Method of extraction and detection of iron (iii) in water solutions
SUBSTANCE: in order to extract iron (III) from water solutions diphenylguanidine (DPG) is applied as the first organic reagent. As the second organic reagent, salicylic acid (SA) is applied, and as solvent of organic phase chloroform is applied. In organic phase complex with molar component ratio DPG: Fe3+:SA, equal 1:1:1, is extracted. Process of iron (III) extraction is carried out at medium acidity pH=1.5-2.5 with the following detection of iron (III) by trimetric method.
EFFECT: invention makes it possible to increase selectivity and simplify process of extraction and detection of iron from water solutions.
2 cl, 5 dwg, 1 ex
The invention relates to the field of analytical chemistry, in particular to methods of separation and determination of iron(III) in aqueous solutions, salts of metals.
The known method acttraction-photometric determination of iron, based on the formation of complex compounds of iron with a reagent extraction in the organic phase and the measurement of the optical density of the extract, and as a complexing reagent is used as trichloracetic sodium in a weakly acidic environment (pH of 2.8-3.2 m), and the extraction is carried out with methylethylketone (and.with. The USSR №971802; C01G 49/00, G01N 21/77, B01D 11/04; publ. 07.11.82, bull. No. 41).
The disadvantage of this method is the low selectivity and sensitivity for determination of iron due to use as extractants of higher alcohols and tributyl phosphate. The use of methylethylketone narrows the optimal range of pH values. Also the disadvantage of this method is the poor solubility of methylethylketone in the water.
The known method of extraction-photometric determination of iron, based on the formation of triple colored complex compounds of iron - on-phenanthrolin - organic reagent, the organic reagent is used undiluted pelargonium acid, which is both a reagent and extractant (and.with. The USSR №880989; C01G 49/00, G01N 21/27, B01D 11/04; publ. 15.11.8, Bul. No. 42).
The disadvantage of this method is the use as an organic reagent pelargonii acid, the solubility of which is 0.026 g in 100 g of water. Also pelargonia acid volatile with water vapor, which can lead to significant errors of determination.
The closest in technical essence to the present invention is a method of determining iron in the metals, their oxides, salts and alloys, including masking of interfering elements, the introduction of organic reagents, extraction of the formed complex with chloroform and subsequent spectrophotometrically, characterized in that for the purpose of increase of accuracy of definition and simplify the process as a masking substance use glycine, and organic reagent - 3-nitroglycerin and diphenylguanidine (and.with. The USSR №1125542; G01N 31/22, B01D 11/04, publ. 23.11.84, bull. No. 43).
However, the known method is the prototype has a low selectivity of reactions and time-consuming, since it is necessary to vary the conditions of the definition and the use of masking agents to eliminate this deficiency.
The task of the invention is to increase the selectivity and to simplify the process of determining microsoldering iron(III) in aqueous solutions.
The problem is solved with the features specified in the 1st paragraph of the formula Fig�t, in common with the prototype, such as a method of separation and determination of iron(III) from aqueous solutions using as the organic reagent of diphenylguanidine, and distinctive essential features, such as the second organic reagent is salicylic acid, and as a diluent of the organic phase chloroform with medium acidity pH=1.5 to 2.5 with subsequent determination of iron(III) titrimetric method.
According to paragraph 2 of the claims in an organic microphase extracted complex with molar ratio of components FGD:Fe3+:IC equal to 1:1:1.
This object is achieved in that the optimal conditions for the formation of microphase in the system diphenylguanidine - salicylic acid - HCl - water, and extraction in complex compounds of iron(III).
The above set of essential features allows to obtain the following technical result - increasing selectivity and simplifying the process of determining microsoldering iron(III) in aqueous solutions.
The proposed method is illustrated by the following graphs.
Fig.1. The distribution of iron ions(III) in the FGD system-SC-HCl-H2O depending on the acidity of the water environment (CFGD=CSC=0,2 mol/l, CFe=0.01 mol/l, Vtotal=20 ml)
Fig.2. The distribution of iron ions(III) in the FGD system-SC-HCl-H O depending on the concentration of salicylic acid (CHCl=0.05 mol/l, WithFGD=0,2 mol/l, CFe=0.01 mol/l, Vtotal=20 ml)
Fig.3. The distribution of iron ions(III) in the FGD system-SC-HCl-H2O depending on the concentration of the FGD (CCHl=0.05 mol/l, CCK=0,2 mol/l, CFe=0.1 mol/l, Vtotal=20 ml)
Fig.4. The dependence of the ratio of FGD:extractable Fe in the complex from the composition of a motorized solution
(∑C(FGD+Fe)=0.1 mol/l, CCK=0,2 mol/l, CHCl=0.05 mol/l, Vtotal=20 ml)
Fig.5. The dependence of the ratio SC:extractable Fe in the complex from the composition of a motorized solution
(∑C(SK+Fe)=0.1 mol/l, WithFGD=0.1 mol/l, CHCl=0.05 mol/l, Vtotal=20 ml)
Organic microphase is formed in the temperature range of 50-95°C. With increasing temperature the process of formation of two-phase equilibrium is accelerated. Upon cooling after extraction of the organic phase, which is the extractant, freezes, however, there is a high degree of extraction of ions in iron(III).
The formation and extraction of the extracted complex of Fe is in a narrow range of concentrations of HCl (0,025-0,1 mol/l). Maximum extraction of iron is observed in the range of 0.05-0.15 mol/l HCl [Fig.1].
The dependence of extraction of iron from the concentration of salicylic acid (SA) for CHCl=0,05 mol/�. The graph of the curve EFe, % - CSCit is seen that the maximum value of the degree of extraction of iron is 95% and observed at CSC=0.1 to 0.15 mol/l [Fig.2].
At optimal concentrations of IC and HCl investigated the effect of the concentration of diphenylguanidine (FGD) on the degree of extraction of iron ions. Maximum extraction of iron is observed when CFGD=0.1 mol/l and CHCl=0,05 mol/l and 91% [Fig.3].
Thus, the optimal conditions for the extraction of iron salicylic acid in the presence of diphenylguanidine should be considered: CHCl=0,025-0,15 mol/l, WithFGD=0,1-0,25 mol/l, WithSC=0.1 to 0.2 mol/l (in the total volume of the extraction system 20 ml).
The sensitivity of detection of 0.25 mg/ml For the determination of iron in the organic phase formed by the UK and FGD, organic microphase was diluted with 3-5 ml of chloroform. Next, a chloroform solution was poured into a titration flask. The iron content was determined by direct complexometric titration in an acidic environment. At optimal concentrations of IC and HCl was determined by the ratio of FGD:Fe, which was equal to 1:1. Thus, one atom of iron in the complex compound has one molecule FGD [Fig.4].
The ratio Fe:the UK also was evaluated using a motorized series. As can be seen, the ratio Fe:the UK is 1:1. Thus, with�Tav extractable complex iron compound includes one molecule of salicylic acid to one iron ion [Fig.5].
Thus, in the organic microphase extracted complex with a molar ratio of FGD:Fe3+:IC equal to 1:1:1. Most likely, in the extraction process produces iron salicylate [FeSal·FGD]X2where X - is an inorganic anion (in the acidic environment of the iron ion is coordinated by one molecule of the UK), which Salvatores one molecule of FGD.
The obtained data on the composition otvlekaeshsja complex compounds of iron allow us to offer the following equations its extraction into microphase and process of education itself microphase:
Example. For the determination of iron(III) in the stratified system FGD-SC-HCl-water did the following. Sample SK, weighing 0.55 g and DPG, weight 0.85 g was placed in a vial of 20 ml, created an HCl concentration of 0.05 mol/l, was added ferric chloride(III) (1·10-4-2·10-2mol/l) and adjusted with water to a volume of 20 ml. Vial was placed in a water bath and heated for 20-30 min. Then the whole system was cooled to room temperature. The aqueous phase was poured into a titration flask and titrated with EDTA until a yellow color. The resulting organic phase was diluted with 3-5 ml of chloroform, and then transferred to a titration flask and titrated with EDTA.
Thus, the proposed method of allocation and ODA�fission of iron(III) in aqueous solutions by diphenylguanidine, it has high sensitivity, it has a good reproducibility and selectivity.
1. A method of separation and determination of iron (III) from aqueous solutions using as the organic reagent of diphenylguanidine, characterized in that as the second organic reagent is salicylic acid, and as a diluent of the organic phase is chloroform with medium acidity pH=1.5 to 2.5 with subsequent determination of iron (III) titrimetric method.
2. A method according to claim 1, characterized in that the organic microphase extracted complex with molar ratio of components FGD:Fe3+:IC equal to 1:1:1.
SUBSTANCE: invention relates to field of analytical chemistry, namely to express-detection of explosive substances (ES) based on organic peroxides. Method is based on fixation of hydroxen peroxide, released in the process of explosive substance decomposition by indicator method. For this purpose change of indicator colour is fixed within 1 minute after contact with solid-phase material, possessing function of surface acidity and providing decomposition of ES to hydrogen oxide. Application of claimed method simplifies analysis of cyclic peroxides due to reduction of the number of analysis stages, as well as to elimination of liquid reagents, including concentrated acids and organic solvents.
EFFECT: invention provides carrying out express-analysis of trace quantities of peroxide ES outside laboratory in wide range of climatic conditions.
6 cl, 2 tbl, 7 ex
SUBSTANCE: invention describes an indicator composition for the detection of disinfectants with an active substance based on quaternary ammonium compounds on surfaces of subjects and detection of disinfection completeness by aerosol spraying, which contains a 0.5-1.5% solution of trinitrotoluene in monoatomic alcohol, with propyl alcohol being applied as the monoatomic alcohol.
EFFECT: convenience and safety of application, increased term of working capacity and interval of application temperatures, protection of the environment, possibility of application at work on vertical, inclined and horizontal surfaces.
SUBSTANCE: indicator testing means for determining content of N-methylaniline in hydrocarbon fuels is neutral aluminium oxide with potassium ferricyanide immobilised on the surface thereof, moulded in form of pellets. The method of determining content of N-methylaniline in hydrocarbon fuels using said indicator testing means is carried out based on colour change thereof after coming into contact with a sample of the analysed sample.
EFFECT: reliability of determining lower concentrations of N-methylaniline in hydrocarbon fuels.
2 cl, 1 tbl, 2 ex
FIELD: measurement equipment.
SUBSTANCE: invention relates to nondestructive examination, to study of metal properties and is intended for confirmation of exhaustion of protective properties of heat-resistant diffusive coatings on details made of carboniferous heat-resistant alloys. The method of confirmation of exhaustion of protective properties of heat-resistant diffusive coatings on details made of carboniferous heat-resistant alloys by change of physical and chemical properties of the surface layer of heat-resistant diffusive coatings during operation in conditions of high temperature, comprises application of reagent on the coating surface, and the fact of exhaustion of protective properties of the heat-resistant diffusive covering is witnessed visually by change of colour of the surface of heat-resistant diffusive coating with formation of carbon and black oxides during the process of chemical reaction between carbide phases, forming in the surface layer of the heat-resistant diffusive coating at the late stages of operation, and reagent.
EFFECT: simplicity, reliability and reliability of tests is achieved.
1 ex, 5 tbl, 10 dwg
SUBSTANCE: invention refers to medicine and describes using resorufin and/or toluidine blue used as an organic oxidation-reduction colouring agent, one or more polyols, glycerol, and water introduced into gelatine and/or hydroxyethylstarch, and/or methlcellulose used as additives, as an oxygen indicator. The indicator is configured so that an oxygen-sensitive product stays visible.
EFFECT: declared invention provides the light- and heat-sensitive visibly discolouring oxygen indicator.
19 cl, 6 tbl, 10 ex
FIELD: measurement equipment.
SUBSTANCE: invention relates to ecology, namely to sanitary-chemical control of the state of environment and can be used for solution of tasks for detection and measurement of harmful substance concentrations in the air. A device for detection of harmful substances in the air includes an air flow booster and the primary chemical transducer; with that, the air flow booster includes the following: a control unit providing setting of parameters of bleed air, operation and control of the device; an air path for transportation of an air flow; an air pump connected to the control unit for pumping of air through the air path; a self-contained power source, and the primary chemical transducer is connected to the air path. With that, the device includes flow and temperature sensors of the pumped air, which are arranged in the air path, as well as sensors of atmospheric pressure and relative humidity of the pumped air, which are arranged outside the air path, and the control unit includes an information display device; at least one control button and an electronic circuit providing the following: recording of data from sensors; determination of air density; control of volumetric flow of the pumped air; adjustment of air sampling time, and analogue-to-digital conversion of the obtained and transmitted data.
EFFECT: improving accuracy of taken air volumes; increasing quick action of operation of the device; control and fixation of parameters of the taken air (volumetric air flow rate, atmospheric pressure, temperature and humidity); increasing ease of use; improving accuracy of readout of information from the primary chemical transducer; providing technical control and fixation of colorimetric changes of the primary chemical transducer; reducing overall dimensions and the weight of the device; enlarging functional capabilities.
24 cl, 1 dwg
SUBSTANCE: invention relates to analytical chemistry, namely to photometric determination of small concentrations of iron (III) in solutions of pure salts. The method includes conversion of iron (III) in a complex compound with an organic reagent and a surface-active substance in a mildly acidic medium by heating the above on water bath with following photometry of the obtained solution, and to a solution of iron (III) with pH 3.9-.5.2 added is 50-fold quantity of an organic reagent, represented by xylenol orange, 1.8-2.2 ml of a surface-active substance in the form of a 2% solution of ETHAL LA-7, and water to 10 ml of the volume with the following heating on water bath at a temperature of 60-80°C for 15 min and addition of 1 ml of acetone into the obtained solution.
EFFECT: invention makes it possible to increase the analysis sensitivity.
SUBSTANCE: invention relates to the field of gases identification and refers to a spectral analysis system for gases identification using a treated tape. The system includes a treated tape, an adjustable colour source, a photodiode, a colour identification sensor and a microprocessor. The adjustable colour source emits radiation in the direction of the treated tape with multiple varied wavelengths. The photodiode measures the radiation reflected from the treated tape. The microprocessor analyses the measurement results and, proceeding from the colour identified and the colour spot intensity, identifies the type and concentration of the gas the treated tape has been exposed to. Additionally, the microprocessor, with the help of the colour identification sensor, controls the radiation wavelength of the adjustable colour source and, whenever required, corrects the colour source radiation.
EFFECT: technical effect consists in increased sensitivity and ensuring the possibility of different type gases detection.
13 cl, 2 dwg
FIELD: oil and gas industry.
SUBSTANCE: at first sample of tested oil product with fixed volume is passed through water-coagulating agent placed between turns of a flat spiral mounted in a cavity of the element having shape of a truncated cone. When the sample is passed along the spiral the time for coagulation of free water microdrops in the sample is extended. Then the sample of the tested oil product is passed through a filter membrane with a deposited layer of water-sensitive chemical agent. At that by means of the hollow element having shape of a truncated cone this sample is localised at the surface of this water-sensitive chemical agent and water availability or concentration is evaluated by its colour changing. Additionally water concentration in the sample of the tested oil product is evaluated against decrease of the sample fixed volume before the water-sensitive chemical agent changes its colour.
EFFECT: improved accuracy of the analysis.
SUBSTANCE: invention relates to field of analytical chemistry, namely to photocolorimetric method of analysis, and can be used for determination of iron (II) content in extract of spruce needles, containing iron (II) in very low concentration. Method includes its transfer into complex compound with organic reagent, with addition of 150-200-fold amount of organic reagent to solution of iron (II) with pH 3, as reagent used is Congo red, 0.2-0.4 ml solution of surface-active substance in form of 0.2% solution of 6-aminocapronic acid, and water to 10 ml with further heating on water bath at temperature 80-98°C for 10-15 min.
EFFECT: increased analysis sensitivity.
SUBSTANCE: method of determining concentration of grafted amino groups on the surface of mineral filling agents includes preparation of acetylating solution by mixing initial components, its addition to weighed portion of modified mineral filler sample, exposure for quantitative realisation of reaction, titration with alkali solution in presence of indicator, calculation of concentration of amino groups by difference of results of idle titration and sample titration. As acetylating solution used is 0.5-0.6 M solution of acetic anhydride in mixed solvent dichloroethane-pyridine in ratio from 0.5:1-2:1, which contains 0.025-0.15 mol/l of chloric acid as catalyst. 0.5-0.6 M of acetylating solution in mixed solvent, containing chloric acid, is added to weighed portion of modified mineral filler, ratio of weighed portion of sample weight to volume of acetylating solution constitutes 1:4-1:5, after which it is exposed and hydrolysing mixture, consisting of dimethylformamide, pyridine, water, taken in ratio 6:3:1 respectively, is added. After that, obtained mixture is centrifuged to separate residue.
EFFECT: simplification and extension of assortment of analysed materials, containing grafted amino groups on the surface of mineral fillers.
13 ex, 1 tbl
SUBSTANCE: method involves potentiometric titration of a sample with complexon (III) with an indicator electrode made of bismuth metal with a buffer solution at pH 4.1-9.0.
EFFECT: easier, more accurate and safer analysis.
2 tbl, 1 dwg
SUBSTANCE: method of determining copper involves direct potentiometric titration of complexon (III) at pH 4.1-9.0 with an indicator electrode of bismuth metal in an acetate buffer solution. The invention enables to determine copper (II) when its content is 32-660 mcg/ml of the solution in an electrochemical cell with unit determination error of not more than 1%.
EFFECT: easy analysis using nontoxic materials.
2 tbl, 1 dwg, 1 ex
SUBSTANCE: method of determining lead involves potentiometric titration of a complexon (III) sample with an indicator electrode of bismuth metal with a buffer solution at pH 3.5-9.0. The invention enables to determine lead (III) with content of 0.14-2.3 mg/ml of a solution in an electrochemical cell with unit determination error of not more than 1%.
EFFECT: easy analysis using nontoxic materials.
2 tbl, 1 dwg
SUBSTANCE: invention can be used in chemical industry. Lithium-iron phosphate having an olivine crystal structure has a composition expressed by the chemical formula (I) L1+aFe1-xMx(PO4-b)Xb (where M is selected from Al, Mg, Ti; X is selected from F, S, N; -0.5≤a≤+0.5; 0≤x≤0.5; and 0≤b≤0.1 ), contains 0.1-5 wt % Li3PO4 and does not contain or contains less than 0.25 wt % Li2CO3. Content of Li3PO4 in the lithium-iron phosphate increases electrochemical stability and ensures thermal safety and ion conductivity.
EFFECT: lithium-iron phosphate according to the present invention can be used as an active material for a positive electrode of a secondary lithium battery.
15 cl, 1 tbl, 5 dwg
SUBSTANCE: invention describes a method of determining weight ratio of polyhexamethylene guanidine hydrochloride in a disinfectant, involving titration of a sample of the analysed disinfectant using a prepared indicator solution and then calculating the amount using a formula. Titration is carried out using a silver nitrate solution. The indicator used is fluorescein. The weight ratio of polyhexamethylene guanidine hydrochloride is calculated using a formula.
EFFECT: faster analysis, high reliability owing to more accurate determination of the end of titration and cheaper analysis.
SUBSTANCE: aqueous solution of an analysed sample of a deicing agent containing 1-50 wt % alkali metal formates is mixed with alkaline bromine solution with bromine concentration of 0.1 mol/dm3 in amount of 0.02-0.08 wt % of the weight of the formate; glacial aceit acid is added until pH drops to less 1; the mixture is held at room temperature; further, potassium iodide solution is added and then titrated with a pentahydrate solution of sodium thiosulphate; aqueous starch solution is then added and titrated until the solution becomes clear. Optimum conditions for carrying out the method are as follows: 15-25°C, relative humidity of 45-80% and atmospheric pressure of 630-800 mm Hg.
EFFECT: improved method.
4 cl, 1 tbl, 1 ex
SUBSTANCE: method involves vpotentiometric titration of a sample with complexon (III) with an indicator electrode made of bismuth metal at pH 1.9-4.2.
EFFECT: high accuracy and simple analysis.
2 tbl, 1 dwg
SUBSTANCE: method for calcium and magnesium evaluation in herbal crude drug is implemented by extraction of the crude drug in 8-12% hydrochloric acid in the relation of the crude drug to the extractant 1:9-11 that is followed by complexometric titration with the use of indicators: for total calcium and magnesium - eriochrome black T; for calcium - murexide or chromium dark blue; for magnesium - pyrocatechin violet.
EFFECT: accelerated and simplified analysis.
SUBSTANCE: 5 cm3 distilled water and 3 cm3 concentrated hydrochloric acid are added to the analysed sample weighing 0.1-0.3 g after dissolution thereof in 40 cm3 glacial acetic acid and using an ultrasonic bath; the mixture is heated to 30-35°C and titration is carried out with bromide-bromate solution until a yellow colour is obtained; methyl red indicator solution in ethyl alcohol is added and post-titration is carried out with the process solution until the pink colour of the indicator turns pale-yellow; a blank test is carried out under similar conditions and in both cases the volume of bromide-bromate solution used during titration is recorded; the weight ratio of the basic substance in the standard sample of the composition β,β'-dihydroxy diethyl sulphide is calculated from a given relationship, and the final result is the arithmetic average of the results of two parallel tests, deviation between which must not exceed ±1.0%.
EFFECT: high accuracy and simple analysis.
2 cl, 2 tbl
SUBSTANCE: bionanoconjugate comprises a nano-sized superparamagnetic particle of cobalt ferrite spinel CoxFe3-xO4, where 0.6≤x≤0.98, obtained by mechanochemical synthesis. To isolate the nucleic acid containing oligo- or poly-A/dA sequence the synthetic single stranded oligonucleotide 5'-dGndTm is used, where n=5-30, m=10-35, one portion of which, consisting of guanine nucleotides in the presence of phosphate anions in the solution is specifically associated with the surface of the nanoparticle and the other - consisting of thymine nucleotides is able to enter into hybridisation with oligo- or poly-A/dA nucleotide sequences. For isolation from the solution in the presence of phosphate anions of specific hetero-nucleotide sequence additionally create a molecule of oligonucleotide-adapter containing the sequence of oligo-dAx at the 3'-end, hybridised with thymine nucleotides of a complex 5'-dGndTm, where n=5-30, m=10-35, and a portion at the 5'-end complementary to a specific hetero-nucleotide sequence in the solution.
EFFECT: invention enables to detect effectively and to isolate the single-stranded nucleic acids.
3 cl, 8 dwg, 1 tbl, 5 ex