Determination Of Nitrophenol Isomers Research Articles

Simultaneous voltammetric determination of nitrophenol isomers based on a modified electrode by silver nanowires and poly-L-arginine

ABSTRACT A novel-modified electrode was constructed for simultaneous determination of 4-nitrophenol (4NP) and 2-nitrophenol (2NP). A glassy carbon electrode (GCE) was modified by silver nanowires and poly-L-arginine (poly-L-Arg/AgNWs/GCE). Compared to GCE, the modified electrode showed more sensitive peak currents for the oxidation and reduction of nitrophenol isomers. Well-resolved oxidation peaks were appeared in cyclic voltammetry at +0.08 V (4NP) and at −0.32 V (2NP). Under optimised experimental conditions, calibration curves were obtained for the two isomers. The linear concentration range was 1.0–210 μM for 4NP, and 3.0–210 μM for 2NP, with limits of detection (LOD) as 0.9 μM and 1.0 μM, respectively. The application of the method to simultaneous determination of nitrophenol isomers in tap and river water samples was satisfactory. Low concentrations of 2NP and 4NP were spiked to the real samples and their recoveries were calculated by the proposed method. The recoveries in tap and river water samples were found to be 96.92% and 104.98% for 4NP (2.0 μM), and 95.31 and 103.88 for 2NP (3.0 μM), respectively. Relative standard deviations were calculated for three replicate measurements of the spiked nitrophenols which were between 3.50% and 4.73%. The sensor showed a long-term stability of more than 1 month.

Sensitive determination of nitrophenol isomers by reverse-phase high-performance liquid chromatography in conjunction with liquid–liquid extraction

ABSTRACTA method for the highly sensitive determination of 2-, 3- and 4-nitrophenols was developed using reverse-phase high-performance liquid chromatography (RP-HPLC) with a UV photodiode array detector. Using a reverse-phase column and 40% aqueous acetonitrile as an eluent (i.e. isocratic elution), the integrated peak area of detector output was linear up to 300 mg/L and the detection limit was 150 µg/L. The sensitivity of this detection method was improved by pretreating the sample solutions with a solvent extraction procedure that makes use of the high partition coefficient of ethyl acetate (EA)/water system. To find an optimum condition for the extraction procedure, this process was simulated by plotting the concentration of nitrophenol extracted in organic solvent against the volume multiplication factor at various partition coefficient of solute. This simulation demonstrated that EA is a superior extractant to other organic solvents. With the newly developed method, the detection limit was extended to 0.3 µg/L. This method offers fast, reliable and more sensitive determination of nitrophenol isomers than any other HPLC method.

Determination of Nitrophenol Isomers in Water

This paper establishes the HPLC method of determining three nitrophenol isomers in municipal sewage, surface water and tap water. After the sample is filtered and distilled, conduct the monitoring analysis on the distillate with HPLC-DAD and quantify it in external standard method. In the municipal sewage treated in bioanalysis method one type of target object o-nitrophenol is found, whose content is 0.11mg·L-1, no target object is found in all the other samples. This method has the adventages of high separation efficiency and high analysis rate. The experiment result shows that the linear correlation coefficient is above 0.983, the recovery rate lies between 78.6% and 105.2%, the minimum detection limit is 0.05mg·L-1(S/N=3.0).

A second-order advantage achieved with the aid of gold nanoparticle catalytic activity. Determination of nitrophenol isomers in binary mixtures

A novel, simple and rapid spectrophotometric method for the determination of nitrophenol (NP) isomer mixtures based on the catalytic activity of gold nanoparticles is described.

An adaptive wavelength interval selection by modified particle swarm optimization algorithm: simultaneous spectral or differential pulse voltammetric determination of multiple components with overlapping peaks

The elimination of wavelengths which contain useless or irrelevant information for calibration model is becoming one of the key steps in multicomponent spectral analysis even in situations where the partial least-squares (PLS) regression is applied. Because of the continuity of most kinds of spectral responses, the adaptive wavelength interval selection by modified particle swarm optimization (PSO) could be proposed in the present study. The proposed method was used for simultaneous spectrophotometric determination of caffeine, aspirin, and phenacetin and simultaneous differential pulse voltammetric determination of nitrophenol isomers. The method was eventually applied to commercial drugs. For comparison, a conventional full-spectrum PSO analysis was also performed. Experimental results demonstrate that the adaptive wavelength interval selection by modified PSO is capable of improving the future predictive ability of the model.

The separation and determination of nitrophenol isomers by high-performance capillary zone electrophoresis

o-Nitrophenol, m-nitrophenol, and p-nitrophenol could well be separated by capillary zone electrophoresis (CZE) by only adjusting the run buffer with methanol. Efficiency up to 10 5 theoretical plates per meter was achieved. The effects of several important factors were investigated to find optimum conditions. The linear range, regression equation, and the recovery were given. This method possessed the advantages of simplicity, rapidity, and good reproducibility; it can be developed for the separation of practical samples in environment analysis.

Analytical applications of crown ethers: III. Extraction and determination of nitrophenol isomers

Extraction of nitrophenols from water samples into benzene has been studied. The extraction is quantitative in the presence of crown ether when the pH of the aqueous phase is in the range 4.7 to 5.7. Beer's law is valid and a spectrophotometric determination of the nitrophenols is proposed.