Fluorimetric determination of hydrogen peroxide in water using acetaminophen

Sensitive determination of hydrogen peroxide in real water samples by high spin peroxo complex

In this paper, a fast, cheap, simple, sensitive and selective spectrophotometric method based on high spin peroxo-Fe(III)-EDTA complex in the alkaline medium was developed for the determination of hydrogen peroxide (H₂O₂) in real water samples. The purple-coloured complex with a maximum absorbance at a wavelength of 525 nm was formed. Various parameters such as type of stabilizer reagent and its concentration, reaction time, Fe(III), EDTA and NH₃ concentration were optimized. The method was confirmed with the Beer’s law with a molar absorption coefficient of 267.36 L mol^-1 cm^-1 in the 8.3 ×10^-6 –4.08 ×10^-3 mol/L concentration range. Sandell’s sensitivity of the proposed method was also calculated as 0.188 μg/cm² . LOD and LOQ were determined as 2.5 ×10^-6 and 8.3 ×10^-6 mol/L, respectively. Intraday and interday relative standard deviation of the proposed method for 2.0 ×10^-4 mol / L of H₂O₂ were found as 1.5% and 6.1%, respectively. The developed method is suitable for fast monitoring of H₂O₂ in different types of aqueous water samples without any sample preparation steps and acceptable recovery values between 90% and 118% were obtained. In the sample analysis, H₂O₂ removed solutions from the real water samples were used for blank correction in their analysis and this process provides more reliable and accurate results in real sample analysis.

Sinusoidal voltage electrodeposition of PEDOT-Prussian blue nanoparticles composite and its application to amperometric sensing of H2O2 in human blood

A selective electrochemical sensor based on poly(3,4-ethylenedioxythiophene) (PEDOT) - Prussian blue nanoparticles (PBNPs) for hydrogen peroxide (H₂O₂) determination was prepared by innovative sinusoidal voltage (SV) method. The successful incorporation of citrate-stabilized PBNPs into PEDOT matrix was confirmed by energy dispersive X-ray analysis (EDX), Raman spectroscopy, UV-Vis spectroelectrochemistry and cyclic voltammetry measurements. The SV preparation method provides a PEDOT-PBNPs coating with rough surface morphology and good electrocatalytic activity toward H₂O₂ reduction. The amperometric response of PEDOT-PBNPs-based sensor at -50 mV vs. Ag/AgCl is linear within the range of concentrations from 5 μM to 1 mM H₂O₂ with a detection limit of 1.4 μM H₂O₂. The proposed Pt/PEDOT-PBNPs sensor displays good repeatability, reproducibility, operational stability as well as good selectivity toward H₂O₂ determination in the presence of interfering species like dopamine (DA), uric acid (UA), KNO₂ glucose (Glu), KNO₃ and ascorbic acid (AA), and was successfully applied to H₂O₂ determination in human blood samples without biofouling.

Fenton reaction-mediated fluorescence quenching of N-acetyl-L-cysteine-protected gold nanoclusters: analytical applications of hydrogen peroxide, glucose, and catalase detection

Given the importance of hydrogen peroxide (H2O2) in many biological processes and its wide application in various industries, the demand for sensitive, accurate, and economical H2O2 sensors is high. In this study, we used Fenton reaction-stimulated fluorescence quenching of N-acetyl-L-cysteine-protected gold nanoclusters (NAC-AuNCs) as a reporter system for the determination of H2O2. After the experimental conditions were optimized, the sensing platform enabled the analysis of H2O2 with a limit of detection (LOD) as low as 0.027 μM. As the glucose oxidase cascade leads to the generation of H2O2 and catalase catalyzes the decomposition of H2O2, these two biocatalytic procedures can be probed by the Fenton reaction-mediated quenching of NAC-AuNCs. The LOD for glucose was found to be 0.18 μM, and the linear range was 0.39-27.22 μM. The LOD for catalase was 0.002 U mL(-1), and the linear range was 0.01-0.3 U mL(-1). Moreover, the proposed sensing methods were successfully applied for human serum glucose detection and the non-invasive determination of catalase activity in human saliva, demonstrating their great potential for practical applications.

Preparation of a Superhydrophobic and Peroxidase-like Activity Array Chip for H2O2 Sensing by Surface-Enhanced Raman Scattering

In this paper, we propose a novel and simple method for preparing a dual-biomimetic functional array possessing both superhydrophobic and peroxidase-like activity that can be used for hydrogen peroxide (H2O2) sensing. The proposed method is an integration innovation that combines the above two properties and surface-enhanced Raman scattering (SERS). We integrated a series of well-ordered arrays of Au points (d = 1 mm) onto a superhydrophobic copper (Cu)/silver (Ag) surface by replicating an arrayed molybdenum template. Instead of using photoresists and the traditional lithography method, we utilized a chemical etching method (a substitution reaction between Cu and HAuCl4) with a Cu/Ag superhydrophobic surface as the barrier layer, which has the benefit of water repellency. The as-prepared Au points were observed to possess peroxidase-like activity, allowing for catalytic oxidation of the chromogenic molecule o-phenylenediamine dihydrochloride (OPD). Oxidation was evidenced by a color change in the presence of H2O2, which allows the array chip to act as an H2O2 sensor. In this study, the water repellency of the superhydrophobic surface was used to fabricate the array chip and increase the local reactant concentration during the catalytic reaction. As a result, the catalytic reaction occurred when only 2 μL of an aqueous sample (OPD/H2O2) was placed onto the Au point, and the enzymatic product, 2,3-diaminophenazine, showed a SERS signal distinguishable from that of OPD after mixing with 2 μL of colloidal Au. Using the dual-biomimetic functional array chip, quantitative analysis of H2O2 was performed by observing the change in the SERS spectra, which showed a concentration-dependent behavior for H2O2. This method allows for the detection of H2O2 at concentrations as low as 3 pmol per 2 μL of sample, which is a considerable advantage in H2O2 analysis. The as-prepared substrate was convenient for H2O2 detection because only a small amount of sample was required in each analysis. Highly sensitive detection was realized using SERS. Therefore, this chip was shown to exhibit significant potential for applications in bioanalysis.

Spectrophotometric determination of hydrogen peroxide in water and cream samples

A simple, rapid and sensitive spectrophotometric method is described for the determination of hydrogen peroxide using toluidine blue as a reagent. The proposed method is based on the liberation of iodine in acidic medium equivalent to the amount of hydrogen peroxide present. The liberated iodine bleaches the blue color of toluidine blue and is measured at 628 nm. The decrease in absorbance is directly proportional to hydrogen peroxide concentration and obeys Beer's law in the range 0.2 x 10(-6) -14 x 10(-6) mol L(-1). The molar absorptivity, sandel's sensitivity, detection limit and quantitation limit of the method were found to be 1.82 x 10(4) L mol(-1) cm(-1), 2.01 x 10(-9) mol L(-1), 1.41 x 10(-6) mol L(-1) and 4.28 x 10(-6) mol L(-1) respectively. The results of analysis of the proposed method are compared favorably with those from a reference method.