Method of photometric determination of iron (iii) in solutions of pure salts

FIELD: chemistry.

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.

1 ex

 

The invention relates to the field of analytical chemistry, namely, the photometric method of analysis, and can be used for the determination of iron (III) in solutions of pure salts containing iron (III) in low concentration.

Known methods photometric determination of iron (III) using aluminon (εMR=10000) in binary systems (Babko, A., Pilipenko A.T. Photometric analysis. General information and equipment. - M.: Chemistry, 1968. - S) using kylinalove orange (εMR=26600) (Bulatov M.I., Kalinkin I.P. Practical guide photocolorimetric and spectrophotometric methods of analysis. - M.: Chemistry, 1972. - S).

The closest to the technical nature of the claimed invention is a method for the photometric determination of iron (III) in solutions of pure salts, including the transfer of iron (III) complex compounds with gliciltirosin blue and surface-active agent in acid medium followed by heating on a water bath, to a solution of iron (III) with a pH of 5.0 to 6.5 add 700-800 times the number gazillionaire blue, 0.2 ml of a solution of surface-active substances obtained by adding 0.2 g tridecylalcohol alcohol and 100 ml of water, and water to 10 ml volume (εMR=600000) (EN 2420733, IPC G01N 31/22, publ. 10.06.2011).

A disadvantage of known methods is N. the high sensitivity.

The technical result is to increase the sensitivity in the photometric determination of iron (III).

The invention consists in that in the method photometric determination of iron (III) in solutions of pure salts, including transforming it into a complex compound with an organic reagent and the surface-active agent in acid medium, by heating on a water bath and the subsequent photometry obtained solution, a solution of iron (III) with a pH of 3.9-5.2 to add a 50-fold amount of organic reagent, which is used selenology orange, 1.8 to 2.2 ml of a solution of surfactant in the form of a 2%aqueous solution ETHAL LA-7, and water to 10 ml volume followed by heating on a water bath at a temperature of 60-80°C for 15 min and added to the resulting solution, 1 ml of acetone.

Surface-active substance (surfactant) containing 2%solution ETHAL LA-7 [ETOH CHEMICALS, LLC PO BOX 5094 GREENVILLE, SC 29606; SURFACTANT: ETHAL LA-7; PHYSICAL FROM @ 25°C: LIQUID; 12,2; TYPiCAL CLOUD PT. °C (1% SOLLUTiON): 49; DRAVES WETTING, SEONDS (0,1% @ 25°C): _; COMMENTS: POE (7) LAAUPYL ALCOHOL-EXCELLENT DETERGENT ANDOIL DISPERSANT FOR METALS, TEXTILES AND COMMERCIAL CLEANERS]. ETHAL LA-7 store-bought chemicals in France, packaging etiketirovki.

Selenology orange - organic reagent used in chelatometric titration. Painting before the titration is red, then yellow. Temperature the tour melting point 222°C; soluble in water, insoluble in ethanol, diethyl ether, acetone. Get aminomethylpropanol crisologo red action CH2O and iminodiacetic acid in CH3COOH.

Example. Determination of Fe (III) with selenology orange in the presence of surfactants. In test tubes placed in 5 ml of 10-4M solution of iron (III), 5 ml of buffer solution with a pH equal to 4.1, 2 ml of 2%aqueous surfactant solution, 1 ml of 10-3M solution kylinalove orange, bring the volume of solution to 10 ml of water, heated on a water bath for 15 minutes at a temperature of 60-80°C. the resulting colloidal solution of complex and organic reagent in the form of small grains of red floated to the surface of the solution. After adding 1 ml of acetone and stirring obtain a homogeneous system whose stability is maintained for at least one hour. Photometrate on ck-2 with wavelength λ=540 nm and the thickness of the cell is l=0.1 cm, relative to the blank solution experience. The linearity of the calibration curve is observed in the concentration range of iron (III) (0.5 to 3)·10-6M is the Molar absorption coefficient equal to:

εMR=0,400(0,210-4/11)0,1=2200000 .

The advantages of the proposed method for the photometric determination of iron (III) with selenology orange in the presence of surfactants the following:

1) dramatically increases the sensitivity of the determination of iron (III) in comparison with the known methods;

2) the reaction of formation of complex compounds is in the aquatic environment;

3) formed complex sustainable;

4) good reproducibility of the analysis.

The way photometric determination of iron (III) in solutions of pure salts, including transforming it into a complex compound with an organic reagent and the surface-active agent in acid medium by heating on a water bath and the subsequent photometry obtained solution, wherein the solution of iron (III) with a pH of 3.9-5.2 to add a 50-fold amount of organic reagent, which is used selenology orange, 1.8 to 2.2 ml of a solution of surfactant in the form of a 2%aqueous solution ETHAL LA-7, and water to 10 ml volume followed by heating at a water bath at a temperature of 60-80°C for 15 min and added to the resulting solution, 1 ml of acetone.



 

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