Determination Of 4-aminophenol Research Articles

A carbon based-screen-printed electrode amplified with two-dimensional reduced graphene/Fe3O4 nanocomposite as electroanalytical sensor for monitoring 4-aminophenol in environmental fluids

The analysis water pollutants are so important strategy for investigation of water quality. On the other hand, 4-aminophenol is known as a hazardous and high-risk compound for humans, and its detection and measurement is very important for investigating the quality of surface and groundwater. In this study, graphene/Fe3O4 nanocomposite was synthesized by a simple chemical method and characterized by EDS and TEM methods and results showed Nano spherical shape of Fe3O4 nanoparticle with diameter about 20 nM decorated at surface of 2D reduce graphene nanosheet (2D-rG-Fe3O4). The 2D-rG-Fe3O4 was used as excellent catalyst at surface of carbon-based screen-printed electrode (CSPE) and used as electroanalytical sensor in monitoring and determination of 4-aminophenol in waste water sample. The results confirmed improving ∼4.0 times in oxidation signal and reducing 120 mV in oxidation potential of 4-aminophenol at surface of 2D-rG-Fe3O4/CSPE compare to CSPE, respectively. The electrochemical investigation showed pH dependence behavior with equal value of electron and proton for -aminophenol at surface of 2D-rG-Fe3O4/CSPE. Using square wave voltammetry method (SWV), the 2D-rG-Fe3O4/CSPE successfully monitored 4-aminophenol in the concentration range 1.0 nM–200 μM. Finally, 2D-rG-Fe3O4/CSPE monitored 4-aminophenol in the different environmental fluids such as urban waste water, industrial waste water and river samples with recovery range 97.2%–104.3% that confirm powerful ability of 2D-rG-Fe3O4/CSPE as analytical tool.

Fabrication of TiO<sub>2</sub>-Carbon Paste Modified Electrochemical Sensor for 4-Aminophenol in Pharmaceutical Samples

In this study the electrochemical behavior of 4-aminophenol at titanium dioxide modified carbon paste electrode was investigated using cyclic voltammetry. The working parameters for both, cyclic- and square wave- voltametric studies have been optimized using 5.0 mM 4-aminophenol (4-APOH) in 0.1 M NaH<sub>2</sub>PO<sub>4</sub>.2H<sub>2</sub>O buffer solution. The modified rather than unmodified carbon paste sensor, in neutral medium, has exhibited strong electro-catalytic activity towards the redox characteristics of 4-aminophenol by showing two-fold peak current enhancement and 174 mV peak potential shift towards negative direction. The red-ox peak current ratio (I <sub>pa</sub>/I <sub>pc</sub> = 1.6) suggested high accumulation efficiency of 4-APOH at the modified sensor. The redox process is quasi reversible and involves the transference of 2e<sup>-</sup>s and 2H<sup>+</sup>s followed by diffusion controlled, non-adsorptive behavior of 4-APOH on the surface of sensor at the interface. Further, the electro-catalytic behavior of the modified sensor has been exploited for quantitative determination of 4-aminophenol in pharmaceutical samples using square wave voltammetry. Under optimal experimental conditions, there was a linear relationship between peak current and concentration in the range 2.5 × 10<sup>-5</sup> to 2.0 × 10<sup>-4</sup> M with a correlation coefficient of 0.998 and limit of detection 1.38 × 10<sup>-8</sup> M. The method was successfully applied for the quantitative determination of 4-aminophenol in pharmaceutical formulations against the commercial drugs <em>viz</em>., <em>PANADOL</em>, and <em>Paracetamol</em> at recovery level of 100 ± 1.7 %.

Determination of 4-aminophenol in a pharmaceutical formulation using surface enhanced Raman scattering: From development to method validation

A surface enhanced Raman scattering (SERS) method able to quantify 4-aminophenol in a pharmaceutical formulation based on acetaminophen, also called paracetamol, was developed and, for the first time, successfully validated. In this context, silver nanoparticles were synthesized according to the method described by Lee–Meisel and used as SERS substrate. The repeatability of the silver colloid synthesis was tested using different methods to characterize the size and the zeta potential of silver nanoparticles freshly synthesized. To optimize the SERS samples preparation, a design of experiments implicating concentrations of citrate-reduced silver nanoparticles and aggregating agent was performed in order to maximize the Raman signal enhancement. Finally, an approach based on tolerance intervals and accuracy profiles was applied in order to thoroughly validate the method in a range of concentrations comprised from 3 to 15µgmL−1 using normalized band intensities. The standard addition method was selected as method calibration. Therefore, measurements were carried out on 4-aminophenol spiked solutions of the pharmaceutical formulation. Despite the well-known stability and reproducibility problems of SERS, the validation was performed using two operators and five batches of nanoparticles, one for each validation day.

Heterogeneous Thermal-Lens Immunoassay for Small Organic Compounds: Determination of 4-Aminophenol

4-Aminophenol was selected as a model hapten for thermal-lens detection in a heterogeneous indirect immunoassay for small organic compounds. The assay is based on the competition of the free hapten and 4-aminophenol labeled with tetramethyl rhodamine isothiocyanate (TRITC) for rabbit anti-4-aminophenol antibodies (4-AP-GA-BSA) immobilized on a transparent poly(ethylene terephthalate) plate. The amount of the colored analyte was directly measured by thermal lensing at the plate surface. The developed method is specific for 4-aminophenol. The limit of detection is 2 x 10(-7) M, which corresponds to the absolute amount of 3 x 10(-11) mol of 4-aminophenol. The sensitivities of the developed thermal-lens and fluorescence-based measurements of the immunoassay under the same conditions are in good agreement with the expected and discussed theoretical sensitivities of photothermal and fluorescence measurements.

USING ZEOLITE-MODIFIED ELECTRODE FOR THE ELECTROCHEMICAL DETERMINATION OF 4-AMINOPHENOL FROM WATER

Two types of zeolite-modified electrodes, e.g., Ag-doped zeolite-expanded graphite-epoxy (AgZEG) and Cu-doped zeoliteexpanded graphite-epoxy (CuZEG) composite electrodes were tested for the application of the electrochemical determination of 4aminophenol (4-AP). The electrochemical techniques used for the electrochemical determination of 4-AP were cyclic voltammetry (CV) and chronoamperometry (CA). Some aspects related to the mechanistic behaviour are discussed. The electrochemical determination of 4-aminophenol on AgZEG and CuZEG composite electrodes was achieved in the concentration range 0.05 to 0.4 mM, with a sensitivity of about 0.2 mA*cm*mM. The electroanalytical performance of the determination of 4-AP on zeolite-modified electrodes was not influenced by the type of electrode.

Rapid detection of Escherichia coli by flow injection analysis coupled with amperometric method using an IrO 2–Pd chemically modified electrode

An amperometric method for the rapid detection of Escherichia coli ( E. coli) by flow injection analysis (FIA) using an IrO 2–Pd chemically modified electrode (CME) was developed in this paper. The method is based on a good marker β- d-galactosidase which was found in E. coli strains. β- d-galactosidase was produced by the induction of isopropyl β- d-thiogalactopyranoside (IPTG) and released from E. coli cells through the permeabilization of both polymyxin B nonapeptide and lysozyme to E. coli cells wall. The released β- d-galactosidase could catalyze the hydrolysis of the substrate p-aminophenyl β- d-galactopyranoside (PAPG) in the culture medium to produce 4-aminophenol which was proportional to the concentration of E. coli. Hence, E. coli could be detected by the determination of 4-aminophenol. An IrO 2–Pd CME, which showed high sensitivity in determination of 4-aminophenol, was prepared as the electro-detector in FIA. The amplified response current of 4-aminophenol obtained at the IrO 2–Pd CME was linear with the concentration of E. coli ranging from 2.0 × 10 2 to 1.0 × 10 6 cfu/mL, the detection limit of this method to E. coli was 150 cfu/mL and the complete assay could be performed in 3 h.

Micro volume rotating disk electrode (RDE) amperometric detection for a bead-based immunoassay

The application of the rotating disk electrode (RDE) directly on a micro drop of 50 μl has been developed for electrochemical detection in a bead-based immunoassay for the model analyte mouse IgG. The enzyme label alkaline phosphatase (ALP) was used for enzymatic turnover of the substrate 4-aminophenyl phosphate (PAPP) to the electroactive product 4-aminophenol (PAP). The determination of 4-aminophenol by the RDE has a linear range from 1.9 × 10 −8 to 1.9 × 10 −4 M. Direct analysis in a drop minimizes enzyme product dilution, a key requirement in achieving very low limits of detection. Furthermore, the detection scheme allows enzyme turnover to be monitored continuously, thus reducing errors associated with obtaining data at fixed times as in flow injection analysis. An unoptimized calibration curve for mouse IgG was obtained from 50 to 5000 ng/ml.

Solid-phase electrochemical enzyme immunoassay with attomole detection limit by flow injection analysis

A sandwich electrochemical enzyme immunoassay with flow injection analysis for the model antigen mouse IgG has been developed with alkaline phosphatase as the enzyme label. The enzyme substrate, 4-aminophenyl phosphate and its enzymatic reaction product, 4-aminophenol have been studied by cyclic and hydrodynamic voltammetry. The determination of 4-aminophenol by flow injection analysis with electrochemical detection (FIAEC) has a linear range of 5.0 × 10 −8 to 1.0 × 10 −5 M, a detection limit of 2.4 × 10 −8 M, and a sample throughput of 72 samples/h. The detection limit is set by a background capacitance response, which depends on the ionic strength difference between the sample and the mobile phase. The sandwich immunoassay has been characterized with respect to substrate concentration for the enzymatic reaction, detection limit, dynamic range and sources of error. Mouse IgG can be determined with a detection limit of 0.81 pg ml −1 by a 30-min substrate incubation time and a six orders of magnitude linear dynamic range.

Determination of 4-aminophenol in water by high-performance liquid chromatography with fluorescence detection

Le phenol (amino-«4») est une metabolite de l'insecticide parathion. Cette methode permet un dosage direct dans l'eau potable et l'eau de surface, pour des concentrations de l'ordre du ppb