Spectrophotometric Determination Of Phenols Research Articles

Spectrophotometric determination of phenol, catechol and resorcinol using denitrification reactions and coupling with benzidine reagent.

Spectrophotometric determination of phenol, catechol and resorcinol using denitrification reactions and coupling with benzidine reagent.

Spectrophotometric determination of phenol and chlorophenols by salting out assisted liquid-liquid extraction combined with dispersive liquid-liquid microextraction.

In this work, salting out liquid-liquid extraction (SALLE) combined with dispersive liquid-liquid microextraction (DLLME) was developed as a novel extraction method for extraction and preconcentration of phenol and chlorophenols (CPs) in environmental water samples. The analytes were derivatized with 4-aminoantipyrineand determined by spectrophotometry. Experimental parameters such as type and volume of the organic solvent, type and amount of salt, pH and vortex time were optimized. Under the optimum conditions, calibration curves were linear in the range of 1-300 μg L-1 and limit of detections (LODs) were in the range of 0.15-0.22 μg L-1. The extraction recoveries and enrichment factors ranged from 94.80% to 106.1% and 78.12 to 82.53, respectively. Repeatability of method based on five replicate measurements of phenols was in the range of 4.8-7.2%. The results obtained in this study showed that the proposed method is simple, rapid and environmentally friendly with high extraction efficiency for preconcentration and determination of phenol and CPs in real samples. The proposed method was also compared with the reference method.

Spectrophotometric Determination of Phenol in Natural Waters by Trichloromethane Extraction Method after Steam Distillation

The concentrations of phenol in natural waters were determined so as to ascertain water quality as water intended for human consumption. Total phenols were determined by molecular spectrophotometry, after steam distillation, complexation with 4 - aminoantipyrene and extraction into trichloromethane . The dynamic range was 0 - 300 mg/L. Experiments were carried out in the Central Science Laboratory Complex, Taraba State University - Jalingo Nigeria. The research work was completed in 4 months. The experimental method was applied in the analysis of environmental samples (river water and groundwater) collected within Jalingo metropolis of Taraba State, N orth Eastern Nigeria. Significant amount of phenols were found in the in the natural water samples with a range of 0.2891 - 0.3952 mg/L. The results indicated high pollution of phenol as the values exceeded the tolerance level of 0.0005 mg/L and maximum co ntaminant level of 0.005 mg/L for

Optimization of dispersive liquid–liquid microextraction for preconcentration and spectrophotometric determination of phenols in Chabahar Bay seawater after derivatization with 4-aminoantipyrine

We have optimized dispersive liquid–liquid microextraction to preconcentrate trace phenolic compounds after derivatization with 4-aminoantipyrine in artificial sea water for spectrophotometric determination. Factors such as reaction time (7.5min), pH (9.5), solvent (chloroform), dispersing solvent (ethanol), and volume ratio of dispersing to organic phase (11:1) were optimized. Under optimum conditions, the limit of detection was 0.18μg/L and the linearity range 1–900μg/L. The relative standard deviation and enrichment factor were 6% (n=7) and 920, respectively. The results demonstrate the efficiency of coupling the 5530 APHA standard for derivation and dispersive liquid–liquid microextraction of phenolic compounds from seawater samples. Using this method, total phenol content in seawater from several locations in Chabahar Bay (southeast Iran) was estimated at 27.8–74.8μg/L.

Spectrophotometric determination of phenol by flow injection on-line preconcentration with a micro-column containing magnetic microspheres functionalized with Cyanex272

A novel magnetic adsorbent, magnetic microsphere functionalized with Cyanex272, has been successfully synthesized via a chemical bonding alkylation method. A flow injection on-line preconcentration, with a micro-column packed with the as-synthesized magnetic adsorbent, coupled with UV-Vis spectrophotometric method was developed for the determination of phenol at a wavelength of 270 nm. Various experimental parameters were optimized as follows: eluent (methanol), sample flow rate (1.4 mL min−1), sample volume (1.4 mL), sample pH (5.0), and eluent flow rate (2.2 mL min−1). Under the optimum conditions, the intra-day and inter-day relative standard deviations were 1.37% and 2.69% (n = 5), respectively. The proposed method has been successfully applied to the determination of phenol in phenol ear drops, compound borax solution, and phenol ointment samples and the accuracy was assessed through recovery experiments.

Spectrophotometric Determination of Phenols in Aqueous Solution via Oxidative-Coupling Reaction with 4-Amino-N,N-Diethylaniline and Potassium Dichromate

A simple and sensitive spectrophotornetric method for the determination ofphenol has been developed. The method is based on the oxidative-coupling reaction ofphenol with 4-amino-N,N-diethylaniline in the presence of potassium dichromate at pH 6 solution to form an intense bluish-green water-soluble dye that is stable and has a maximum absorption at 670nm. A plot of absorbance versus concentration shows that Beer's law is obeyed over the concentration range of 2.5-250 jag of phenol in a final volume of 25ml,(i-e 0.1-lOppm) with a molar absorptivity of 3.95 x 104 l.mor'cm"', a percentage recoveries of 98.10-100.75% and a relative standard deviation of better than ±0.4%, depending on the concentration level. The optimum conditions for full colour development are described and the proposed method is extended to some other phenolic compounds.

4-Aminoantipyrine spectrophotometric method of phenol analysis: Study of the reaction products via liquid chromatography with diode-array and mass spectrometric detection

The synthesis of new pyrazolone molecules and their application as chromogenic agents in phenol analysis by the 4-aminoantipyrine method has been described by our group in previous published papers. A fully detailed mechanism is given therein based on experimental and theoretical data. In this paper, the study of the reaction products and by-products via liquid chromatography with diode array and mass spectrometric detection is presented, sorting out the spectrophotometric determination of phenols.

Spectrophotometric Determination of Phenols in Water Samples by the GHPSAM Method

The generalized H-point standard-additions method (GHPSAM) is proposed in order to obtain the phenol concentration in water samples when the matrix is completely unknown. The procedure involves solid-phase extraction in BondElut PPL cartridges and data handling of the UV-visible spectrophotometry measurements. The spectral regions where the unknown interferent behaviour can be considered as linear are found and the analyte concentration free from bias error is estimated. The percentages of recovery of phenols in spiked samples were similar to those obtained by HPLC. Cresols or chlorophenols can be also determined in real samples by this method. The concentration range tested was 0.075 – 12.5 mg L−1 and the limits of detection found were in the 2.4 – 5.4 μg L−1 range. The method has been applied to real harbour water samples. The results obtained are compared to those provided by HPLC.

Spectrophotometric Determination of Phenols and Cyanides After Distillation from Natural Waters

Total phenols were determined by molecular spectrophotometry, after distillation, complexation with 4-aminoantipyrine and extraction into chloroform. Cyanides were also determined spectrophotometrically after distillation from the acidified samples, and complexation in moderate acidic solution with barbituric acid. The dynamic ranges were 0 – 100 μg L−1 for total phenols and 0 – 30 μg L−1 for cyanides. The above methods were applied in the analysis of river, lake and stream waters collected from Northern Greece. The seasonal and spatial variation of concentrations was evaluated by two-way ANOVA. Background levels (4 – 12 μg L−1 for total phenols and 0.3 – 3 μg L−1 for cyanides), were found in almost all surface waters, with some exceptions.

Spectrophotometric Determination of Trace Phenol in Water After Preconcentration on an Organic Solvent-Soluble Membrane Filter

A simple and rapid preconcentration technique based on collecting trace phenol on a membrane filter and dissolving the membrane filter in an organic solvent has been proposed and applied to the spectrophotometric determination of phenol in water. At pH 9.0 phenolic compounds form dyes with 4-aminoantipyrine in the presence of potassium ferricyanide. The product is collected on a 0.45 μm nitrocellulose filter as an ion associate of the dye with a cation surfactant. The ion associate along with the filter is dissolved in a small volume of 2-methoxyethanol and the absorbance of the resulting solution is measured at 480 nm against a reagent blank. Beer's law is obeyed over the range 1.25 - 30 μg of phenol in 5 ml of solvent and the detection limit (three times the standard deviation of the blank) is 2.0 μg 1−1 as phenol. The components normally present in water do not interfere in the presence of proper masking agents. The proposed method has been applied to the analysis of water samples from several sources. The recoveries of the phenol added to the samples are quantitative, and results found are satisfactory.

Determination of Microamounts of Phenols by Thermal Lens Spectrometry

The conditions for unified spectrophotometric determination of phenols (using phenol, resorcinol, and pyrogallol as model substances) in batch mode by their azo coupling with p-nitrophenyldiazonium were optimised. The detection limits are 50–120 ng ml–1. The data were used in the search for the optimum conditions for thermal lens determination of the test phenols. The main disadvantage of thermal lens determination of phenols by this procedure is a high blank signal. To decrease the blank signals, the concentration of the reagent was decreased by a factor of 40. The detection limits of the test phenols are 2–9 ng ml–1, the linear calibration range is two orders of magnitude. The relative standard deviation (3–8%) is similar to that of spectrophotometric determination.

Spectrophotometric determination of phenols by coupling with diazotized 2,4,6-trimethylaniline in a micellar medium

The unstable absorbances and large values of the blanks obtained when a phenol is determined by coupling with a diazotized arylamine are caused by hydroxy-de-diazoniation of the diazonium ions, followed by coupling of the resulting phenol with the reagent excess in the basic medium. Diazotized 2,4,6-trimethylaniline (TMA) produces 2,4,6-trimethylphenol, which does not couple with the reagent excess, and gives low blanks. A sodium dodecyl sulfate micellar medium is used to prepare the TMA solutions and to catalyse the coupling reaction. The limits of detection were in the range 0.2–4.6 µmol dm–3, with a repeatability of about 2%. The procedure was applied to the determination of epinephrine and paracetamol in pharmaceutical preparations.

Spectrophotometric determination of phenol in air

Spectrophotometric determination of phenol in air

A critical investigation of the liebermann colour test: The formation and behaviour of phenolindophenol in strong acid media

The Liebermann test has been investigated by spectroscopic and Chromatographic methods. Phenols in concentrated sulphuric acid reacted with nitrite to give green to blue solutions which turned to red or violet, yellow or brown, respectively, after dilution with water. Alkalization of these solutions changed the colour to green or blue, but also to yellow or brown, respectively. The reaction of phenols withp-nitrosophenol was also studied. Except for 4-iodophenol and hydroquinone, phenols substituted in thep-position did not react with either nitrite orp-nitrosophenol. Negative reactions were obtained with 2- and 3-nitrophenols, 2- and 3-hydroxybenzoic acids and 2,6-dichlorophenol, although these phenols have a freep-position. The sensitivity is much poorer than that of other reactions for detection of phenols, e.g. the Emerson or Gibbs reactions. The Liebermann test is often recommended as a generic test for phenols, but its importance, selectivity and sensitivity seem to have been considerably overestimated. Application of the reaction for spectrophotometric determination of phenols is impracticable, because of the very poor reproducibility, the small yield of reaction product and the inconvenience of working with concentrated sulphuric acid media.p-Nitrosophenol was found to be the operative species and the main product was phenolindophenol, which is present in its diprotonated form H2In2+ in the medium of concentrated sulphuric acid. Further forms of the dye can exist, depending on the pH or Ho of the medium. The orange spiro(7-hydroxyacridine-9,1′-cyclohexa-2′,5′-dien)-2,4′-dione was found to be the main byproduct of the reaction. The formation of further by-products was observed, of which 1,4-benzoquinone and 4-nitrophenol were identified.

Spectrophotometric Determination of Phenols in Air

Spectrophotometric Determination of Phenols in Air

Spectrophotometric determination of phenols in waste water by the 4-aminoantipyrine method with iodine

Spectrophotometric determination of phenols in waste water by the 4-aminoantipyrine method with iodine

Spectrophotometric determination of phenol by the 4-aminoantipyrine method after steam distillation in a semimicro kjeldahl apparatus in the presence of a large amount of sodium chloride

Phenol is quantified rapidly and accurately by the 4-aminoantipyrine spectrophotometric method after adding 15 g of sodium chloride to a 25-ml sample and distilling in a Semimicro steam distillation apparatus of the Pregl—Parnas—Wagner type. The large amount of sodium chloride provides a saturated solution of the salt during the course of the distillation and causes most of the phenol to be contained in the first few milliliters of distillate. The method has been used to quantify up to 25 mg of phenol per 25 ml.