Spectrophotometric Determination of Trace Chromium(VI) in Mass Chromium(III)

There is little conclusive evidence of the toxic effects of Cr(III) so far, but Cr(VI) has carcinogenic activity, so the analysis of the chromine ions is very important in environmental research and the quality control of industry products. Usually Cr(III) and Cr(VI) interfere with each other in the species analysis, the measurement of Cr(VI) of numerous previous papers is related to the Cr(VI) samples, which contain a little Cr(III). When the amount of trivalent chromine exceeds ten …     

Spectrophotometric Determination of Chromium(VI) with Cr(VI)-o-Cl-PF–TDPC Ternary Complex after Preconcentration on an Organic Solvent-soluble Membrane Filter

Abstract

A simple and rapid preconcentration technique, based on collecting trace hexavalent chromium on an organic soluble membrane filter is described. At pH 5.0, chromium(VI), o-chlorophenyl-fluorone (o-Cl-PF) and tetradecylpyridinium chloride (TDPC) form the ternary ion-associate chelate, which can be collected on a 0.2μm nitrocellulose membrane. The filter is dissolved in a small volume of dimethyl sulfoxide (DMSO) acidified with 0.15 mL 3 mol/L sulfuric acid, and the absorbance of the resulting solution is measured at 545 nm wavelength against the reagent blank. The absorbance is proportional to the content of hexavalent chromium in the range of 0.1–1.8μg, in 5 mL solvent. The sensitivity of the ternary complex reaction is very high with molar absorptivity of 1.2 × 10⁵. A detection limit better than 0.3 μg/L can be achieved. The ions normally present in water do not interfere when mixed masking agents are added. The proposed method has been applied to the analysis of water samples from several sources, the recoveries of the hexavalent chromium added to the samples are quantitative, and results found are satisfactory.     

Kinetic–Spectrophotometric Determination of Trace Silver(I) Using Its Catalytic Effect on the Oxidation Reaction of Fuchsin by Peroxodisulfate in the Presence of 1,10-Phenanthroline As an Activator

A kinetic spectrophotometric method for the determination of trace amounts of Ag(I) in the range of 2–20 ng mL^–1 is reported. The method is based on the catalytic effect of Ag(I) on the oxidation reaction of fuschin by potassium peroxodisulfate in the presence of 1,10-phenanthroline as an activator at pH = 5. The reaction is followed spectrophotometrically by measuring the change in absorbance (A) at 544 nm using a fixed time method (6 min). The reaction variables were optimized in order to achieve the highest sensitivity. The 3s criterion detection limit was 0.7 ng mL^–1, and the relative standard deviation for ten replicate measurements of 16 ng mL^–1 of Ag(I) was 0.95% (n = 10). The method was successfully applied to the determination of silver in expired black and white photographic films and results showed good agreements with those obtained by atomic absorption spectrometry.     

Kinetic Determination of Iodide Traces Based on the Manganese(III) Metaphosphate–Arsenic(III) Reaction in the Presence of Orthophosphoric Acid

The kinetics of the iodide-catalyzed Mn(III) metaphosphate–As(III) reaction was studied in the presence of orthophosphoric acid. The reaction rate was followed spectrophotometrically at 516nm. It was established that orthophosphoric acid increased the reaction rate and that the extent of the non-catalytic reaction was extremely small. A kinetic equation was postulated and the apparent rate constant calculated. The dependence of the reaction rate on temperature was investigated and the energy of activation and other kinetic parameters determined. Iodide was determined under the optimal experimental conditions in the range 0.6–2.5ng·mL^–1 with a relative standard deviation of up to 6.7% and a detection limit of 0.12ngmL^–1. The effect of foreign ions on the accuracy of the determinations was also investigated.     

A Study on the Kinetics of the Catalytic Reforming Reaction of CH4 with CO2： Determination of the Reaction Order

The kinetics of the catalytic reforming reaction of methane with carbon dioxide to produce synthesis gas on a Ni/(α-A1203 and a HSD-2 type commercial catalyst has been studied. The results indicate that the reaction orders are one and zero for methane and carbon dioxide, respectively, when the carbon dioxide partial pressure was about 12.5-30.0 kPa and the temperature was at 1123-1173 K. However, when the carbon dioxide partial pressure was changed to 30.0-45.0 kPa under the same temperature range of 1123-1173 K, the reaction orders of methane and carbon dioxide are one. Furthermore, average rate constants at different temperatures were determined.     

A Highly Sensitive Spectrophotometric Assay of Bleomycins Based on the Fading Reaction of Some Halofluorescein Dyes

In weak acidic medium, anticancer antibiotics bleomycin A5 （BLMA5） and bleomycin A2 （BLMA2） can react with halofluorescein dyes such as erythrosin （Ery）, eosin Y （EY）, eosin B （EB） and rose bengal （RB） by virtue of electrostatic attraction and hydrophobic force to form the ion-association complexes, which can result in the fading reactions of four halofluorescein dyes. The maximum fading wavelengths of these four dyes were located at 527 nm for Ery, 515 nm for EY, 517 nm for EB and 546 nm for RB, respectively. The decrements of absorbance （AA） were directly proportional to the concentrations of bleomycin in a certain range. A new method for the determination of bleomycins anticancer drugs based on fading reactions of halofluorescein dyes has been developed. The method was not only highly sensitive but also simple and rapid. The molar absorptivities （ε） ranged from 1.5 × 10^5 to 7.5 × 10^5 L·mol^-1·cm^-1. It was applied to determination of the bleomycins in human serum, urine and rabbit serum samples. In this work, the spectral properties and the optimum reaction conditions were investigated. The structure of ion-association complexes and the reaction mechanism were discussed.     

Catalytic Kinetic Spectrophotometric Method for Determination of Phosphate Ion

The kinetic method for the determination of phosphate microamounts was described. The developed method is based on catalytic effect of phosphate on sodium pyrogallol-5-sulphonate （PS） by dissolved oxygen. The reaction was followed spectrophotometrically by measuring the rate of change in the values of the absorbance of the oxidation product at 437 nm. The optimum reaction conditions are PS （0.44×10^-3 mol·L^-1） and HClO4 （3.6×10^-6 mol·L^-1） at 25 ℃. Following this procedure, phosphate can be determined with a linear calibration graph up to 0.23 μg·mL^-1. The interference effect of several species was also investigated and it was found that the most common cations and anions did not interfere with the determination. The developed procedure was successfully applied to the determination of phosphate in natural waters and soil.     

Electroactive Composite Pd–Polypyrrole and Its Catalytic Properties in the Reaction of Styryl Bromide Cyanation

A composite material in the form of powder is synthesized by a redox reaction in mixed aqueous solution of Pd(NH₃)₄Cl₂ + pyrrole. The composite consists of polypyrrole globules with palladium nanoparticles uniformly distributed inside the latter. Being applied as a film on the electrode surface, both components of this material exhibit redox activity. Palladium particles inside the composite exhibit catalytic properties in cyanation of styryl bromides, a reaction widely used in fine organic synthesis.     

On the Effect of Hydrogen Peroxide on the Flow‐Injection Determination of Platinum Based on Luminol Chemiluminescent Reaction

Abstract

A flow‐injection chemiluminescent (CL) method for the determination of trace amounts of Pt(IV) based on the oxidation reaction of luminol in alkaline solution is proposed. The effect of Pt(IV) on the oxidation of luminol was studied in the absence and in the presence of hydrogen peroxide. The positive effect of hydrogen peroxide as well as chloride ions on the sensitivity of measurements was observed. The developed method is characterized by a low limit of detection of Pt (LOD=0.06 ng mL^?1) and good reproducibility (RSD=2.2%). The addition of hydrogen peroxide to the reaction medium resulted in decreasing of platinum detection limit to 0.03 ng mL^?1.     

Study on New Spectrophotometric Determination of Arsenic (V) with Chlorpromazine

IntroductionChlorpromazineasanewchromogenicreagenthasbeenemployedforthedeterminationofvanadium(V)inthislaboratoryi.ItwasfoundthatthisreagentalsogaveasensitivereactionwithheteropolyacidofAs,P,Ge,andStinstronglyacidicmedium.Inthispaper,anewmethodforspectrophotometricdeterminationofarsenic(V)withchlorpromazineisreported.Theoptimumconditionsforcolordevelopmentofthecomplexandtheeffectsofforeignionswerestudied.Itispossibletoestablishasensitiveandselectivespectrophotometricmethodforthedeterminatio…     

Study on New Spectrophotometric Determination of Vanadium(V) with Chlorpromazine

InanopoonoNChlorprOmallne[2-chloro-lG(3-dimethyltalnoPrOPytoenomiazine1isameddnefOrtrantwhitVandwidelvusedasanhmchohcasenI'J].butthereisnorrmrtonitsaDDlicationinanalghcalcheAnsnyuptonow.ThestrUctUralformulaOfchiormomedneisInviewOfPhenoffoazinebeingagoodelectronJcdonoraccordingtoitsmolecularstrUctUre,chlorPromallnemaybeokidizedinvthengboesandcolorofandaIsobeco1oredforitScomPlexationwithsomemetalions.Accordingly,itcanbePrwhctedthatchlorprOmednewhghtbeusedasagoodsPectroscoricreagentfO…     

Flow Injection and Batch Spectrophotometric Determination of Ibuprofen Based on its Competitive Complexation Reaction with Phenolphthalein‐β‐Cyclodextrin Inclusion Complex

Abstract

Rapid, simple, and accurate spectrophotometric method is presented for the determination of ibuprofen by batch and flow injection analysis methods. The method is based on ibuprofen competitive complexation reaction with phenolphthalein‐β‐cyclodextrin (PHP‐β‐CD) inclusion complex. The increase in the absorbance of the solution at 554 nm by the addition of ibuprofen was measured. Ibuprofen can be determined in the range 8.0×10^?6 ?3.2×10^?4 and 2.0×10^?5?5.0×10^?3 mol l^?1 by batch and flow methods, respectively. The limit of detection and limit of quantification were 6.19×10^?6 and 2.06×10^?5 mol l^?1 for batch and 1.77×10^?5 and 5.92×10^?5 mol l^?1 for flow method, respectively. The sampling rate in flow injection analysis method was 120±5 samples h^?1. The method was applied to the determination of pharmaceutical formulations.     

Study of the Electrochemiluminescence Based on the Reaction of p-Hydroxyphenylpyruvic Acid with Tris(2,2'-bipyridine)ruthenium(Ⅱ)

p-hydroxyphenylpyruvic acid (pHPP) is an important intermediate in the metabolism of tyrosine. Under normal circumstances pHPF is readily converted to 2,5-dihydroxyphenylacetic acid by p-hydroxy-phenylpyruvate oxidase and the levels of pHPP encountered in blood and urine are extremely low. However, in a few individuals suffering from a congenital metabolic defect known as tyrosinemia, the oxidase is not available which leads to dramatic elevation of pHPP levels in blood and urine^[1]. Therefore, a selective and sensitive method for measuring pHPT is very useful for the diagnosis and treatment of such disease. In this paper the electrochemiluminescence(ECL) based on the reaction of pHPP with tris(2,2'-bipyridine)ruthenium(Ⅱ)[Ru(bpy)₃²⁺] in a flow injection system has been studied and a sensitive ECL method has been developed to detect pHPP in aqueous solution.     

Novel Spectrophotometric Method for Determination of Macro-paracetamol via Reaction with Bromine

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Study on the Spectrophotometric Determination of Rare Earths with a New Chromogenic Reagent Dibromo-p-methyl-chlorosulfonazo(DBMCSA)

IntroductionAbstract:Anewmethodforthedeterminationofceriumsubgrouprareearthswasstudiedandreportedinthispaper.ItwasfoundthaiceriumsubgrouprareearthelementsreactwithDBMCSAin0.6mol/Lhydrochloricacidmediumtol'ormstablebluecomplexes.Theabsorbancesofequalamountsofceriumsubgrouprareearthsareclosetoeachotherattheirmaximumadsorptivewavelength(641"m).Beer'slawisobeyedfor0-20igofrareearthsin25mlofsolution.Themethodhasbeenappliedtothedeterminationofthetotalamountofceriumsubgrouprareearthsinsteelandcas…     

Catalytic Spectrophotometric Determination of Ultratrace Amounts of Silver with Solubilizing Effect of Nonionic Surfactant

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Stodies on the Witting Reaction (Ⅹ Ⅹ Ⅻ) Phase Transfer Catalytic Bis-Witting Reaction of 1,2-and 1,3-Bisylide

Insplteofsometechnicalproblems,theWittigreactionisstillparticu1arlyusefulforthesynthesisofvarlousalkenesowlngtoltsknownversatllity.SlnceMarklandMerzL1'1ntroducedtheconceptofphasetransfercatalysisinWittigreaction,thisreac-tlonwasmod1fiedandcanbeperformed1naverys1mpleway.Recently,bls-W1ttlgreac-tlonhasbecomeasyntheticmethodforacyclicandcycllcpolyenes[:jespec1allyforthesynthesisofnaturalproductsL'1.However,llttleattentionwaspaidtoPTC-bis-Wittigreactlon.AsapartofourongolngstudiesofWittigreact…     

Indirect Spectrophotometric Determination of Sulphide with the Complex of Cd(Ⅱ)-5-Br-PADAP-CPB

ampornoNTh6SpetemofCd-&Br-PADAPis~SenSitbo(s=l.4Xlotl.mol-l.CIn-'),ltwaSuSUaIly~todet6rInintal-[1],butitedotodboboeofitsWatertheOlUbuny,italSocanbeodtodetermineodboinwater8oforbobytheuseOfnthe8ufor[2J.Intthework,catiOnisuthetantwasedinCd-5Br-PADAPsy8tem,itssensitivityndthenduzn~tionwavelengthhaofthecomplexcanbeincred2O%and2onInreSpeivelybycom-P8tisonwithliteratureL2J.TheapplicaiOnOfdsterwicomplexspstemtosperOPhOtomethedeterminaiOnofsulPhidefromitseboOfdecreaseinabeorPtboonth…