scholarly journals Spectrophotometric determination of active chlorine by the color of indophenolic compounds

2019 ◽  
Vol 57 (3) ◽  
pp. 93-98
Author(s):  
Svetlana E. Pratskova ◽  
◽  
Oksana E. Sirenko ◽  
Keyword(s):  
Sodium Nitroprusside ◽  
Natural Waters ◽  
Tap Water ◽  
Active Chlorine ◽  
Molar Ratios ◽  
Spectrophotometric Methods ◽  
Organic Impurities ◽  
Ph Range ◽  
Fold Excess

Chlorination is a method of disinfection and oxidation of organic impurities in water. Chlorine is present in aqueous solutions in various forms, which are formed as a result of the chlorination of water. Spectrophotometric methods are very important for determining small amounts of chlorine and its compounds. The article presents a modification of the classical indophenolic method. Determination of active chlorine should be carried out at room temperature, maintaining the solutions for 50 minutes, the pH range is 11.9 ± 0.1. The optimal concentration of reagents: 33-fold excess of N-phenanthranilic acid, 2-fold excess of sodium nitroprusside, and the concentration of ammonium chloride should be 4 to 7 times less than the concentration of active chlorine. The following interaction scheme was proposed: oxidation of ammonia to chloramine with hypochlorite, amination of N-phenanthanilate with the formation of sodium 4-amino-N-phenylanthranilate, oxidation of 4-amino-N-phenylanthranilate with sodium hypochlorite to an indamin compound, followed by complexation with sodium nitroprusside. The linearity range of the calibration curve is 1-23 mg/l, the convergence is 2.3%, the relative error is 1%. The molar ratios of ions and oxidizing agents present in natural waters that do not interfere with the determination of active chlorine are investigated. The optimal concentrations of reagents, sequential variation of the concentration of solutions and fixing the change in light absorption were established. The ratio of the stoichiometric coefficients according to the reaction equation was: ammonium: N-phenanthranilic acid: sodium nitroprusside: hypochloride was 1: 2: 1: 1. It is proposed to use this method to determine the active chlorine in tap water. It is recommended to use the calibration schedule to determine the preliminary content, and to establish a more accurate concentration, use the method of additives.

scholarly journals Potentiometric sensor for iron (III) quantitative determination: experimental and computational approaches

BMC Chemistry ◽  
2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Somayeh Badakhshan ◽  
Saeid Ahmadzadeh ◽  
Anoushiravan Mohseni-Bandpei ◽  
Majid Aghasi ◽  
Amir Basiri
Keyword(s):  
Tap Water ◽  
Basis Set ◽  
Stable Complex ◽  
Wastewater Sample ◽  
Adsorption Sites ◽  
Electrocoagulation Process ◽  
Nernstian Slope ◽  
Dynamic Concentration ◽  
Ph Range

AbstractThe current work deals with fabrication and validation of a new highly Fe3+ selective sensor based on benzo-18-crown-6 (b-18C6) using the potentiometric method. The proposed sensor revealed satisfactory performance for quantitative evaluation of Fe3+ trace amount in environmental samples. The ratio of membrane ingredients optimized and the membrane with the composition of 4:30:65.5:0.5 mg of b-18C6:PVC:o-NPOE:KTpClPB exhibited the desirable Nernstian slope of 19.51 ± 0.10 (mV per decade of activity) over the pH range from 2.5 to 5.7 with an acceptable dynamic concentration range of 1.0 × 10−6 M to 1.0 × 10−1 M and lower detection limit of 8.0 × 10−7 M. The proposed sensor demonstrated an appropriate reproducibility with a rapid response time of 12 s and the suitable lifetime of 10 weeks. To validate the accurate response of the proposed sensor, AAS technique applied for the determination of Fe3+ in real aqueous mediums such as drinking tap water and hospital wastewater sample after treatment by electrocoagulation process. Theoretical studies carried out using DFT/B3LYP computational level with 6-311G basis set to optimize the adsorption sites of Fe+3 cationic species by b-18C6. The obtained adsorption energy with large negative value confirmed the formation of a stable complex.

Development of Extractive Spectrophotometric Methods for the Determination of Iron(III) with Dimercaptophenole and Heterocyclic Diamines

2019 ◽  
Vol 41 (6) ◽  
pp. 993-993
Author(s):  
Kuliev Kerim Avaz Kuliev Kerim Avaz ◽  
Verdizade Nailya Allahverdi and Mamedova Shafa Aga Verdizade Nailya Allahverdi and Mamedova Shafa Aga
Keyword(s):  
Relative Yield ◽  
Molar Absorptivity ◽  
Linear Calibration ◽  
Spectrophotometric Methods ◽  
Biological Water ◽  
Color Development ◽  
Straight Line ◽  
Ph Range ◽  
Intersection Curves

Dimercaptophenole (DM) is proposed as a new sensitive reagent for the sensitive extractive spectrophotometric determination of Fe(II). DM in the presence hydrophobic amins reacts with Fe(II) in the pH range 5.3 -7.2 to form a coloured complex. Chloroform, dichloroethane, and carbon tetrachloride appeared to be the best extractants. The absorption spectrum of Fe (II)-DM-Am complexes in chloroform shows maximum absorbance at 552-583 nm. It was observed that the color development was instantaneous and stable. Linear calibration graphs were obtained for 0.03-4.2 μg mL −1 of Fe.The molar absorptivity calculated was found to be (3.08-4.33) and#215; 104 dm3 mol−1 cm−1 and the sensitivity of the method as defined by sandaland#39;s was 1.29-1.82 ng cm-2. The stoichiometry of the complex is established as 1:1:2 (M : L : Am) by equilibrium shift method, and confirmed the methods of relative yield, Asmus straight line and the intersection curves. It may be satisfactorily applied for the determination of Fe(III) with present method. The results of the prescribed procedure applied for the determination of the micro amounts of iron in pharmaceutical, biological, water, food and in plant samples are presented.

Determination of ΔH0f298(C6F10,g) and ΔH0f298(C6F12,g) from studies of the combustion of decafluorocyclohexene and dodecafluorocyclohexane in oxygen and calculation of the resonance energy of hexafluorobenzene

1979 ◽  
Vol 57 (6) ◽  
pp. 685-688 ◽  
Author(s):  
Stanley James W. Price ◽  
Henry J. Sapiano
Keyword(s):  
Material Balance ◽  
Resonance Energy ◽  
Combustion Method ◽  
Heats Of Formation ◽  
Reaction Products ◽  
Molar Ratios ◽  
Direct Combustion ◽  
Related Compounds ◽  
Fold Excess

The heats of formation of decafluorocyclohexene and dodecafluorocyclohexane have been determined by the direct combustion method previously developed and used for hexafluorobenzene and related compounds. The combustion of decafluorocyclohexene and dodecafluorocyclohexane formed the reaction products CO2, CF4, and F2. In both cases a portion of the compound remained unburned. The unburned material was collected and quantitatively determined gravimetrically. A material balance was obtained for carbon and fluorine on the basis of CO2, CF4, and F2 and the amount of unburned compound. With a ten-fold excess of oxygen, the average CO2-to-CF4 molar ratios for C6F10 and C6F12 are 2.03 ± 0.01 and 1.35 ± 0.01, respectively. The values obtained for the heats of formation are ΔH0f298(C6F10,g) = −1906.6 ± 7.2 kJ mol−1 and ΔH0f298(C6F12,g) = −2368.9 ± 7.6 kJ mol−1. ΔH0f298 for the reaction C6F10(g) + F2(g) → C6F12(g) was calculated to be −462.3 ± 14.8 kJ mol−1 and the 'resonance energy' of C6F6 is estimated at −36.4 kJ mol−1.

Development of a preconcentration method for indomethacin in natural waters using dispersive liquid–liquid microextraction based on solidification of floating organic drop technique

2018 ◽  
Vol 53 (1) ◽  
pp. 41-50 ◽  
Author(s):  
Nesrin Topaç ◽  
Cennet Karadaş ◽  
Derya Kara
Keyword(s):  
Water Samples ◽  
Natural Waters ◽  
Limit Of Detection ◽  
Tap Water ◽  
Chloride Concentration ◽  
Extraction Solvent ◽  
Dispersive Liquid Liquid Microextraction ◽  
Preconcentration Method ◽  
Liquid Microextraction

Abstract A new dispersive liquid–liquid microextraction method based on the solidification of a floating organic drop was developed for the preconcentration of indomethacin in natural waters followed by ultraviolet-visible (UV-Vis) spectrophotometric detection. 1-undecanol and ethanol were used as the extraction solvent and the disperser solvent, respectively. An investigation of the main experimental parameters that may affect the extraction efficiency, such as sample pH, volume of extraction and disperser solvents, sodium chloride concentration and centrifugation time was undertaken. The effect of interfering ions on the recovery of indomethacin was also examined. Under optimal conditions without any preconcentration, the limit of detection was 17.9 μg/L calculated from LOD = 3 Sb/m and was also calculated as 74.9 μg/L from the regression values of the calibration line using 3.19 Se/m. The proposed preconcentration method was successfully applied to determination of indomethacin in spiked tap water and river water samples. The recovery values for spikes added to water samples were between 94.5 and 103.0%.

scholarly journals A spectrophotometric investigation of the complex between titanyl oxalate and 3-hydroxyflavone in water ethanolic mixtures

2000 ◽  
Vol 65 (9) ◽  
pp. 631-638 ◽  
Author(s):  
Mara Aleksic ◽  
Slavica Blagojevic ◽  
Dusan Malesev ◽  
Zorica Radovic
Keyword(s):  
Stability Constant ◽  
Room Temperature ◽  
Aqueous Ethanol ◽  
Ethanol Solution ◽  
Aqueous Ethanol Solution ◽  
Spectrophotometric Methods ◽  
Oxalate Anion ◽  
Ph Range ◽  
Titanyl Oxalate

It has been established, by the application of suitable spectrophotometric methods and pH-metric measurements, that titanyl oxalate anion and 3-hydroxyflavone (3HF) form a [TiO(C2O4)2(C15H9O3)2]4-complex. The investigation of the composition and the concentration stability constant of the complex were carried out in a 50 % aqueous ethanol solution at room temperature (20?C), in the pH range from 1.9 to 9.0. The concentration stability constant of the complex, log b2, ranged from 16.65 at pH 5.0 to 13.96 at pH 7.0. The conditions for the spectrophotometric determination of 3HF by means of the complex formation were investigated in the concnetration range from 2.5?10-5 to 3.0?10-4 mol dm-3 3HF.

A new extraction–spectrophotometric method for the determination of phosphate

1978 ◽  
Vol 56 (13) ◽  
pp. 1729-1738 ◽  
Author(s):  
Kunnath S. Subramanian ◽  
Alfio Corsini
Keyword(s):  
Spectrophotometric Method ◽  
Natural Waters ◽  
Amyl Alcohol ◽  
Tungstophosphoric Acid ◽  
Molar Ratio ◽  
Molybdenum Blue ◽  
Phosphorus Containing ◽  
Precision And Accuracy ◽  
Ph Range

A new extraction–spectrophotometric method has been developed for the determination of trace amounts of phosphorus as orthophosphate. The method is based on the chemistry of 12-tungstophosphoric acid, H3PW12O40 (TPA). In the procedure, orthophosphate is converted quantitatively to TPA in aqueous solution at a tungstate–phosphate molar ratio ≥24, in the pH range 1.2 to 1.9 and in the temperature range 60 to 100 °C. The TPA is subsequently extracted into n-amyl alcohol and its absorbance measured at 267 nm. Beer's law is followed up to at least 25 µg/ml P. The method is less prone to solution conditions and species interference (especially As(V) and Si(IV)) than the widely used molybdenum-blue methods and is competitive in terms of sensitivity, precision, and accuracy. The TPA method was applied successfully to the determination of phosphate in a variety of phosphorus-containing specimens including natural waters, ores, and alloys.Based on potentiometric and spectrophotometric studies, a scheme which accounts for the observed heptaproticity of TPA is proposed.

scholarly journals Determination of the fenvalerate insecticide in natural waters by a photochemically-induced fluorescence method

2015 ◽  
Vol 34 (2) ◽  
pp. 245 ◽  
Author(s):  
Diène Diégane Thiaré ◽  
Atanasse Coly ◽  
Diégane Sarr ◽  
Abdourakhmane Khonté ◽  
Amadou Diop ◽  
...  
Keyword(s):  
Natural Waters ◽  
Sea Water ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Irradiation Time ◽  
Tap Water ◽  
Analytical Sensitivity ◽  
Photochemically Induced Fluorescence ◽  
Relative Standard

<p>The fenvalerate pyrethroid insecticide was determined in various types of natural waters of Senegal by means of a newly-developed, simple, rapid and very sensitive photochemically-induced fluorescence (PIF) method. The PIF method was optimized with respect to the irradiation time, solvent and pH. The obtained calibration curves yielded correlation coefficients very close to unity. The limit of detection (LOD) and of quantification (LOQ) values were very low (LOD = 0.01–0.66 ng/ml and LOQ = 0.04–2.20 ng/ml, according to the solvent), and the relative standard deviation (RSD) values were small, ranging between 0.1 and 1.5 %, which indicated a very good analytical sensitivity and a great repeatability of PIF. Recovery studies were performed on spiked distilled water, tap water, sea water, well water, river water and draining water samples of Senegal, using the liquid-liquid extraction (LLE), solid phase extraction (SPE), and standard addition procedures. Satisfactory recovery results (about 85–121%) were obtained for the determination of fenvalerate in an aquatic environment.</p>

Potentiometric Determination of Trace Amounts of Aluminium Utilizing Polyvinyl Chloride Membrane and Coated Platinum Sensors Based on E-N′-(2-Hydroxy-3-methoxybenzylidene) benzohydrazide

2013 ◽  
Vol 96 (1) ◽  
pp. 204-211 ◽  
Author(s):  
Somayeh Tajik ◽  
Mohammad Ali Taher ◽  
Iran Sheikhshoaie
Keyword(s):  
Polyvinyl Chloride ◽  
Tap Water ◽  
Direct Determination ◽  
Ion Concentration ◽  
Nonaqueous Media ◽  
Wide Range ◽  
And Performance ◽  
Ph Range ◽  
Polyvinyl Chloride Membrane

Abstract This paper describes the construction and performance characteristics of novel polyvinyl chloride membrane (PME) and coated platinum (CPtE) aluminium (Al) ion selective electrodes based on E-N′-(2-hydroxy-3-methoxybenzylidene) benzohydrazide. The electrodes exhibited linear responses with near Nernstian slopes of 19.9 ± 0.3 (PME) and 20.1 ± 0.4 (CPtE) mV/decade of activity within the Al3+ ion concentration range of 3.0 × 10–7 to 1.0 × 10–2 M for the PME and 1.0 × 10–7 –1.0 × 10–2 M for the CPtE. These sensors were applicable in a pH range of 3.0 to 7.0. The LODs of the PME and CPtE were 1.7 × 10–7 and 5.6 × 10–8 M, respectively. They had a response time of less than 10 s and could be used practically for a period of at least 2 months without measurable divergence in results. The isothermal temperature coefficient of the PME was 1.12 × 10–3 V/°C, and it can tolerate partially nonaqueous media up to 25%. The electrodes showed excellent selectivity towards Al3+ ions in the presence of a wide range of alkali, alkaline earth, and transition metals ions. They were successfully applied for the direct determination of Al3+ ions in tap water, aqueduct water, mineral water, and Al–Mg syrup and as indicator electrodes in potentiometric titration of Al ions with EDTA.

scholarly journals Extractive spectrophotometric determination of some α-adrenergic-antagonists in pure forms and in pharmaceutical formulations

2012 ◽  
Vol 18 (2) ◽  
pp. 179-191 ◽  
Author(s):  
Sheikh El ◽  
Nahla Esmail ◽  
Ayman Gouda ◽  
Walid Basset
Keyword(s):  
Pharmaceutical Formulations ◽  
Bromothymol Blue ◽  
Bromocresol Green ◽  
Spectrophotometric Methods ◽  
Basic Nitrogen ◽  
Doxazosin Mesylate ◽  
Adrenergic Antagonists ◽  
Ph Range ◽  
Good Agreement

A simple, rapid, and extractive spectrophotometric methods was developed for the determination of some postsynaptic ?-1 adrenoreceptor antagonist; doxazosin mesylate (DOX), terazosin (TRZ) and alfuzosine HCl (ALF) in pure forms and pharmaceutical formulations. The developed methods are based on the formation of yellow colored chloroform ion-pair complexes between the basic nitrogen of the drugs and dyes, namely; bromocresol green (BCG), bromothymol blue (BTB), methyl orange (MO) and alizarine red S (ARS), in acidic buffer of pH range (3.0-5.0). The formed complexes were extracted with chloroform or dichloromethane and measured at 418, 414, 425 and 426 nm for DOX and at 419, 415, 425 and 428 for TRZ and at 418, 412, 421 and 427 nm for ALF using BCG, BTB, MO and ARS, respectively. The analytical parameters and their effects on the reported systems are investigated. Beer?s law was obeyed in the range 1.0-130 ?g mL?1 with correlation coefficient (n = 6) ? 0.9991. The molar absorpitivity, Sandell sensitivity, detection and quantification limits were also calculated. The composition of the ion associates was found 1:1 by Job?s method. The proposed methods have been applied successfully for the analysis of the studied drugs in pure forms and in pharmaceutical formulations with percentage recoveries ranges from 99.18-100.61. The results of analysis were validated statistically. The results were in good agreement and compared with those obtained with reported methods.

Separation and Preconcentration of Trace Amounts of Rhodium Using a Dispersive Liquid–Liquid Microextraction Method and Its Determination by Flame Atomic Absorption Spectrometry

2014 ◽  
Vol 97 (3) ◽  
pp. 933-937 ◽  
Author(s):  
Fateme Mirrahimi ◽  
Mohammad Ali Taher
Keyword(s):  
Tap Water ◽  
Chelating Agent ◽  
Absorption Spectrometry ◽  
Flame Atomic Absorption ◽  
Separation And Preconcentration ◽  
Dispersive Liquid Liquid Microextraction ◽  
Ph Range ◽  
Extracting Solvent ◽  
Liquid Microextraction

Abstract A sensitive and selective method for the determination of low levels of rhodium (Rh) in environmental samples is needed. In the proposed method, an extracting solvent with a lower toxicity and density than the other solvents typically used in dispersive liquid–liquid microextraction was used to extract trace amounts of Rh from aqueous samples. Rh ions were complexed with 1-(2-pyridylazo)-2-naphthol in the pH range of 3.2–4.7 and extracted with dispersive liquid–liquid microextraction. The type and volume of the extracting solvent and dispersive solvent, centrifugation time, pH, amount of the chelating agent, and sample ionic strength were carefully studied. Under the optimal conditions, the LOD and RSD were 0.36 ng/mL (3Sb/m, n = 7) and ±2.0% (n = 7), respectively. The calibration curve was linear in the range of 4.0–800 ng/mL. The method was applied to the determination of Rh in well and tap water, and spiked recoveries were in the range of 96–103.7%.

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