Detection of Vanillylmandelic Acid and Homovanillic Acid Using Urea-Derivative-Modified Graphite Electrode

Vanillylmandelic acid (VMA) and homovanillic acid (HVA) are diagnostic markers of neuroblastoma. The purpose of this study was to understand the reason for the discrimination of structural analogues (VMA and HVA) onto a graphite electrode coated with an electrochemically oxidized urea derivative. Density functional theory calculations (DFT), FTIR spectroscopic measurements, and electrochemical impedance spectroscopic measurements were used in this work. Density functional theory calculations (DFT) were used to identify the most suitable binding sites of the urea derivative and to describe possible differences in its interaction with the studied analytes. The FTIR measurement indicated the enhancement and disappearance of NH vibrations on graphite and platinum surfaces, respectively, that could be connected to a different orientation and thus provide accessibility of the urea moiety for the discrimination of carboxylates. Additionally, the higher the basicity of the anion, the stronger the hydrogen-bonding interaction with -NH-groups of the urea moiety: VMA (pKb = 10.6, KAds = (5.18 ± 1.95) × 105) and HVA (pKb = 9.6, KAds = (4.78 ± 1.58) × 104). The differential pulse voltammetric method was applied to detect VMA and HVA as individual species and interferents. As individual analytes, both HVA and VMA can be detected at a concentration of 1.99 × 10-5 M (RSD ≤ 0.28, recovery 110-115%).

Electrochemical behavior of fungicide tebuconazole and its voltammetric determination on an oxygen-terminated boron-doped diamond electrode

The first study on electrochemical oxidation of triazole fungicide tebuconazole was performed using an oxygen-terminated boron-doped diamond electrode. The irreversible anodic process occurring at + 1.75 V (vs Ag/AgCl/KCl(sat.)) in 0.1 mol/L HNO3 was studied by cyclic voltammetry, IR spectroelectrochemistry, and density functional theory calculations. The oxidation of tebuconazole leads to the formation of the hydroxylated and dihydroxylated derivatives on the 4-chlorophenyl moiety. Also, the corresponding o-quinone derivative was detected. Further, the anodic signal was used to develop a differential pulse voltammetric method for tebuconazole determination with the following parameters: linear dynamic range from 5.0 × 10−7 to 8.3 × 10−5 mol/L and limit of detection of 1.5 × 10−7 mol/L. The method was successfully applied to the analysis of a commercially available pesticide formulation and model samples of river water after preconcentration of tebuconazole using Amberlite® IRC120 H ion-exchange resin in H+ cycle.

Ultrasensitive Electrochemical Sensor Based on SnO2 Anchored 3D Porous Reduced Graphene Oxide Nanostructure Produced via Sustainable Green Protocol for Subnanomolar Determination of Anti-Diabetic Drug, Repaglinide

Herein, we have reported on a simple, environmentally friendly, and ultra-sensitive electrode material, SnO2@p-rGO, used in a clean sustainable manner for rapid electrochemical determination of an anti-diabetic agent, repaglinide (RPG). Three-dimensional porous reduced graphene oxide nanostructure (p-rGO) was prepared via a low-temperature solution combustion method employing glycine. The aqueous extract of agricultural waste “cotton boll peel” served as stabilizing and reducing agents for the synthesis of SnO2 nanoparticles. The structural and morphological characterization was carried out by XRD, Raman, SEM, EDX, FTIR, absorption, and TGA. The oxidation process of RPG was realized under adsorption controlled with the involvement of two protons and electrons. The sensor displayed a wider linearity between the concentration of RPG and oxidation peak current in the ranges of 1.99 × 10−8–1.45 × 10−5 M and 4.99 × 10−8–1.83 × 10−5 M for square-wave voltammetric and differential pulse voltammetric methods, respectively. The lower limit of detection value of 0.85 × 10−9 M was realized with the SWV method. The proposed sensor was applied for the quantification of RPG in fortified urine samples and pharmaceutical formulations. Furthermore, the sensor demonstrated reproducibility, long-term stability, and selectivity in the presence of metformin and other interferents, which made the proposed sensor promising and superior for monitoring RPG.

Electrochemical Detection of Olivetol Based on Poly(L-Serine) Film Layered Copper Oxide Modified Carbon Paste Electrode (p-L-Serine/CuO/CPE)

Olivetol is an important polyphenol compound and intermediate in the synthesis of cannabinoids possessing many types of biological activities. A facile electrochemical sensor for olivetol was fabricated based on p-L-serine, and copper oxide (CuO) nanoparticles modified carbon paste electrode (p-L-serine/CuO/CPE). The proposed p-L-serine/CuO/CPE was applied to the electrochemical detection of olivetol by cyclic voltammetry (CV) and differential pulse voltammetric (DPV). Through the characterizations of materials and modified electrodes, the p-L-serine/CuO/CPE exhibited enhanced electrochemical signals for olivetol compared to bare CPE and CuO/CPE in both CV and DPV methods. Under the optimized conditions, the proposed p-L-serine/CuO/CPE showed a good quantitative analysis ability and a wide analysis range from 20 to 100 μmol L-1 of olivetol with a limit of detection of 1.04 μmol L-1. Based on the reproducibility, repeatability, and stability exhibited by this fabricated sensor and the cheap and accessible raw materials, the p-L-serine/CuO/CPE became a novel determination choice for olivetol in the electrochemical method with the advantages of being cost-effective and convenient.

Electroanalysis of Naringin at Electroactivated Pencil Graphite Electrode for the Assessment of Polyphenolics with Intermediate Antioxidant Power.

A simple and rapid differential pulse voltammetric (DPV) method using a single-use electroactivated pencil graphite electrode (PGE*) is proposed for the rapid screening of the total content of polyphenolics (TCP) with intermediate antioxidant power (AOP) in grapefruit peel and fresh juice. The results were compared and correlated with those provided by the HPLC-DAD-MS method. NG voltammetric behavior at PGE* was studied by cyclic voltammetry and an oxidation mechanism was suggested. The experimental conditions (type of PGE, electroactivation procedure, pH, nature and concentration of supporting electrolyte) for NG DPV determination were optimized. The NG peak current varied linearly with the concentration in the ranges 1.40 × 10-6-2.00 × 10-5 and 2.00 × 10-5-1.40 × 10-4 mol/L NG and a limit of detection (LoD) of 6.02 × 10-7 mol/L NG was attained. The method repeatability expressed as relative standard deviation was 7.62% for the concentration level of 2.00 × 10-6 mol/L NG. After accumulation for 240 s of NG at PGE* the LoD was lowered to 1.35 × 10-7 mol/L NG, the linear range being 6.00 × 10-7-8.00 × 10-6 mol/L NG. The developed electrochemical system was successfully tested on real samples and proved to be a cost-effective tool for the simple estimation of the TCP with intermediate AOP in citrus fruits.

Hydrothermal synthesis of N,S-doped carbon quantum dots as a dual mode sensor for azo dye tartrazine and fluorescent ink applications

In this paper, blue-emitting N,S-doped carbon quantum dots (N,S-CQDs) were fabricated via a hydrothermal process from a mixture of o-phenylenediamine and methionine. They exhibit photoluminous (PL) emission at 440 nm, with a quantum yield (QY) of 20 %. Various physio-chemical approaches were employed to explore the structural, morphological, optical and electrochemical behaviour of the N,S-CQDs. The functional groups such as carboxyl (–COOH), hydroxyl (–OH), amino (–NH2) and thiol (-SH) on the N,S-CQDs surface allows it to have good QY, and excellent water solubility. The proposed sensor could detect tartrazine (TT), a common synthetic food dye using fluorescence and electrochemical approaches. The fluorescence method achieved a limit of detection (LOD) of 80 nM within the linear range of 0–10 μM. A combination of static quenching process and inner filter effect (IFE) was involved in the sensing mechanism. In electrochemical sensing, the differential pulse voltammetric (DPV) method was successfully applied within the linear range of 5–35 nM and a LOD of 2 nM. Both methods were successfully used to determine tartrazine levels in soft drinks and candies. In addition, the N,S-CQDs based fluorescent ink was developed for writing, drawing and fingerprint imaging applications.