A sensitive and selective voltammetric method for the detection of pyrogallol in tomato and water samples using platinum electrode modified with alizarin red S film

In contrast to the hyperactive platinum electrode, ARS modified platinum electrode presents a remarkable inertness toward adsorption and surface processes and lends it for further voltammetric applications. Measuring pyrogallol levels in samples is significant for assessing their antioxidant activity, which is crucial for understanding their potential health benefits and ability to combat oxidative stress. In addition, the excess consumption of pyrogallol can have significant negative effects on human health. A voltammetric sensor has been developed for the determination of pyrogallol using ARS modified platinum electrode. The electrode was prepared by electrodeposition of alizarin red S on a platinum electrode using cyclic voltammetry with a potential scan range of - 0.4 to 1.2 V against an Ag/AgCl quasi reference electrode for 60 cycles as optimum number of cycles. The modified electrode was characterized by CV and SEM techniques. This modified alizarin red S platinum electrode showed remarkable electrocatalytic performance and stability, resulting in a significant increase in pyrogallol oxidation current by 11.05% compared to the pyrogallol oxidative current at the unmodified platinum electrode. A well-defined oxidation peak was observed at ~ 0.40 V. The sensor exhibited a low limit of detection (LOD) of 0.28 µM and a linear standard curve covering the ranges of 1.0-40 µM and 0.01-10.0 mM pyrogallol. Extensive studies were performed to evaluate possible interferences from various organic and inorganic compounds and yielded satisfactory results that confirm the selectivity of the developed sensor for pyrogallol determination. In addition, the ARS-Pt electrode provided consistently reliable results for the accurate detection of pyrogallol in water and tomato samples.

Exposure to pyrogallol impacts the hemato-biochemical endpoints in catfish (Clarias gariepinus)

Pyrogallol is widely used in several industrial applications and can subsequently contaminate aquatic ecosystems. Here, we report for the first time the presence of pyrogallol in wastewater in Egypt. Currently, there is a complete lack of toxicity and carcinogenicity data for pyrogallol exposure in fish. To address this gap, both acute and sub-acute toxicity experiments were conducted to determine the toxicity of pyrogallol in catfish (Clarias gariepinus). Behavioral and morphological endpoints were evaluated, in addition to blood hematological endpoints, biochemical indices, electrolyte balance, and the erythron profile (poikilocytosis and nuclear abnormalities). In the acute toxicity assay, it was determined that the 96 h median-lethal concentration (96 h-LC50) of pyrogallol for catfish was 40 mg/L. In sub-acute toxicity experiment, fish divided into four groups; Group 1 was the control group. Group 2 was exposed to 1 mg/L of pyrogallol, Group 3 was exposed to 5 mg/L of pyrogallol, and Group 4 was exposed to 10 mg/L of pyrogallol. Fish showed morphological changes such as erosion of the dorsal and caudal fins, skin ulcers, and discoloration following exposure to pyrogallol for 96 h. Exposure to 1, 5, or 10 mg/L pyrogallol caused a significant decrease in hematological indices, including red blood cells (RBCs), hemoglobin, hematocrit, white blood cells (WBC), thrombocytes, and large and small lymphocytes in a dose-dependent manner. Several biochemical parameters (creatinine, uric acid, liver enzymes, lactate dehydrogenase, and glucose) were altered in a concentration dependent manner with short term exposures to pyrogallol. Pyrogallol exposure also caused a significant concentration-dependent rise in the percentage of poikilocytosis and nuclear abnormalities of RBCs in catfish. In conclusion, our data suggest that pyrogallol should be considered further in environmental risk assessments of aquatic species.

N,N-dicarboxymethyl Perylene-diimide-modified CdV2O6 Nanorods for Colorimetric Sensing of H2O2 and Pyrogallol

The peroxidase-like activity of CdV₂O₆ nanorods has been considerably improved by modification with N, N-dicarboxymethyl perylene-diimide (PDI) as a photosensitizer. The peroxidase-like behaviors are evaluated by virtue of the colorless chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB), which is fast changed into blue oxTMB in the presence of H₂O₂ in only 90 s. PDI-CdV₂O₆ exhibits high stability at elevated temperatures and PDI-CdV₂O₆ retains more than 70% of its catalytic activity over a wide range of 15 to 60 °C. The catalytic mechanism of PDI-CdV₂O₆ is ascribed to the synergistic interaction between PDI and CdV₂O₆ and the generation of •O₂^- radicals. Based on the enhanced peroxidase-like activity of PDI-CdV₂O₆, a selective colorimetric sensor has been constructed for H₂O₂ and pyrogallol (PG) with detection limits of 36.5 μM and 0.179 μM, respectively. The feasibility of the proposed sensing platform has been validated by detecting H₂O₂ in milk and pyrogallol in tap water.

A low-cost carbon-based electrochemical platform for determining 2,3-dihydroxyphenol: applications in natural water and biodiesel samples

2,3-Dihydroxyphenol (DHP) is a phenolic compound that has been used as an additive in biodiesel to avoid the auto-oxidation of biofuels and also in the production of cosmetic products. However, this substance can be released into the environment during its manufacture, transport, disposal and industrial use and can be harmful to health due to its toxicity, and hence, monitoring its presence in different samples is very important. Therefore, this work describes an electroanalytical study of DHP using different carbon-based pastes prepared to evaluate which one would be more promising to be used as an electrochemical platform for DHP quantification. The materials studied (graphite, carbon black and carbon nanotubes) in this work were characterized by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and the Boehm method. Voltammetric studies showed that pure carbon black presented a higher current density for detecting DHP than the other materials tested (graphite, carbon black + graphite, carbon nanotubes, carbon nanotubes + graphite). In studying the medium's pH, the highest currents occurred in acid media and acetate buffer solutions. After optimizing the experimental parameters, it was possible to obtain a wide range of linear responses from 0.1 to 10 000 μmol L^-1 for DHP and a good limit of detection (LOD) of 0.03 μmol L^-1. The selectivity of the electrode was tested for different species that may be present in samples containing DHP. Finally, the electrode was applied to determine DHP in natural water and biodiesel samples, showing recovery values between 98 and 102%, indicating good accuracy.

Novel imidazole fluorescent poly(ionic liquid) nanoparticles for selective and sensitive determination of pyrogallol

This paper reports novel imidazole fluorescent poly(ionic liquid) nanoparticles (FPILNs) of poly(1-[(4-methyphenyl)methyl]-3-vinyl-imidazolium bromide (poly([MVI]Br) for selective and sensitive determination of pyrogallol. An imidazole ionic liquid of 1-[(4-methyphenyl)methyl]-3-vinyl-imidazolium bromide ([MVI]Br) was synthesized and used as the only monomer to obtain poly([MVI]Br) possessing phenyl fluorophores using a radical polymerization technique. The obtained poly([MVI]Br) can form nanoparticles in water. Scanning electron microscopy and dynamic light scattering results revealed majority of poly([MVI]Br) FPILNs with diameters ranging from 40 to 400nm. Although [MVI]Br showed weak fluorescence intensity, poly([MVI]Br) FPILNs exhibited strong fluorescence intensity with a quantum yield of 0.192, which is attributed to the presence of significant number of phenyl fluorophores and rigid construction. The selective and sensitive determination of pyrogallol was achieved through fluorescence quenching of poly([MVI]Br) FPILNs, and the quenching was attributed to the oxidation of poly([MVI]Br) FPILNs by O₂˙¯ produced by pyrogallol autoxidation. The poly([MVI]Br) FPILNs-based sensor demonstrated a good linear relationship between the extent of fluorescence quenching and the concentration of pyrogallol in a range of 0.05 - 10.0μM, achieving a detection limit of 0.01μM. Furthermore, the poly([MVI]Br) FPILNs-based assay detected pyrogallol in environmental water samples, suggesting its potential to be applied for practical purposes.